GB2612697A

GB2612697A - Binder

Info

Publication number: GB2612697A
Application number: GB2213988.5A
Authority: GB
Inventors: Gorbold Ian; Boustead Paul
Original assignee: LONGCLIFFE QUARRIES Ltd
Current assignee: LONGCLIFFE QUARRIES Ltd
Priority date: 2021-09-27
Filing date: 2022-09-26
Publication date: 2023-05-10
Also published as: GB202113748D0; GB202213988D0

Abstract

A binder for screed compositions comprising calcium carbonate (CaCO3), neopentylglycol (NPG), a superplasticiser comprising one or more modified polycarboxylated ethers (PCE), a stabiliser comprising a high molecular weight synthetic polymer/powder, a curing agent, and 0.5-10 wt% of silicon dioxide (SiO2). The binder may comprise calcium carbonate, the curing agent and an adjuvant, wherein the adjuvant comprises calcium carbonate, neopentylglycol, superplasticiser, stabiliser, and silicon dioxide. The binder may further comprise calcium sulphate, which may be present in the adjuvant. The binder may be in powder form. The curing agent may comprise a fatty alcohol, with a chain length of C8-C22, and may comprise a carrier material comprising silica gel. The binder may be used in a screed or concrete, further comprising sand, cement and/or water. A screed comprising the binder, a concrete comprising the binder, and a method of forming a binder are also defined, wherein the method comprises combining and milling calcium carbonate, neopentylglycol, a plasticiser comprising one or more modified polycarboxylated ethers, a stabiliser comprising starch, a curing agent and silicon dioxide to form an adjuvant, and then combining with calcium carbonate to form a binder. Alternatively, the curing agent may be present separately from the adjuvant.

Description

Intellectual Property Office Application No GI32213988.5 RTM Date:6 March 2023 The following terms are registered trade marks and should be read as such wherever they occur in this document: Dynamon Longcliffe Viscocrete Sika Starvis Melflux

BASF

Intellectual Property Office is an operating name of the Patent Office www.gov.uk/ipo Binder

Field

The invention relates to a binder for screed compositions and a method of manufacture thereof. In particular, the invention relates to a binder for screed compositions comprising calcium carbonate, a curing agent and 0.5-10 wt% silicon dioxide.

Background

Screed is a levelled layer of material which is typically applied to a floor or other surface.

It is predominantly used as a top finishing layer, as it has a smoother texture compared to concrete. Screed is made using a binder system, wherein a binder material is mixed with wet ingredients (predominantly water) to form a free flowing material. However, some problems can arise when applying screed. In particular, screed formulations, if applied in the absence of a curing agent, will often harden too quickly, resulting in plastic cracking. Therefore, curing agents are sprayed onto screed formulations after application to the floor to retard setting. Whilst this post-application of curing agents prevents cracking, it introduces an additional step into the screed application process, wherein the correct amount of curing agent must be evenly applied to the screed surface before it sets. As a result of insufficient or uneven application of the curing agent, cracks can appear in screed despite the use of curing agents.

Further, cracking can also occur if the formulation of the binder and/or the proportions of binder to the wet ingredients is not adequate. Other problems include segregation and bleeding. Also, sometimes screed can take a long time to dry, which is not only inconvenient but can also cause setbacks to further work scheduled, which may have cost implications both for the contractor and for the customer.

Plasticisers and superplasticisers are used in screed compositions (or the like) to improve the workability and flow enablement of the mixture. However, they are usually added in liquid form as a final step in the mixing process. EP 2423365 Al discloses a process for preparation of cement/mortar/concrete systems, wherein the calcium carbonate based filler used is treated with an efficient amount of a treating agent, which comprises one or more superplasticisers. The aim of the pre-treatment step is to produce improved high performance fluid cement (or the like). Specifically, EP 2423365 Al refers to well-known liquid plasticisers for use as a treating agent, such as Dynamon NRG 100 and CHRYSaEPremia 196.

