SE1850989A1

SE1850989A1 - An apparatus and method of improving the quality of an asphalt pavement

Info

Publication number: SE1850989A1
Application number: SE1850989A
Authority: SE
Inventors: Conny Andersson
Original assignee: Adelo Ab
Priority date: 2018-08-20
Filing date: 2018-08-20
Publication date: 2020-02-21
Also published as: WO2020038958A1; SE543878C2

Abstract

14(14) ABSTRACT ln a method of and an apparatus for improving the quality of an asphalt pavement,the asphalt is charged in a supply arrangement (2) adapted to be fitted in an inletspace (11) ofa road finishing machine (1). The supply arrangement comprises arotary vessel (3) having a top inlet (30) for receiving the asphalt and a bottomoutlet (31) for discharging the asphalt, the bottom outlet (31) being smaller thanthe top inlet (30); a frame (4) supporting the rotary vessel (3); a bearingarrangement (7) carried by the frame (4) and carrying the vessel (3) rotatably; amotor (6) carried by the frame (4) for enabling rotation of the rotary vessel (3); anda transmission (5) for transmitting a rotation provided by the motor (6) to the rotaryvessel (3), and further by providing said rotary vessel (3) with a feeding member(300) comprising at least one pushing member (301)with a feeding surface (301A)attached to the inner surface (304) of the rotary vessel (3). (Pig. 3)

Description

1 (14) AN APPARATUS AND METHOD OF IMPROVING THE QUALITY OF ANASPHALT PAVEMENT FIELD OF INVENTIONThe present invention relates to an apparatus and a method of improving thequality of an asphalt pavement.ln the present context, the term "asphalt" is intended to mean a mixtureconsisting of mineral aggregate bound together with asphalt (bitumen).

BACKGROUND OF THE INVENTION Upon asphalting of a surface, homogeneousness is important, since it is theworst parts that initiate maintenance measures. ln practice, it is impossible toimprove the quality of an asphalt pavement at ambient temperature.Thermographic photographing reveals segregation problems, which may becaused by the asphalt plant, the transport of the asphalt out on the road, orpractical measures in connection to the change from one lorry batch to the nextone.

US 6,122,601 (Swanson et al.) discloses a compacted material densitymeasurement and compaction tracking system, namely a two-component systemto obtain uniform density of compacted materials and track the compaction of thematerials. The first component provides an automated, real-time compactiondensity meter and method of use to measure the density of the compactedmaterial. The second component provides a Geographic Information System (GIS)for tracking compaction of a surface at specific locations. These two componentscombined provide a system to measure the density of the compacted material andrecord the location of each density measurement. The can be utilized for manycompaction operations, such as the roller compaction of concrete, pavement, soil,landfills, and asphalt pavements.

From WO2007106033 there is known a system for preventing separation ofasphalt compositions, comprising separation preventing compartments arranged ina silo, intended for loading of asphalt onto vehicles, separation preventingcompartments intended to be arranged to a deck of a vehicle to be loaded with 2(14) asphalt, and separation preventing means arranged in a hopper of a paver to beloaded with asphalt from a vehicle. This design is relatively complex and maycause jamming problems.

Further, US 2014/0308074 (Rutz et al.) discloses a road finishing machine witha thermographic device releasably fixed to a portion of the machine for recording ageoreferenced thermographic data record of at least one region of a pavementlayer. The thermographic device includes a housing in which a detection unit fordetecting a thermographic data record and a further detection unit for detecting aspace-related data record for the thermographic data record are disposed.

SUMMARY OF THE INVENTION lt is an object according to the invention to provide a method and apparatus thatin reliable manner can improve quality of the newly produced asphalt pavement,as defined in claims 1 and 7.

Thanks to the invention it is achieved a method and apparatus by means ofwhich it is possible to produce an asphalt pavement that has an improved qualitydue to supplying and distributing the asphalt to the paving machine in a state thatis considerably much more homogenous than prior art methods/apparatuses. Byrotating the rotary vessel including its content of asphalt, the asphalt is made morehomogenous, whereby the sensitivity to formation of tracks in the pavement isreduced and likewise also quality defects caused by the batchwise supply ofasphalt to the rotary vessel.

