NL2021994B1

NL2021994B1 - Process for improving skid resistance of rejuvenated asphalt road constructions using brushing

Info

Publication number: NL2021994B1
Application number: NL2021994A
Authority: NL
Inventors: Nicolaas Gielis Jacobus; Bennie Elzinga Foeke; Jan Lommerts Bert; Wilhelmus Jacobus Struik Johannes; Nowrozon Nahar Sayeda; Josephus Maria De Ridder Wilhelmus
Original assignee: Latexfalt Bv
Priority date: 2018-11-14
Filing date: 2018-11-14
Publication date: 2020-05-20
Also published as: NL2021994B9

Abstract

The invention relates to a process for rejuvenating a porous asphalt road construction having pores extending into the asphalt road construction and having an upper surface having a macro surface texture and a micro surface texture, wherein said upper surface is defined as the surface that can be in contact with the tyres of vehicles driving on the porous asphalt road construction, said process comprising the steps of: i) applying a rejuvenating binder in liquid form to the porous asphalt road construction; and ii) removing at least part of the rejuvenating binder from the upper surface of the porous asphalt road construction obtained in step (ii) by treating the porous asphalt road construction with one or more rotating road sweeping brooms.

Description

PROCESS FOR IMPROVING SKID RESISTANCE OF RE JUVENATED ASPHALT ROAD CONSTRUCTIONS USING BRUSHING

FIELD OF THE INVENTION

The invention relates to a process for rejuvenating porous asphalt road constractions. More in particular the invention relates to a process for rejuvenating porous asphalt road constructions and increasing the skid resistance of the porous asphalt road constructions after rejuvenation.

BACKGROUND OF THE INVENTION

Porous or open courses have been used for years as surface courses or upper layers of asphalt road constructions. These layers, whose advantages are known, provide significant benefits both for the road user and for the environment. Rainwater is absorbed in the porous layer, so that rainfall will not result in water splashing up from the road. In addition, because of the porosity, the noise produced by vehicle tyres is absorbed and reduced, resulting in less noise nuisance from the road traffic in the vicinity of the road.

The majority of the road infrastructure of the Netherlands’ main road network consists of asphalt surfacing having a porous wearing course (one-layer or two-layer porous asphalt). A two-layer porous asphalt surface consists of two superposed layers of porous asphalt wherein the lower layer is a coarse-grained layer with large pores allowing sufficient throughput of water across the layer, and wherein on top of said lower layer a relatively thin fine-grained surface course is installed which is for example optimized for reducing traffic noise.

However, with their open structure, roads having an open asphalt top-layer have a greater tendency to wear by for example raveling (loss of aggregate material due to disruption of the bonds between the aggregates) and by oxidation of the bitumen. As a consequence, very open asphalt top-layers must be rejuvenated about every 4 to 12 years. Processes for rejuvenating aged porous asphalt road constructions by applying a rejuvenating liquid binder to the asphalt road construction are well known in the art. In this respect, reference is made to WO2012/169890Al and EP3103921 Al.

In order to drive on a road safely, the wearing course has to be sufficiently skid-resistant. To this end, a certain degree of friction is required in the contact area between the tyres of a vehicle and the wearing course. The extent of friction between tyre and wearing course depends on the environmental conditions. Moreover, contamination by oil or mud can have a negative effect on the coefficient of friction. It is well known that the processes for rejuvenating aged porous asphalt road constructions leave a film layer of rejuvenating binder on the road surface. This film layer of rejuvenating binder adversely affects the coefficient of friction and the skid resistance of the wearing course. If a vehicle brakes with wheels blocked, the film layer of rejuvenating binder will melt as a consequence of the heat generated by the friction. The coefficient of friction will drop sharply, resulting in lower braking deceleration and thus a longer braking distance.

After the rejuvenation process, the road is reopened for traffic. If the film layer of the rejuvenating binder on the wearing course becomes worn by traffic, the skid resistance will improve again. Heavy traffic for a limited period of time or lower traffic during extended periods of time are needed to wear off the remnants of the rejuvenation binder that is present on the top surface of the wearing course, resulting in increased skid resistance, ultimately reaching the skid resistance of the asphalt road construction before rejuvenation.

When putting a rejuvenated wearing course into use, different countries set requirements in terms of skid resistance in order to guarantee safe driving conditions. Moreover, after opening of the wearing course for traffic, the skid resistance is monitored periodically throughout the term of use of the wearing course. In The Netherlands, Rijkswaterstaat sets requirements in terms of a minimum wet skid resistance and dry skid resistance. For safety reasons, in case of reduced skid resistance, it may be necessary to inform road users about a longer braking distance, to temporarily lower the maximum speed on the road after rejuvenation of the wearing course and/or to take additional measures until the skid resistance reaches sufficiently high values to guarantee safe driving conditions.

In the past, different techniques were used for shortening the period required for recovering sufficient skid resistance of the asphalt road construction to guarantee safe driving conditions. One option is to add sand or gravel to the asphalt road construction directly after rejuvenation. Other techniques concern removal of the bituminous skin layer by planishing or planing the asphalt road construction, or by subjecting the asphalt road construction to high pressure waterjets. In this respect, reference is made to J.L.M. Voskuilen and W. Nijssen, 'Proef toont succes van afstrooien zoab+ aan, Land + Water, 4, April 2008, pp 30-31, to J. Voskuilen and F. Geijsendorpher, 'Aanvangsslroeflieid, Asfalt, 3, September 2009, pp 4-7, and to E. Vos, 'Skid resistance on national roads', Rijkswaterstaat, Ministry of Infrastructure and the Environment, 2015, page 35.

Still other techniques concern decreasing the thickness of the layer of the rejuvenating liquid binder, still in its liquid form, by forcing it to penetrate further into the porous asphalt road construction using a concentrated air flow, or by compacting the layer of the rejuvenating liquid binder, still in its liquid form, using a compactor equipped with rubber tyres.

US2005/265784A1 discloses a method for the treatment of an asphalt structure with a composition comprising oxidized asphalt cutback, an active silicone compound providing a solvent-soluble water repellant and a petroleum-based solvent for realizing both internal protection and surface protection of the asphalt structure. To carry out such a treatment, an apparatus is used by which the composition is sprayed onto the asphalt structure, after which a cylindrical brush rotating at high speed forces the composition thus sprayed onto the asphalt into the asphalt structure.

EP3103921 Al discloses a method for the treatment of an asphalt structure with a liquid binder agent, wherein, in subsequent steps, liquid binder agent is sprayed onto the asphalt structure and a concentrated air flow is directed at the liquid binder agent on the asphalt structure to force the liquid binder agent to penetrate the asphalt structure. It is described in EP3103921A1 that tyre rollers comprising rubber tyres can be employed in addition to the air flow for forcing residual binder off the stones at the road, so as to prevent the road surface exhibiting insufficient skid resistance after treatment. Moreover, it is described that granular chipping material can be spread over the road surface after blowing to bind the remnants of the binder to the road surface and also to prevent insufficient skid resistance.

WO2012/169890A1 discloses the application of bituminous emulsions in repairing asphalt road constructions, in particular very open asphalt road constructions. A process for repairing an asphalt road construction is disclosed, wherein (a) a bituminous emulsion is applied to the asphalt road construction, (b) the applied bituminous emulsion is forced to penetrate the asphalt road construction, and (c) sand or gravel is added to the asphalt road construction. Examples of ways to force the applied bituminous emulsion to penetrate the asphalt road construction that are described in WO2012/169890A1 are the use of a wet rubber tyred roller, a compactor equipped with rubber tyres on which water is applied, a truck equipped with a rubber flap, or a sweeping or brushing device provided with steel or polymer brushes.

With the techniques disclosed in the prior art, the time needed after rejuvenation of the porous asphalt road construction to reach sufficient skid resistance in order to guarantee safe driving conditions is relatively long. Accordingly, it is an object of the invention to provide a process for rejuvenating of porous asphalt road constructions wherein the return of skid resistance after rejuvenating of the asphalt road construction is accelerated. Moreover, it is an object of the invention to provide a process for rejuvenating of porous asphalt road constructions wherein the skid resistance after rejuvenation of the porous asphalt road construction is increased.

SUMMARY OF THE INVENTION

The present inventors have found that the above objects can be met by brushing the porous asphalt road construction after the actual rejuvenation process, i.e. after applying a rejuvenating binder in liquid form, with a road sweeping broom having a specific design and having filaments with specific properties.

It was found that, with these road sweeping brooms, the residual film thickness of rejuvenating binder can be effectively reduced without adversely affecting the macro surface texture and most of the micro surface texture of the porous asphalt road construction, with a corresponding increase in skid resistance.

Hence, in a first aspect the invention provides a process for rejuvenating a porous asphalt road construction, said porous asphalt road construction having pores extending into the asphalt road construction and having an upper surface having a macro surface texture and a micro surface texture, wherein said upper surface is defined as the surface that can be in contact with the tyres of vehicles driving on the porous asphalt road construction, said process comprising the steps of:

i) applying a rejuvenating binder in liquid form to the porous asphalt road construction; and ii) removing at least part of the rejuvenating binder from the upper surface of the porous asphalt road construction obtained in step (i) by treating the porous asphalt road construction with one or more rotating road sweeping brooms, wherein a road sweeping broom comprises:

a disc (1) having an upper surface (la) and a lower surface (lb);

a driving shaft (2) for rotating the road sweeping broom, wherein the driving shaft (2) is secured to the disc (1) at the center of the upper surface (la) and wherein the driving shaft (2) points in a direction perpendicular to the upper surface (la); and n bundles of filaments that are secured at their first ends (3a) to the lower surface (lb) of the disc (1), wherein the bundles of filaments have an angle (9>0° with the driving shaft (2) such that their second ends (3b) point radially outwardly;

wherein n is an integer being 2 or larger, wherein the filaments have a total length of between 10 and 50 cm, preferably between 15 and 25 cm, and a cross-section of between 0.5 and 15 mm², preferably between 0.7 and 5 mm², wherein the filaments in a single bundle are bound together over a length (4) extending from the first end (3a) of between 5 and 15 cm, provided that at least 0.5 cm of the total length of the filaments is not bound together, such that the filaments in a single bundle cannot move substantially independently over the length (4).

The inventors have further established that by applying an aqueous solution comprising one or more first surfactants, wherein the concentration of the one or more first surfactants in the aqueous solution is between 0.005 and 1 wt% based on the weight of the aqueous solution, said aqueous solution having a surface tension of lower than 45 mN/m at a temperature of 20°C, to the porous asphalt road construction before performing the actual rejuvenation process, i.e. before applying a rejuvenating binder in liquid form, the residual film thickness can be effectively further reduced.

Without wishing to be bound by theory, it is hypothesized that the aqueous solution comprising the one or more first surfactants reduces the film thickness of the rejuvenating liquid binder on the (peaks of the) upper surface of the porous asphalt road construction, and further that the aqueous solution comprising the one or more first surfactants positively influences the transport of rejuvenating liquid binder from the peaks of the upper surface of the porous asphalt road construction into the inner pores by compaction and/or by using a concentrated air flow. Moreover, again without wishing to be bound by theory, it is hypothesized that the aqueous solution comprising the one or more first surfactants reduces the tendency of the rejuvenating binder in the form of a bituminous binder emulsion to destabilize on (top of the peaks of) the upper surface of the porous asphalt road construction, and that a stable bituminous binder emulsion can be forced more easily from the peaks of the upper surface of the porous asphalt road construction to the inner pores by compaction and/or by using a concentrated air flow.

Consequently, the process as defined hereinbefore preferably comprises the steps of

a) applying an aqueous solution comprising one or more first surfactants, wherein the concentration of the one or more first surfactants in the aqueous solution is between 0.005 and 1 wt% based on the weight of the aqueous solution, said aqueous solution having a surface tension of lower than 45 mN/m at a temperature of 20°C, to the porous asphalt road construction;

b) step (i) of applying the rejuvenating binder in liquid form to the porous asphalt road construction obtained in step (a);

c) forcing the rejuvenating binder to penetrate the pores of the porous asphalt road construction obtained in step (b) using a compactor, preferably equipped with rubber tyres; and

d) step (ii) of removing at least part of the rejuvenating binder from the upper surface of the porous asphalt road construction obtained in step (c).

BRIEF DESCRIPTION OF THE FIGURES

Figure 1 depicts the dry braking deceleration of part of the wearing course of the Al2 motorway near Veenendaal in The Netherlands before and after rejuvenation of the two-layer porous asphalt (ZOAB).