As detailed in GB2593467 (application number GB2004179.4), the applicant developed a binder composition for use in screed compositions, which has one or more of the properties of improved workability, ease of dispensing, self-levelling capabilities, is fast drying, and wherein the resultant screed composition is simple and cost effective to manufacture.

GB2593467 describes binder or screed composition in which all actives, in particular the superplasticiser and the curing agent are integral to the formulation, and ideally in powder form removing the need for the mixing of components in different phases (e.g. solid and liquid) or the need for a post-application step.

Whilst binders detailed in GB2593467 demonstrate numerous advantages over existing binders, there is always a need to further improve the pumpability, the compressive strength of the screed, and the compatibility with cement replacements (such as Ground Granulated Blast-furnace Slag and Portland Limestone Cement). The invention is intended to overcome or ameliorate at least some aspects of these problems.

Accordingly, in a first aspect of the invention there is provided a binder for screed compositions comprising: calcium carbonate, neopentylglycol, superplasticiser comprising one or more modified polycarboxylated ethers, stabiliser comprising a high molecular weight synthetic polymer/powder, a curing agent, and 0.5-10 wt% silicon dioxide.

It may be the case that calcium carbonate is present in the binder at the level of 85-95 wt%, often 90-94 wt%.

Often, the binder will comprise one or more of the components independently in amounts of 87-95.5 wt% calcium carbonate; 0.5-2.5 wt% neopentylglycol; 0.1-1 wt% of a superplasticiser often comprising one or more modified polycarboxylated ethers; 0.1-0.5 wt°/0 of a stabiliser often comprising a high molecular weight synthetic polymer/powder; 0.05-1 wt% curing agent, 0.5-3 wt% silicon dioxide, and 1-5 wt% calcium sulphate.

In many cases, one or more of the components may be present at the level 89-95.5 wt% calcium carbonate; 1-2 wt% neopentylglycol; 0.25-0.75 wt% of a superplasticiser comprising one or more modified polycarboxylated ethers; 0.2-0.4 wt% of a stabiliser comprising a high molecular weight synthetic polymer/powder; 0.1-0.8 wt% curing agent, 0.5-3 wt% silicon dioxide, and 2-4 wt% calcium sulphate; or any of these levels combined with the levels described immediately above.

The applicant has found that the binder according to the invention, when used in screed compositions or the like, not only results in a fluid, easy to dispense, self-levelling and rapid drying final product that is essentially free of cracks, but also has enhanced pumpability, improved mix rheology of the screed when combined with the binder, higher compressive strength, and better compatibility with cement replacements. Moreover, the binder is more tolerant of fluctuations within sand quality, meaning that the resultant screed is of a high quality, even when mixed with poorer quality sands. In addition, the applicant has found that, in some instances, the final product can dry within 24 hours offering huge benefits relative to existing systems which can take a number of days to dry. The rapid drying reduces the down time in build projects, improving efficiency and reducing costs as projects can be finished more rapidly with less construction down time.

For ease of reference, the term "screed composition" includes any one of a screed composition, a cement composition, a mortar composition, a concrete composition or similar cementous products.

The curing agent may be any component which promotes "curing" (i.e. toughening or hardening of the screed) at a controlled rate, in particular the curing agents described herein will typically slow drying slightly (e.g. by 10%) to ensure that the surface dries without cracking often by preventing early shrinkage. Often the curing agent will be a powder, although liquid curing agents may also be used. In many cases, the curing agent will comprise a straight or branched chain fatty alcohol, often of chain length in the range C8 -C22. In some examples, the curing agent may comprise a carrier material, such as a silicon dioxide-containing compound, to act as a carrier for the fatty alcohol. As such, the curing agent may comprise a fatty alcohol on (supported on, for instance by absorption or adsorption) an inorganic carrier material, such as a silicon dioxide-containing material, for instance silica gel. This may improve the stability of the curing agent, by preventing degradation of the fatty alcohol. In addition, as some fatty alcohols are liquids at room temperature, combining these with the carrier material provides for a curing agent which is in powder form, and so is easier to store and transport. The carrier material also facilitates with dispersion of the curing agent within the mixture. It may be that the density of the powder is in the range 500 -750 kg/m3, often in the range 540 -740 kg/m3. It may be the case that the curing agent is present in the binder at the level of 0.05-1 wt%, often 0.1-0.8 wt%, more often 0.2-0.7 wt%.