Suitably, the rotary vessel generally has the shape of a truncated coneconverging downward and having a substantially vertical symmetry axis, and therotary vessel is rotated around the symmetry axis. Such a shape makes it easy tocharge, rotate and empty the vessel.

When making an asphalt pavement with conventional technology, the pavementquality on the left-hand side often differs from that on the right-hand side. To atleast reduce this difference, it is preferred to provide a distributing devicepositioned under the bottom outlet and adapted to be located above the belt conveyon 3(14) Tests have indicated that an improvement of about 20 % is well within reach bymeans of the invention, which implies enormous savings due to the fact that thelife time of the pavement will be prolonged proportionally.

Further advantages and preferred embodiments according to the invention willbe described in the following detailed description of the invention, which shall notbe construed to have any limiting effect in relation to the scope of claims. As isevident for the skilled person the basic principles according to the invention maybe used in a variety of actual method steps.

BRIEF DESCRIPTION OF THE DRAWINGS ln the following, the invention will be described in more detail with reference topreferred embodiments and the appended drawings wherein Fig. 1 is a schematic perspective view of a known pavement machine, i.e. aroad finishing machine, Fig. 2 shows a schematic perspective view of the pavement machine of Fig. 1arranged in accordance with the invention, including an embodiment of supplyarrangement in accordance with the invention, Fig. 3 shows a schematic perspective view of an embodiment of the supplyarrangement in accordance with the invention, seen from behind, Fig. 4 shows a schematic perspective view of an embodiment of the supplyarrangement in accordance with the invention, seen from the front, Fig. 5 shows a schematic view from above of a preferred embodiment of thesupply arrangement in accordance with the invention, Fig. 6 shows a partial vertical cross-sectional view along Vl-Vl in Fig 5, of thepreferred embodiment, Fig. 7 shows a plan view of a distributing device that may be used together withwith the invention, and, Fig. 8 shows a vertical cross-sectional view through the distributing device ofFig. 7. 4(14) MODE(S) FOR CARRYING OUT THE INVENTION ln Fig. 1 there is shown a road finishing machine 1, preferably provided with asensor 10 for scanning the temperature of an asphalt pavement P directly afterlaying of the asphalt pavement. The sensor 10 preferably is in form of line scannerthat measures the IR radiation. ln the preferred embodiment, the line scanner 1 isconnected to a quality measurement system as disclosed in WO2016198333,which is herewith introduced by way of reference.

Further the pavement machine has an inlet space 11 for supply of asphalt, e.g.from a truck (not shown). ln the bottom of the inlet space 11 there is a beltconveyor 12 (e.g. belt conveyor or screw conveyor), or two parallel conveyors 12that feed the asphalt to the screed 13 of the pavement machine, whereby asphaltis distributed to form a pavement P. The screed 13 distributes the asphaltwidthwise and levels and shapes it, and it usually includes leveling arms,moldboard, end plates, burners, vibrators, and slope sensors and controls. ln Fig. 2, there is shown a pavement machine 1 of Fig. 1 provided with a supplyarrangement 2 in accordance with the invention. Accordingly, the supplyarrangement 2 is intended to be used in connection with already existingpavement machines 1 but may of course also be used in connection with new kindof pavement machines. As is evident from the following the supply arrangement 2preferably is arranged with devices (see items 30, 45, 46) that will facilitate shiftingof the supply arrangement 2 from one place to another, e.g. different pavementmachines 1.

The supply arrangement 2 comprises a conical rotary vessel 3, a frame 4,rotatably supporting the rotary vessel 3, and as shown in Figs. 3 and 4, a bearingarrangement 7, a transmission 5, and a motor 6 for enabling rotation of the rotaryvessel 3. Below the rotary vessel 3 there may be a distributing device 9, shown inFigs. 7 and 8, for optimizing the distribution of asphalt supplied by the feedingarrangement/conveyor 12.