Figure 2 depicts the wet skid resistance of part of the wearing course of the A12 motorway near Veenendaal in The Netherlands before and after rejuvenation of the two-layer porous asphalt (ZOAB).

Figure 3 depicts the wet skid resistance of part of the wearing course of the N31 between Harlingen and Zurich in The Netherlands before and after rejuvenation of the porous asphalt (ZOAB).

Figure 4 depicts the dry braking deceleration of part of the wearing course of the Al2 motorway between Lunetten and Veenendaal in The Netherlands before and after rejuvenation of the two-layer porous asphalt (ZOAB).

Figure 5 depicts the wet skid resistance of part of the wearing course of the A12 motorway between Lunetten and Veenendaal in The Netherlands before and after rejuvenation of the twolayer porous asphalt (ZOAB).

Figure 6 shows a first embodiment of the road sweeping broom for use in the process according to the invention. The road sweeping broom has a circular disc (1) with an upper surface (la) and a lower surface (lb). A driving shaft (2) for rotating the road sweeping broom is secured to the circular disc (1) at the center of the upper surface (la). This driving shaft (2) points in a direction perpendicular to the upper surface (la). The bundles of filaments are secured at their first ends (3a) to the lower surface (lb) of the circular disc (1). These bundles are evenly distributed along the perimeter (Ic) of the circular disc (1). The angle between the bundles of filaments and the driving shaft (2) is indicated with Θ. The second ends (3b) of the bundles of filaments point radially outwardly such that the circular disc (1) with the bundles of filaments together have the form of a truncated or frustrated cone, the disc (1) being the top of the truncated or frustrated cone.

Figure 7 shows a second embodiment of the road sweeping broom for use in the process according to the invention. In the second embodiment, the bundles of filaments are evenly distributed along the perimeter (1c) of the circular disc (1) and along a second circle (5) radially inward of the perimeter (Tc).

Figure 8 shows a third embodiment of the road sweeping broom for use in the process according to the invention. In this third embodiment, different fractions of the filaments in a single bundle are helically wound to helically wound sub-bundles and the helically wound subbundles are in turn also helically wound, resulting in double helical bundles of filaments.

DEFINITIONS

The term skid resistance as used herein refers to the friction between tyres of vehicles and the road and is defined as the coefficient of friction measured under standardized conditions.

The term ‘’initial skid resistance as used herein refers to the skid resistance of the porous asphalt road construction directly after the rejuvenation process of the porous asphalt road construction and before opening the road construction for traffic.

In the context of the present invention, ‘(initial) skid resistance is expressed in terms of ‘wet skid resistance and/or ‘dry skid resistance. The term ‘wet skid resistance as used herein encompasses the skid resistance of a wet road and is measured in accordance with E. Vos, ‘Meet- en rekenprotocol Actuele Stroefheidscore AS’, RWS/GPO, version 1.0, 8 July 2013, resulting in a dimensionless coefficient of friction. The term ‘dry skid resistance as used herein concerns the skid resistance of a dry road and is expressed in the dry braking deceleration (expressed in m/s²). Hence it is not expressed in terms of the coefficient of friction as is the case with wet skid resistance. This does not particularly matter because the dimensionless coefficient of friction and the dry braking deceleration are numerically correlated (see E. Vos, ‘Skid resistance on national roads, Rijkswaterstaat, Ministry of Infrastructure and the Environment, 2015, page 21 and 48). Braking deceleration of a dry road surface is determined under standardized conditions in accordance with P. Kuiper, ‘Meet- en rekenprotocol Droge remvertraging (middels meting onder verkeer), RWS/GPO, version 1.0, 18 July 2014.

The term ‘surfactant as used herein refers to surface acting agents that are able to reduce the surface tension of aqueous solutions to values lower than 45 mN/m at a temperature of 20°C. The surface tension as used herein is measured using the Wilhehny plate method. Many surfactants have in certain aqueous solutions or mixtures also emulsifying properties in which case they can also be called emulsifiers.

The term ‘surface texture of a road construction as used herein refers to the roughness of the surface of a porous asphalt road construction. Surface texture influences the friction between the tyres of vehicles and the road construction. Sufficient surface texture is therefore needed to maintain sufficient skid resistance. Both macro surface texture and micro surface texture contribute to friction and skid resistance.

The term ‘macro surface texture as used herein refers to the roughness of the surface on a macro scale, such as roughness caused by stones or aggregates protruding from the surface of the asphalt. Sufficient macro surface texture is important for having sufficient skid resistance at higher driving speed of a vehicle.

The term ‘'micro surface texture as used herein refers to the roughness of the surface on a micro scale, such as roughness on the surfaces of the stones or aggregates themselves.

DETAILED DESCRIPTION

In a first aspect of the invention, a process for rejuvenating a porous asphalt road construction is provided, said porous asphalt road construction having pores extending into the asphalt road construction and having an upper surface having a macro surface texture and a micro surface texture, wherein said upper surface is defined as the surface that can be in contact with the tyres of vehicles driving on the porous asphalt road construction, said process comprising the steps of:

a disc (1) having an upper surface (la) and a lower surface (lb);

a driving shaft (2) for rotating the road sweeping broom, wherein the driving shaft (2) is secured to the disc (1) at the center of the upper surface (la) and wherein the driving shaft (2) points in a direction perpendicular to the upper surface (la); and n bundles of filaments that are secured at their first ends (3a) to the lower surface (lb) of the disc (1), wherein the bundles of filaments have an angle θ>0° with the driving shaft (2) such that their second ends (3b) point radially outwardly;

The inventors have established that a film layer of the rejuvenating liquid binder - or rejuvenating solidified binder after some time - of a certain thickness remains on the upper surface of the porous asphalt road construction after step (i), and that this film thickness can be effectively reduced without adversely affecting the macro surface texture and most of the micro surface texture of the porous asphalt road construction using one or more road sweeping brooms as defined hereinbefore and hereinafter in step (ii). This reduced film thickness of the rejuvenating liquid binder - or rejuvenating solidified binder after some time - on the (peaks of the) upper surface of the porous asphalt road construction as compared to a process wherein step (ii) is not applied results in an improved dry and wet skid resistance after rejuvenation and in an acceleration of the return of the dry and wet skid resistance to their initial values before rejuvenation.

In a very preferred embodiment, steps (i) and (ii) are performed under dry weather conditions.

In a preferred embodiment, the porous asphalt road construction has a mean profile depth (MPD), as determined using ISO 13473-2:2002(EN), of between 0.4 and 1.9 mm.

In another preferred embodiment, the porous asphalt road construction comprises very porous asphalt concrete (ZOAB), 2-layer very porous asphalt concrete (2-layer ZOAB), stone mastic asphalt (SMA), compacted asphalt concrete (DAB), thin low-noise asphalt top-layer (DGD), road constructions with a surface dressing of a binder and chippings, or combinations thereof. Non-limiting examples of the porous asphalt road constructions comprise AC (8) Surf DAB, AC (11) Surf DAB, AC (16) Surf DAB, SMA(l l), SMA (8), SMA (5), ZOAB (16), 2layer ZOAB fine, 2-layer ZOAB course and DGD (5), wherein the value between parentheses is the largest particle size of the stones applied in the porous asphalt road construction. More preferably, the porous asphalt road construction comprises very porous asphalt concrete (ZOAB) or 2-layer very porous asphalt concrete (2-layer ZOAB).

In a preferred embodiment, in a very first step, before step (i), the porous asphalt road construction is cleaned.

As will be appreciated by the person skilled in the art, only the upper part of the porous asphalt road construction is cleaned, or, in other words, the porous upper part of the asphalt road construction that is accessible for cleaning purposes. Cleaning preferably takes place no longer than 2 weeks before steps (i) as defined hereinbefore. Moreover, cleaning is preferably performed after a period of humid weather conditions, since humid weather conditions improve the loosening and removal of dirt from within the porous structure of the upper part of the porous asphalt road construction. In a preferred embodiment, cleaning involves subjecting the upper part of the porous asphalt road construction to high-pressure water jets (typically 70 to 100 bar) and subsequently removing water, dirt and loose particles, such as for example sand, rubber particles and surface runoff, from the upper layer of the porous asphalt road construction by suction. As a result, the pores of the upper layer of the porous asphalt road construction are thoroughly cleaned, while the water is also removed from the surface. In this respect, reference is made to E. Vos, Skid resistance on national roads, RWS/GPO, Ministry of Infrastructure and the Environment, 2015, page 35.

In an embodiment, the rejuvenating binder in liquid form is applied in step (i) to the porous asphalt road construction in an amount of between 0.05 and 4 kg per square meter of the porous asphalt road construction, preferably in an amount of between 0.2 and 1.2 kg, more preferably in an amount of between 0.6 and 1.0 kg, even more preferably in an amount of between 0.7 and 0.9 kg, such as about 0.8 kg. The rejuvenating binder in liquid form applied in step (i) typically has a temperature of between ambient temperature and 80 °C, preferably a temperature of between 45 and 80 °C.

In a typical embodiment, application of the rejuvenating binder in liquid form in step (i) to the porous asphalt road construction is performed using a vehicle equipped with a spraying device at the back. In a preferred embodiment, the vehicle equipped with the spraying device at the back drives with a speed of between 60 and 90 m/min during step (i).

The rejuvenating binder in liquid form is preferably chosen from the group consisting of waterborne bituminous emulsions, waterborne polyurethane resins, waterborne epoxy resins, waterborne natural or synthetic resins emulsions, waterborne vegetable, animal or mineral oil emulsions, or combinations thereof. In case the viscosity of these rejuvenating binder in liquid form is below 25 times the viscosity of water, the rejuvenator can also be applied in its pure form, i.e. in a non-waterborne state. More preferably, the rejuvenating binder in liquid form is a waterborne bituminous emulsion. Waterborne bituminous emulsions for rejuvenating porous asphalt road constnictions are well known in the art and are for example described in WO2012/169890A1, which is incorporated herein by reference in its entirety.

The time between applying the rejuvenating binder in liquid form to the porous asphalt road construction in step (i) and step (ii) of removing at least part of the rejuvenating binder from the upper surface of the porous asphalt road construction is preferably between 0.5 and 120 minutes, more preferably between 5 and 60 minutes, even more preferably between 6 and 40 minutes.

In another preferred embodiment, the time between applying the rejuvenating binder in liquid form to the porous asphalt road construction in step (i) and step (ii) of removing at least part of the rejuvenating binder from the upper surface of the porous asphalt road construction is sufficiently long for the residual film layer of the rejuvenating binder on the upper surface of the porous asphalt road construction to solidify such that it can be advantageously be removed using brushing.

In a preferred embodiment, the one or more road sweeping brooms in step (ii) are rotated about their driving shafts at between 50 and 250 rpm, preferably between 80 and 150 rpm, more preferably between 90 and 120 rpm, and the contact pressure between the one or more rotating road sweeping brooms and the porous asphalt road constaiction is between 300 and 50000 Pa, more preferably between 5000 and 45000 Pa, even more preferably between 20000 and 40000 Pa, such as 35000 Pa.

Before, during and/or after the brushing of step (ii), water can be applied to cool the one or more road sweepings brooms and/or to remove fouling from the one or more road sweepings brooms.

Preferably, step (ii) is performed with a vehicle comprising a sufficient number of road sweeping brooms to brush a width of between 1 and 3.5 m of the asphalt road construction in a single run. The road sweeping brooms on the vehicle may be positioned in two rows a certain distance apart in the driving direction of the vehicle which may be staggered in the direction perpendicular to the driving direction. Although step (ii) is preferably performed in a single run, the brushing operation may also be performed two or more times.

Preferred embodiments of the one or more road sweeping brooms as applied in step (ii) of the process as defined hereinbefore are as follows.

The disc (1) in the one or more road sweeping brooms applied in step (ii) preferably is a circular disc (1). The diameter of the circular disc (1) preferably is between 30 and 60 cm, more preferably between 40 and 55 cm, such as about 50 cm.

The n bundles of filaments, n being an integer of 2 or larger, in each of the one or more road sweeping brooms applied in step (ii) are preferably evenly distributed along the perimeter (1c) of the circular disc (1), such as one bundle of filaments every 360/« °.