Where the curing agent includes a silicon dioxide-containing material, this is distinct from, and in addition to, the 0.5-10 wt% silicon dioxide that is also present in the binder composition.

The integral presence of the curing agent removes the need for the post-application of curing agent after the screed has been laid, ensuring even distribution of the curing agent throughout the screed composition, such that localised cracking due to poor application of the screed to the surface is minimised or eliminated. Further, it has been found that by incorporating the curing agent directly into the composition the surface produced is harder and so more robust than surfaces where the curing agent is applied using post-application methods.

In addition to the curing agent, the binder includes 0.5-10 wt% silicon dioxide, optionally 0.5-3 wt%. (When the curing agent includes a silicon dioxide-containing material, this is in addition to the curing agent, and separate from it). The applicant has found that inclusion of silicon dioxide improves the mix rheology of resultant screed. Moreover, the presence of silicon dioxide results in a screed formulation with enhanced compressive strength compared to existing screed formulations, and with better compatibility with cement replacements. The binders also allow for enhanced pumpability. It may be the case that silicon dioxide is present in the binder at the level of 1-9 wt%, more often 2-4 wt%.

The silicon dioxide is preferably in particulate form, such as a powder. It may be that the density of the powder is in the range 200 -800 kg/m3, often in the range 500 -700 kg/m3. It may be the case that the density is in the range of 200 -400 kg/m3, often in the range of 200 -350 kg/m'.

It may be the case that the silicon dioxide is in particulate form, and the silicon dioxide particles comprise water. Often the silicon dioxide particles consist of silicon dioxide and water. Typically, the silicon dioxide particles comprise less than 5 wt% water, more typically less 3 wt% water, more typically less than 1 wt°/0 water.

It is generally the case that the particle size of the silicon dioxide is in the range of 30-90 pm, often in the range of 40-80 pm. Typically, greater than 75% of the silicon dioxide particles are of size in the range of 30-90 pm. Preferably, greater than 95%. Ensuring that the particle size distribution is well controlled, and that the particles are of defined particle size with minimal particles outside the distribution, will ensure a good distribution of particles throughout the binder, making it easier to produce a homogeneous product.

Neopentyl glycol can be incorporated within the binder to prevent shrinkage and cracking of the resultant screed composition. However, finely dispersed particles of neopentyl glycol can form explosive mixtures in air. The applicant has found that mixing and milling neopentyl glycol with inert limestone (calcium carbonate), often in a premixing step to form an adjuvant, renders the finely dispersed neopentyl glycol particles non-explosive. It may be the case that neopentylglycol is present at the level of 0.5-2.5 wt%, often 0.751.5 wt%, more often 1-2 wt%.

A superplasticiser may be incorporated within the binder to act as a flow enabler, aiding the working of the resultant screed composition. As mentioned previously, standard practice in the field of cement and screed manufacture is to add a liquid plasticiser separately at the point of use, reducing efficiency and making the screed formation process more time consuming for the user. Further, there is also a need to remember the extra step of adding the plasticiser, which means a higher chance of error in the formation process. However, inclusion of a superplasticiser in the initial binder composition removes the need for this additional step, simplifying the manufacturing process and saving cost. Further, superplasticisers comprising polycarboxylate ethers provide cement dispersion by steric stabilisation as opposed to electrostatic repulsion, which results in a screed composition with good workability. It may be the case that the superplasticiser comprising one or more modified polycarboxylated ethers is present in the binder at the level of 0.11 wt°/0, often 0.25-0.75 wt%, more often 0.3-0.6 wt°/o.