As shown in Figs. 3, 4 and 5 the rotary vessel 3 generally has the form of atruncated cone that has a substantially vertical rotation axis C and a largeropening at the top forming an inlet 30 and a smaller opening 31 at the bottomforming an outlet. Preferably the inner side of the vessel 3 has a surface 304 (14) provided with some kind of irregularities 32, providing a kind of engagement to theasphalt within the vessel 3 to safe guard that the asphalt follows the rotation of thevessel 3, to improve a mixing effect. ln the preferred embodiment, theseirregularities 32 may for instance be formed by folding a plurality of valleys alongvertical planes or by welding flat sub-plate members 33 to form correspondingvalleys. ln this manner, there is formed a kind of valleys 32 between platemembers assisting in providing a kind of engagement to asphalt within the vessel3. lt is evident for the skilled person that many different kind of engagementmembers 32 may be used, as will be presented more in detail in relation to Fig 5. below. ln a preferred embodiment as indicated in Fig 3 and shown in Figs. 5 and 6, thevessel 3 is arranged with a feeding member 300 attached adjacent the outlet 31 ofthe vessel, to safe guard that the material also in connection with low fill levels inthe vessel 3 will rotate together with the rotation of the vessel 3. The feedingmember 300 preferably comprises at least one pushing member 301 that providesa feeding surfaces 301A, that will push on the material to follow the rotation of thevessel 3 and thereby assist in providing the desired rotation of the material. Morepreferred there is arranged at least two pushing members 301, by means of atleast one plate extending along a chorda of the vessel 3.

As shown in Fig. 5 in one embodiment there is provided four pushing members301 providing four feeding surfaces 301A, by arranging four plates 306, 307, 308,309, joined at the center C to form a cross member, i.e. having two perpendicularparts extending along the diameter chorda of the vessel 3. Each plate 306, 307,308, 309 is at its outer end attached to the inner peripheral surface 304 of thevessel 3. Accordingly, such a feeding member 300 will provide four feedingsurfaces 301A that will push on the material to follow the rotation of the vessel 3and thereby assist in providing the desired rotation of the material. ln an alternateembodiment the plates of the feeding member 300 may be shorter and have theirinner ends attached to an annulus (not shown) or merely comprise one plate alonga chosen chorda or comprise two or more plates arranged along shorter chordasthan the diameter. 6(14) As shown in Fig. 3 a plate used for this purpose should present a certain heightY to provide a sufficient feeding surface 301A. ln a preferred embodiment theheight is in the range of 50-300 mm, more preferred 100-200 mm. Further thelower edge of a plate should preferably be arranged at a distance above the edgeof the outlet 31, e.g. in the range of 50-200 mm, which may provide furtherassistance in homogenization of the asphalt, i.a. by arranging for randomlydistributing asphalt supplied from different batches and/or layers in a batch.

As shown in Figs. 2-4 the upper outer side of the vessel 3 may be arranged withskirt 34 that is rigidly attached to the frame 4 and that may provide protection andinsulation. ln many applications, as shown in Fig 6, it may be preferred to not usea skirt 34.

The transmission 5 includes an annular gear 50 that is rigidly connected to therotary vessel 3 and in meshing engagement with a drive gear 51 driven by themotor 6.

The frame 4 may preferably include three connected base beams, i.e. twoparallel side beams 40 and one transversal beam 41 at the front. Extendingupwardly from the base beams 40, 41 there are a plurality of support beams 43,supporting a fixed part 73 of a bearing and also a support platform 44 for the motor6 and drive gear 51. A forvvardly extending frame part 47 carries lifting eyelets 45or similar devices (also preferably provided at the top of the rotary vessel 3), aload exchanging member 46 and wall members 49A, 49B. Preferably the sidebeams 40 are length adjustable by arranging telescopically adjustable beammembers 48, which may be adjusted to extend the length of the sides. ln Fig. 6 there is a detailed view of the rotary part of the transmission 5 and thebearing 7. As shown, the annular gear 50 has an inner side 70 that forms therotary surface of the bearing 7, in radial sliding (lubricated) contact with the outersurface of a fixed bearing ring 71. Balls 72 may be used to take the axial load. Thedrive gear 51 interacts with the outwardly protruding teeth 52 of the annular gear50. The annular gear 50 is fixed to a transmission ring welded onto the outer sideof the rotary vessel 3. The fixed bearing ring 71 is fixed to bearing part 73, which inturn is fixed to the support beams 43.