In another preferred embodiment, the n bundles of filaments, n being an integer of 2 or larger, in each of the one or more road sweeping brooms applied in step (ii) are preferably evenly distributed along the perimeter (1c) of the circular disc (1) and along a second circle (5) radially inward of the perimeter (1c).

The total number of bundles of filaments n is preferably between 2 and 100, more preferably between 50 and 90.

The filaments in the one or more road sweeping brooms applied in step (ii) are preferably made of metal.

In a very preferred embodiment, the metal is steel, more preferably spring steel, such as AISI 1095 spring steel. Spring steel has good abrasion resistance and can be deformed to substantial extent without resulting in plastic deformation.

In another very preferred embodiment the filaments have a composition of between 98.38 and 98.8 wt% of iron, between 0.9 and 1.03 wt% of carbon, between 0.3 and 0.5 wt% of manganese, less than 0.050 wt% of sulphur and less than 0.040 wt% of phosphorus.

In yet another very preferred embodiment the filaments have a composition of between 0.7 and 0.8 wt% of carbon, between 0.5 and 0.8 wt% of manganese, less than 0.035 wt% of sulphur and less than 0.0039 wt% of phosphorus, and the rest being iron.

In another very preferred embodiment the filaments have a composition of between 0.1 and 0.3 wt% of silicon, between 0.7 and 1 wt% of carbon, between 0.2 and 0.6 wt% of manganese, and the rest being iron.

In yet another very preferred embodiment the filaments have a composition of between 0.70 and 0.90 wt% of chromium, between 0.55 and 0.65 wt% of carbon, between 0.75 and 1.00 wt% of manganese, and the rest being iron.

In still another very preferred embodiment the filaments have a composition of between 1.80 and 2.20 wt% of silicon, between 0.50 and 0.60 wt% of carbon, between 0.70 and 0.95 wt% of manganese, and the rest being iron.

In yet another very preferred embodiment the filaments have a composition of between 0.90 and 1.20 wt% of chromium, between 0.47 and 0.55 wt% of carbon, between 0.10 and 0.20 wt% of vanadium, up to 1.10 wt% of manganese, up to 0.40 wt% silicon, and the rest being iron.

In still another very preferred embodiment the filaments have a composition of between 16 and 18 wt% of chromium, between 0.08 and 0.15 wt% of carbon, between 6.00 and 8.00 wt% of nickel, up to 2.00 wt% of manganese, and the rest being iron.

The number of filaments in the individual bundles in the one or more road sweeping brooms applied in step (ii) is preferably at least 20, more preferably between 20 and 300, even more preferably between 25 and 100.

In an embodiment, the filaments in the individual bundles of the one or more road sweeping brooms applied in step (ii) are helically wound. Such helical winding limits the movement of individual filaments within a bundle.

In a further embodiment, different fractions of the filaments in the individual bundles of the one or more road sweeping brooms applied in step (ii) are helically wound to helically wound sub-bundles and the helically wound sub-bundles are also helically wound. As an example, the filaments in a single bundle can be divided in five fractions of equal numbers of filaments. The filaments of each individual fraction can then be helically wound, resulting in five helically wound sub-bundles. The five helically wound sub-bundles can in turn be helically wound to obtain a bundle of filaments having a double helical structure.

The angle Θ in the one or more road sweeping brooms is preferably between 20 and 50°, more preferably between 30 and 40°, such as about 35°.

In a very preferred embodiment, the individual filaments in a bundle of the one or more road sweeping brooms applied in step (ii) have a rectangular cross section with a width of between 2 and 7.5 mm and a thickness of between 0.5 and 2 mm.

In another embodiment, the individual filaments in a bundle of the one or more road sweeping brooms applied in step (ii) have a circular cross section with a diameter of between 0.2 and 2 mm, preferably between 0.8 and 1.2 mm.

In a particularly preferred embodiment, the filaments in a bundle of the one or more road sweeping brooms applied in step (ii) have a length of between 20 and 25 cm, have a rectangular cross section with a width of between 2 and 3.5 mm, a thickness of between 0.5 and 1.5 mm, and are made of steel, preferably spring steel.

In a preferred embodiment, mineral particles or aggregates are distributed across the porous asphalt road construction obtained in step (i) and/or across the porous asphalt road construction obtained in step (ii).

This process of distributing mineral particles or aggregates is also called 'sanding'’ or 'gritting'’ in the art.

Although the distribution of mineral particles or aggregates across the porous asphalt road construction does not affect the rejuvenation of the porous asphalt road construction itself and does not or not considerably shorten the period required for recovering the skid resistance of the road construction before rejuvenation, it may provide a direct, but temporary, increase of the skid resistance such that the porous asphalt road construction, following rejuvenation, can be opened for traffic at an earlier stage.

In a very preferred embodiment, the mineral particles or aggregates are only distributed across the porous asphalt road constraction obtained in step (ii), i.e. after the brushing step.

Distribution of mineral particles or aggregates as defined hereinbefore across the porous asphalt road construction is preferably performed between 8 and 120 minutes, more preferably between 10 and 60 minutes, after applying the rejuvenating binder in liquid form to the porous asphalt road constmction in step (i).

The mineral particles or aggregates typically have a particle size of between 0.2 and 2 mm, preferably between 0.5 and 2 mm. The mineral particles or aggregates preferably are angular materials. It is within the skills of the artisan to choose suitable mineral particles or aggregates with a suitable particle size to temporarily increase the skid resistance. Preferred non-limiting examples of mineral particles or aggregates are optionally dried crusher sand with a d-D of 0-2 mm as determined using NEN-EN 13043:2015, optionally dried moraine sand with a d-D of 0-2 mm as determined using NEN-EN 13043:2015, grit and gravel, finely ground (blast furnace) slag, such as NeoRough*', aluminum silicates, such as Eurogrit^R!, synthetic aluminum silicate glass melts, such as Asilgrip⁵ with a d-D of 1-3 mm as determined using NEN-EN 13043:2015, and granite particles, such as 202 Bestone® 0/2. In a very preferred embodiment, the mineral particles or aggregates are angular granite particles with a d-D of 0-2 mm as determined using NEN-EN 13043:2015.

In a preferred embodiment, between 0.1 and 0.6 kg of mineral particles or aggregates as defined hereinbefore per square meter of the porous asphalt road construction is applied, more preferably between 0.3 and 0.5 kg, such as 0.35 or 0.4 kg.

In a typical embodiment, the distribution of mineral particles or aggregates as defined hereinbefore across the porous asphalt road construction is performed with a gritting truck equipped with a dish spreader at the back. In a preferred embodiment, the gritting truck drives with a speed of between 60 and 90 m/min during distribution of mineral particles or aggregates.

In a preferred embodiment, the mineral particles or aggregates are distributed across the porous asphalt road construction obtained in step (ii), and step (ii) and the step of distributing mineral particles or aggregates are performed with a single vehicle equipped with one or more of said road sweeping brooms at the front and a dish spreader at the back.

As explained hereinbefore, the inventors have established that applying step (ii) in the rejuvenation process as defined hereinbefore reduces the film thickness of the rejuvenating liquid binder - or solidified after some time - on the (peaks of the) upper surface of the porous asphalt road construction without adversely affecting the macro surface texture and most of the micro surface texture of the porous asphalt road construction.

Nevertheless, the inventors have established that even after applying step (ii) of the process described hereinbefore, a film layer of the rejuvenating liquid binder - or rejuvenating solidified binder after some time - of a certain thickness remains on the upper surface of the porous asphalt road construction and that this film thickness can be effectively further reduced by applying an aqueous solution comprising one or more first surfactants, wherein the concentration of the one or more first surfactants in the aqueous solution is between 0.005 and 1 wt% based on the weight of the aqueous solution, said aqueous solution having a surface tension of lower than 45 mN/m at a temperature of 20°C, to the porous asphalt road construction before step (i) of applying the rejuvenating binder in liquid form to the porous asphalt road construction.

Hence, in a preferred embodiment, the process as defined hereinbefore comprises the steps of

Without wishing to be bound by any theory it is believed that the aqueous solution comprising the one or more first surfactants positively influences the transport of rejuvenating binder from the peaks of the upper surface of the porous asphalt road construction into the inner pores by compaction and further by using a concentrated air flow.

This reduced film thickness of the rejuvenating liquid binder - or rejuvenating solidified binder after some time - on the (peaks of the) upper surface of the porous asphalt road construction as compared to a process wherein step (a) is not applied results in an improved dry and wet skid resistance after rejuvenation and in an acceleration of the return of the dry and wet skid resistance to their initial values before rejuvenation.

In a preferred embodiment, in a very first step, before step (a), the porous asphalt road construction is cleaned as described hereinbefore.

In a very preferred embodiment, steps (a) and (b), more preferably steps (a) to (d), are performed under dry weather conditions. Moreover, in a very preferred embodiment, at least the upper part of the porous asphalt road construction is dry when step (a) is applied.

In a preferred embodiment, the aqueous solution applied in step (a) has a surface tension of higher than 20 mN/m and lower than 45 mN/m at a temperature of 20°C. In another preferred embodiment, the aqueous solution applied in step (a) has a surface tension of lower than 40 mN/m at a temperature of 20°C, more preferably lower than 35 mN/m, even more preferably lower than 30 mN/m, even more preferably lower than 25 mN/m.

In another preferred embodiment, the aqueous solution applied in step (a) comprises between 0.01 and 0.1 wt%, based on the weight of the aqueous solution, of said one or more first surfactants, more preferably between 0.03 and 0.07 wt% of said one or more first surfactants. The one or more first surfactants can be chosen from the groups consisting of nonionic, anionic, cationic and amphoteric surfactants. The one or more surfactants preferably have a HLB-value of higher than 7.

The aqueous solution applied in step (a) can further comprise acids and/or bases to adjust the pH and/or the solubility of the one or more first surfactants.

Advantageously, the one or more first surfactants are chosen from the group consisting of fatty acid amine surfactants, alkyl di-amine surfactants, amido-amine surfactants, imidazoline-containing surfactants, betaine-containing surfactants and tall oil-containing surfactants. Very preferred first surfactants are fatty acid amido alkyl betaines, such as TEGO® Addibit EK 50 from Evonik Industries. Other very preferred first surfactants are N-tallowalkyl1,3-propanediamines, such as Redicote E-9 from AkzoNobel.

In a preferred embodiment, the rejuvenating binder in liquid form applied in step (b) is chosen from the group consisting of waterborne bituminous emulsions, waterborne polyurethane resins, waterborne epoxy resins, waterborne natural or synthetic resins emulsions, waterborne vegetable, animal or mineral oil emulsions, the one or more first surfactants in the aqueous solution applied in step (a) are chosen from the group consisting of fatty acid amido alkyl betaines, and the pH of the aqueous solution applied in step (a) is between 1.7 and 3.

In another preferred embodiment, the rejuvenating binder in liquid form applied in step (b) is chosen from the group consisting of waterborne bituminous emulsions, waterborne polyurethane resins, waterborne epoxy resins, waterborne natural or synthetic resins emulsions, waterborne vegetable, animal or mineral oil emulsions, the one or more first surfactants in the aqueous solution applied in step (a) are chosen from the group consisting of N-tallowalkyl-1,3propanediamines, and the pH of the aqueous solution applied in step (a) is between 1.7 and 3.

In a typical embodiment, application of the aqueous solution to the porous asphalt road construction in step (a) is performed using a vehicle equipped with a spraying device at the back or with a rubber flap at the back that is continuously wetted with the aqueous solution of step (a) and is in close contact with the porous asphalt road construction. In another embodiment, application of the aqueous solution to the porous asphalt road construction in step (a) is performed using a vehicle equipped with a spraying device at the front.

In a preferred embodiment, the vehicle equipped with the spraying device at the back or front, or with the rubber flap at the back drives with a speed of between 60 and 90 m/min during step (a).

In an embodiment, the aqueous solution is applied in step (a) to the porous asphalt road constaiction in an amount of between 5 and 250 g per square meter of the porous asphalt road construction, more preferably in an amount of between 30 and 180 g, even more preferably in an amount of between 50 and 150 g, such as about 100 g. In this context, the wording square meter of the porous asphalt road construction' is not synonymous to the surface area of a square meter of the porous asphalt road construction', because the surface area of one square meter of a porous asphalt road construction is higher than 1 square meter due to the rough and/or porous surface of the porous asphalt road construction.

In a very preferred embodiment, the vehicle used for step (b) equipped with the spraying device at the back drives at the same speed as the vehicle equipped with the spraying device as used in step (a).

