Products, methods and systems for the repair or reinstatement of a recessed portion of an area of hard standing

Abstract

Disclosed herein is a products, systems and compositions for the repair or reinstatement of a recessed portion of an area of hard standing, optionally for the repair of a pothole. Methods of preparing the product, systems and composition are also disclosed, along with methods of use.

Description

[0001] Products, methods and systems for the repair or reinstatement of a recessed portion of an area of hard standing.

[0002] The invention relates to the repair of damage to surfaces of areas of head standing, for example, driveways, roads, pavements or the like, in particular, in the form of potholes which are created over time and trenches which are typically created to allow access for installation or repair of underground services. The potholes are typically caused by removal of the top surface of the road over time due, for example, to the excessive wear or impact from vehicles, ingress of rain or frost and / or inferior materials or base structure, or a combination of the same. The invention is now described with reference to potholes but in a non-limiting manner.

[0003] The occurrence of potholes is well known and can become more prevalent as the age of the driveway, road or pavement increases without general maintenance of the same being performed.

[0004] A conventional approach to repairing potholes has been to remove a portion of the surface surrounding the potholes to form a base and create a new surface using hot tarmacadam. The material is required to be above a specific temperature to allow the same to be sufficiently pliable and to be applied when hot onto the base and manipulated and compacted quickly before the same starts to cool and solidify and form the new surface. This process can be expensive in terms of man power and machinery which are required to be present on site and the materials which are used and also involves the removal of part of the surrounding surface which may be unaffected, and so material usage Is greater. The tarmacadam is a mix of aggregate materials, such as sand and crushed rock, which is bound together with tar or bitumen. In order to obtain the hot material, it is typically required for the contractor to visit a location at which the material is prepared and heated, such as for example, a quarry or a roads depot and then transport a quantity of the hot tarmacadam and other equipment required to lay the same to the location of the pothole. However, in order for the heated material to be effective it is required to maintain the material above a predetermined temperature until the same has been applied onto the base. In order to do this, apparatus can be provided on the transport vehicle to heat the tarmacadam during transport and so provide an increase in the time and distance over which the tarmacadam can be moved and then still be usable but even then, the time available from the collection of the hot material to the application on the surface is in the region of 3 hours which can be restrictive and can require many trips to and from the depot and the particular locations of application. Furthermore, the volume of the tarmacadam which is required to be collected, at the depot, is typically in the region of a minimum of a ton in weight and therefore relatively large volumes of material are required to be used. All of these issues means that the ability for urgent and immediate repairs of potholes to be performed is significantly restricted. It is also not very environmental friendly.

[0005] An alternative approach is to apply a “cold” or ambient temperature material known as a cold lay asphalt or cold mix asphalt material, which comprises an emulsified or cementitious bitumen blended with aggregates of the same size, into the pothole to fill the same and the surface of the added material can then be compacted so as to preferably be substantially flush with the adjacent surface of the surrounding road, driveway or path. This represents a cheaper option as there is no need to remove the surrounding surface and the filling material, which again is tarmacadam based, does not need to be heated so can be carried to any location loose, or in bags or other containers, and directly applied so as to provide the ability for a relatively rapid response and repair of the pothole. However, it is found that in practice the material can take a relatively long time to fully harden and the repair may only last for a short period of time such as, for example, a number of weeks, after which the repair material becomes loose and the pothole reappears and so requires further maintenance and repair at relatively regular intervals. Thus, in many cases, initial cost savings achieved by using the cold filling material may be only temporary due to the required repeated repairs which are required to be performed. However, due to funding constraints and the need to provide safe road surfaces, this quick, often temporary fix, is still often chosen so as to meet immediate safety requirements and to avoid incurring significant one-off expenses of the conventional hot tarmacadam application. However, this repair process can in many instances be no more than a cosmetic repair.

[0006] Accordingly, there is a need for an improved product for repair or reinstatement of recessed portions of an area of hard standing, such as potholes.

[0007] Summary of Invention

[0008] In an aspect of the invention there is provided a product for the repair or reinstatement of a recessed portion of an area of hard standing, optionally for the repair of a pothole, the product comprising a composition within a sealed container, wherein the composition comprises: a binding agent comprising a prepolymer comprising functional groups capable of curing by cross-linking; and

[0009] an aggregate mixed with the binding agent.

[0010] The term prepolymer is known in the art and is intended to be given its conventional meaning. For example, it includes a substance which has been isolated at an intermediate stage in polymerization that can undergo further reaction, such as cross-linking, to form a cured polymer. The cross-linking may be any conventional means and may occur, for example, upon exposure to moisture or exposure to radiation (such as UV light). Other types of cross-linking may occur upon exposure to heat or oxygen.

[0011] Advantageously, the product, which could also be referred to as a system or as a kit, provides a simple and quick solution for repairing or reinstating areas of hard standing. Unlike traditional pothole repair products comprising emulsified or cementitious bitumen that harden though evaporation of solvent or water (i.e. hardening by physical processes), the use of the prepolymer, which could also be referred to as a resin, provides a curable component that strongly binds the particles of the aggregate to each other (by chemical bonding) within the recessed portion. It can therefore form a high strength area of hard standing that can withstand the impacts associated with long term use of a road or driveway, such as the continued driving of cars and trucks, and / or the impacts of adverse weather.

[0012] Advantageously, the cross-linking of the prepolymer can allow for facile curing (e.g. hardening) of the prepolymer, thereby binding together the aggregate without requiring the introduction of a secondary component (e.g. without a separate hardener component). This can be referred to as a 1K binder.

[0013] The product therefore provides the convenience advantages of the previously known cold mix asphalt materials, while also provide a strong and robust material which is capable of providing a longer-lasting and more durable repair / reinstatement.

[0014] Providing a strong more durable repair / reinstatement, which avoids the need for further action while also avoiding the need transport hot tarmacadam to site, means the product also provides for a more environmentally sustainable method for repairing area such as potholes and avoids the needs for materials such as cement which are known to have detrimental environmental impact.

[0015] Furthermore, the chemical cross-linking reaction can occur faster than the physical hardening caused by the evaporation of the solvent in known cold mix asphalt materials, for example providing a fully cured material in a matter of hours, e.g. in up to 1, 2, 3, 4, or 5 hours. Advantageously, this reduces the time taken for the repair, and means areas such as roads need to be closed for less time. This reduces the inconvenience for other users.

[0016] Resin bound surfacing is currently used to lay driveways and walkways / paving. However, the present invention presents a fundamentally different approach. Conventional resin bound surfacing typically requires onsite mixing of a two-component resin (a base resin and a hardener) which reacts on site to prepare a binder that is subsequently mixed with an aggregate and then laid on the relevant area, e.g. driveway. This requires separately transporting the respective reactants to the site, and considerable care in handling and reacting the relevant components to control the chemical reaction. In comparison the product of the invention uses a prepared prepolymer which is ready mixed with the aggregate to provide a single product that is ready for application and is in a state that can harden quickly making the product ideal for conveniently repairing or reinstating areas of hard standing, e.g. potholes. In advantageous embodiments this composition can for example be carried by hand in the sealed container to the application site ready for application. As a result, the described inventive product is easier to handle, simpler to apply on site, and able to cure quicker than conventional products, making it ideally suited to pothole repair or similar.

[0017] In a further aspect there is provided a method of repairing or reinstating a recessed portion of an area of hard standing, optionally repairing a pothole, using the above product, the method comprising the following steps:

[0018] removing at least a part of the composition from the sealed container; contacting the composition with the recessed portion; and

[0019] initiating the cross-linking the prepolymer, thereby binding together the aggregate.

[0020] Advantageously, this provides a very simple, time effective and convenient method for repairing or reinstating an area of hard standing. Typically, the area of hard standing is a road, driveway, or pavement. In one embodiment the recessed portion is a pothole which is required to be repaired, or is a trench which is required to be reinstated in the area of hardstanding.

[0021] It is not intended that the method above be limited by the order of the steps. For example, the cross-linking of the polymer may be initiated before, or at substantially the same time as, contacting the composition with the recessed portion, or could occur after. Indeed, initiating the cross-linking the prepolymer may occur when removing at least a part of the composition from the sealed container, such as by exposing a prepolymer to moisture in the atmosphere, or UV lights, at the implantation site.

[0022] In a further aspect there is provided the use of the above product in repairing or reinstating a recessed portion of an area of hard standing, optionally in repairing a pothole. It will be appreciated that this use can comprise the steps of the method described herein. In a further aspect there is provided a method of preparing the above product, the method comprising:

[0023] preparing a binding agent by reacting a first monomer with a second monomer, wherein the reactive groups of the first monomer are in stoichiometric excess relative to the corresponding reactive groups in the second monomer such that it forms the prepolymer with functional groups capable of curing by cross-linking;

[0024] mixing the binding agent with an aggregate to provide the composition; and sealing the composition within the container.

[0025] In a further aspect of the invention there is provided a composition for the repair or reinstatement of a recessed portion of an area of hard standing, optionally for the repair of a pothole, suitable for use in the product described above and herein, the composition comprising

[0026] a binding agent comprising a prepolymer comprising functional groups capable of curing by cross-linking; and

[0027] an aggregate mixed with the prepolymer;

[0028] preferably wherein the binding agent further comprises bitumen.

[0029] In a further aspect, there is provided the use of the above composition for the repair or reinstatement of a recessed portion of an area of hard standing.

[0030] In a further aspect, there is provided a binding agent for use in the repair or reinstatement of a recessed portion of an area of hard standing (such as by inclusion in the composition or product described above), the binding agent comprising:

[0031] a prepolymer comprising functional groups capable of curing by cross-linking; and bitumen.

