Composition

Abstract

A composition comprises elastomer particles having an average diameter of less than 8mm and which are derived from rubber tyres. The tyres may be aircraft tyres and may be formed from vulcanised rubbe

Description

The present invention relates to compositions for pothole repair on road surfaces. Potholes are a common occurrence on road surfaces. They develop over time as a result of a weakness in the original road surface installation. Weaknesses in a road surface can occur due to a number of factors which include improper compaction of the road surface. Potholes are one of the main causes for claims on car insurance and cost the industry millions of pounds in the United Kingdom, alone. Potholes often occur from repeated loading from vehicles which can compromise the structural integrity of the road surface giving rise to cracks which permit the ingress of rainwater. The water can propagate the crack further from hydraulic force created by vehicles travelling over the surface and displacing the water or from the water freezing and expanding. Erosion of the roadbed can occur in this way and the road surface sinks into the eroded sections under the loading from vehicles. To repair a pothole, an appropriate amount of asphalt is prepared to fill the void. At the time of placement, the fill material is soft and compressible. Following placement, the fill material is compressed so that it is substantially level with the overall road surface. The fill material is then allowed to cure and harden to form a contiguous surface with the existing road surface. However, existing repair compositions are susceptible to crack development its margins where it meets the pre-existing hardened road surface allowing water ingression which tends to flow under the repair composition between it and the original road bed or road surface material. This water can then unseat the pothole repair material from hydraulic force from travelling vehicles or the water freezing as described above. As a consequence, the repair to the road surface is often only a temporary fix, which requires further attention within a short period of time. Depending upon the environmental conditions, the repair may have to be repeated on a regular basis to maintain the road surface, which can be a costly exercise. It would be advantageous to overcome or alleviate one or more of the problems associated with the prior art. In accordance with a first aspect of the present invention, there is provided a composition for repairing a road surface comprising asphalt and / or bitumen, said composition comprising: a) elastomer particles having a particle diameter of less than 8mm b) Asphalt, bitumen and / or concrete The composition of the present invention can be prepared and applied at lower temperatures compared with traditional methods for pothole repair. For example, known methods comprise heating asphalt to between 280 - 320°C and applying the heated composition to the pothole, allow to cool and cure. In contrast, an embodiment of the present invention need only be heated to 120 -160°C and applied to the pothole, allowed to cool and cure. Thus the present invention makes use of less energy to deploy and can make significant cost efficiencies. In addition, there is a more water-resistant interface between the existing road surface and the repair composition in comparison to known technology, reducing the likelihood of water ingress therebetween. The longevity of repairs made using the present invention are significantly better, thus reducing the need for frequent repairs, reducing the carbon foot print and cost. Advantageously, the elastomer particles comprise rubber, natural rubber, polyurethane, polybutadiene, neoprene and / or silicone. Advantageously, the elastomer is vulcanised. More advantageously, the elastomer particles comprise vulcanised rubber derived from used vehicle tyres. Even more advantageously, the elastomer particles are derived from aircraft tyres. The elastomer particles may comprise highly unsaturated diene elastomers, for example, polybutadienes (BR), polyisoprenes (IR), natural rubber (NR), butadiene copolymers, isoprene copolymers and mixtures of these elastomers. Also suitable for use in particular embodiments of the present invention are rubber elastomers that are copolymers and include, for example, butadiene-styrene copolymers (SBR), butadiene-isoprene copolymers (BIR), isoprene-styrene copolymers (SIR) and isoprene-butadiene-styrene copolymers (SBIR) and mixtures thereof. Also suitable for use in particular embodiments of the present invention are rubber elastomers that that include, for example, natural rubber, synthetic cis-1,4 polyisoprenes and mixtures thereof. Advantageously, the elastomer particles are derived from recycled tyres that are comminuted to a crumb and then further refined to a micro powder. The elastomeric particles may comprise less than 10% (by weight) of the repair composition. Advantageously, the elastomeric particles may comprise less than 5% (by weight), less than 2.5% (by weight), less than 1.25% ( by weight) or less than 1.0 % ( by weight) of the repair composition. Advantageously, the elastomer particles comprise 1.25% (by weight) of the repair composition. In an embodiment, when used with asphalt, 