In a very preferred embodiment, the rejuvenating binder in liquid form is applied in step (b) to the porous asphalt road construction obtained in step (a) within 3 minutes from applying the aqueous solution of step (a) to the porous asphalt road construction.

In a preferred embodiment, a single vehicle equipped with a spraying device at the front for application of the aqueous solution to the porous asphalt road construction of step (a) and equipped with a spraying device at the back for application of the rejuvenating binder in liquid form to the porous asphalt road construction is used, such that both steps (a) and (b) are or can be applied by the same vehicle in a single run.

In step (c), the rejuvenating binder is forced to penetrate the pores of the porous asphalt road construction using a compactor. In a very preferred embodiment, the compactor is equipped with rubber tyres. Without additional measures, the rejuvenating binder may adhere to the compactor, such as to the rubber tyres of the compactor, during compaction, resulting in fouling of (the rubber tyres of) the compactor and an inhomogeneous layer thickness of the rejuvenating binder on the porous asphalt road construction. The inventors found that this adherence of the rejuvenating binder to the (rubber tyres of the) compactor can be avoided or at least reduced by applying in step (c) an aqueous solution comprising one or more second surfactants, said aqueous solution having a surface tension of lower than 45 mN/m at a temperature of 20°C, onto the compaction surface of the compactor, preferably onto the rubber tyres, in the form of a film layer before the compaction surface of the compactor, preferably the rubber tyres, contacts the porous asphalt road construction to be compacted. Preferred values of the surface tension of the aqueous solution applied in step (c), the concentration of the one or more second surfactants and the type of the one or more second surfactants, are already described in the context of the aqueous solution applied in step (a) comprising the one or more first surfactants.

In a preferred embodiment, the concentration of the one or more second surfactants in the aqueous solution applied onto the compaction surface of the compactor in step (c) is between 0.005 and 1 wt%, based on the weight of the aqueous solution, more preferably between 0.01 and 0.1 wt%, even more preferably between 0.03 and 0.07 wt%.

The aqueous solution applied in step (c) can further comprise acids and/or bases to adjust the pH and/or the solubility of the one or more second surfactants.

In a preferred embodiment, the one or more first surfactants in the aqueous solution applied in step (a) and the one or more second surfactants in the aqueous solution applied in step (c) are identical.

The compaction pressure in step (c) in the interface between the porous asphalt road construction and the compactor, preferably in the interface between the porous asphalt road construction and the rubber tyres of the compactor, is advantageously between 0.3 and 2 MPa, such as 1.3 MPa.

In a preferred embodiment, the rubber tyres of the compactor are pneumatic tyres having an internal pressure of between 3 and 9 bar A.

The compactor, preferably equipped with rubber tyres, typically drives with a speed of approximately 60-90 m/min, about 10 to 40 meters behind the vehicle applied in step (b) which is equipped with the spraying device at the back.

More than one compactor, preferably equipped with rubber tyres, may be deployed.

In another preferred embodiment, steps (a), (b) and (c) are performed with a single vehicle equipped with a spraying device for step (a) at the front and with a spraying device for step (b) at the back, wherein the vehicle is coupled at the back to a compaction trailer, preferably equipped with rubber tyres, for step (c). The single vehicle for steps (a), (b) and (c) typically drives with a speed of approximately 60-90 m/min.

In a very preferred embodiment, before distributing any mineral particles or aggregates across the porous asphalt road construction, before removing rejuvenating binder from the upper surface of the porous asphalt road construction using the one or more rotating road sweeping brooms in step (d) and after applying the compaction in step (c), the rejuvenating binder is forced to penetrate further into the pores of the porous asphalt road construction using a concentrated air flow.

In a preferred embodiment, the concentrated air flow is directed into a direction perpendicular or substantially perpendicular to the porous asphalt road construction.

In a typical embodiment, the step of forcing the rejuvenating binder to penetrate further into the pores of the porous asphalt road construction is performed with a road surface dryer being a truck equipped with a gas turbine which produces a large flow of air into a direction substantially perpendicular to the porous asphalt road construction, such as 7-10 m³ air/s at a temperature between ambient temperature and 475°C. In a preferred embodiment, the road surface dryer equipped with a gas turbine drives with a speed of between 60 and 90 m/min. In a very preferred embodiment, the road surface dryer drives at the same speed as the compactor as applied in step (c).

In another preferred embodiment, the road surface dryer is further equipped with a sprinkler system to apply an aqueous solution comprising one or more second surfactants, said aqueous solution having a surface tension of lower than 45 mN/m at a temperature of 20°C, as defined hereinbefore, onto the tyres to limit adherence of rejuvenating binder to the tyres during contact of the tyres with the porous asphalt road construction comprising rejuvenating binder. Preferred values of the surface tension of the aqueous solution applied in this step, the concentration of the one or more second surfactants and the type of the one or more second surfactants, are already described in the context of the aqueous solution applied in step (a) comprising the one or more first surfactants.

A typical distance applied between the compacter of step (c) and the road surface dryer is typically between 20 and 200 meters.

In a preferred embodiment, mineral particles or aggregates are distributed across the porous asphalt road construction obtained in step (c) and/or across the porous asphalt road construction obtained in step (d).

In a very preferred embodiment, the mineral particles or aggregates are only distributed across the porous asphalt road construction obtained in step (d). i.e. after the brushing step.

Preferred mineral particles or aggregates are as defined hereinbefore.

In a typical embodiment, the distribution of mineral particles or aggregates as defined hereinbefore across the porous asphalt road construction is performed with a gritting truck equipped with a dish spreader at the back. In a preferred embodiment, the gritting truck drives with a speed of between 60 and 90 m/min during distribution of mineral particles or aggregates. In another preferred embodiment, the gritting truck is further equipped with a sprinkler system to apply an aqueous solution comprising one or more second surfactants as defined hereinbefore, onto the tyres to limit adherence of rejuvenating binder to the tyres during contact of the tyres with the porous asphalt road construction comprising rejuvenating binder. Preferred values of the surface tension of the aqueous solution, the concentration of the one or more second surfactants and the type of the one or more second surfactants, are already described in the context of the aqueous solution applied in step (a) comprising the one or more first surfactants.

In a preferred embodiment, the mineral particles or aggregates are distributed across the porous asphalt road construction obtained in step (d), and step (d) and the step of distributing mineral particles or aggregates are performed with a single vehicle equipped with one or more of said road sweeping brooms at the front and a dish spreader at the back.

Thus, the invention has been described by reference to certain embodiments discussed above. It will be recognized that these embodiments are susceptible to various modifications and alternative forms well known to those of skill in the art.

Furthermore, for a proper understanding of this document and its claims, it is to be understood that the verb ‘to comprise’ and its conjugations are used in its non-limiting sense to mean that items following the word are included, but items not specifically mentioned are not excluded. In addition, reference to an element by the indefinite article ‘a’ or ‘an’ does not exclude the possibility that more than one of the element is present, unless the context clearly requires that there be one and only one of the elements. The indefinite article ‘a’ or ‘an’ thus usually means ‘at least one’.

EXAMPLES

Example 1

On July 25^th 2018, sub-sections of rejuvenated ZOAB (16) surface on Latexfait B.V.’s premises in Koudekerk a/d Rijn, The Netherlands, were mechanically treated with different techniques with the purpose of removing or reducing the thickness of the film layer of the rejuvenating binder on the upper surface of the porous asphalt road construction without adversely affecting the macro surface texture and the micro surface texture of the porous asphalt road construction.

The upper surface is the surface that can be in contact with the tyres of vehicles driving on the porous asphalt road construction.

At the start of the rejuvenation process, the weather was dry, the asphalt temperature was about 24°C, the air temperature was about 24.5°C and the relative humidity was about 62.1%. The upper layer of the wearing course to be rejuvenated was dry.

Every sub-section had a surface area of 3 m by 0.5 m. All sub-sections were treated with 400 g/m² of Modimuls ZV, a bituminous binder emulsion from Latexfait B.V., Netherlands. The Modimuls ZV was allowed to dry for 10 minutes before the upper surface of the porous asphalt road construction was subjected to different mechanical cleaning techniques.

Half of every sub-section was sanded after applying the Modimuls ZV and prior to starting the mechanical cleaning of the upper surface. 202 Bestone® 0/2 (d-D = 0-2 mm, as determined using NEN-EN 13043:2015) was applied in an amount of about 450 g/m².

Section 1 (sanded and non-sanded part) was treated with a road sweeping broom having 8 bundles of steel pins. Different fractions of the steel pins in the individual bundles were helically wound to helically wound sub-bundles and the helically wound sub-bundles were also helically wound resulting in a double helical structure. The bundles of steel pins had an angle of about 35° with the driving shaft. About 60% of the length of the steel pins in the individual bundles was bound together using a metal ring, such that the steel pins in a single bundle could not move substantially independently over this length. The geometry of the road sweeping broom used on Section 1 is schematically shown in Figure 8. The road sweeping broom was rotated about its driving shaft at about 100 rpm, the contact pressure between the rotating road sweeping broom and the porous asphalt road constraction was about 25 kPa and the contact time was about 0.6 seconds.

Section 2 (sanded and non-sanded part) was treated with a road sweeping roller having bundles of twisted steel pins. During cleaning this roller was rotated at about 80 rpm about an axis parallel to the road structure and perpendicular to the driving direction. The contact pressure between the rotating road sweeping roller and the porous asphalt road construction was about 11 kPa and the contact time was about 3 seconds.

Section 3 (sanded and non-sanded part) was treated with a road sweeping disc having 4 circular rubber pads of 28 cm diameter each. Additional sand was used during cleaning. During cleaning each rubber pad in the road sweeping disc was individually rotated about its driving shaft at about 80 rpm in the plane parallel to the porous asphalt road construction. The contact pressure between the rotating rubber pads and the porous asphalt road construction was about 700 Pa and the contact time was about 3 seconds.

Section 4 (sanded and non-sanded part) was treated with a road sweeping disc having 6 wooden blocks comprising steel pins of circular cross section with 1.2 mm diameter protruding about 3 cm from the wooden blocks in a direction perpendicular to the porous asphalt road construction. During cleaning the road sweeping disc was rotated about its driving shaft at about 80 rpm. The contact pressure between the rotating road sweeping disc and the porous asphalt road construction was about 115 kPa and the contact time was about 1 second.

Section 5 (sanded and non-sanded part) was treated with a road sweeping device having 3 diamond discs that could rotate individually about their individual driving shafts in the plane parallel to the porous asphalt road construction. During cleaning the diamond discs were rotated about their individual driving shafts at about 80 rpm. The contact pressure between the diamond discs and the porous asphalt road construction was about 1500 Pa and the contact time was about 1 second.

The road sweeping broom having bundles of steel pins used in Section 1 resulted in lowering of the thickness of the binder film on the upper surface of the porous asphalt road construction. The edges of stones in the upper surface were cleaned. Due to the centrifugal forces, relatively large (1-2 mm) unbound or loosely bound aggregates were removed from the surface.

The road sweeping roller having bundles of twisted steel pins used in Section 2 resulted in lowering of the thickness of the binder film on the upper surface of the porous asphalt road construction. The tops and edges of stones in the upper surface were cleaned. Some parts of the upper surface were polished such that the micro surface texture of the porous asphalt road construction was adversely affected, as determined with microscopic analysis. Large particles were carried with the roller in the direction of driving.

The disc with the rubber pads used in Section 3 did not result in a lowering of the thickness of the binder film on the upper surface of the porous asphalt road construction. No cleaning effect was observed but rather a smearing of the binder across the surface.

The road sweeping disc having wooden blocks comprising steel pins applied in Section 4 resulted in a lowering of the thickness of the binder film on the upper surface of the porous asphalt road construction. No cleaning of the upper surface was observed. The contact area of the pins was not sufficient to remove all large particles of 202 Bestone® 0/2.

The road sweeping device with the diamond discs used in Section 5 trimmed off the stone tops, thereby adversely affecting the micro and macro surface texture of the porous asphalt road consriuction.

Example 2

Based on the findings of Example 1, further tests were performed with road sweeping brooms having bundles of steel filaments. On August 23^rd 2018, sub-sections of rejuvenated ZOAB (16) surface on Latexfait B.V.’s premises in Koudekerk a/d Rijn, The Netherlands, were mechanically treated with the purpose of removing or reducing the thickness of the film layer of the rejuvenating binder on the upper surface of the porous asphalt road construction without adversely affecting the macro surface texture and the micro surface texture of the porous asphalt road construction.