[0032] In a further aspect, there is provided a prepolymer for use in the repair or reinstatement of a recessed portion of an area of hard standing, the prepolymer capable of curing by crosslinking when exposed to moisture and binding together an aggregate,

[0033] wherein the prepolymer is a polyurethane derived from the reaction of a diisocyanate with a polyether polyol,

[0034] wherein the diisocyanate is selected from methylene diphenyl diisocyanate (MDI), methylene 4,4'-biscyclohexylisocyanate (HDMI), hexamethylene diisocyanate (HDI), isophorone diisocyanate (I PDI), toluene diisocyanate (TDI), naphthalene diisocyanate (NDI), p-phenylene diisocyanate (PPDI), or combinations thereof; and wherein the prepolymer comprises from 1g to 20g unreacted isocyanate groups per 100g of prepolymer. Preferably, the polyether polyol is a trifunctional polyether polyol (e.g. a polyether triol). The amount of unreacted isocyanate groups can be determined in accordance with Method A of EN ISO 14896:2009 (further described herein).

[0035] In a further aspect, there is provided the use of the prepolymer immediately above for binding an aggregate. In a further aspect, there is provided the use of the prepolymer immediately above for repair or reinstatement of a recessed portion of an area of hard standing. For example, there is provided the use of the prepolymer immediately above with an aggregate for repair or reinstatement of a recessed portion of an area of hard standing.

[0036] Embodiments of the various aspects of the invention are described in the application. For the avoidance of doubt, it will be appreciated, where appropriate, that any embodiments as described herein in relation to one aspect of the present invention will also apply to the other aspects of the present invention.

[0037] Binding Agent

[0038] In any of the aspects or embodiments described herein, the prepolymer comprising functional groups capable of curing by cross-linking may be a prepolymer comprising functional groups capable of curing by cross-linking when exposed to moisture and / or exposed to UV light.

[0039] In preferred embodiments, the binding agent comprises a prepolymer comprising functional groups capable of curing by cross-linking when exposed to moisture.

[0040] In particularly preferred embodiments, the binding agent comprises a prepolymer comprising functional groups capable of curing by cross-linking when exposed to moisture vapour in the atmosphere.

[0041] Advantageously, the ability to cross-link when exposed to moisture provides a very simple method for curing the prepolymer that can be conducted anywhere. It can even allow for the prepolymer to cure without any additional input. The composition can merely be retained in a dry, or at least substantially dry, condition within the sealed container until it is needed, and then it can be exposed to moisture vapour in the air and / or water can be added deliberately, thereby initiating the cross-linking and the hardening of the prepolymer. This binds together the aggregate and provides a strong material without the need to for any specialist equipment, or the supply of multiple products to the repair site. Indeed, the container could be a bag that is carriable to the desired site, opened and used to repair or reinstate the area of hard standing with minimal effort or cost.

[0042] It will be appreciated that the functional groups capable of curing by cross linking are typically unreacted functional groups, such as NCO. As discussed above, the cross-linking may be any conventional means and may occur, for example, upon exposure to moisture and / or exposure to radiation (such as UV light). Other types of cross-linking may occur upon exposure to heat or oxygen. The skilled person will understand which groups may suitable enable such cross¬ linking under the stated conditions. Functional groups that are able to cross link when exposed to moisture for example include NCO (i.e. isocyanate) groups. Functional groups which may undertake cross-linking when exposed to UV light include unsaturated groups such as alkene groups.

[0043] In any of the aspects or embodiments described herein, the functional groups of the prepolymer may be isocyanate groups. Advantageously, the use of isocyanate groups has been found to provide effective cross-linking of the prepolymer when exposed to moisture. In particular, isocyanate groups have been observed to result in curing on short time scales (a few hours) to form a strong cured polymer, even in the presence of relatively low levels of moisture, such as moisture within the atmosphere.

[0044] The skilled person will be able to adjust (e.g. tailor) the residual amount of (unreacted) functional groups in the prepolymer by controlling the stoichiometry of the starting reactant mixture used to form the prepolymer. For example, in an example wherein an isocyanate monomer is reacted with a polyol to form the prepolymer, it will be appreciated that adding a stoichiometric excess of isocyanate groups relative to reactive hydroxyl groups will result in a prepolymer which has a predictable amount of unreacted isocyanate groups present in the prepolymer. The amount of excess functional groups in the prepolymer can be increased or decreased as desired, depending on the given application and the degree of cross-linking that is desired in the final cured product.

[0045] In any aspects or embodiments of the invention described herein, the prepolymer may comprise from 0.1 g to 40g of unreacted isocyanate groups per 100g of prepolymer. The prepolymer may comprise from 1 to 20g of unreacted isocyanate groups per 100g of prepolymer. The prepolymer may comprise from 5g to 20g of unreacted isocyanate groups per 100g of prepolymer. The binding agent (which comprises the prepolymer) may comprise from 0.1 g to 40g of unreacted isocyanate groups per 100g of binding agent. The binding agent may comprise from 1 to 20g of unreacted isocyanate groups per 100g of binding agent. The binding agent may comprise from 3g to 15g of unreacted isocyanate groups per 100g of binding agent. Preferably, the binding agent may comprise from 3g to 10g of unreacted isocyanate groups per 100g of binding agent. In particularly preferred embodiments, the binding agent may comprise from 5 to 9g of unreacted isocyanate group per 100g of binding agent.

[0046] The amount of unreacted isocyanate groups (g per 100g) can be determined by titration. In particular, the amount of unreacted isocyanate groups can be determined in accordance with Method A of EN ISO 14896:2009. Full details of the method are provided in the Examples section below. Advantageously, it has been found that by controlling the amount of unreacted isocyanate groups, the viscosity of the binding agent and the amount of cross-linking upon exposure to water can be controlled.

[0047] It will be appreciated that it is desirable for repair or reinstatement of surfaces that the binding agent has a viscosity that allows it to be readily workable when being applied to the respective surface. A viscosity that remains flowable is advantageous as this will allow the prepolymer to be readily handled when applying the aggregate, so as to be pourable from the container to the surface during use. Furthermore, prepolymers having a desirable viscosity will allow it to be sufficiency flowable that it can coat the aggregate, while still being thick enough that it is retained on the surface of the aggregate. This helps to ensure the prepolymer aggregate mixture remains stable for long periods (i.e. avoiding the aggregate from settling out).

[0048] In some embodiments, the prepolymer is a polyurethane. Alternatively, the prepolymer may be a polyurea.

[0049] The polyurethane prepolymer may be derived from the reaction of a di isocyanate or triisocyanate with a polyol (e.g. triol). Preferably the polyurethane prepolymer is derived from the reaction of a diisocyanate with a polyol. It will be appreciated that the diisocyanate / triisocyanate and the polyol, may be traditional small molecule monomers, or may themselves be polymeric components that act as monomers to form the prepolymer.

[0050] In some embodiments, the polyurethane prepolymer is derived from the reaction of a diisocyanate or triisocyanate with a polyol, wherein the NCO: OH stoichiometric ratio is from 1:1 to 40: 1. The ratio may be from 5:1 to 20: 1. For example the NCO: OH stoichiometric ratio may be from 7:1 to 15:1. Advantageously, it has been found that working within these ratios limits to amount of polymerisation leadings to a prepolymer that has a desirable amount of unreacted functional groups, and can easily cured to a fully hardened state, while remaining a thick liquid that can coat the aggregate.

[0051] In some embodiments, the diisocyanate or triisocyanate is an aromatic diisocyanate.

[0052] In some embodiments, the diisocyanate is selected from: methylene diphenyl diisocyanate (MDI), methylene 4,4'-biscyclohexylisocyanate (HDMI), hexamethylene diisocyanate (H DI), isophorone diisocyanate (I PDI), toluene diisocyanate (TDI), naphthalene diisocyanate (NDI), p-phenylene diisocyanate (PPDI), derivatives therefrom, or combinations thereof.

[0053] In particularly preferred embodiments, the diisocyanate is methylene diphenyl diisocyanate (MDI).

[0054] In some embodiments, the polyol comprises primary hydroxy groups. Advantageously, primary hydroxyl groups provide high reactivity, which can provide an increased cure rate for the resultant prepolymer.

[0055] In some embodiments, the polyol has two reactive hydroxyl groups (a difunctional polyol / diol), three reactive hydroxyl groups (a trifunctional polyol / triol) or four reactive hydroxyl groups (a tetrafunctional polyol / tetrol).

[0056] In preferred embodiments, the polyol is a trifunctional polyol (e.g. a triol). Advantageously, trifunctional polyols have been found to provide a system that cures quickly and has increased tensile strength compared to a difunctional polyol. Without wishing to be bound by theory, it is believed that trifunctional polyol provides a branched system that presents more terminal hydroxyl groups and provides a 3D network with higher crosslink density.

[0057] Alternativity the polyol may be a difunctional polyol (diol).

[0058] In some embodiments, the polyol may be a polyether polyol. Advantageously, the use of a polyether functionality has been found to provide improved physical properties to the final repaired area of hard standing, including moisture / water resistance, rebound and resilience strength, and improved flexibility.

[0059] The polyether polyol may comprise a poly(alkylene glycol) (PAG), for example a poly(C2-6 alkylene glycol). The C2-6 alkylene group may comprise ethylene and / or propylene. The polyether polyol may comprise the polymerisation product of ethylene oxide and / or propylene oxide. The polyether polyol may comprise (or may be) a polyethylene glycol (PEG) or a polypropylene glycol (PPG). The polyether polyol may comprise (or may be) a copolymer of ethylene oxide and propylene oxide, such as a block copolymer; polyethylene glycol (PEG); and / or polypropylene glycol (PPG).

[0060] Alternatively, the polyol may be a polyester polyol, or a phenol-formaldehyde resin.

[0061] In some embodiments, the polyol is a trifunctional polyether polyol.

[0062] In some embodiments, the polyol has a hydroxyl number of 160 mg KOH / g or lower, as measured in accordance with DIN 53240. Full details of the method are provided in the Examples section below. The polyol may have a hydroxyl number of 80mg KOH / g or lower. For example, the polyol may have a hydroxyl number of 40 mg KOH / g or lower.

[0063] Advantageously using a lower hydroxyl number has been found to provide a binding agent that is more flexible, easier to manipulate and resistant to weathering.

[0064] In some embodiments, the polyol has a viscosity of around 1000 mPa s or less measured at 25 degrees Celsius in accordance with DIN EN 12092.

[0065] In some embodiments, the polyol has a density of 1.2 g / cm or less measured in accordance with DIN 51 757 at a temperature of 25°C.