12.5 kg's to 1 metric tonne of asphalt, the present invention drastically reduces the energy required (up to 38%) to create the repair composition. The average particle size of the elastomeric particles may be less than 8mm in diameter, advantageously less that 6mm, more advantageously less than 4 mm, most advantageously 0.001 -1mm and / or mixtures thereof. The average particle size may be 300 pm or less. The repair composition may comprise an aggregate stone mastic asphalt, (SMA) stone mastic asphalt surface course material. The aggregate composition and elastomeric particles may provide inherit strength characteristics and increased resistance to rutting over and above than seen with hot road asphalt. The present invention may provide a highly durable material with its surface texture meeting the requirements set out by the transport infrastructure. The present invention will now be described, by way of example only, with reference to the accompanying examples. EXAMPLE 1 A comprehensive range of test equipment, a wide range of material characteristics were measured using the present invention including stiffness and fatigue and permanent deformation by both indentation and vacuum tri-action methods, aggregates, bitumen and fillers. Rubber crumb is a free-flowing black crumb produced from recycled rubber material as defined by ASTM D 5603-01 Grades 1, 2, 3, and 4. The rubber crumb is made by ambient grindings of truck tyre buffings recovered from worn truck tyres that are made ready for remoulding. The crumb is a clean product that is prepared to be essentially free from steel, textile and other non-rubber substances. The polymer represents a blend of (NR) natural rubber and styrene-butadiene rubber (SBR) and other constituents as indicated in the table 1 below. Table 1 Rubber Gra^yfats Property W&f Stza | I % 8 ?! I V;. <7 & 7 % fem AS” MS In accordance with another aspect of the present invention, there is provided a water-based epoxy composition for application to substrates. 5 The composition may comprise a curing agent and a resin, comprising any one or more of styrene butadiene, poly butadiene and / or polyisobutylene-isoprene. The substrate may comprise concrete. The present invention may be chemical resistant, may be applied to damp substrates, hygienic, zero voc system, solvent free / environmentally friendly, odour free and / or may apply, using brush or 10 roller. The composition may be applied to substrates in factories, warehouses, plant rooms, garages, aircraft hangars or the like. The composition advantageously provides excellent resistance to a wide range of chemicals, and is resistant to one or more of the following: 10% Sulphuric Acid 10% Hydrochloric Acid, Petrol, Skydrol, 20% Sodium Hydroxide, Ethylene Glycol, Methyl Ethyl Ketone, Trichlorethylene. 15 “Water based or aqueous" means that the adhesive comprises a water component. The term “drying" means the substantial removal of water from the adhesive composition through evaporation, heating or vacuum drying. "Substantially water resistant" means that an adhesive bond formed between two contact adhesive films as defined above is substantially resistant to the effects of boiling water on the strength of the contact adhesive bond. 5 The composition of the present invention may comprise a plurality of constituents as set out in table 2 below. Table 2 EXAMPLE 2 10 In an embodiment, Concrete substrates were at least 28 days old and be clean, dry, sound and free of laitance, oil, grease and any other surface contamination which could impair adhesion. Existing floor areas require mechanical abrasion to reveal clean concrete. Enclosed vacuum blasting equipment or equivalent vonarx type scabbiers should be used. Any areas which have been contaminated with oil or grease should be treated with hot compressed air blasting equipment. This 15 will drive out any deep-seated contamination. Any areas of damaged concrete should be broken out and reinstated. For small areas of thin section repairs - less than 10mm in depth - an epoxy resin repair mortar should be used. For larger area thicker section repairs a polymer reinforced cementitious repair mortar should be used. Any cracks in the substrate in excess of 1mm wide should be chased out to a minimum width and depth of 5mm and repaired with an epoxy resin mortar. Finer cracks do not normally require pre-treatment as they can be flooded with the present invention resin coating. Any existing floor coatings which are not soundly bonded to the substrate must be removed prior to the application of the present invention. Adhesion tests should be carried out to ensure compatibility with the present invention. For newly laid concrete substrates which have been allowed to cure for the minimum 28 days, a light pass with enclosed vacuum blasting equipment is required. This will lightly texture the substrate and ensure that all laitance and the remnants or any curing membranes are removed. Any flexible joints within the concrete substrate should be protected within masking tape. The perimeters of the area being treated, along with any grids, drains etc. should be protected with masking tape. The curing agent, pack A, is added to the resin component, pack B, and mixed for sixty seconds using a mechanical paint stirrer. The coating