At the start of the rejuvenation process, the weather was dry, the asphalt temperature was about 21.5°C, the air temperature was about 22°C and the relative humidity was about 72%. The upper layer of the wearing course to be rejuvenated was dry.

The part of the asphalt road construction to be rejuvenated was divided into 5 different sections. In all sections the wearing course was pre-wetted with about 0.1 kg/m² of an aqueous solution having a pH of 2.3 comprising 0.05 wt% of surfactant TEGO' Addibit EK 50 from Evonik Industries.

Brushing took place using two different road sweeping brooms (provided by Gielis, Geldrop). The first road sweeping broom had a geometry as depicted in Figure 7. The diameter of circular disc (1) was 50 cm. The number of bundles of filaments, evenly distributed along the perimeter (Tc) of the circular disc (1) and along a second circle (5) radially inward of the perimeter (Tc), was 77, of which 41 were evenly distributed along the perimeter (1c). The angle between the bundles of filaments and the driving shaft (2) was 35°. The filaments in a single bundle were bound together over a length (4) extending from the first end (3a) of 12 cm. A single bundle of filaments had a length of 22.5 cm and a diameter of about 11 mm. The individual filaments had a rectangular cross-section of 2.85 by 0.85 mm and a length of 22.5 cm. The filaments were made of spring steel AISI 1095 having a modulus of elasticity of 207 GPa and a density of 7.86 g/cm³.

The second road sweeping broom had a similar geometry as the first road sweeping broom. The diameter of circular disc (1) was 50 cm. The number of bundles of filaments, evenly distributed along the perimeter (1c) of the circular disc (1), was 40. Different fractions of the filaments in the individual bundles were helically wound to helically wound sub-bundles and the helically wound sub-bundles were also helically wound to obtain a double helical structure. The angle between the bundles of filaments and the driving shaft (2) was 35°. The filaments in a single bundle were bound together over the full length of the filaments using a hose extending from the first end (3a). A single bundle of filaments had a length of 25 cm and a diameter of about 25 mm. The individual filaments had a circular cross section with a diameter of 1 mm and a length of 25 cm. The filaments were made of spring steel AISI 1095 having a modulus of elasticity of 207 GPa and a density of 7.86 g/cm³.

Section 1 was sprayed with about 0.3 kg/m² of Modimuls ZV. About 1 hour after applying the Modimuls ZV, one sub-section of section 1 was brushed with the first road sweeping broom at about 110 rpm, with a speed of 0.5 km/h and a contact pressure of about 33.5 kPa. A second sub-section of section 1 was brushed with the second road sweeping broom at about 110 rpm, with a speed of 0.5 km/h and a contact pressure of about 12.5 kPa.

Section 2 was sprayed with about 0.3 kg/m² of Modimuls ZV, directly followed by sanding with about 0.35 kg/m² crusher sand (d-D = 0-2 mm, as determined using NEN-EN 13043:2015) and compaction using a roller having a contact pressure of 35 kPa. The Modimuls ZV was forced to further penetrate the asphalt using a blower having an air speed of about 60 km/h. About 1 hour after applying the Modimuls ZV, brushing took place using the first road sweeping broom.

Section 3 was sprayed with about 0.3 kg/m² of Modimuls ZV, followed by sanding with about 0.35 kg/m² 202 Bestone¹ 0/2 (d-D = 0-2 mm, as determined using NEN-EN 13043:2015) and compaction using a roller having a contact pressure of 35 kPa. The Modimuls ZV was forced to further penetrate the asphalt using a blower having an air speed of about 60 km/h. About 1 hour after applying the Modimuls ZV, brushing took place using the first road sweeping broom.

Section 4 was sprayed with about 0.3 kg/m² of Modimuls ZV. About 10 minutes after applying the Modimuls ZV, brushing took place using the first road sweeping broom.

Section 5 was sprayed with about 0.6 kg/m² of Modimuls ZV. About 10 minutes after applying the Modimuls ZV, brushing took place using the first road sweeping broom.

It was concluded from this experiment (visual inspection and micrographs) that nonsanded sections were easy to clean. If mineral particles or aggregates are distributed across a still wet residual film layer of the rejuvenating binder, the wet binder incorporates the mineral particles or aggregates to form a mastic and the effect of the brushing step diminishes.

Section 4 was cleaned more easily than Section 5, having a thicker layer of rejuvenating binder. Cleaning of Section 4 (brushing 10 minutes after applying the Modimuls ZV) turned out to be very effective. Baishing with the first road sweeping broom (bundles of steel sheets) turned out to be better than brushing with the second road sweeping broom (helical bundles of steel pins).

Comparative Example 1

On May 12^th 2017, part of the wearing course of the A12 motorway, comprising twolayer porous asphalt (ZOAB), near Veenendaal in The Netherlands was rejuvenated using the following process.

One week before rejuvenation, the relevant part of the motorway was thoroughly cleaned using a high-pressure jet ZOAB cleaner from Wolfswinkel Reiniging, Maarsbergen, The Netherlands.

During the rejuvenation process, the weather was dry. Moreover, the upper layer of the wearing course to be rejuvenated was dry. The average temperature was about 15 °C.

In a first step, about 0.8 kg/m² of Modimuls ZV was applied to the wearing course using a spray bar positioned at the back of a truck. The truck drove with a speed of approximately 8090 m/min. The temperature of the Modimuls ZV was between 55 and 65°C.

In a second step, the Modimuls ZV was forced to further penetrate from the peaks of the upper surface into the pores of the wearing course using a compactor equipped with pneumatic aibber tyres (HAMM GRW-180i-12H). Water with 0.05 wt% of surfactant TEGO⁸Addibit EK 50 from Evonik Industries, having a surface tension of 32.9 mN/m at a temperature of 20°C, was continuously distributed as a film layer onto the rubber tyres to prevent adherence of Modimuls ZV to the tyres during contact of the tyres with the wearing course comprising Modimuls ZV. The compactor equipped with rubber tyres drove with a speed of approximately

80-90 m/min, about 30 to 40 meters behind the spraying truck. This means that compaction took place between 20 and 30 seconds after spraying the Modimuls ZV on the wearing course. The compaction pressure in the interface between the ZOAB road construction and the rubber tyres was about 1.3 MPa.

In a third step, the Modimuls ZV was forced to still further penetrate from the peaks of the upper surface into the pores of the wearing course using a road surface dryer (SurfaceJet, from Wolfswinkel Reiniging, Maarsbergen, The Netherlands) equipped with a LGH2500 gas turbine Turbojet, which produces a large amount of very warm air (about 450°C). The gas turbine has a capacity of 7-10 m³ air/s. The road surface dryer drove with a speed of approximately 67 m/min, at least 20 meters behind the spraying truck. The distance between the compacter and the road surface dryer increased during the process because of their different speeds. This means that surface drying took place at least 18 seconds after compaction.

In a fourth step, for the purpose of temporarily improving the initial skid resistance, the wearing course was gritted with 0.35 kg/m² of dried moraine sand (d-D = 0-2 mm, as determined using NEN-EN 13043:2015) using a gritting truck equipped with a dish spreader that was NIDO-calibrated on material type, grain size and specific gravity. The gritting truck was further equipped with a sprinkler system to apply water with 0.05 wt% of surfactant TEGO* Addibit EK 50 from Evonik Industries, having a surface tension of 32.9 mN/m at a temperature of 20°C, onto the tyres to limit adherence of Modimuls ZV to the tyres during contact of the tyres with the wearing course comprising Modimuls ZV. The gritting truck drove with a speed of approximately 67 m/min, about 50 to 100 meters behind the road surface dryer. This means that gritting took place between 45 and 90 seconds after surface drying.

Dry skid resistance of the rejuvenated wearing course, i.e. dry braking deceleration, was measured in accordance with P. Kuiper, 'Meet- en rekenprotocol Droge remvertraging (middels meting onder verkeer)’, RWS/GPO, version 1.0, 18 July 2014, directly before opening of the motorway for traffic (at t=0), and 1, 2, 4, 8, 16, 24, 48 and 72 hours after opening of the motorway for traffic. Results are given in Table 1 and in Figure 1 (solid line). Figure 1 also depicts the value of the dry braking deceleration directly before rejuvenation (dashed line).

Wet skid resistance of the rejuvenated wearing course was measured in accordance with E. Vos, ‘Meet- en rekenprotocol Actuele Stroejheidscore AS’, RWS/GPO, version 1.0, 8 July 2013, directly before opening the motorway for traffic (at t=0), and 1, 2, 4, 8, 16, 24, 48 and 72 hours after opening the motorway for traffic. Results are given in Table 1 and in Figure 2 (solid line). Figure 2 also depicts the value of the wet skid resistance directly before rejuvenation (dashed line).

Figure 1 and Figure 2 show that, although the initial skid resistance of the rejuvenated wearing course directly before opening the motorway for traffic is quite good, both the dry 5 braking deceleration and the wet skid resistance sharply decrease after opening of the motorway for traffic. It takes at least ten hours to reach sufficient skid resistance (dry braking deceleration and wet skid resistance) to guarantee safe driving conditions (according to the requirements set by Rijkswaterstaat and being in force in November 2017).

Table 1: Skid resistance of the A12 wearing course before and after rejuvenation

	Comparative Example 1
Directly before rejuvenation	Dry braking deceleration [m/s²]	Wet skid resistance [-]
	7.6	0.59
Time after opening (at t=0) [hrs]	Dry braking deceleration [m/s²]	Wet skid resistance [-]
0	6.2	0.46
1	4.0	0.34
2	3.9	0.33
4	4.1	0.35
8	4.3	0.37
16	4.7	0.40
24	4.8	0.44
48	5.1	0.45
72	5.4	0.44

Example 3

A rejuvenation process was performed on September 10^th 2018, on the N31 between 15 Harlingen and Zurich in the Netherlands. The wearing course consisted of single layer ZOAB (16). At the start of the rejuvenation process, the weather was dry, the asphalt temperature was about 22.2°C, the air temperature was about 19.4°C and the relative humidity was 68.7%. The upper layer of the wearing course to be rejuvenated was dry.

Two hours prior to rejuvenation, the relevant part of the motorway was thoroughly cleaned using a high-pressure jet ZOAB cleaner from De Jong Zuurmond B.V., The Netherlands.

The part of the asphalt road construction to be rejuvenated was divided into different sections. The following steps were applied to all sections.

The wearing course was pre-wetted with about 0.1 kg/m² of an aqueous solution having a pH of between 2.2 and 2.4 (adjusted with 30% HC1) comprising 0.05 wt% of surfactant TEGO^a Addibit EK 50 from Evonik Industries.

Subsequently, about 0.8 kg/m² of Modimuls ZV, a bituminous binder emulsion from Latexfait B.V., Netherlands, was applied to the wearing course using a spray bar positioned at the back of a truck. The track drove with a speed of approximately 80-90 m/min. The temperature of the Modimuls ZV was between 55 and 65°C.

In a second step, the Modimuls ZV was forced to further penetrate from the peaks of the upper surface into the pores of the wearing course using two compactors equipped with pneumatic rubber tyres (GRW 280-12H Pneumatic tyre roller). Water with 0.05 wt% of surfactant TEGO' Addibit EK 50 from Evonik Industries, having a surface tension of 32.9 mN/m at a temperature of 20°C, was continuously distributed as a film layer onto the rubber tyres to prevent adherence of Modimuls ZV to the tyres during contact of the tyres with the wearing course comprising Modimuls ZV. The compactors equipped with rubber tyres drove with a speed of approximately 80-90 m/min. The compaction pressure in the interface between the ZOAB road construction and the rubber tyres was about 0.461 MPa.

In a third step, the Modimuls ZV was forced to still further penetrate from the peaks of the upper surface into the pores of the wearing course using a road surface dryer (SurfaceJet, from Wolfswinkel Reiniging, Maarsbergen, The Netherlands) equipped with a LGH2500 gas turbine Turbojet. The road surface dryer drove with a speed of approximately 85 m/min, at least 20 meters behind the spraying track.