[0066] In some embodiments, the binding agent consists of the prepolymer (i.e. the binding agent is the prepolymer). In other embodiments, the binding agent comprises other components with the prepolymer. Suitable additional components may for example include one or more of diluents, or dyes. Accordingly, the binding agent may comprise the prepolymer in an amount of from 20% to 80% by weight. For example, the binding agent may comprise the prepolymer in an amount of from 30% to 60% by weight.

[0067] In advantageous embodiments, the binding agent further comprises bitumen.

[0068] The term “bitumen” is well known in the art and is intended to be given its conventional meaning. For example, this includes the usual viscous mixture of hydrocarbons obtained as a residue from petroleum distillation that can be used for road surfacing. Advantageously, the inclusion of bitumen into the binding agent has been found to provide a composition that can cure to match the colour and texture of surface being repaired, such as roads and pathways without adversely affecting the strength of the final product. This can allow the product to be used for repairing potholes in roads and blend in with the existing surface. The bitumen can also improve the binding of the aggregate and provide a more flexible final product.

[0069] In some embodiments, bitumen is present in the binding agent in an amount from 20 to 80% by weight. For example, the bitumen may be present in the composition in an amount from 40 to 70% by weight.

[0070] Accordingly, in some exemplary embodiments, the binding agent may thus comprise prepolymer in an amount from 20 to 80 % by weight and bitumen in an amount from 20 to 80% by weight.

[0071] In other exemplary embodiments, the binding agent may thus comprise prepolymer in an amount from 30 to 60 % by weight and bitumen in an amount from 40 to 70% by weight.

[0072] It will be appreciated that bitumen is mixture of hydrocarbons and includes various functional groups. For example, hydroxyl (-OH), Carboxylic (-COOH), Phenolic (Ar-OH) and Amines(- NH2). The inclusion of these functional groups in the binding agent may cause the bitumen to react with the (unreacted) functional groups of the prepolymer (e.g. -NCO groups) causing the prepolymer to prematurely cure. For example, excess -NCO groups may react with the above-mentioned functional groups to form urethane linkages, amides, aryl urethanes and urea linkages respectively.

[0073] If (unreacted) functional groups (e.g. isocyanate groups, “-NCO”) of the prepolymer are quenched by reaction with the bitumen, then there is a risk that not enough reactive functional groups will remain in the prepolymer after bitumen incorporation to provide desirable cross-linking (i.e. curing) at the installation site. As a result, it may be desirable to stabilise the bitumen such that it does not react with (i.e. fully quench) the unreacted functional groups of the prepolymer. For example, the functional groups in the bitumen may be protected, such as protected prior to the addition of the bitumen to the binding agent (e.g. by reaction with an isocyanate compound such as MDI). The skilled person is familiar with the use of protecting groups to temporarily or permanently block reactive functional groups so as to prevent the functional group reacting undesirably with other components in the reaction mixture. Such protection will thus be understood as the chemical modification of a reactive functional group through the introduction of another moiety that limits the further reactivity of that functional group. In other words, the potentially reactive functional group is blocked. Such bitumen as so protected can also be referred to as a stabilised bitumen, e.g. MDI-stabilised bitumen.

[0074] Accordingly, in some embodiments, the bitumen comprises hydroxy, carboxylic, phenolic and / or amine functional groups that are protected. For example, hydroxy, carboxylic, phenolic and / or amine functional groups of the bitumen may have been protected prior to addition of the bitumen to the binding agent

[0075] In some embodiments, bitumen comprises functional groups that are protected with a compound comprising the same functional groups as the functional groups of the prepolymer. It will be appreciated that protecting the bitumen by reacting the functional groups of the bitumen with compounds that comprise the same functional group of the prepolymer avoids the functional groups of the bitumen quenching the unreacted groups of the prepolymer once mixed.

[0076] In particularly preferred embodiments, the functional groups of the bitumen are protected with an isocyanate, i.e. by reacting with a compound comprising an isocyanate group.

[0077] Accordingly, in some embodiments, the bitumen comprises hydroxy, carboxylic, phenolic and / or amine functional groups that are protected by an isocyanate, i.e. by reacting the bitumen with a compound comprising an isocyanate group. The isocyanate may be a diisocyanate such as MDI.

[0078] Put another way, the bitumen may be a derivative of bitumen obtained by reacting bitumen with an isocyanate, such as a diisocyanate. Advantageously reacting the functional groups of the bitumen with a diisocyanate, such as MDI, can leave some excess isocyanate groups in the bitumen which can react with any isocyanate groups of the prepolymer upon exposure to moisture.

[0079] Accordingly, in some embodiments, the bitumen may be a derivative of bitumen obtained by reacting the hydroxy, carboxylic, phenolic and / or amine functional groups of the bitumen with a diisocyanate selected from: methylene diphenyl diisocyanate (MDI), methylene 4,4'-biscyclohexylisocyanate (HDMI), hexamethylene diisocyanate (HDI), isophorone diisocyanate (I PDI), toluene diisocyanate (TDI), naphthalene diisocyanate (NDI), p- phenylene diisocyanate (PPDI), derivatives therefrom, or combinations thereof; preferably with methylene diphenyl diisocyanate (MDI).

[0080] In some embodiments, the bitumen comprises urethane, amide and / or urea protecting groups.

[0081] In further embodiments, the bitumen comprises urethane, amide and / or urea linkages and further comprise unreacted isocyanate groups.

[0082] In some embodiments, the binding agent may further comprise a phthalate. For example, diisononyl phthalate (DINP). The phthalate may be used as a diluent.

[0083] The bitumen (e.g. bitumen comprising functional groups that are protected, also referred to herein as stabilised bitumen or derivatives of bitumen) may be mixed with the prepolymer. For example, the bitumen may be homogenously mixed with the prepolymer. Alternatively, the bitumen (e.g. the bitumen comprising functional groups that are protected) may be incorporated in the prepolymer by mixing bitumen into the reaction that forms the prepolymer.

[0084] In some embodiments, the binding agent further comprises a polymerisation suppressant. An example suppressant is benzoyl chloride but other compounds could also be used. The suppressant may be present in the binding agent in an amount from 0.001% to 0.1% by weight of the binding agent. Advantageously the suppressant can slow down / supress the premature polymerisation / cross-linking of the prepolymer within the sealed container, allowing for longer shelf life.

[0085] In some embodiments, the binding agent is present in the composition in an amount from 2 to 20 % by weight. The binding agent may be present in the composition in an amount from 5% to 12% by weight. For example, the binding agent may be present in the composition in an amount from 6 to 10% by weight. Advantageously, these amounts of binding agent have been found to strongly bind together the aggregate, while still ensuring that the sufficient aggregate in the composition to provide the repaired / reinstated area of hard standing with high strength properties.

[0086] Accordingly, in some embodiments, the repaired or reinstated area of hard standing (i.e. the bound aggregate once the prepolymer has cured) has a compressive strength of at least 100 N / cm2, such as at least 300 N / cm2, e.g. from 400 to 1000 N / cm2The compressive strength can be measured according to methodology provided in the examples section.

[0087] In some embodiments, the binding agent has a viscosity of from 3,000mPa.s to 30,000mPa.s measured in accordance with ISO 2555:2018 at 25 degrees Celsius and at 1 atm. The binding agent may have a viscosity of from 6,000mPa.s to 15,000mPa.s. The viscosity may be measured using a Brookfield-type rotational viscometer. Providing a viscosity that allows for the binding agent to coat and suspend the aggregate such that they remain mixed over extended periods of time is advantageous because the product can be ready to use immediately once the sealed contained is opened without any need for further mixing. Coating of the aggregate can also help ensure that all of the aggregate is sufficiently bound leading to a strong repair / reinstatement of the area of hard standing.

[0088] Accordingly, in some embodiments the aggregate remains suspended in the binding agent for at least 10 days under gravity at a temperature of 25°C. It will be appreciated that this can be achieved by controlling the viscosity of the binding agent.

[0089] In some embodiments, the composition comprising the binding agent has a working time, during which the same can still be sufficiently fluid to be worked, of from 5 mins to 5 hours at a temperature of 20 °C and humidity of 50%.

[0090] Aggregate

[0091] In some embodiments, the aggregate is present in the composition in an amount greater than 10% by weight, such as greater than 50% by weight.

[0092] Typically, the aggregate is present in the composition in an amount of from 80 to 98 % by weight The aggregate may be present in the composition in an amount of from 88% to 95% by weight. For example, the aggregate may be present in an amount of from 90 to 94% by weight. Advantageously, these amounts of aggregate have been found to provide a high strength final material (i.e. a high strength repaired / reinstated area of hard standing).

[0093] Accordingly, in exemplary embodiments, the aggregate is present in the composition in an amount of from 80 to 98 % by weight of the composition and the binding agent is present in the composition in an amount from 2 to 20 % by weight of the composition; optionally wherein the binding agent comprises the prepolymer in an amount from 20 to 80 % by weight of the binding agent and bitumen in an amount from 20 to 80% by weight of the binding agent. In other exemplary embodiments, the aggregate is present in the composition in an amount of from 88 to 95 % by weight of the composition and the binding agent is present in the composition in an amount from 5 to 12 % by weight of the composition; optionally wherein the binding agent comprises the prepolymer in an amount from 30 to 60 % by weight of the binding agent and bitumen in an amount from 40 to 70% by weight of the binding agent.

[0094] In other exemplary embodiments, the aggregate is present in the composition in an amount of from 88 to 95 % by weight of the composition, the prepolymer is present in the composition in an amount of 2 to 5 % by weight of the composition and bitumen is present in the composition in an amount from 3 to 7% by weight of the composition.

[0095] In some embodiments that water content of the aggregate is less than 1% by weight of the aggregate. That water content of the aggregate may be less than 0.1% by weight For example, the water content of the aggregate may be less than 0.05% by weight. The water content of the aggregate may be determined by ASTM C566 (Total Evaporable Moisture of Aggregate by Drying).