Segregation of a screed composition is where the constituent materials separate, resulting in a weaker material, due to the lack of homogeneity. Bleeding is a particular form of segregation where water in the concrete, cement, screed or the like rises to the surface, as the solid material is unable to retain all the water; this process inevitably weakens the structure of the material. Inclusion of a stabiliser within the binder assists in the prevention of bleeding and segregation, and will result in a binder which will produce a more structurally sound screed composition. It may be the case that the stabiliser comprising a high molecular weight synthetic polymer/powder is present in the binder at the level of 0.1-0.5 wt%, often 0.2-0.4 wt%. As used herein, the term "high molecular weight synthetic polymer/powder" relates to synthetic polymers or powders with a number average molecular weight greater than or equal to 800 g/mol. The number average molecular weight of the stabiliser may be in the range of 800 g/mol to 10,000 g/mol, often 1,000 g/mol to 5,000 g/mol. The number average molecular weight can be measured using any known technique, such as for example gel permeation chromatography (GPC), mass spectrometry, osmometry, light scattering, or viscometry.

Calcium sulphate may be incorporated within the binder to further aid in prevention of cracking upon drying. The calcium sulphate may be present in the binder at the level of 1-10 wt%, often at the level of 1-5 wt%, more often at the level of 2-4 wt%.

As noted above, the term "screed" is intended to include not only screeds, but also concretes, cements or similar cementous products. In particular, however, the binder is intended for use with screed products or shrink resistant concretes. The binder lends itself particularly to use in screeds as it provides excellent fluidity, a property of particular importance to the levelling process. As such a self-levelling screed can be provided.

Optionally, there is provided a binder according to the first aspect of the invention, comprising: calcium carbonate, the curing agent, and an adjuvant, the adjuvant comprising: further calcium carbonate, the neopentylglycol, the superplasticiser, the stabiliser, and the silicon dioxide. The adjuvant may further comprise calcium sulphate.

It may be that the binder comprising the adjuvant will comprise, independently, one or more of the components in the levels: 75-90 wt% binder calcium carbonate; 0.05-1 wt% binder curing agent; and 10-20 wt% of an adjuvant, the adjuvant comprising: 30-45 wt% calcium carbonate; 10-15 wt% neopentylglycol; 2-8 wt% of a superplasticiser comprising one or more modified polycarboxylated ethers; 1-5 wt% of a stabiliser comprising a high molecular weight synthetic polymer/powder; 5-10 wt% silicon dioxide; and 15-40 wt% calcium sulphate.

As noted above, the pre-formation of the adjuvant stabilises the neopentyl glycol, ensuring safer handling of the binder during manufacture and in subsequent use. Further, inclusion of a powdered plasticiser instead of a liquid plasticiser allows for better dispersion within the binder, resulting in a final product with enhanced workability.

Adding the curing agent directly to the calcium carbonate, and not to the adjuvant, can be advantageous in terms of overall product stability, as the adjuvant cannot be stably stored for as long when the curing agent is in direct contact with the other adjuvant components.

The curing agent will often be present in the range 1 -10 kg/m3, often 2 -8 kg/m3 or 4 -6 kg/m3 of the screed, although the range 1 -10 kg/m3 would provide for binders which prevent cracking when used in screed compositions. Alternatively, the curing agent could be said to be present in the range 0.05-1 wt%, 0.1 to 0.8 wt°/0 or 0.2 -0.6 wt% of the binder, or in the range 0.5 -5 wt% or 1 -4 wt% of an adjuvant which is then added to calcium carbonate to form the binder. Although improvements are observed below these levels, above the minimum levels suggested here, cracking is almost never observed.