Brushing took place about 10 minutes after applying the Modimuls ZV to the ZOAB and about 5 minutes after applying the SurfaceJet blower. These 10 minutes were sufficient to obtain about 80 % cure, determined by qualitative inspection, of the Modimuls ZV on the upper surface of the ZOAB. Two brushing vehicles were used (Gielis, Geldrop). The first brushing vehicle was a track equipped with 5 road sweeping brooms at the front. The road sweeping brooms were positioned in two rows (two brooms in the first row and three in the second row) a certain distance apart in the driving direction of the vehicle and were staggered in the direction perpendicular to the driving direction. The total width of the asphalt road construction covered by the 5 road sweeping brooms was 3.3 m, which covered the width of the individual sections.

The road sweeping brooms had a geometry as depicted in Figure 7. The diameter of circular disc (1) was 50 cm. The number of filaments bundles, evenly distributed along the perimeter (1c) of the circular disc (1) and along a second circle (5) radially inward of the perimeter (1c), was 77, of which 41 were evenly distributed along the perimeter (1c). The angle between the bundles of filaments and the driving shaft (2) was 35°. The filaments in a single bundle were bound together over a length (4) extending from the first end (3a) of 12 cm. A single bundle of filaments had a length of 22.5 cm and a diameter of about 11 mm, The individual filaments had a rectangular cross-section of 2.85 by 0.85 mm and a length of 22.5 cm. The filaments were made of spring steel AISI 1095 having a modulus of elasticity of 207 GPa and a density of 7.86 g/cm³. The filaments had, during use, an abrasion rate of about 1 cm/hour.

The second brashing vehicle was a Bob-Cat equipped with 3 road sweeping brooms at the front, identical to those on the first brushing vehicle. The road sweeping brooms were positioned in two rows (one broom in the first row and two in the second row) a certain distance apart in the driving direction of the vehicle and were staggered in the direction perpendicular to the driving direction. The total width of the asphalt road construction covered by the 3 road sweeping brooms was 1.5 m.

For the next steps, the sections were treated differently. The treated asphalt road construction encompassed 10.400 m² and was divided into four sections.

Section 1 was brushed one time, 5 minutes after applying the Modimuls ZV, with the first vehicle equipped with 5 road sweeping brooms and was sanded 2 hours after applying the Modimuls ZV with crusher sand. The first vehicle drove with a speed of about 60 m/min. The road sweeping brooms were rotated at a speed of 110 rpm. The contact pressure between the rotating road sweeping brooms and the porous asphalt road construction was 33.5 kPa. The crusher sand (d-D = 0-2 mm, as determined using NEN-EN 13043:2015) was applied in an amount of about 0.35 kg/m² using a sanding truck equipped with a dish spreader that was NIDO-calibrated on material type, grain size and specific gravity.

Section 2 was treated in the same way as Section 1 except for an additional brushing step with the second vehicle immediately following the first brushing step. The second vehicle drove with a speed of about 60 m/min. The road sweeping brooms were rotated at a speed of 110 rpm.

Section 3 was treated in the same way as Section 2 except for a different sanding step. Sanding was performed directly after brushing with 202 Bestone¹' 0/2. The 202 Bestone - 0/2 (d-D = 0-2 mm, as determined using NEN-EN 13043:2015) was applied in an amount of about 0.35 kg/m² using a sanding truck equipped with a dish spreader that was NIDO-calibrated on material type, grain size and specific gravity.

Section 4 was treated in the same way as Section 2 except for a different sanding step. Sanding was performed directly after brushing.

From visual inspection, it was noticed that brushing resulted in a cleaner upper surface of the ZOAB, meaning that part of the solidified rejuvenating binder had been removed from the upper surface. The two brushing passes resulted in an cleaner surface than only one brushing step with the first vehicle.

Skid resistance of Section 3 was analyzed using the British Pendulum skid resistance tester (according to standard NEN-EN 13036-4:2011) and using Floor Slide Control 2000 (according to standard DIN 51131:2014-02). Results are given in Tables 2 and 3:

Table 2: results British Pendulum skid resistance test for Section 3

Section 3, 202 Bestone* 0/2 directly sanded	British Pendulum number (BPN), [-]	Average BPN, [-]
Reference (Section 3 before treatment)	104, 105, 104	104
Baished one time, dry condition	95, 100, 110	102
Baished one time, wet condition	80, 90, 95, 97	91

Table 3: results Floor Slide Control 2000 test for Section 3

Section 3, 202 Bestone 0/2 directly sanded	Dynamic coefficient of friction, [-]	Average dynamic coefficient of friction, [-]
Reference (Section 3 before treatment)	0.48	0.48
Brushed two times, dry condition	0.57, 0.60	0.59
Brushed two times, wet condition	0.54, 0.51	0.53
Brushed one time, dry condition	0.57, 0.54, 0.55	0.55
Brushed one time, wet condition	0.52, 0.51	0.52

Wet skid resistance of the rejuvenated wearing course of Sections 1 to 4 was measured in accordance with E. Vos, 'Meet- en rekenprotocol Actuele Stroefheidscore AS’, RWS/GPO, version 1.0, 8 July 2013, directly before opening the motorway for traffic (at t=0), and 1, 2, 4, 8 and 16 hours after opening the motorway for traffic.

Results are given in Table 4 and in Figure 3 (dashed lines line). Figure 3 also depicts an estimate of the wet skid resistance directly before rejuvenation (solid line).

The line with the solid circles corresponds to Section 1 (brushed one time, sanded after 2 hours with crusher sand).

The line with the open triangles corresponds to Section 2 (brushed two times, sanded after 2 hours with crusher sand).

The line with the solid squares corresponds to Section 3 (brushed two times, directly sanded with 202 Bestone® 0/2).

The line with the open rhombuses corresponds to Section 4 (brushed two times, directly sanded with crusher sand).

Figure 3 shows that the wet skid resistance of the rejuvenated wearing course directly before opening the motorway for traffic is quite good and that, although the wet skid resistance shows some decrease after opening of the motorway for traffic, at least for Sections 1 and 2, it increases again overtime and remains sufficient to guarantee safe driving conditions (according to the requirements set by Rijkswaterstaat and being in force in September 2018).

Table 4: Wet skid resistance of the wearing course N31 before and after rejuvenation

Time	Wet skid resistance, [-]
Section 1	Section 2	Section 3	Section 4
Directly before rejuvenation	0.55	0.55	0.55	0.55
Time after opening (at t=0) [hrs] 0	0.48	0.54	0.49	0.44
1	0.4	0.41	0.36	0.34
2	0.42	0.43	0.39	0.35
4	0.41	0.42	0.4	0.35
8	0.43	0.45	0.36	0.35
16	0.4	0.46	0.42	0.38

It was concluded that sanding about 2 hours after applying the rejuvenating binder in liquid form to the porous asphalt road constaiction resulted in better anti-skid performance than sanding directly after the brushing step. Moreover, brushing two times instead of one time resulted in better anti-skid performance. Furthermore, sanding with angular 202 Bestone® 0/2 resulted in better anti-skid resistance than sanding with crusher sand.

Example 4

A rejuvenation process was performed on October 12^th 2018, on the A12 motorway between Lunetten and Veenendaal in the Netherlands. The wearing course consisted of 4-8 ZOAB. At the start of the rejuvenation process, the weather was dry, the asphalt temperature was about 15.6°C, the air temperature was about 21.1°C and the relative humidity was 72.8%. The upper layer of the wearing course to be rejuvenated was dry.

Two weeks prior to rejuvenation, the relevant part of the motorway was thoroughly cleaned using a high-pressure jet ZOAB cleaner from Wolfswinkel Reiniging Maarsbergen, The Netherlands.

The wearing course was pre-wetted with about 0.1 kg/m² of an aqueous solution having a pH of between 2.2 and 2.4 comprising 0.05 wt% of surfactant TEGO® Addibit EK 50 from Evonik Industries.

Subsequently, about 0.8 kg/m² of Modimuls ZV was applied to the wearing course using a spray bar positioned at the back of a truck. The truck drove with a speed of approximately 8090 m/min.

In a second step, the Modimuls ZV was forced to further penetrate from the peaks of the upper surface into the pores of the wearing course using two compactors equipped with pneumatic rubber tyres (GRW 280-12H Pneumatic tyre roller). Water with 0.05 wt% of surfactant TEGO^R Addibit EK 50 from Evonik Industries, having a surface tension of 32.9 mN/m at a temperature of 20°C, was continuously distributed as a film layer onto the rubber tyres to prevent adherence of Modimuls ZV to the tyres during contact of the tyres with the wearing course comprising Modimuls ZV. The compactors equipped with rubber tyres drove with a speed of approximately 80-90 m/min. The compaction pressure in the interface between the ZOAB road construction and the rubber tyres was about 0.461 MPa.

In a third step, the Modimuls ZV was forced to still further penetrate from the peaks of the upper surface into the pores of the wearing course using a road surface dryer (SurfaceJet, from Wolfswinkel Reiniging, Maarsbergen, The Netherlands) equipped with a LGH2500 gas turbine Turbojet. The road surface dryer drove with a speed of approximately 85 m/min.

Brushing took place about 30 minutes after applying the Modimuls ZV to the ZOAB. The brushing vehicle used (Gielis, Geldrop) was identical to the first brushing vehicle described in Example 3. The brushing vehicle drove with a speed of about 30 m/min. The road sweeping brooms were rotated at a speed of 110 rpm. The contact pressure between the rotating road sweeping brooms and the porous asphalt road construction was 33.5 kPa.

202 Bestone® 0/2 (d-D = 0-2 mm, as determined using NEN-EN 13043:2015) was applied in an amount of about 0.385 kg/m² using a sanding truck equipped with a dish spreader that was NIDO-calibrated on material type, grain size and specific gravity. The sanding truck drove with a with a speed of approximately 80-90 m/min. The time between applying the Modimuls ZV and applying 202 Bestone® 0/2 to the ZOAB was 40 minutes. Because the sanding truck drove at a higher speed than the brushing vehicle, the time between brushing and sanding varied. The minimum time between brushing and sanding was 10 minutes.

Dry skid resistance of the rejuvenated wearing course, i.e. dry braking deceleration, was measured in accordance with P. Kuiper, 'Meet- en rekenprotocol Droge remvertraging (middels meting onder verkeer)’, RWS/GPO, version 1.0, 18 July 2014, directly before opening of the motorway for traffic (at t=0), and 1, 2, 4, 8 and 16 hours after opening of the motorway for traffic. Results are given in Table 5 and in Figure 4 (solid line). Figure 4 also depicts an estimate of the dry braking deceleration directly before rejuvenation (dashed line).

Wet skid resistance of the rejuvenated wearing course was measured in accordance with E. Vos, 'Meet- en rekenprotocol Actuele Stroefheidscore AS’, RWS/GPO, version EO, 8 July 2013, directly before opening the motorway for traffic (at t=0), and 1, 2, 4, 8 and 16 hours after opening the motorway for traffic. Results are given in Table 5 and in Figure 5 (solid line).

Figure 5 also depicts the value of the wet skid resistance directly before rejuvenation (dashed line).

Figure 4 and Figure 5 show that the initial skid resistance of the rejuvenated wearing course directly before opening the motorway for traffic is quite good and that, although the dry braking deceleration shows some decrease after opening of the motorway for traffic, the skid 10 resistance (dry braking deceleration and wet skid resistance) remains sufficient to guarantee safe driving conditions (according to the requirements set by Rijkswaterstaat and being in force in October 2018).