H14) Further, Fig 5 shows that a plurality of feeding ribs 303 may be attached to theinner surface 304 of the vessel 3, which extend along vertical planes from aposition adjacent the out|et to a position above half the height of the vessel 3.

At the bottom of the vessel, and in close proximity to the out|et 31, there isprovided a distributing device 9. As indicated in Figs. 7 and 8, the distributingdevice 9 is intended to be positioned between the out|et 31 and the conveyor 12 ofthe paving machine 1, i.e. between the side beams 41.

The distributing device 9 has a width W that substantially corresponds to thediameter D of the out|et 31 of the vessel 3. The length thereof is adapted to be agood fit within the paving machine 1. The distributing device 9 has two parallelouter frame members 90, 91 extending longitudinally in relation to the pavingmachine 1, i.e. the feed direction of the conveyor 12. A plurality of dividingmembers 93 are arranged transversely from one side to the other within thedistributing device 9, i.e. from one longitudinal frame member 90 to the other 91.Each dividing member 93A-93E has a different height h. At a most upstreamposition (with reference to the feed direction of the conveyor 12) there is a firstdividing member 93A having the largest height, h1. ln parallel therewith there arepositioned a plurality of further such dividing walls 93B-93E, wherein each dividingwall in the direction towards the discharge end of the conveyor the height hdecreases for each dividing wall. ln the shown example, there are positioned fivesuch dividing walls 93A-93E, wherein each of said dividing walls is positionedsuch that it crosses at least a subsection of the circle defined by the out|et 31 fromthe vessel 3. Accordingly, the total distance between the five dividing walls in thelongitudinal direction is substantially the same as or less than the diameter D ofthe out|et 31. Further, as is shown there is a substantially proportional decrease ofthe height h in the direction of feeding, such that the first dividing wall 93A has aheighth1 that is 5 times the height h5 of the final dividing wall 93E. The height h1 ofthe first dividing wall 93A will be smaller than height H of the frame members 90,91, such that there is created a gap g between the lower end thereof and theconveyor 12, which gap will get larger and larger in the feeding direction.

Furthermore, at the far end, downstream, of the distributing device 9 there isarranged a rearrangement device 95. The rearrangement device 95 has a s(14) concave surface 95A directed “obliquely” against the flow of asphalt that issupplied by means of the conveyor 12, forming a kind of roof that is higher at thecenter than near the sides, so that the asphalt layer on leaving the distributingdevice 9 is cambered. The rearrangement device 95 will create a form of the bedof asphalt leaving it, such that it minimizes, preferably eliminates, slipping of partsof the bed of asphalt, e.g. by creating sides that do not slope more than 45°.Further the rearrangement device 95 will create a counter pressure that is alsobeneficial.

The function of the invention is as follows. The supply arrangement 2 is fittedinto a paving machine 1, preferably by lifting it into the supply space 11 by use ofthe lifting eyelets 45. The distributing device 9 may be positioned on top of theconveyor member/s 12 of the paving machine 1 before or aftervvard. ln any casethe rotary vessel 3 and its frame 4 are positioned on top of the distributing device 9to be positioned as indicated in Fig. 6. ln operation, asphalt will be supplied into the rotary vessel 3 from above, e.g. bymeans of an intermediate feeder that is supplied from a truck tipping asphalt fromits flatbed (not shown), i.e. in a conventional manner for supplying asphalt to thepaving machine 1. Thanks to the rotation of the rotary vessel 3, the asphaltsupplied will be thoroughly intermixed, whereby temperature differences that haveappeared due to the transport and/or storage will be leveled-out. ln a preferredmanner then asphalt is supplied off-centered to the rotary vessel 3, i.e. onto theinner surface 304 of the rotary vessel, in order to possibly further improveintermixing of the asphalt in the rotary vessel. The conveyor 12 of the pavingmachine 1 continuously moves during operation and accordingly will bring alongthe asphalt A that is supplied on to it via the outlet 31 of the rotary vessel 3.