[0096] It will be appreciated that the binding agent should ideally be substantially absent of any water or moisture (e.g. no water or moisture) so as to avoid premature curing / cross-linking before delivery to the application site, e.g. prior to placing in, or whilst being stored or transported in the sealed container. Accordingly, in some embodiments the water content of the composition is less than 1% by weight, e.g. less than 0.5 % by weight. The water content of the composition may for instance be less than 0.1% by weight of the composition. For example, the water content of the composition may be less than 0.05% by weight of the composition.

[0097] Minimising the water content of the aggregate, and of the composition, allows for the prepolymer to remain in its unreacted form until it is deliberately exposed to moisture (e.g. by exposure to the atmosphere or by deliberate application of water). This prevents premature hardening of the composition and provides a product with a long shelf life, allowing it to be packaged, sold, and transported to the desired site whilst still remaining workable until curing / cross-linking is required at the installation site.

[0098] In some embodiments, the aggregate comprises an igneous or metamorphic rock or a mineral such as quartz. In preferred embodiments, the aggregate comprises, optionally consists of, igneous rock. The igneous rock may have a hardness on the Mohs scale of 6 or greater. For example, the aggregate may comprise, optionally consists of, granite. Advantageously this aggregate provides a rough, open texture that allows good traction between the surface of the repaired / reinstated area of hard standing and foot or vehicle traffic.

[0099] In some embodiments, the aggregate comprises a mixture of size grades. In particular, the aggregate may comprise (or may have been formed from) a mixture of a) 2 to 12mm, such as 2 to 5 mm, aggregate; b) 1 to 3 mm aggregate and c) less than 1 mm aggregate.

[0100] Advantageously, using a mixture of sizes allows for tight compaction of the aggregate leading, which when bound together, provides a area of hard standing with high compressive strength that is substantially water impermeable.

[0101] For avoidance of doubt, the above grades of aggregate are standard terms of the art and are intended to be given their normal meaning. For instance, a 2 to 5 mm aggregate refers to an aggregate that has been obtained by sieving through screens that have mesh with apertures of 2 and 5 mm.

[0102] It will be appreciated that most aggregate is non-spherical, and therefore the size refers the length of the critical width dimension that determines the ability of the aggregate to pass through the mesh of the sieve. For example, it is possible for aggregate with a narrowest dimension of 5mm, but a widest dimension of 8mm to be within the 2 to 5mm bracket as it will still pass through the 5mm screen if it falls on its narrowest side.

[0103] In such embodiments, the 2 to 12mm, such as 2 to 5 mm, aggregate may form 50 to 65% by weight of the aggregate. The 1 to 3 mm aggregate may form 20 to 30% by weight of the aggregate. The less than 1 mm aggregate may form 10 to 25% by weight of the aggregate.

[0104] Accordingly in some embodiments the aggregate comprises, or may have been formed from:

[0105] 50 to 65% by weight aggregate with a size between 2 to 12mm, preferably 2 to 5mm,

[0106] 20 to 30% by weight aggregate with a size between 1 to 3mm; and

[0107] 10 - 25% by weight aggregate with a size of less than 1mm,

[0108] wherein the sizes are determined by sieving.

[0109] The aggregate with a diameter less than 1 m may comprise:

[0110] 20 to 35% by weight aggregate with a size of less than 0.3mm, 25 to 40% by weight aggregate with a size between 0.3 to 0.6mm; and

[0111] 30 to 45% by weight aggregate with a size between 0.6 to less than 1mm wherein the sizes are determined by sieving.

[0112] The choice of colour of the aggregate used in the mixture is at the discretion of the user and may be dependent on the desired application and installation site. Typically, colour matching of the composition to the area of hard standing (e.g. road, path, etc.) is desirable to restore the initial aesthetic appearance of the surface to be repaired or reinstated. For example, if the composition is to be installed in a road or public footpath, darker colours such as blacks and / or greys are usually desired to match the original tarmac-based surface. The aggregate may thus comprise a black aggregate. The aggregate may comprise a grey aggregate. The aggregate may comprise a mix of black and grey coloured aggregate. The colour of the aggregate may be the natural colour of the material, e.g. rock, or may result from dying the aggregate the desired colour. The aggregate may thus be dyed black and / or grey. These colours allow the repaired or reinstated portion to blend with the normal colour of roads and pavements.

[0113] In further exemplary embodiments, the aggregate is present in the composition in an amount of from 80 to 98 % by weight of the composition; the binding agent is present in the composition in an amount from 2 to 20 % by weight of the composition; the binding agent comprises the prepolymer in an amount from 20 to 80 % by weight of the binding agent and comprises bitumen in an amount from 20 to 80% by weight of the binding agent; and the prepolymer is polyurethane comprising isocyanate groups capable of curing by cross-linking upon exposure to moisture.

[0114] In another exemplary embodiments, the aggregate is present in the composition in an amount of from 88 to 95 % by weight of the composition and the binding agent is present in the composition in an amount from 5 to 12 % by weight of the composition; the binding agent comprises the prepolymer in an amount from 30 to 60 % by weight of the binding agent and bitumen in an amount from 40 to 70% by weight of the binding agent; and the prepolymer is polyurethane comprising isocyanate groups capable of curing by cross-linking upon exposure to moisture.

[0115] In further exemplary embodiments, the aggregate is present in the composition in an amount of from 80 to 98 % by weight of the composition; the binding agent is present in the composition in an amount from 2 to 20 % by weight of the composition; the prepolymer is polyurethane comprising isocyanate groups capable of curing by cross-linking upon exposure to moisture; and the binding agent comprises 1g to 20g unreacted isocyanate groups per 100g of prepolymer. The amount of unreacted isocyanate may be calculated according to the method provided herein.

[0116] In further exemplary embodiments, the aggregate is present in the composition in an amount of from 80 to 98 % by weight of the composition; the binding agent is present in the composition in an amount from 2 to 20 % by weight of the composition; the prepolymer is polyurethane comprising isocyanate groups capable of curing by cross-linking upon exposure to moisture; the binding agent comprises 1g to 20g unreacted isocyanate groups per 100g of prepolymer; and the binding agent further comprises bitumen; optionally wherein the bitumen comprises functional groups that are protected.

[0117] Other components

[0118] In some embodiments the composition further comprises kerosene. Advantageously, the presence of kerosene reduces the viscosity of the composition and makes the composition easier to compact when in the recessed portion.

[0119] In some embodiments the composition further comprises one or more UltraViolet (UV) stability additives.

[0120] In some embodiments, the composition further comprises a colouring agent to allow the composition, once hardened, to have a colour which is similar to that of the area of hard standing. For example, a black dye to match traditional roads, or a coloured dye to match coloured sections of roads, such as bus lanes or bike lanes.

[0121] Container

[0122] As described above, the compositions described herein may be advantageously transported to the installation site in a container in a form ready for cross-linking at the site. For example, as described above, the composition may be provided within a sealed container.

[0123] It will be appreciated that the reference to “sealed” means that the container is closed and the composition inside the container is substantially unaffected by the environment outside of the container. For example, the container may be substantially air and / or water impermeable. In other words, the container may be substantially airtight and / or moisture sealed. It will be appreciated that limiting the moisture transfer to the composition reduces any premature cross-linking of a prepolymer that cross-links upon expose to water, providing a long shelf life. The container may also block UV light preventing premature cross-linking of a prepolymer that cross-links upon expose to UV light. The container may also stop other methods of initiating cross linking, such as preventing the prepolymer being exposed to heat or oxygen.

[0124] The sealed container may be a bag. The sealed container may be a plastic bag, for example a polyethylene bag.

[0125] The sealed container may comprise a barrier material which provides resistance to the permeation of moisture through the container (i.e. a low moisture transfer rate). For example, the container may comprise a metallic or metallised layer, such as a layer of aluminium.

[0126] In some embodiments the container is a bag that comprises a plastic material, such as polyethylene, and further comprises aluminium. In particularly advantageous embodiments, the bag is a composite comprising polyethylene, aluminium and nylon.

[0127] In some embodiments, the composition is stored within the sealed container in an environment, or atmosphere, that is free, or substantially free, from moisture. For example, the composition could also be stored under dry air. In preferred embodiments, the composition is stored in an inert atmosphere within the sealed container. For example, the composition may be stored under nitrogen. Alternatively, the composition may be vacuum sealed in the container. Advantageously, minimising moisture in the container reduces premature cross-linking of the prepolymer, providing a long shelf life to the product.

[0128] Method of repairing or reinstating a recessed portion of an area of hard standing

[0129] As described above, an aspect of the invention relates to a method of repairing or reinstating a recessed portion of an area of hard standing, optionally repairing a pothole, using the above product (i.e. the product comprising the composition in a sealed container), the method comprising the following steps:

[0130] removing at least a part of the composition from the sealed container; contacting the composition with the recessed portion; and

[0131] initiating the cross-linking of the prepolymer, thereby binding together the aggregate. In some embodiments, initiating the cross-linking the prepolymer comprises contacting the composition with moisture. Contacting the composition with moisture may comprise exposing the composition to water vapour in the air. Alternatively, or additionally, contacting the composition with the moisture may comprise adding water to the composition (i.e. deliberately), such as after contacting the composition with the recessed portion. Adding water may be allow for the composition to cross-link quickly, which might be advantageous when the repair is being performed to an area of hard standing which is particularly hazardous, such as, for example, in a carriageway of a road. Adding water to the composition in this way may be done by any conventional means. It may for instance involve spraying water onto the composition. It may for instance involve pouring water, or otherwise spreading water, onto the composition. Water may be added to the composition such that the composition fills the recessed portion.

[0132] In alternative embodiments, initiating the cross-linking the prepolymer comprises exposing the composition to UV light. In other embodiments, initiating the cross-linking the prepolymer comprises exposing the composition to heat. In other embodiments, initiating the cross¬ linking the prepolymer comprises exposing the composition to oxygen.

[0133] Contacting the composition with the recessed portion can be done by any suitable means. In some embodiments, it involves pouring the composition out of the container into the recessed portion. Alternatively, or additionally, it could involve mechanically removing the composition from the container and into the recessed portion. Any conventional means may be employed in this regard, such as by shovelling the composition out of the container and into the recessed portion.