Table 5: Skid resistance of the A12 wearing course before and after rejuvenation

Directly before rejuvenation	Dry braking deceleration [m/s²]	Wet skid resistance [-]
	8.40	0.52
Time after opening (at t=0)	Dry braking deceleration	Wet skid resistance
[hrs]	[m/s²]	[-]
0	6.84	0.41
2	4.59	0.44
4	5.13	0.48
8	5.90	0.49

Claims

1. Werkwijze voor het verjongen van een poreus-asfalt wegconstructie, waarin de poreus- asfalt wegconstructie poriën heeft die doordringen in de asfalt wegconstructie en een bovenste oppervlak met een macro-oppervlaktetextuur en een microoppervlaktetextuur, waarin genoemd bovenste oppervlak wordt gedefinieerd als het oppervlak dat in contact kan zijn met de banden van voertuigen die op de poreus-asfalt wegconstructie rijden, waarin genoemde werkwijze de volgende stappen omvat:A method for rejuvenating a porous-asphalt road construction, wherein the porous-asphalt road construction has pores penetrating the asphalt road construction and an upper surface with a macro-surface texture and a micro-surface texture, wherein said upper surface is defined as the surface that may be in contact with the tires of vehicles driving on the porous-asphalt road construction, said method comprising the following steps:

i) het toepassen van een verjongingsbindmiddel in vloeibare vorm op de poreusasfalt wegconstructie; en ii) het verwijderen van ten minste een deel van het verjongingsbindmiddel van het bovenste oppervlak van de poreus-asfalt wegconstructie verkregen in stap (i) door het behandelen van de poreus-asfalt wegconstructie met één of meer roterende straatveegborstels, waarin een straatveegborstel omvat:i) applying a rejuvenation binder in liquid form to the porous asphalt road construction; and ii) removing at least a portion of the rejuvenating binder from the top surface of the porous-asphalt road structure obtained in step (i) by treating the porous-asphalt road structure with one or more rotating road sweeping brushes, which includes a road sweeping brush:

een schijf (1) met een bovenoppervlak (la) en een onderoppervlak (1b);a disk (1) with a top surface (1a) and a bottom surface (1b);

een aandrijfas (2) voor het roteren van de straatveegborstel, waarin de aandrijfas (2) gefixeerd is op de schijf (1) in het midden van het bovenoppervlak (la) en waarin de aandrijfas (2) in een richting loodrecht op het bovenoppervlak (la) wijst; en n bundels met filamenten die aan hun eerste uiteinden (3a) gefixeerd zijn aan het onderoppervlak (1b) van de schijf (1), waarin de bundels met filamenten een hoek θ>0° vormen met de aandrijfas (2), zodat hun tweede uiteinden (3b) in radiale richting naar buiten wijzen;a drive shaft (2) for rotating the street sweeping brush, in which the drive shaft (2) is fixed on the disk (1) in the center of the top surface (1a) and in which the drive shaft (2) is oriented in a direction perpendicular to the top surface ( la) points; and n bundles of filaments fixed at their first ends (3a) to the bottom surface (1b) of the disk (1), in which the bundles of filaments form an angle θ> 0 ° with the drive shaft (2), so that their second ends (3b) point radially outwards;

waarin n een geheel getal is dat 2 of groter is, waarin de filamenten een totale lengte hebben van tussen 10 en 50 cm, bij voorkeur tussen 15 en 25 cm, en een dwarsdoorsnede van tussen 0.5 en 15 mm², bij voorkeur tussen 0.7 en 5 mm², waarin de filamenten in een enkele bundel samengebonden zijn over een lengte (4) die zich uitstrekt vanaf het eerste einde (3a) van tussen 5 en 15 cm, onder de voorwaarde dat ten minste 0.5 cm van de totale lengte van de filamenten niet samengebonden is, zodat de filamenten in een enkele bundel in hoofdzaak niet onafhankelijk van elkaar kunnen bewegen over de lengte (4).wherein n is an integer 2 or greater, wherein the filaments have a total length of between 10 and 50 cm, preferably between 15 and 25 cm, and a cross section of between 0.5 and 15 mm ² , preferably between 0.7 and 5 mm ² , in which the filaments are tied together in a single bundle over a length (4) extending from the first end (3a) of between 5 and 15 cm, provided that at least 0.5 cm of the total length of the filaments are not bound together, so that the filaments in a single bundle cannot substantially move independently along the length (4).

2. Werkwijze volgens conclusie 1, waarin schijf (1) in de één of meer straatveegborstels toegepast in stap (ii) een cirkelvormige schijf (1) is, waarin de diameter van de cirkelvormige schijf (1) bij voorkeur tussen 30 en 60 cm ligt, bij sterkere voorkeur tussen 40 en 50 cm.A method according to claim 1, wherein disc (1) in the one or more street sweeping brushes used in step (ii) is a circular disc (1), wherein the diameter of the circular disc (1) is preferably between 30 and 60 cm , more preferably between 40 and 50 cm.

3. Werkwijze volgens conclusie 2, waarin de n bundels met filamenten in de één of meer straatveegborstels toegepast in stap (ii) gelijkmatig verdeeld zijn langs de omtrek (1c) van de circulaire schijf (1).The method of claim 2, wherein the n bundles of filaments in the one or more street sweeping brushes used in step (ii) are evenly distributed along the circumference (1c) of the circular disk (1).

4. Werkwijze volgens conclusie 2, waarin de « bundels met filamenten in de één of meer straatveegborstels toegepast in stap (ii) gelijkmatig verdeeld zijn langs de omtrek (1c) van de circulaire schijf (1) en langs een tweede cirkel (5) in radiaal binnenwaartse richting van de omtrek (1c).The method of claim 2, wherein the bundles of filaments in the one or more street sweeping brushes used in step (ii) are evenly distributed along the circumference (1c) of the circular disk (1) and along a second circle (5) in radially inward direction of the circumference (1c).

5. Werkwijze volgens één van de conclusies 1 tot en met 4, waarin de filamenten in de één of meer straatveegborstels toegepast in stap (ii) zijn gemaakt van metaal, bij voorkeur gemaakt van staal.The method of any one of claims 1 to 4, wherein the filaments in the one or more street sweeping brushes used in step (ii) are made of metal, preferably made of steel.

6. Werkwijze volgens conclusie 5, waarin de filamenten gemaakt zijn van verenstaal.The method of claim 5, wherein the filaments are made of spring steel.

7. Werkwijze volgens één van de conclusies 1 tot en met 6, waarin het aantal bundels met filamenten n in elk van de één of meer straatveegborstels toegepast in stap (ii) tussen 2 en 100 ligt, bij voorkeur tussen 50 en 90.A method according to any one of claims 1 to 6, wherein the number of filament bundles n in each of the one or more street sweeping brushes used in step (ii) is between 2 and 100, preferably between 50 and 90.

8. Werkwijze volgens één van de conclusies 1 tot en met 7, waarin het aantal filamenten in elke individuele bundel in de één of meer straatveegborstels toegepast in stap (ii) ten minste 20 bedraagt, bij voorkeur tussen 20 en 300, bij sterkere voorkeur tussen 25 en 100.A method according to any one of claims 1 to 7, wherein the number of filaments in each individual bundle in the one or more street sweeping brushes used in step (ii) is at least 20, preferably between 20 and 300, more preferably between 25 and 100.

9. Werkwijze volgens één van de conclusies 1 tot en met 8, waarin de filamenten in de individuele bundels van de één of meer straatveegborstels toegepast in stap (ii) helixvormig gewonden zijn.The method of any one of claims 1 to 8, wherein the filaments in the individual bundles of the one or more street sweeping brushes used in step (ii) are helically wound.

10. Werkwijze volgens één van de conclusies 1 tot en met 9, waarin verschillende fracties van de filamenten in de individuele bundels van de één of meer straatveegborstels toegepast in stap (ii) helixvormig gewonden zijn tot helixvonnig-gewonden subbundels en waarin de helixvonnig-gewonden subbundels ook helixvormig gewonden zijn.The method of any one of claims 1 to 9, wherein different fractions of the filaments in the individual bundles of the one or more street sweeping brushes used in step (ii) are helically wound into helix-wound sub-bundles and wherein the helix-wound are sub-bundles are also helically wound.

11. Werkwijze volgens één van de conclusies 1 tot en met 10, waarin de hoek Θ in de één of meer straatveegborstels tussen 20 en 50° ligt, bij voorkeur tussen 30 en 40°.A method according to any one of claims 1 to 10, wherein the angle Θ in the one or more street sweeping brushes is between 20 and 50 °, preferably between 30 and 40 °.

12. Werkwijze volgens één van de conclusies 1 tot en met 11, waarin de filamenten in een bundel van de één of meer straatveegborstels toegepast in stap (ii) een rechthoekige dwarsdoorsnede hebben met een breedte van tussen 2 en 7.5 mm en een dikte van tussen 0.5 en 2 mm.The method of any one of claims 1 to 11, wherein the filaments in a bundle of the one or more street sweeping brushes used in step (ii) have a rectangular cross section with a width of between 2 and 7.5 mm and a thickness of between 0.5 and 2 mm.

13. Werkwijze volgens één van de conclusies 1 tot en met 11, waarin de filamenten in een bundel van de één of meer straatveegborstels toegepast in stap (ii) een circulaire dwarsdoorsnede met een diameter van tussen 0.2 en 2 mm hebben, bij voorkeur tussen 0.8 en 1.2 mm.The method according to any one of claims 1 to 11, wherein the filaments in a bundle of the one or more street sweeping brushes used in step (ii) have a circular cross section with a diameter of between 0.2 and 2 mm, preferably between 0.8 and 1.2 mm.

14. Werkwijze volgens één van de conclusies 1 tot en met 13, waarin de één of meer straatveegborstels in stap (ii) worden geroteerd rond hun aandrijfassen met tussen 50 en 250 rpm en waarin de contactdruk tussen de één of meer roterende straatveegborstels en de poreus-asfalt wegconstructie tussen 300 en 50000 Pa ligt.The method of any one of claims 1 to 13, wherein the one or more street sweeping brushes are rotated in step (ii) about their drive shafts by between 50 and 250 rpm and wherein the contact pressure between the one or more rotating street sweeping brushes and the porous -asphalt road construction is between 300 and 50000 Pa.

15. Werkwijze volgens één van de conclusies 1 tot en met 14, waarin de tijd tussen het toepassen van het verjongingsbindmiddel in vloeibare vorm op de poreus-asfalt wegconstructie in stap (i) en stap (ii) waarin ten minste een deel van het verjongingsbindmiddel wordt verwijderd van het bovenste oppervlak van de poreusasfalt wegconstructie tussen 0.5 en 120 minuten bedraagt, bij voorkeur tussen 5 en 60 minuten, bij sterkere voorkeur tussen 6 en 40 minuten.The method of any one of claims 1 to 14, wherein the time between applying the rejuvenation binder in liquid form to the porous asphalt road structure in step (i) and step (ii) wherein at least a portion of the rejuvenation binder is removed from the top surface of the porous asphalt road construction is between 0.5 and 120 minutes, preferably between 5 and 60 minutes, more preferably between 6 and 40 minutes.

16. Werkwijze volgens één van de conclusies 1 tot en met 15, waarin minerale deeltjes of aggregaten worden gedistribueerd over de poreus-asfalt wegconstructie verkregen in stap (i) en/of over de poreus-asfalt wegconstructie verkregen in stap (ii), bij voorkeur alleen over de poreus-asfalt wegconstructie verkregen in stap (ii).The method according to any one of claims 1 to 15, wherein mineral particles or aggregates are distributed over the porous-asphalt road construction obtained in step (i) and / or over the porous-asphalt road construction obtained in step (ii), at preferably only over the porous-asphalt road construction obtained in step (ii).

17. Werkwijze volgens conclusie 16, waarin tussen 0.1 en 0.6 kg/m² van de minerale deeltjes of aggregaten wordt toegepast, bij voorkeur tussen 0.2 en 0.5 kg/m² A method according to claim 16, wherein between 0.1 and 0.6 kg / m ² of the mineral particles or aggregates is used, preferably between 0.2 and 0.5 kg / m ²

18. Werkwijze volgens één van de conclusies 1 tot en met 17, waarin het verjongingsbindmiddel in vloeibare vorm wordt toegepast in stap (i) op de poreus-asfalt wegconstructie in een hoeveelheid tussen 0.05 en 4 kg/m², bij voorkeur in een hoeveelheid tussen 0.2 en 1.2 kg/m², bij sterkere voorkeur in een hoeveelheid tussen 0.6 en 1.0 kg/m², bij nog sterkere voorkeur in een hoeveelheid tussen 0.7 en 0.9 kg/m², zoals ongeveer 0.8 kg/m².A method according to any one of claims 1 to 17, wherein the rejuvenation binder in liquid form is applied in step (i) on the porous-asphalt road construction in an amount between 0.05 and 4 kg / m ² , preferably in an amount between 0.2 and 1.2 kg / m ² , more preferably in an amount between 0.6 and 1.0 kg / m ² , even more preferably in an amount between 0.7 and 0.9 kg / m ² , such as about 0.8 kg / m ² .