The distributing device 9 may provide for a further leveling out of the asphaltmixture by means of the dividing walls 93. A first volume A1 will be supplied nearthe bottom of the distributing device 9 in connection with a first dividing wall 93Aadjacent the upstream end of the conveyor 12. Thereafter, a second volume A2will be added (on top of the first volume A1) that is supplied down between the firstdividing wall 93A and the second dividing wall 93B, etc., and moved by theconveyor 12 towards the outlet end 94 of the distributing device 9. At the outlet 9(14) end 94 of the distributing device 9, a final rearrangement device 95 is provided,the rearrangement device 95 will create a form of the bed of asphalt leaving it,such that it minimizes, preferably eliminates, slipping of parts of the bed of asphalt,e.g. by creating sides that do not slope more than 45°. Further the rearrangementdevice 95 will create a counter pressure that is also beneficial. Thanks to theinvention very much more evenly distributed asphalt will be supplied to the pavingmachine 1, which will improve the quality of the asphalt.

Tests have indicated that an improvement of about 20 % is well within reach bymeans of the invention, which implies enormous savings, due to the fact that thelife time of the pavement will be prolonged proportionally.

The invention is not limited to what is defined above but may be varied withinthe scope of the claims. For instance, it is evident that a pavement machine 1without sensor 10 and without a distributing device 9 may be used to achieve thebasic advantages of the invention. Moreover, the skilled person realizes that insome applications in may be sufficient to use merely one dividing member 93arranged transversely from one side to the other within the distributing device 9,and in others two or three or perhaps more than five. Further it is to be understoodthat the rearrangement device 95 may be positioned adjacent the outlet end 94 oranywhere between the outlet end 94 and the position for the outlet. Moreover, it isevident that many of the expression used are in no way limiting, e.g. that therelationship value may take other formats than the one exemplified above.

Claims

1. O(14)

2. CLAIIVIS:

3. A method of producing an asphalt pavement, wherein asphalt is fed to a roadfinishing machine (1) having an inlet space (11), a screed (13), and aconveyor (12) forming a bottom of the inlet space (11) and conveying theasphalt to the screed (13) for leveling the layer of asphalt and partiallycompacting it to a desired shape, said method comprising: a) providing a supply arrangement (2) for supplying asphalt to the conveyor(12), said supply arrangement (2) being adapted to be fitted in the inletspace (11) and including: - a rotary vessel (3) having a top inlet (30) for receiving the asphalt anda bottom outlet (31) for discharging the asphalt, the bottom outlet (31)being smaller than the top inlet (30); b) positioning the supply arrangement (2) in the inlet space (11); c) charging asphalt in the rotary vessel (3), d) rotating the rotary vessel (3) to homogenize the asphalt as to particle sizeand temperature; and e) continuously letting asphalt flow from the bottom outlet (31) of the rotary vessel (3) down onto the conveyor (12),characterized by,providing a frame (4) supporting the rotary vessel (3); - a bearing arrangement (7) carried by the frame (4) and carrying thevessel (3) rotatably;- a motor (6) carried by the frame (4) for enabling rotation of the rotaryvessel (3); and- a transmission (5) for transmitting a rotation provided by the motor (6)to the rotary vessel (3), andfurther by providing said rotary vessel (3) with a feeding member (300)comprising at least one pushing member (301) attached to the innersurface (304) of the rotary vessel (3), and rotating said rotary vessel (3) tothereby cause a feeding surface (301A) of said pushing member (301) topush asphalt in the direction of rotation of the rotary vessel (3).