[0134] The method may further comprise compacting the composition inside the recessed portion. This can ensure that a high-density composition is applied to the recessed portion and the composition contacts all of the edges of the recessed portion such that it binds strongly to the existing area of hard standing. It can also help provide an external surface which is substantially flat and preferably flush with the external surface of the area of hard standing adjacent the repaired or reinstated portion. Method of preparing the product

[0135] As described above, an aspect of the invention relates to a method of preparing the above product (i.e. the product comprising the composition in the sealed container), the method comprising:

[0136] preparing a binding agent by reacting a first monomer with a second monomer, wherein the reactive groups of the first monomer are in stoichiometric excess relative to the corresponding reactive groups in the second monomer such that it forms the prepolymer with functional groups capable of curing by cross-linking;

[0137] mixing the binding agent with an aggregate to provide the composition; and sealing the composition within the container.

[0138] For the avoidance of doubt, all the features described above in relation to the product, or to any of its constituent parts, are also intended to be disclosed in relation to this method of preparation. However, for completeness, some specific comments and features are also presented below.

[0139] In some embodiments, the method of preparing the product further comprises the step of drying the aggregate prior to mixing the binding agent with the aggregate. In some embodiments, the aggregate is dried to a moisture content of less than 1 % by weight. The aggregate may be dried to a moisture content of less than 0.1% by weight. For example, the aggregate may be dried to a moisture content of from 0.01% to 0.05% by weight. The water content of the aggregate may be determined by ASTM C566 (Total Evaporable Moisture of Aggregate by Drying). As described above, minimising the water content of the aggregate allows for the prepolymer to remain in its unreacted form until it is deliberately exposed to moisture. This prevents premature hardening of the composition and provides a product with a long shelf life, allowing it to be packaged, sold, and transported to the desired site.

[0140] The aggregate may be dried using a rotary dryer or fluid bed dryer at a temperature of from 50 to 150°C. The aggregate may be heated for 1 to 120 mins, such as 1 to 30 mins.

[0141] However, it will be appreciated that other forms of drying are also possible.

[0142] In some embodiments, the first monomer is a diisocyanate or triisocyanate and the unreacted functional groups are isocyanate groups. The diisocyanate or triisocyanate may be an isocyanate as defined above in relation to the prepolymer. In some embodiments, the second monomer is a polyol. The polyol may be a polyol as defined above in relation to the prepolymer.

[0143] Accordingly, in some embodiments, reacting a first monomer with a second monomer, wherein the reactive groups of the first monomer are in stoichiometric excess relative to the corresponding reactive groups in the second monomer, comprises reacting a diisocyanate or triisocyanate with a polyol, wherein the diisocyanate or triisocyanate is in excess compared to the polyol. In particular, wherein the isocyanate groups (NCO) of the diisocyanate or triisocyanate are in stoichiometric excess compared to the hydroxy (OH) groups of the polyol.

[0144] In this regard, it will also be appreciated that the terms first monomer and second monomer are not intended to refer only to small molecular monomers, but encompass short polymeric components that can act as monomers in their own right, e.g. a trifunctional polyether polyol.

[0145] In some embodiments, reacting a first monomer with a second monomer, wherein the first monomer is in excess compared to the second monomer comprises reacting a diisocyanate or triisocyanate with a polyol, wherein the stoichiometric ratio of NCO groups to OH groups in the reaction is from 1:1 to 40:1. The stoichiometric ratio of NCO groups to OH groups in the reaction may be from 5:1 to 20:1. For example, the stoichiometric ratio of NCO groups to OH groups in the reaction may be from 7:1 to 15:1.

[0146] In some embodiments, the water (moisture) content of the polyol is less than 0.5%. The water (moisture) content of the polyol may be less than 0.1%. For example, the water (moisture) content of the polyol may be less than 0.05%. As described in relation to the aggregate, minimising moisture in the composition is beneficial since the prepolymer cross¬ links with moisture. Minimising moisture therefore allow for a long shelf-life and prevents premature polymerisation or premature cross linking of the prepolymer.

[0147] As described above in relation to the prepolymer, the first monomer may be an diisocyanate selected from: methylene diphenyl diisocyanate (MDI), methylene 4,4'- biscyclohexylisocyanate (HDMI), hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), toluene diisocyanate (TDI), naphthalene diisocyanate (NDI), p-phenylene diisocyanate (PPDI), derivatives therefrom, or combinations thereof. In preferred methods, these may be carbodiimide-modified diisocyantes. For example, the first monomer may be a carbodiimide-modified 4,4'-methylene diphenyl diisocyanate (MDI).

[0148] Advantageously, the carbodiimide modification lowers the crystallisation temperature allowing it to stay a liquid at room temperature, which allows the material to be stored and used more easily.

[0149] In some embodiments, the method further comprises adding a polymerisation suppressant to the binding agent. An example suppressant is benzoyl chloride but other compounds could also be used. The suppressant may be present in the binding agent in an amount from 0.001% to 0.1% by weight of the binding agent. Advantageously the suppressant can slow down / supress the premature polymerisation / cross-linking of the prepolymer within the sealed container, allowing for longer shelf life.

[0150] The step of mixing the binding agent with an aggregate to provide the composition may involve mixing the binding agent with the aggregate in amounts required to achieve the amount of each components specified above.

[0151] For example, the binding agent may be mixed with the aggregate in an amount such that it constitutes 2 to 20 % by weight, preferably 5% - 12% by weight, such as 6 to 10% by weight of the composition.

[0152] The aggregate may be mixed with the binding agent in an amount such that it is present in the composition in an amount from 50 to 98 % by weight, preferably, 88% to 95% by weight, such as 90 to 94% by weight of the composition.

[0153] It will be appreciated that the aggregate may be the aggregate as defined above. For example, it may comprise, optionally consists of, an igneous rock, such as granite.

[0154] In some embodiments, the method further comprises adding bitumen to the binding agent. The bitumen may be added to the binding agent in an amount from 20 to 80% by weight relative to the total weight of the binding agent. For example, the bitumen may be added in an amount from 40 to 70% by weight relative to the total weight of the binding agent.

[0155] In some embodiments, the method further comprises the step of protecting the bitumen prior to adding the bitumen to the binding agent. As mentioned above, protecting the bitumen can stop, or at least reduce, the bitumen reacting with the unreacted functional groups of the polymer. To protect the bitumen, the method may comprise the step of reacting the bitumen with a compound comprising the functional groups of the prepolymer. Accordingly, in preferred embodiments, the method may comprise the step of reacting the bitumen with an isocyanate prior to adding the bitumen to the binding agent. In some embodiments the method comprises reacting the bitumen with a diisocyanate selected from: methylene diphenyl diisocyanate (MDI), methylene 4,4'-biscyclohexylisocyanate (HDMI), hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), toluene diisocyanate (TDI), naphthalene diisocyanate (NDI), p-phenylene diisocyanate (PPDI), derivatives therefrom, or combinations thereof.

[0156] Preferably the method comprises reacting the bitumen with methylene diphenyl diisocyanate (MDI).

[0157] In some embodiments, the method further comprises diluting the bitumen, e.g. with a phthalate, prior to adding the bitumen to the binding agent. For example, it may be diluted with diisononyl phthalate (DINP).

[0158] In some embodiments, the method comprises the step of homogenously mixing the bitumen with the prepolymer.

[0159] In other embodiments, the bitumen is added during the reaction of the primary monomer with a secondary monomer.

[0160] In some embodiments, sealing the composition within the container comprises sealing the composition within the container in an environment free, or substantially free, from moisture. In some embodiments, sealing the composition within the container comprises sealing the composition within an inert atmosphere within the container. In other embodiments, sealing the composition within the container, comprises vacuum sealing the composition within the container.

[0161] Further description of the invention

[0162] In a further aspect of the invention there is provided a system for the repair or reinstatement of a recessed portion of an area of hard standing, said system including a container in which a material which is to be placed into the said recessed area is retained in a substantially sealed condition until the material is required to be used and wherein the said material includes aggregate and a binding agent which, when exposed to moisture and / or air, binds together said aggregate so as to fill and form a substantially integral part of the said area of hard standing. The binding agent, aggregate and container may be the binding agent, aggregate, and container as described above.

[0163] in one embodiment the binding agent comprises a single component.

[0164] Preferably, in whichever embodiment, the binding agent is provided in the form of a resin. Typically, said resin is curable upon exposure to moisture and / or air. The resin may be the prepolymer of any of the embodiments defined above.

[0165] in one embodiment, said resin is an MDI (methylene diphenyl diisocyanate)-based resin.

[0166] Preferabiy, said resin is a polyurethane resin, e.g the polyurethane prepolymer defined above.

[0167] In one embodiment the binding agent is a hybrid of bitumen and polyurethane, which enables the material to include benefits of both forms of binding agents with the inclusion of the bitumen potentially improving the flexibility of the material. The bitumen may be the bitumen of any of the embodiments defined above.

[0168] In one embodiment said resin is provided in the material in an amount of 2% - 10% by weight. The resin may be provided in the material in an amount of 3% - 6% by weight. Alternatively, the resin may be present in an amount of 6 to 10%.

[0169] In one embodiment, the curing of the resin occurs once the container in which the same is held is opened from a previously substantially sealed condition and the material exposed to the external environment, by moisture in the said environment.

[0170] In one embodiment, the material may also include a hydrocarbon component such as kerosene so as to further encourage the bonding of the aggregates which form part of the mixture.

[0171] In one embodiment, a liquid, such as water, is added to the material once the container has been opened and typically once the material has been moved into the recessed area. In one embodiment, the water may be applied using a spray apparatus.

[0172] In one embodiment the liquid is added during the application of the material to fill the recessed portion. In one embodiment the material has greater resistance to the effects of Ultraviolet light and therefore avoid the aging and failure which affects bitumen based conventional materials. In one embodiment the material includes one or more UltraViolet (UV) stability additives.

[0173] In one embodiment, the resin includes a colouring agent, such as black dye, to allow the material, once hardened, to have a colour which is similar to that of the area of hard standing.