Above the maximum levels suggested here, cracking is prevented and so there is no need to add more curing agent to the composition beyond the 10 kg/m3, and often the 8 kg/m3 or 6 kg/m3 suggested.

The binder will often be "dry" in the sense that it will not be diluted with liquids. The "dry" binder may be flaked, granular or in powder form. Often, the binder will be in powder form. Dry products are easier to both transport and store than pre-formed liquid products, making transport more cost effective for the manufacturer and the customer. Powder is the preferred dry form of the binder as powders form homogeneous mixtures most easily.

It will generally be the case that the calcium carbonate of the binder is in the range 9899.5 wt% pure. This ensures consistent product performance, as such high purity of the primary component of the mixture means that few by-products are produced. Preferably, the calcium carbonate comprises in the range 0.001-0.1 wt% water, as a dry product will form a chemically stable and consistent binder.

Generally, the calcium carbonate will be from the same source, regardless of whether it is in the adjuvant or bulk binder. Therefore, all references to the physical properties of the calcium carbonate (or limestone, used herein interchangeably), apply to calcium carbonate in the adjuvant and/or in the bulk binder. It is generally the case that the particle size of the calcium carbonate be in the range of 1-75 pm. Typically, greater than 75% of the calcium carbonate particles are of size in the range of 1-75 pm. Preferably, greater than 95%. Ensuring that the particle size distribution is well controlled, and that the particles are of defined particle size with minimal particles outside the distribution, will ensure a good distribution of particles throughout the binder, making it easier to produce a homogeneous product.

The particle sizes of the other components of the adjuvant/binder will be in a similar range to the calcium carbonate, so as to ensure thorough mixing of all components within the 35 adjuvant/binder.

It is also generally the case that the neopentylglycol of the binder is in the range 99-99.9 wt% pure, to ensure minimal side reactions within the binder or screed composition.

According to a second aspect of the invention, there is provided a screed comprising the binder of the first aspect of the invention. Further provided, in a third aspect of the invention, there is provided a concrete comprising the binder of the first aspect of the invention.

The screed or concrete may comprise one or more of sand, cement and water as would be known to the person skilled in the art.

In a fourth aspect of the invention there is provided a method for producing a binder for screed compositions, comprising the steps of: (i) combining calcium carbonate, neopentylglycol, a plasticiser comprising one or more modified polycarboxylated ethers, a stabiliser comprising starch, a curing agent, and silicon dioxide; (ii) milling the combination of (i) to form an adjuvant; and (iii) combining the adjuvant with calcium carbonate to form a binder, wherein silicon dioxide is present at the level of 0.5-10 wt% of the binder formulation. It may be the case that step (i) further comprises combining calcium sulphate.

Where calcium sulphate is present, the method may comprise, independently, the following levels of components, such that the method may comprise the steps of: (i) combining by weight of the adjuvant formed 30-45 wt% calcium carbonate, 10-15 wt% neopentylglycol, 2-8 wt% of a plasticiser comprising one or more modified polycarboxylated ethers, 1-5 wt% of a stabiliser comprising starch, 5-10 wt% silicon dioxide, 15-40 wt% calcium sulphate, and 0.5 to 5 wt% curing agent; (ii) milling the combination of (i) to form an adjuvant; and (Hi) combining the adjuvant with 75-90 wt%, often 80-90 wt%, by weight of the binder calcium carbonate to form a binder, wherein silicon dioxide is present at the level of 0.5-10 wt% of the binder formulation.

In some examples, the curing agent may be added after the other components of the binder have been combined, this can improve the storage stability and workability of the resulting binder. In such cases, the adjuvant comprises calcium carbonate, neopentylglycol, plasticiser, stabiliser, and silicon dioxide as described above, and the adjuvant and curing agent are added to the calcium carbonate to form a binder, such that there is provided a method for producing a binder for screed compositions, comprising the steps of: (i) combining calcium carbonate, neopentylglycol, a plasticiser comprising one or more modified polycarboxylated ethers, a stabiliser comprising starch, and silicon dioxide; (ii) milling the combination of (i) to form an adjuvant; and (Hi) combining the adjuvant with calcium carbonate, and curing agent to form a binder. It may be the case that step (i) further comprises combining calcium sulphate.