19. Werkwijze volgens één van de conclusies 1 tot en met 18, waarin het verjongingsbindmiddel in vloeibare vorm wordt gekozen uit de groep bestaande uit watergedragen bitumineuze emulsies, watergedragen polyurethaanharsen, watergedragen epoxyharsen, watergedragen natuurlijke of synthetische harsemulsies, watergedragen emulsies van plantaardige, dierlijke of minerale olie, of combinaties daarvan, waarin het vloeibare verjongingsbindmiddel bij voorkeur een watergedragen bitumineuze emulsie is.A method according to any one of claims 1 to 18, wherein the rejuvenating binder in liquid form is selected from the group consisting of waterborne bituminous emulsions, waterborne polyurethane resins, waterborne epoxy resins, waterborne natural or synthetic resin emulsions, waterborne emulsions of vegetable, animal or mineral oil, or combinations thereof, wherein the liquid rejuvenation binder is preferably a waterborne bituminous emulsion.

20. Werkwijze volgens één van de conclusies 1 tot en met 19, waarin de poreus-asfalt wegconstructie zeer open asfaltbeton (ZOAB), 2-laags zeer open asfaltbeton (2-laags ZOAB), steen mastiek asfalt (SMA), dicht asfaltbeton (DAB), dunne geluidsarme asfaltdeklaag (DGD), wegconstructies waarvan het oppervlak is behandeld met een binder en steenslag, of combinaties daarvan, omvat.A method according to any one of claims 1 to 19, wherein the porous asphalt road construction is very open asphalt concrete (ZOAB), 2-layer very open asphalt concrete (2-layer ZOAB), mastic asphalt concrete (SMA), dense asphalt concrete ( DAB), thin soundproof asphalt covering (DGD), road structures the surface of which has been treated with a binder and crushed stone, or combinations thereof.

21. Werkwijze volgens één van de conclusies 1 tot en met 20, omvattende de stappen:The method of any one of claims 1 to 20, comprising the steps of:

a) het toepassen van een waterige oplossing die één of meer eerste oppervlakteactieve stoffen omvat, waarin de concentratie van de één of meer eerste oppervlakte-actieve stoffen in de waterige oplossing tussen 0.005 en 1 gew.% ligt gebaseerd op het gewicht van de waterige oplossing, waarbij genoemde waterige oplossing een oppervlaktespanning van lager dan 45 mN/m heeft bij een temperatuur van 20°C, op de poreus-asfalt wegconstructie:a) using an aqueous solution comprising one or more first surfactants, wherein the concentration of the one or more first surfactants in the aqueous solution is between 0.005 and 1% by weight based on the weight of the aqueous solution , wherein said aqueous solution has a surface tension of less than 45 mN / m at a temperature of 20 ° C, on the porous asphalt road construction:

b) stap (i) van het toepassen van het verjongingsbindmiddel in vloeibare vorm op de poreus-asfalt wegconstructie verkregen in stap (a);b) step (i) of applying the rejuvenation binder in liquid form to the porous-asphalt road structure obtained in step (a);

c) het geforceerd laten indringen van het verjongingsbindmiddel in de poriën van de poreus-asfalt wegconstructie verkregen in stap (b) gebruikmakend van een wals die bij voorkeur met rubberbanden uitgeaist is; enc) forcing the rejuvenation binder into the pores of the porous-asphalt road construction obtained in step (b) using a roller preferably with rubber tires; and

d) stap (ii) van het verwijderen van ten minste een deel van het verjongingsbindmiddel van het bovenste oppervlak van de poreus-asfalt wegconstructie verkregen in stap (c).d) step (ii) of removing at least a portion of the rejuvenation binder from the top surface of the porous-asphalt road structure obtained in step (c).

22. Werkwijze volgens conclusie 21, waarin minerale deeltjes of aggregaten worden gedistribueerd over de poreus-asfalt wegconstructie verkregen in stap (c) en/of over de poreus-asfalt wegconstructie verkregen in stap (d), bij voorkeur alleen over de poreusasfalt wegconstructie verkregen in stap (d).The method of claim 21, wherein mineral particles or aggregates are distributed over the porous-asphalt road construction obtained in step (c) and / or over the porous-asphalt road construction obtained in step (d), preferably only over the porous asphalt road construction obtained in step (d).

23. Werkwijze volgens conclusie 22, waarin tussen 0.1 en 0.6 kg/m² van de minerale deeltjes of aggregaten wordt toegepast, bij voorkeur tussen 0.2 en 0.5 kg/m².The method according to claim 22, wherein between 0.1 and 0.6 kg / m ² of the mineral particles or aggregates is used, preferably between 0.2 and 0.5 kg / m ² .

24. Werkwijze volgens één van de conclusies 21 - 23, waarin alvorens minerale deeltjes of aggregaten over de poreus-asfalt wegconstructie te distribueren, alvorens verjongingsbindmiddel van het bovenste oppervlak van de poreus-asfalt wegconstructie met de één of meer straatveegborstels te verwijderen in stap (d) en na toepassen van een compactering in stap (c), het verjongingsbindmiddel gedwongen wordt om verder in de poriën van de poreus-asfalt wegconstructie te dringen, gebruikmakend van een geconcentreerde luchtstroom, bij voorkeur gericht in een richting loodrecht op de poreus-asfalt wegconstructieThe method of any one of claims 21 to 23, wherein before distributing mineral particles or aggregates over the porous-asphalt road construction, before removing rejuvenation binder from the top surface of the porous-asphalt road construction with the one or more road sweeping brushes in step ( d) and after applying a compaction in step (c), the rejuvenation binder is forced to penetrate further into the pores of the porous asphalt road construction, using a concentrated air stream, preferably directed in a direction perpendicular to the porous asphalt road construction

25. Werkwijze volgens één van de conclusies 21 tot en met 24, waarin de walsdruk in stap (c) in het grensvlak tussen de poreus-asfalt wegconstructie en de rubberbanden van de wals tussen 0.3 en 2 MPa ligt.The method according to any one of claims 21 to 24, wherein the rolling pressure in step (c) in the interface between the porous-asphalt road construction and the rubber tires of the roller is between 0.3 and 2 MPa.

26. Werkwijze volgens één van de conclusies 21 tot en met 25, waarin de één of meer eerste oppervlakte-actieve stoffen worden gekozen uit de groep bestaande uit vetzuuramine oppervlakte-actieve stoffen, alkyl-di-amine oppervlakte-actieve stoffen, amido-amine oppervlakte-actieve stoffen, imidazoline-bevattende oppervlakte-actieve stoffen, betaïne-bevattende oppervlakte-actieve stoffen en tallolie-bevattende oppervlakteactieve stoffen.The method of any one of claims 21 to 25, wherein the one or more first surfactants are selected from the group consisting of fatty acid amine surfactants, alkyl diamine surfactants, amido amine surfactants, imidazoline-containing surfactants, betaine-containing surfactants, and tall oil-containing surfactants.

27. Werkwijze volgens één van de conclusies 21 tot en met 26, waarin de wals in stap (c) is uitgerust met rubberbanden en waarin de rubberbanden pneumatische rubberbanden zijn die een interne druk van tussen 3 en 9 barA hebben.A method according to any of claims 21 to 26, wherein the roller in step (c) is equipped with rubber tires and wherein the rubber tires are pneumatic rubber tires having an internal pressure of between 3 and 9 barA.

28. Werkwijze volgens één van de conclusies 21 tot en met 27, waarin de waterige oplossing die één of meer eerste oppervlakte-actieve stoffen omvat wordt toegepast op de poreusasfalt wegconstructie in stap (a) in een hoeveelheid tussen 5 en 250 g/m², bij voorkeur in een hoeveelheid tussen 30 en 180 g/m², bij sterkere voorkeur tussen 50 en 150 g/m².A method according to any one of claims 21 to 27, wherein the aqueous solution comprising one or more first surfactants is applied to the porous asphalt road construction in step (a) in an amount between 5 and 250 g / m ^2. , preferably in an amount between 30 and 180 g / m ² , more preferably between 50 and 150 g / m ² .

29. Werkwijze volgens één van de conclusies 21 tot en met 28, waarin de waterige oplossing die één of meer eerste oppervlakte-actieve stoffen omvat welke toegepast wordt in stap (a) een oppervlaktespanning heeft die hoger dan 20 mN/m is en lager dan 45 mN/m, bij voorkeur lager dan 40 mN/m, bij sterkere voorkeur lager dan 35 mN/m bij een temperatuur van 20 °C.The method of any one of claims 21 to 28, wherein the aqueous solution comprising one or more first surfactants used in step (a) has a surface tension greater than 20 mN / m and less than 45 mN / m, preferably less than 40 mN / m, more preferably less than 35 mN / m at a temperature of 20 ° C.

30. Werkwijze volgens één van de conclusies 21 tot en met 29, waarin de wals in stap (c) is uitgerust met rubberbanden en waarin een waterige oplossing die één of meer tweede oppervlakte-actieve stoffen omvat, waarbij genoemde waterige oplossing een oppervlaktespanning heeft bij een temperatuur van 20°C die lager is dan 45 mN/m, toegepast wordt op de rubberbanden in de vorm van een filmlaag, vóór de rubberbanden in aanraking komen met de poreus-asfalt wegconstructie welke gewalst moet worden.A method according to any of claims 21 to 29, wherein the roller in step (c) is equipped with rubber tires and wherein an aqueous solution comprising one or more second surfactants, said aqueous solution having a surface tension at a temperature of 20 ° C lower than 45 mN / m is applied to the rubber tires in the form of a film layer before the rubber tires come into contact with the porous-asphalt road construction to be rolled.

31. Werkwijze volgens conclusie 30, waarin de één of meer tweede oppervlakte-actieve stoffen worden gekozen uit de groep bestaande uit vetzuuramine oppervlakte-actieve stoffen, alkyl-di-amine oppervlakte-actieve stoffen, amido-amine oppervlakte-actieve stoffen, imidazoline-bevattende oppervlakte-actieve stoffen, betaïne-bevattende oppervlakte-actieve stoffen en tallolie-bevattende oppervlakte-actieve stoffen.The method of claim 30, wherein the one or more second surfactants are selected from the group consisting of fatty acid amine surfactants, alkyl diamine amine surfactants, amido amine surfactants, imidazoline containing surfactants, betaine-containing surfactants and tall oil-containing surfactants.

32. Werkwijze volgens conclusie 30 of 31, waarin de één of meer eerste en tweede oppervlakte-actieve stoffen identiek zijn.The method of claim 30 or 31, wherein the one or more first and second surfactants are identical.

33. Werkwijze volgens één van de conclusies 30 tot en met 32, waarin de waterige oplossing die één of meer tweede oppervlakte-actieve stoffen omvat, welke wordt toegepast op de rubberbanden in stap (c), een oppervlaktespanning van hoger dan 20 mN/m en lager dan The method of any one of claims 30 to 32, wherein the aqueous solution comprising one or more second surfactants applied to the rubber tires in step (c) has a surface tension of greater than 20 mN / m and lower than

45 mN/m heeft, bij voorkeur lager dan 40 mN/m, bij sterkere voorkeur lager dan 35 mN/m bij een temperatuur van 20 °C.45 mN / m, preferably less than 40 mN / m, more preferably less than 35 mN / m at a temperature of 20 ° C.

34. Werkwijze volgens één van de conclusies 21 tot en met 33, waarin stappen (a), (b) en 5 (c) worden uitgevoerd met een enkel voertuig uitgerust met een sproei-inrichting voor stap (a) aan de voorzijde en met een sproei-inrichting voor stap (b) aan de achterzijde, waarbij het voertuig aan de achterkant is gekoppeld aan een walsaanhanger, welke bij voorkeur uitgerust is met rubberbanden, voor stap (c).A method according to any of claims 21 to 33, wherein steps (a), (b) and 5 (c) are performed with a single vehicle equipped with a sprayer for step (a) at the front and with a rear sprayer for step (b), wherein the rear vehicle is coupled to a roller trailer, which is preferably equipped with rubber tires, for step (c).

10 35. Werkwijze volgens conclusie 22, waarin minerale deeltjes of aggregaten gedistribueerd worden over de poreus-asfalt wegconstructie verkregen in stap (d) en waarin stap (d) en de stap waarin minerale deeltjes of aggregaten gedistribueerd worden, worden uitgevoerd met een enkel voertuig uitgerust met één of meer van genoemde straatveegborstels aan de voorzijde en een strooischijf aan de achterzijde.35. The method of claim 22, wherein mineral particles or aggregates are distributed over the porous-asphalt road structure obtained in step (d) and wherein step (d) and the step in which mineral particles or aggregates are distributed are performed with a single vehicle equipped with one or more of the aforementioned street sweeping brushes at the front and a spreading disc at the rear.