[0174] In one embodiment the system includes apparatus to allow for the application of compaction forces onto the material so as to form an external surface which is substantially flat and preferably flush with the external surface of the area of hard standing adjacent the repaired or reinstated portion.

[0175] In one embodiment the aggregate which is used may be granite or similar material.

[0176] In one embodiment the aggregate which is includes is a mixture of different size ranges from relatively small particular sizes of 0.1mm in diameter, commonly referred to as fines, to 6mm in diameter for a material for use in relatively shallow recessed portions of a depth of say 30mm or aggregate of up to 10mm in diameter for material to be used in the repair of larger and / or deeper recessed portions of a depth of say 50mm. This encourages improved bond strength between the aggregate and with the base of the area of hardstanding and sidewalls of the recessed portion.

[0177] In one embodiment the container is a bag into which the material is placed and the bag is then sealed, possibly vacuum sealed, so as to be substantially airtight and moisture sealed, during storage and transport to the location for use.

[0178] In one embodiment the recessed portion is a pothole which is required to repaired or a trench which is required to be reinstated in the area of hardstanding.

[0179] Typically the area of hard standing is any of a road, driveway, pavement or the like.

[0180] In a further aspect of the invention there is provided a material for use in the repair or reinstatement of a recessed portion of an area of hard standing, said material comprising a binding agent mixed with aggregate and retained in a substantially airtight and / or moisture sealed condition to allow the same to be stored and transported to the site of use in a substantially fluid condition and, when exposed to moisture and / or air the binding agent cures to bind the aggregate such that the material hardens in situ in the recessed portion into which the same has been poured and forms a substantially integral part of the area of hard standing.

[0181] The binding agent and aggregate may be the binding agent and aggregate described above.

[0182] In one embodiment, the binding agent comprises a single component.

[0183] Preferably, the binding agent is provided in the form of a resin. Typically, said resin is curable upon exposure to moisture and / or air. The resin may be the prepolymer of any of the embodiments defined above.

[0184] In one embodiment, said resin is an MDI (methylene diphenyl diisocyanate)-based resin.

[0185] Preferably, said resin is a polyurethane resin, e.g. the polyurethane prepolymer defined above.

[0186] In one embodiment, said resin is provided in the material in an amount of 2% - 10% by weight. The resin may be provided in the material in an amount of 3% - 6% by weight. Alternatively, the resin may be present in an amount of 6 to 10%.

[0187] In one embodiment the material is stored and transported in a container such as a bag. The container may be the container of any of the embodiments defined above. In one embodiment the bag includes said material to a specific weight.

[0188] In one embodiment, the aggregate provided in the material is provided in a range of predetermined sizes and most typically, a number of different ranges of predetermined sizes of aggregate are selected and then mixed together along with the resin.

[0189] In one embodiment the material includes a hydrocarbon component, such as kerosene and / or bitumen and / or a colouring agent.

[0190] In one embodiment a liquid such as water is added to the material once removed from the said container.

[0191] Typically, the resin is not classified as hazardous for the aquatic environment.

[0192] Typically, as a result of the curing reaction, a chemically inert, non-biodegradable solid substance is created. Typically, the resin is based on aromatic isocyanates and the binding agent is capable of curing in ambient moisture conditions although curing may be accelerated and / or improved by the addition of liquid thereto. Typically, when cured, the material provides a durable and water impermeable body.

[0193] Typically, the material has a working time during which the same can still be sufficiently fluid to be worked for an hour in a temperature of 20 °C and humidity of 50%.

[0194] In a further aspect there is provided a method for the repair or reinstatement of a recessed portion of an area of hardstanding, said method comprising the steps of; transporting a material to a location for use in an air tight and / or moisture sealed container, opening the container at the location of use, pouring the said material in a fluid condition into the recessed portion to substantially fill the same, compacting the said material and allowing the same to harden and wherein the said material includes a mixture of aggregate and an air and / or moisture curable binding agent.

[0195] The binding agent, aggregate and container may the binding agent, aggregate and container as described above.

[0196] In one embodiment, the binding agent comprises a single component.

[0197] Preferably, the binding agent is provided in the form of a resin. Typically, said resin is curable upon exposure to moisture and / or air. The resin may be the prepolymer of any of the embodiments defined above.

[0198] In one embodiment, said resin is an MDI (methylene diphenyl diisocyanate)-based resin.

[0199] Preferably, said resin is a polyurethane resin, e.g. the polyurethane prepolymer defined above.

[0200] In one embodiment, said resin is provided in the material in an amount of 2% - 10% by weight. The resin may be provided in the material in an amount of 3% - 6% by weight. Alternatively, the resin may be present in an amount of 6 to 10%.

[0201] In one embodiment a liquid such as water is added to the material once removed from the container to encourage the curing of the resin and hence hardening of the material in the recessed portion. Typically, the water will be applied where there is a need to cure and harden and bond the mixture as soon as possible such as, for example, if the repair is being performed to an area of hard standing which is particularly hazardous, such as, for example, in a carriageway of a road.

[0202] In a further aspect there is provided a method for forming a material for use in the repair or reinstatement of a recessed portion of an area of hardstanding, wherein said method comprises the steps of preparing aggregate material by drying the same to remove moisture therefrom, grading said aggregate into a number of size ranges, selectively combining aggregate of at least two of said size ranges, mixing said aggregate with a curable binding agent so as to form a fluid mixture and placing a quantity of the said material mixture into a container and sealing the same so as to retain the said material in a substantially fluid condition.

[0203] The binding agent, aggregate and container may be the binding agent, aggregate and container described above.

[0204] In one embodiment, the binding agent comprises a single component.

[0205] Preferably, the binding agent is provided in the form of a resin. Typically, said resin is curable upon exposure to moisture and / or air. The resin may be the prepolymer of any of the embodiments defined above.

[0206] In one embodiment, said resin is an MDI (methylene diphenyl diisocyanate)-based resin.

[0207] Preferably, said resin is a polyurethane resin, e.g. the polyurethane prepolymer defined above.

[0208] In one embodiment, said resin is provided in the material in an amount of 2% - 10% by weight. The resin may be provided in the material in an amount of 3% - 6% by weight. Alternatively, the resin may be present in an amount of 6 to 10%.

[0209] In one embodiment the preparation method includes the steps of adding a hydrocarbon component such as kerosene to the aggregate and / or resin and / or adding a colouring agent to the resin.

[0210] In one embodiment, in order to manufacture the said mixture, the aggregate which is used, is initially dried to a predetermined level such that, in one embodiment, the same has a moisture content below 2.0% moisture content, such as less than 0.1% by weight as determined by ASTM C566 (Total Evaporable Moisture of Aggregate by Drying). Once dried, the aggregate is then mixed to provide the range of different sizes which, in one embodiment, for relatively small scale repairs, may comprise aggregate from a size of 6mm down to 0.6mm diameter and for larger scale repairs, for example, 10mm down to 0.6mm. While the proportions of the different sizes of aggregate may change for particular uses, it is a preferred part of the invention to provide the aggregate of the different dimensions in the said mixture.

[0211] In accordance with aspects of the present invention there is therefore provided a repair system which comprises a filling material including a curable binding agent, typically in the form of a resin, mixed with aggregate of a range of sizes so as to improve the bond between the aggregate and bonds with the base and sidewalls of the recessed portion into which the material is placed so as to form a repair which is substantially stronger than that which is achievable when using the conventional bitumen based repair material. Furthermore, the increased strength characteristic is apparent throughout the structure once cured and in situ, which is in contrast to the conventional systems in which air curable binding agents, such as bitumen, are used and which therefore only form a hard top surface or crust where the material is exposed to air. The material of the current invention with the increased strength throughout, therefore greatly increases the durability of the repair which is made and this is confirmed by the significant difference between the results of 3 point bend tests performed on the conventional cold lay repair material and that of the current invention which indicate significant strength improvements.

[0212] Thus, as the material, following mixing, is provided in a substantially airtight container which, when opened, allows the resin to start to cure and in particular, cure once applied into the pothole to fill the same to thereby form a new surface which is a substantially integral part of the structure of the road, driveway or pavement.

[0213] Brief Description of Figures

[0214] Specific embodiments of the invention are now described with reference to the accompanying drawings; wherein

[0215] Figures 1a and b illustrate surface damage in the form of a pothole of the type which can be repaired in accordance with the present invention.

[0216] Figures 2a-c illustrate the steps undertaken to repair the pothole shown In Figures 1 a-b; and Figure 3 illustrate the process followed in accordance with one embodiment of the invention to form the material in accordance with the invention.

[0217] Detailed Description of Figures

[0218] In Figures 1a and b there is illustrated a recessed portion in the form of a pothole 2 in an area of hardstanding 4 in the form of a road surface and it will be seen that the pothole typically comprises an area over which the upper surface 6 of the road has disintegrated and has a depth 8 which passes down to the sublayer 10 of the road. In many cases, the depth of the pothole 2 may simply cause annoyance but in other instances, can be hazardous to drivers who drive over the same due to potential damage to their vehicles and / or other drivers who may come into collision with the drivers who are attempting to avoid potholes in the road surface. The potholes may also represent a trip hazard to pedestrians.

[0219] There is therefore a clear need to be able to repair potholes rapidly especially during winter conditions where rain and / or frost may rapidly expand potholes from relatively minor damage to a significant and hazardous damage. This rapid response and repair or reinstatement can be effectively achieved in accordance with the invention as now described which provides a rapid and effective ability to repair the said potholes.

[0220] In accordance with the invention there is provided a composition / material 12 which is formed from a binding agent or resin which is mixed with aggregate such as relatively hard wearing granite.

[0221] Figures 2a-c illustrate the process for repair of the pothole 2 in accordance with the invention. In Figure 2a the material in accordance with the invention is poured from a container 14, in the form, in this embodiment of a bag, in which the material has been stored, transported and maintained in a substantially fluid condition, although other types of sealed containers, such as tubs with lids, or the like could equally be used. The composition / material 12 is poured into the pothole to a sufficient amount so as to fill and possibly overfill the pothole 2, as illustrated in Figure 2b. Also illustrated in Figure 2 is the optional step of applying a liquid such as water 15 to encourage the curing of the resin in the material and hence hardening of the material from a fluid to a substantially solid condition. It is particularly effective for the liquid to be sprayed on to cover all of the material and so, in one possible application process, the material is poured into the hole, then sprayed with water, the material is then moved around, sprayed with water again, and then compacted in order to ensure that all or the majority of the material is contacted directly or at least influenced by the water so that even if parts of the material don’t receive moisture directly, it still cures effectively to form the unitary body over time.