Where calcium sulphate is present, this method could be further defined as a method for producing a binder for screed compositions, comprising the steps of: (i) combining, independently by amount, by weight of the adjuvant 30-45 wt% adjuvant calcium carbonate, 10-15 wt% adjuvant neopentylglycol, 2-8 wt% adjuvant of a plasticiser comprising one or more modified polycarboxylated ethers, and 1-5wt% adjuvant of a stabiliser comprising starch, 5-10 wt% silicon dioxide, and 15-40 wt% calcium sulphate; (ii) milling the combination of (i) to form an adjuvant; and (iii) combining the adjuvant with 75-90 wt%, often 80-90 wt% of the binder calcium carbonate, and 0.05 -1 wt% of the binder curing agent to form a binder, wherein silicon dioxide is present at the level of 0.5-10 wt% of the binder formulation.

It is generally the case that combining steps (i) and/or (iii) comprise mixing of the components for a time in the range 1 to 5 minutes as this balances homogenous mixing with the time spent ensuring an effective binder mix. Often the range will be 1 to 3 minutes.

Unless otherwise stated, each of the integers described may be used in combination with any other integer as would be understood by the person skilled in the art. Further, although all aspects of the invention preferably "comprise" the features described in relation to that aspect, it is specifically envisaged that they may "consist" or "consist essentially" of those features outlined in the claims. In addition, all terms, unless specifically defined herein, are intended to be given their commonly understood meaning in the art.

Further, in the discussion of the invention, unless stated to the contrary, the disclosure of alternative values for the upper or lower limit of the permitted range of a parameter, is to be construed as an implied statement that each intermediate value of said parameter, lying between the smaller and greater of the alternatives, is itself also disclosed as a possible value for the parameter.

In addition, unless otherwise stated, all numerical values appearing in this application are to be understood as being modified by the term "about".

In order that the invention may be more readily understood, it will be described further with reference to the specific examples hereinafter.

Examples

Comparative Binder Compositions A and B Comparative Example Binders are described below: Binder Composition A Wt% SuperlonTM filler L150 97.64 (Limestone -sold by Longcliffe) Neopentyl glycol (NPG) 1.5 ViscocreteTM 520P 0.55 (Plasticiser -sold by Sika) StarvisTM 3040F 0.31 (Stabiliser -sold by BASF) Me!flux 5919F Powder Dosed at 0.4 -0.8 wt% as required (Curing Agent -sold by BASF) Binder Composition B Wt% SuperlonTM filler L150 97.64 (Limestone -sold by Longcliffe) Neopentyl glycol (NPG) 1.5 MelfluxTM AP101F 0.55 (Plasticiser -sold by BASF) StarvisTM 3040F 0.31 (Stabiliser -sold by BASF) Me!flux 5919FPowder Dosed at 0.4 -0.8 wt% as required (Curing Agent -sold by BASF) Method of manufacture of Comparative Binder Compositions A and B Binder compositions A and B can both be prepared by the method outlined below.

Firstly, SuperlonTM filler L150, neopentyl glycol (NPG), ViscocreteTM 520P (or MelfluxTM AP101F for Binder composition B), and StarvisTM 3040F, are combined in a ploughshare batch mixer to form an adjuvant. Specifically, the components are combined in the following proportions by weight: (ii) Adjuvant INV% SuperlonTM filler L150 76.4 Neopentyl glycol (NPG) 15 ViscocreteTM 520P (or MelfluxTM AP101F) 5.5 StarvisTM 3040F 3.1 The four components of the adjuvant are then metered into a ploughshare batch mixer via loss in weight control systems. The residence time of the four components within the mixer is in the range of 1 to 3 minutes (adjustable by computer control).