4. A method as claimed in claim 1, wherein the rotary vessel (3) generally hasthe shape of a truncated cone converging downward and having asubstantially vertical symmetry axis (C), and the rotary vessel (3) is rotatedaround the symmetry axis (C). 11 (14)

5. A method as claimed in claim 2, further comprising improving thehomogenization by providing irregularities (32) on said inner surface (304) ofthe rotary vessel (3), wherein preferably the irregularities (32) are in the formof valleys.

6. A method as claimed in any one of claims 1-3, further providing a plurality ofpushing members (301) attached to the inner surface (304) of the rotaryvessel (3).

7. A method as claimed in claim 1, further positioning a distributing device (9)under the bottom outlet (31) and above the conveyor (12), comprising twoparallel outer frame members (90, 91) extending in the feed direction of theconveyor (12); and at least one dividing member (93) extending transverselyfrom one outer frame member (90) to the other (91 ), the dividing member (93) being adapted to be spaced from the conveyor (12) by a gap (g), and by: - dividing the flow of asphalt from the bottom outlet (31) into a plurality oflayers by making the asphalt pass through passages on each side of theat least one dividing member (93) to the conveyor (12); and - feeding the plurality of homogenized asphalt layers on top of one anotherby the conveyor (12).

8. A method as claimed in claim 1, wherein the distributing device (9) comprises: - a plurality of, parallel dividing member/s (93) extending transversely fromone outer frame member (90) to the other (91), the dividing members (93)being adapted to be spaced from the conveyor (12) by gaps (g) ofdifferent size, wherein the size of the gaps (g) increasing in the feeddirection of the conveyor (12). - dividing the flow of asphalt from the bottom outlet (31) into a plurality oflayers by making the asphalt pass through passages on each side of thedividing members (93) to the conveyor (12).

9. A supply arrangement for supplying asphalt pavement, said supplyarrangement adapted to be included in an arrangement for supplying asphaltto a road finishing machine (1), said road finishing machine (1) having aninlet space (11), a screed (13), and a conveyor (12) forming a bottom of the

10.

11.

12. 12(14) inlet space (11) and conveying the asphalt to the screed (13), said supply arrangement being adapted to be fitted in the inlet space (11) and comprising: - a rotary vesse| (3) having a top inlet (30) for receiving the asphalt and abottom outlet (31) for discharging the asphalt, the bottom outlet (31) beingsmaller than the top inlet (30); characterized by, - a frame (4) supporting the rotary vesse| (3); - a bearing arrangement (7) carried by the frame (4) and carrying thevesse| (3) rotatably; - a motor (6) carried by the frame (4) for enabling rotation of the rotaryvesse| (3); and - a transmission (5) for transmitting a rotation provided by the motor (6) tothe rotary vesse| (3), and further by providing said rotary vesse| (3) with afeeding member (300) comprising at least one pushing member (301)with a feeding surface (301A) attached to the inner surface (304) of therotary vesse| (3). A supply arrangement as claimed in claim 7, wherein the rotary vesse| (3)generally has the shape of a truncated cone converging downward andhaving a substantially vertical rotation axis (C). A supply arrangement as claimed in claim 7 or 8, wherein said feedingmember (300) comprises a plurality of pushing members (301) attached tothe inner surface (304) of the rotary vesse| (3). A supply arrangement as claimed in any of claims 7 - 9, wherein the rotaryvesse| (3) has an inner surface (304) arranged with irregularities (32). A supply arrangement as claimed in claim 10, wherein said irregularities (32)are formed by valleys between sub-plate members (33) that constitute thewall with said inner surface (304). A supply arrangement as claimed in claim 10 or 11, wherein saidirregularities (32) include engagement members (303) that protrude from saidinner surface (304), preferably in the form of longish ribs that extendsubstantially in a vertical plane. 1304)

13. A supply arrangement as claimed in any one of claims 10-12, further comprising a distributing device (9) located under the bottom outlet (31) ofthe rotary vessel (3) comprising two parallel outer frame members (90, 91);and, at least one dividing member (93) extending transversely from one outerframe member (90) to the other (91), the at least one dividing member (93)being spaced from the conveyor (12) to form a gap (g) between it and theconveyor (12).