[0222] While hardening compaction apparatus 16 can be used to apply a compressing force 18 onto the top surface 20 of the composition / material 12, as shown in Figure 2c to make the surface 20 substantially flush with the top surface 22 of the area of hard standing 4 and this also increases the density of the material 12 and bonding of the aggregate and of the material 12 to the side walls 24 and base 26 of the area of hard standing so that, when hardened, the same forms a substantially unitary part of the area of hardstanding 4 and the pothole no longer exists.

[0223] In order to form the material, typically, as shown in the flow diagram of Figure 3, the aggregate is dried 28 so as to remove moisture from the same and in turn form the subsequent material mixture formed and then stored. The aggregate is then graded at step 30 into different size ranges and the required size ranges are selected for the particular material mixture which is to be formed and with respect to the subsequent use of the same. A prepolymer or resin 32 is also prepared and additional components e.g. bitumen, colouring agent 34 and / or kerosene 36 and / or any other required component can be selectively added. The selected aggregate sizes are mixed along with the binding agent in the form of a flowable composition at stage 38. Once the same has been mixed to the required extent the composition is then placed into a bag or other form of container at step 40 and the filled container is sealed at step 42 so as to retain the material in a substantially air and moisture sealed condition so as to maintain the flowability of the material / composition and allow the same to be stored and transported relatively easily to the location of use.

[0224] In one embodiment, the resin is formed of a plurality of components which are mixed together.

[0225] In one embodiment, the resin includes less than 30% of 4.4-dipthenylnethanediisocyanate, isomers and homologues. In one embodiment, the resin includes less than 15% of methylenediphenyl diisocyanate. In one embodiment the resin, or the composition in general, may include bitumen.

[0226] Typically, the prepolymer or resin is provided in a liquid form and mixed with the aggregate material and when the composition / material is removed from the container and placed into the repair location, the prepolymer or resin binding agent subsequently cures and hardens to combine and retain the aggregate material as a substantially unitary body. Typically, the curing effects occurs with contact and / or exposure to moisture and / or moisture vapour in the air. Typically, when a liquid such as water is added, the resin reacts and cures more quickly with the release of carbon dioxide.

[0227] The following non-limiting examples illustrate embodiments of the invention.

[0228] Examples

[0229] Preparation of Pre-Polymer (Binding Agent)

[0230] A trifunctional polyether polyol monomer with a moisture content of 0.05% or below is contacted with a carbodiimide-modified 4,4’-methylene diphenyl diisocyanate (MDI) monomer in a 7:1 to 15:1 NCO: OH stoichiometric ratio to form a mixture. The mixture is agitated until the mixture undergoes a visible change in appearance from substantially transparent to an opaque and / or cloudy white state. The temperature of the mixture is increased to between around 60 °C and around 100 °C for up to 90 minutes or until the mixture visually transitions from an opaque / cloudy white state to a translucent, yellow state. Preferably, benzoyl chloride (0.02 wt%) is added to the mixture, before allowing the temperature of mixture to reduce to between 15 °C and 27 °C, e.g. room temperature. It is preferable for the method, or at least one of the steps of the method, to be performed under an inert atmosphere, such as nitrogen.

[0231] Stabilisation of Bitumen

[0232] Bitumen is heated for at least 30 minutes between around 115 °C and around 210 °C, preferably between 120 °C and 160 °C, until melted (dependent on the grade and composition of the bitumen). A mixture of MDI and diisononyl phthalate is contacted with the bitumen, in a ratio of 1:1:3 by weight respectively, and the mixture is periodically agitated for around 90 minutes to produce stabilised bitumen. These steps are preferably performed under an inert environment, such as nitrogen, or a low-humidity environment, such as dry air.

[0233] Preparation of Aggregate

[0234] The aggregate is first cleaned to remove any unwanted dust and / or dirt, before reducing the moisture content of the aggregate to between 0.05% and 0.1% by heating the aggregate between 50°C and 150°C for up to 15 mins in a rotary dryer or fluid bed dryer. The aggregate is passed through one or more sieves, such as a stack of sieves of progressively smaller openings, to further remove any remaining dust and / or aggregate particles outside of the desired particle size range.

[0235] Sieve analysis may be utilised to confirm the granularity of the aggregate. For example, the aggregate may be passed through a vibrating or electromagnetic sieve shaker to separate the aggregate into various size ranges. The vibrating or electromagnetic sieve shaker may comprise a stack of one or more sieves, wherein the mesh size of each sieve other than the top sieve comprising the stack is smaller than the sieve directly above.

[0236] In an exemplary method of sieve analysis, an electromagnetic sieve shaker comprises three sieves stacked vertically with mesh sizes from top to bottom of 1 mm, 0.6 mm and 0.3 mm, respectively. The aggregate is transferred to the top sieve of the sieve stack and vibration is applied for at least 5 minutes. The contents of each sieve are then weighed to determine the percentage of aggregate within each particle size range in respect of the total aggregate weight.

[0237] Preparation of a Composition

[0238] A prepolymer was prepared as described above comprising 44.99 wt% trifunctional polyol, 54.99 wt% MDI and 0.02 wt% benzoyl chloride. The prepolymer was then mixed with stabilised bitumen prepared as described above in a 1:1 weight ratio. The mixing occurred over a period of at least 30 minutes with periodic agitation. The temperature of stabilised bitumen was around 60 °C before contacting the stabilised bitumen with pre-polymer. The temperature of the mixture was then reduced to between 15 °C and 27 °C, e.g. room temperature.

[0239] An aggregate blend was prepared as described above comprising 55% by weight 2-5 mm black granite, 20% by weight 1-3 mm grey granite, and 25% by weight grey granite fines. The aggregate blend was then mixed with the pre-polymer / bitumen mixture binding agent in a ratio of 23:2 weight ratio using a ribbon blenderat 15rpm for up to 10 minutes under a nitrogen atmosphere or dry air.

[0240] The resultant composition was then sealed in a bag within a nitrogen atmosphere. The bag comprised a polyethylene, aluminium and nylon composite material. Strength Testing

[0241] The compressive strength of a cured composition according to the present invention was measured in accordance with BS 6319-2. BS 6319-2 describes the standard method for measuring compressive strength of resin-based mortars or polymer-cement compositions. The process is described below:

[0242] 1. Make cube test specimens (usually 40 mm × 40 mm × 40 mm).

[0243] 2. Condition specimens at 20 °C before testing.

[0244] 3. Use a compression testing machine with clean, flat platens.

[0245] 4. Place the cube with cast faces touching the platens (no packing).

[0246] 5. Apply load continuously at a controlled rate until failure.

[0247] 6. Calculate compressive strength from maximum load cube area.

[0248] 7. Test at least three specimens and report the average strength.

[0249] The sample exhibited a high strength of 597.3 N / cm2. In comparison, a hardened sample of a commercially obtained sample of ColdLay Macadam for repairs to paths and driveways exhibited a much lower compressive strength of 75.4 N / cm2. As discussed above, a high strength product is highly desirable, particularly in the repair of potholes on roads and pavements subject to high traffic.

[0250] Determination of Isocyanate Content

[0251] The isocyanate content of the prepolymer was determined according to EN ISO 14896. The method involved titration following the reaction of the prepolymer with dibutylamine. HCI was used as a titrant and TRIS (tris(hydroxymethyl)aminomethane) was used as a standard. A detailed description is provided below.

[0252] Titre

[0253] 420 mg TRIS was weighed into a titration vessel. 20 mL of deionized water and 50 mL acetone were added. After a pause of 20 s, the solution was titrated with HCI (1.0 mol / L aqueous solution) until the first equivalence point.

[0254] The titre of the titrant (HCI) was then determined based on Equation 1 below: ms

[0255] 1

[0256]

[0257] ” c(Hap" Ms'

[0258] Equation 1

[0259] Wherein:

[0260] f: Titre of the selected titrant;

[0261] ms: Mass of standard (TRIS) in mg;

[0262] VEP-I: Titrant consumption until the first equivalence point in mL;

[0263] c(HCI): Concentration of the titrant (HCI) in mol / L; and

[0264] Ms: Molecular weight of the standard (TRIS) - 121.14 g / mol

[0265] Sample testing

[0266] Around 2 g of sample was weighed out and dissolved in 30 mL of toluene. 18.0 mL of reaction solution (1 mol / L dibutylamine in toluene) was added and allowed to react for 10 min while stirring. 30 mL of acetone was then added and the excess of dibutylamine was back titrated with HCI (1 mol / L aqueous solution).

[0267] Blank

[0268] A blank sample was treated and titrated in exactly the same way as the actual sample but without any sample.

[0269] The isocyanate content was then determined based on Equation 2 below:

[0270] (^BLANK ~ Wm) *?xC(HCI) *

[0271]

[0272] 10 x

[0273] Equation 2 Wherein:

[0274] NCO: isocyanate content of the sample in g isocyanate / 100 g;

[0275] VEP-I: Titrant consumption until the first equivalence point in mL in the sample testing;

[0276] VBLANK: Used titrant in mL for the Blank back titration;

[0277] c(HCI): Concentration of the selected titrant (HCI) in mol / L - 1.0 mol / L;

[0278] f: Titre of the selected titrant - as determined in Equation 1;

[0279] MA: Molecular weight of NCO - 42.02 g / mol;

[0280] ms: Sample size in g; and

[0281] 10: Conversion factor for %.