After mixing in the ploughshare is complete, the resulting adjuvant will be discharged into a turbine mill.

The adjuvant is then transported and stored, so that it can be used to prepare Binder Composition A or B. Binder Compositions A and B are produced by mixing the respective adjuvant with SuperIon L150, and the curing agent powder in the following proportions: SuperlonTM filler 1150 (or equivalent such as 90 wt% SuperlonTM L100 or SuperlonTM A6) Adjuvant 9.2 -9.6 wt% Me!flux 5919F 0.4 -0.8 wt% The adjuvant, curing agent and SuperlonTM filler L150 are discharged into a continuous ploughshare mixer via a metered loss in weight system. The retention time within the mixer is between 1 and 3 minutes. The retention time is controlled by adjustment of a weir at the exit of the mixer. Finished Binder Composition A and B may then be pneumatically conveyed into dedicated storage silos ready for use in concrete or cement or the like.

The resulting binder compositions can provide screed formulations with excellent compressive ( 25 N/mm2 after 28 days) and flexural (6 N/mm2) strength.

Invention The present inventors have found that the addition of silicon dioxide, and preferably also calcium sulphate leads to improved mix rheology, enhanced pumpability of the resultant screed, and also screed formulations having a high compressive strength. Moreover, binders according to the invention have better compatibility with cement replacements, such as Portland limestone cement. In addition, they are more tolerant of fluctuations within sand quality.

When silicon dioxide, and preferably also calcium sulphate, are included in comparative binder compositions A and B at a level of 0.5-4 wt % of the total binder composition, the resulting screed formulations have even higher compressive and flexural strength.

Specifically, the present inventors have found that the addition of silicon dioxide, and preferably also calcium sulphate, at a level of 2-4 wt% to comparative binder compositions A and B results in screed formulations having a compressive strength of around between 2 and 3 N/mm2, and a flexural strength of around 1 N/mm2, higher than the values listed above for comparative screed formulations using binder compositions A and B. In addition, the present inventors have found that the addition of silicon dioxide at a level of 0.5-1.5 wt%, and, and preferably also calcium sulphate at a level of 2-4 wt%, to comparative binder compositions A and B results in screed formulations having a compressive strength of around between 30-35 N/mm2, and a flexural strength of around 7-9 N/mm2, higher than the values listed above for comparative screed formulations using binder compositions A and B. Binders according to the invention can be prepared using the method outlined above for comparative binder formulations A and B. It would be appreciated that the process and apparatus of the invention are capable of being implemented in a variety of ways, only a few of which have been illustrated and described above.