[0282] As will be appreciated, the prepolymer may be capable of reacting with moisture vapour in the air. The testing of the sample was therefore conducted in inert conditions by covering the sample in an inert gas (e.g. nitrogen)

[0283] Determination of Hydroxyl Value

[0284] The hydroxyl value, i.e. the degree of esterification, of the prepolymer was determined according to ASTM E1899. The hydroxyl value is given in milligrams of potassium hydroxide per gram of sample. Tetrabutyl ammonium hydroxide (TBAOH) (0.1 mol / L) in isopropanol / methanol (cb(MeOH) = 50% (v / v)) was used as a titrant. A 500 mL solution of toluene-4-sulphonyl-isocyanate (TSI) (20 mL) in acetonitrile, referred to as TSI solution henceforth, was made in advance.

[0285] Titre

[0286] 60 mL deionised water was added to approximately 180 mg potassium hydrogen phthalate (KHP). The suspension was stirred for around one minute to dissolve the KHP. The solution was then titrated until the first equivalence point using the titrant. The titre of the titrant (TBAOH) was then determined based on Equation 3 below:

[0287] nx

[0288] X *w*w*w*w*w*w*w*w*^^

[0289]

[0290] ' Vmx c(TBAOH) x Ms

[0291] Equation 3

[0292] Wherein:

[0293] f: Titre of the selected titrant;

[0294] ms: Mass of standard (KHP) in mg;

[0295] VEPI: Titrant consumption until the first equivalence point in mL;

[0296] c(TBAOH): Concentration of the selected titrant in mol / L; and

[0297] Ms: Molecular weight of the standard (KHP) - 204.22 g / mol.

[0298] Sample

[0299] The required amount of sample to be used was calculated as follows:

[0300] 40

[0301]

[0302] Equation 4

[0303] Wherein:

[0304] ms: Sample size in g; and

[0305] OHVexpeded: Expected hydroxyl value. The required amount of sample as calculated in Equation 4 was weighed into the titration vessel and dissolved in 10 mL acetonitrile, and the solution was stirred for 30 s. 10 mL TSI solution was added before covering and stirring the mixture. After 5 minutes, 0.5 mL deionised water was added, the lid closed again, and the solution stirred for another 60 s. 40 mL acetonitrile was added, and the solution was titrated until after the second end point with the titrant.

[0306] The hydroxyl value of the sample was then determined based on Equation 5 below:

[0307] OHV “ ~x x^(TBAOH)xMA

[0308]

[0309] Equation 5

[0310] Wherein:

[0311] OHV: Hydroxyl value of the sample in mg KOH / g sample;

[0312] VEPI: Titrant consumption until the first equivalence point in mL;

[0313] VEPS: Titrant consumption until the second equivalence point in mL;

[0314] c(TBAOH): Concentration of the selected titrant in mol / L;

[0315] f: Titre of the selected titrant - as determined in Equation 3;

[0316] MA: Molecular weight of KOH; here 56.11 g / mol; and

[0317] ms: Sample size in g

[0318] Although the present invention has been described in detail, it should be understood that various changes, substitutions, and alterations are contemplated without departing from the principle and scope of the invention. Accordingly, the scope of the present invention defined herein and particularly the following claims should be interpreted in consideration of the appropriate equivalents. The terms "a", "an" and "the" do not preclude the presence of multiple referents, unless the context clearly dictates otherwise. Optional, optionally, or preferably means that the feature or activity may or may not be present. Either is contemplated. In embodiments, the optional / preferable feature or features may be present. Alternatively, the optional feature or features may not be present. Ranges may be expressed herein as “from” one particular value, and / or “to” another particular value, which is intended to be inclusive of the end-points of the range.

Claims

CLAIMS:

1. A product for the repair or reinstatement of a recessed portion of an area of hard standing, the product comprising a composition within a sealed container; wherein the composition comprises:a binding agent comprising a prepolymer comprising functional groups capable of curing by cross-linking; andan aggregate mixed with the binding agent2. A product according to claim 1, wherein the functional groups are isocyanate groups.

3. A product according to claim 2, wherein the binding agent comprises of from 0.1 g to 40g, optionally 1g to 20g, further optionally 3g to 10g, unreacted isocyanate groups per 100g of prepolymer.

4. A product according to any preceding claim, wherein the prepolymer is a polyurethane, preferably wherein the prepolymer is derived from the reaction of a diisocyanate or triisocyanate with a polyol.

5. A product according to claim 4 wherein the prepolymer is derived from the reaction of a diisocyanate or triisocyanate with a polyol, wherein the NCO stoichiometric ratio is of from 1:1 to 40:1, preferably from 5:1 to 20:1, such a 7:1 to 15:1.

6. A product according to claims 4 or 5, wherein the diisocyanate or triisocyanate is a diisocyanate selected from: methylene diphenyl diisocyanate (MDI), methylene 4,4'- biscyclohexyl isocyanate (HDMI), hexamethylene diisocyanate (HDI), isophorone diisocyanate (I PDI), toluene diisocyanate (TDI), naphthalene diisocyanate (NDI), p- phenylene diisocyanate (PPDI), derivatives therefrom, or combinations thereof; preferably wherein the diisocyanate monomer is methylene diphenyl diisocyanate (MDI).

7. A product according to claims 4 to 6 wherein the polyol is a trifunctional polyol, preferably a trifunctional polyether polyol.

8. A product according to any preceding claim, wherein the binding agent has a viscosity of from 3,000mPa.s to 30,000mPa.s, optionally 6,000mPa.s to 15,000mPa.s, measured at 25 degrees Celsius in accordance with ISO 2555:2018.

9. A product according to any preceding claim, wherein the binding agent is present in the composition in an amount from 2 to 20 % by weight, optionally 5% to 12% by weight, such as 6 to 10% by weight.

10. A product according to any preceding claim wherein the aggregate is present in the composition in an amount from 80 to 98 % by weight, optionally 88% to 95% by weight, such as 90 to 94% by weight.

11. A product according to any preceding claim wherein the binding agent further comprises bitumen, preferably wherein the prepolymer is present in the binding agent in an amount of 30 to 60% by weight of the binding agent and bitumen is present in the binding agent in an amount from 40 to 70% by weight of the binding agent.

12. A product according to claims 20 or 21, wherein hydroxy, carboxylic, phenolic and / or amine functional groups of the bitumen are protected, preferably wherein the functional groups have been protected with an isocyanate, such as methylene diphenyl diisocyanate (MDI).

13. A product according to any preceding claim, wherein the aggregate comprises, optionally consists of, an igneous rock, such as granite; a metamorphic rock; or a mineral; such as quartz; preferably wherein the aggregate comprises granite.

14. A product according to any preceding claim, wherein the aggregate comprises:50 to 65% by weight aggregate with a size between 2 to 5mm,20 to 30% by weight aggregate with a size between 1 to 3mm; and10 - 25% by weight aggregate with a size of less than 1mm;wherein the sizes are determined by sieving.optionally wherein the aggregate with a size less than 1mm comprise:20 to 35% by weight aggregate with size of less than 0.3mm,25 to 40% by weight aggregate with a size between 0.3 to 0.6mm; and30 to 45% by weight aggregate with a size between 0.6 to less than 1mm.

15. The product according to any preceding claim, wherein the sealed container is a bag, optionally a bag comprising polyethylene, nylon and aluminium.

16. The product according to any preceding claim, wherein the composition is stored in an inert atmosphere, such as nitrogen, within the sealed container and / or the composition is vacuum sealed in the container.

17. A method of preparing a product according to any of claims 1 to 16, the method comprising:preparing a binding agent by reacting a first monomer with a second monomer, wherein the reactive groups of the first monomer are in stoichiometric excess relative to the corresponding reactive groups in the second monomer such that it forms the prepolymer with functional groups capable of curing by cross-linking;mixing the binding agent with an aggregate to provide the composition; and sealing the composition within the container.

18. The method according to claim 17 further comprising the step of drying the aggregate prior to mixing the binding agent with the aggregate, optionally wherein the aggregate is dried to a moisture content of less than 1% by weight, preferably less than 0.1% by weight, such as from 0.01% to 0.05% by weight.

19. The method according to claims 17 or 18, wherein the first monomer is a diisocyanate or triisocyanate and the functional groups are isocyanate groups; and the second monomer is a polyol, preferably a trifunctional polyol, such as a trifunctional polyether polyol.

20. The method according to claims 19, wherein the stoichiometric ratio of NCO groups to OH groups in the reaction is from 1:1 to 40:1, preferably from 5:1 to 20:1, such as 7:1 to 15:1.

21. The method according to any of claims 17 to 20, further comprising adding bitumen to the binding agent, preferably in an amount from 40 to 70 wt% relative to the total weight of the binding agent; optionally further comprising the step of reacting thebitumen with an isocyanate, preferably with methylene diphenyl diisocyanate (MDI), prior to adding the bitumen to the binding agent.

22. A method of repairing or reinstating a recessed portion of an area of hard standing, optionally repairing a pothole, using the product according to any of claims 1 to 16, the method comprising the following steps:removing at least a part of the composition from the sealed container; contacting the composition with the recessed portion; andinitiating the cross-linking the prepolymer, thereby binding together the aggregate.

23. A composition for the repair or reinstatement of a recessed portion of an area of hard standing suitable for use in the product of claim 1, the composition comprisinga binding agent comprising a prepolymer comprising functional groups capable of curing by cross-linking when exposed to moisture; andan aggregate mixed with the binding agent;optionally wherein the binding agent is as described according to any one of claims 2 to 9, 11 and 12.

24. A binding agent for use in the repair or reinstatement of a recessed portion of an area of hard standing, the binding agent comprising:a prepolymer comprising functional groups capable of curing by cross-linking; andbitumen.

25. A prepolymer for use in the repair or reinstate a recessed portion of an area of hard standing, the prepolymer capable of curing by crosslinking when exposed to moisture and binding together an aggregate,wherein the prepolymer is a polyurethane derived from the reaction of a diisocyanate with a polyether polyol,wherein the diisocyanate monomer is selected from methylene diphenyl diisocyanate (MDI), methylene 4,4'-biscyclohexylisocyanate (HDMI), hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), toluene diisocyanate (TDI), naphthalene diisocyanate (NDI), p-phenylene diisocyanate (PPDI), or combinations thereof; and wherein the prepolymer comprises from 1g to 20g unreacted isocyanate groups per 100g of prepolymer.

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