Claims

Claims 1. A binder for screed compositions comprising: calcium carbonate, neopentylglycol, superplasticiser comprising one or more modified polycarboxylated ethers, stabiliser comprising a high molecular weight synthetic polymer/powder, a curing agent, and 0.5-wt% of silicon dioxide.
2. A binder according to claim 1, comprising: calcium carbonate, the curing agent, and an adjuvant, the adjuvant comprising: calcium carbonate, the neopentylglycol, the superplasticiser, the stabiliser, and the silicon dioxide.
3. A binder according to claim 1, further comprising calcium sulphate, optionally wherein the calcium sulphate is present in the range of 1-10 wt%.
4. A binder according to claim 2, wherein the adjuvant further comprises calcium sulphate.
5. A binder according to claim 3 independently comprising: 87-95.5 wt% calcium carbonate; 1-2 wt% the neopentylglycol; 0.1-1.0 wt% of the superplasticiser; 0.2-0.4 wt% of the stabiliser; 0.05-1 wt% the curing agent; 0.5-3 wt% the silicon dioxide; and 1-5 wt% calcium sulphate.
6. A binder according to claim 4, independently comprising: 75-90 wt% calcium carbonate; 0.05-1 wt% the curing agent; and 10-20 wt% of an adjuvant, the adjuvant comprising: 30-45 wt% calcium carbonate; 10-15 wt% the neopentylglycol; 2-8 wt% of the superplasticiser; 1-5 wt% of the stabiliser 5-10 wt% the silicon dioxide; and 15-40 wt% calcium sulphate.
7. A binder according to any preceding claim, wherein the binder is powder form.
8. A binder according to any preceding claim, wherein the calcium carbonate is in the range 98-99.5 wt% pure.
9. A binder according to any preceding claim, wherein the calcium carbonate comprises in the range 0.001-0.1 wt% water.
10. A binder according to any preceding claim, wherein the calcium carbonate is of particle size in the range of 1-75 pm, optionally wherein greater than 95% of the calcium carbonate particles are of size in the range of 1-75 pm.
11. A binder according to any preceding claim, wherein the silicon dioxide is of particle size in the range of 30-90 pm, optionally wherein greater than 95% of the silicon dioxide is of particle size in the range of 30-90 pm.
12. A binder according to any preceding claim, wherein the neopentylglycol is in the range 99-99.9 wt% pure.
13. A binder according to any preceding claim, wherein the curing agent comprises a fatty alcohol.
14. A binder according to claim 13, wherein the fatty alcohol is of chain length in the range C8 -C22.
15. A binder according to any preceding claim wherein the curing agent comprises a carrier material, optionally wherein the carrier material comprises silica gel.
16. A screed comprising the binder of any preceding claim.
17. A concrete comprising the binder of any one of claims 1 to 15. 30
18. A screed or concrete according to claim 16 or claim 17, further comprising one or more of sand, cement and water.
19. A method for producing a binder for screed compositions, comprising the steps of: (i) combining calcium carbonate, neopentylglycol, a plasticiser comprising one or more modified polycarboxylated ethers, a stabiliser comprising starch, a curing agent, and silicon dioxide; (ii) milling the combination of (i) to form an adjuvant; and (iii) combining the adjuvant with calcium carbonate to form a binder; wherein silicon dioxide is present at the level of 0.5-10 wt% of the binder.
20. A method for producing a binder for screed compositions, comprising the steps of: (i) combining calcium carbonate, neopentylglycol, a plasticiser comprising one or more modified polycarboxylated ethers, a stabiliser comprising starch, and silicon dioxide; (ii) milling the combination of (i) to form an adjuvant; and (iii) combining the adjuvant with calcium carbonate, and curing agent to form a binder; wherein silicon dioxide is present at the level of 0.5-10 wt% of the binder.
21. A method according to claim 19, wherein step (i) further comprises combining calcium sulphate.
22. A method according to claim 20, wherein step (i) further comprises combining calcium sulphate.
23. A method according to claim 21, comprising the steps of: (i) combining 30-45 wt% calcium carbonate, 10-15 wt% the neopentylglycol, 2 -8 wt% of the plasticiser, 1-5 wt% of the stabiliser, 5-10 wt% silicon dioxide, 15-40 wt% calcium sulphate and, 0.5-5 wt% the curing agent; (ii) milling the combination of (i) to form an adjuvant; and (iii) combining the adjuvant with 75-90 wt% calcium carbonate to form a binder.
24. A method according to claim 22, comprising the steps of: (i) combining 30-45 wt% adjuvant calcium carbonate, 10-15 wt% adjuvant the neopentylglycol, 2-8 wt% adjuvant of the plasticiser, and 1-5 wt% adjuvant of the stabiliser, 5-10 wt% silicon dioxide, and 15-40 wt% calcium sulphate; (ii) milling the combination of (i) to form an adjuvant; and (iii) combining the adjuvant with 75-90 wt% of the binder calcium carbonate, and 0.05-1 wt% of the binder of the curing agent to form a binder.
25. A method according to any of claims 20 -24, wherein the combining steps (i) and/or (iii) comprise mixing of the components for a time in the range 1-5 minutes.