is applied to the prepared floor using a roller or brush. The present invention composition is normally applied as a three coat system, with the second and third coats being applied as soon as possible after the previous coats have cure to a tack-free finish. In order to optimise inter-coat adhesion, the time lapse between subsequent coatings must not be allowed to exceed 24 hours. Should this occur, the coating will require light abrading and degreasing. At an ambient temperature of 20°c, The composition of the present invention may be lightly trafficked after 24 hours, with 48 hours being required prior to heavier trafficking. As soon as the final application has cured sufficiently to accept light trafficking all masking tape should be removed. In accordance with another aspect of the present invention, there is provided a self extinguishing neoprene rubber sheet derived from a composition as described hereinabove. Thicknesses up to 8mm and 5m Long for 8mm and above. Properties of the sheet are set out in table 3 below. Table 3 Specifications Values Test Methods Con^prsss^n S&t 0SO81 34.8¾ ISO 815 EMncai Resistance 18 m2* Ohms am UNE 21383^ Etogatran at Break 550% ASWP412 Highest Recmwwded wx Hone Lowest Recommended Working "emcvrutwe -25’C None bhve K SS (b* z"'' Specie ..^Shw 15? g / cm3 AST? ?22^ Tear Strength Twite Strength.......................................... 27.3 KWm JWA........................................................... ISO 34 ASTM 0412 In accordance with a further aspect of the present invention, there is provided a flame retardant rubber sheet derived from a composition as described hereinabove. 5 In an embodiment, properties of the rubber sheet material may comprise any one or more of the 06 03 25 properties set out in the table 4 below. Table 4 Test Method Density >90 kg / M3 BS EN ISO 845 Colour Dark Grey Thickness 5mm to 100mm Fire Propagation Index < 12 BS 476 pt 6 Surface Spread of Flame Class 1 Bs 476 pt 7 Building Regs 1991 (Fire Safety) Class 0 BS 476 pt 6 &7 Operating Temperature -30°C to 100°C UL94 Classification 94 V-0 UL94 Surface Burning Behaviour Class A ASTM E84-95 Air Erosion Resistance (4001-6000 fpm) Pass ASTM C1071-9112.7) Fungus Resistance Test Does not support growth ASTM G21 Mildew (Fungus) Resistance Does not support growth ASTM D-2020 Water Vapour Sorption <9% ASTM C553-92 Thermal Conductivity 0.364 Btu-in / hr-ft2°F ASTM C518-91 Corrosiveness (galvanised steel) Pass ASTM C665-95 Hot Surface Performance @100°C 96 hr Pass ASTM C411-97 In an embodiment, properties of the rubber sheet material may comprise any one or more of the properties set out in the table 5 below. 06 03 25 Table 5 Technical Specifications SM172 EPDM EN 45575-2 + Al 2015 Halogen Free Properties Test Method Values FPS Units Test Method Values Metric Units Specific Gravity DIN 53508 1.45 +- 0.05 ASTM D297 1.45 +- 0.05 Hardness DIN 53505 70 +- 5 Sh A ASTM D2240 70 +- 5 Sh A Tensile Strength (min) DIN 53504 995 PSI ASTM D412 70 kg / cm2 Elongation at Break (min) DIN 53504 400% ASTM D412 400% Compression set (70°C / 24 hrs / 25% set) (max) DIN 53517 25% ASTM D395 Method B 25% Tear resistance (angular) (min) DIN 53515 112 Lbs / lnch ASTM D624 20 kg / cm Change in properties Heat ageing (168 hrs at 85°C) ASTM D573 — Hardness +10 (max) +10 (max) — Tensile Strength (%) +15 / -15 +15 / -15 — Elongation at break (%) +10 / -30 +10 / -30 Polymer 100% EPDM 100% EPDM Ozone 200 PPHM 96H 40’C 20% No cracks ASTM D1149 No cracks Hazard Level EN 45 545 HL3 EN 45 545 HL3 Fire Resistance BS 476, Part 7 vehicle cat, La acc. To BS 6853 Class 3 BS 476, Part 7 vehicle cat, La acc. To BS 6853 Class 3 Chemical Resistance — Ozone Very Good Very Good — Dilute Acids and Bases Good Good — Concentrated Acids and Bases Medium Medium — Oils Medium Medium Temperature Range -30°C to +100°C -30°Cto +100°C Colour Black Black 5 In an embodiment, the material may be used for absorbing sound for noise reduction. SeuRd Absorption ©25mm (formal Inddssce) NRC >0.4D SauRd Absorption ©12 mm Random incidence} NRC >0.28 Scond Absorption ©25mm (formal Incidence) NRC >O.SD Soimd Absorption ©50mm (formal Inddsnw) HRC >0.78 In accordance with a further aspect of the present invention, there is provided an under rail pad comprising an elastomeric body having an upper surface adapted to underlie the undersurface of a rail being deformable to dampen rail vibration when the rail is loaded wherein the elastomeric body comprises a composition as described hereinabove. For the purposes of vibration damping and ballast protection, under rail pads are arranged on or fastened to the bottom sides of track sleepers which carry the rails. An elastomer is a dimensionally stable but elastically deformable material which can be elastically deformed under tensile and / or pressure loading and then, after the loading has ended, however, at least predominantly returns to its original undeformed shape again. A specific embodiment of the invention will now be described by way of example only with reference to the accompanying drawings, in which: Fig. 1 shows an under rail pad in accordance with the present invention; and Fig. 2 shows the under rail pad of Fig. 1 and a rail on a substrate. Figs. 1 and 2 show an under rail pad 10 comprises a rectangular planar body 12 having an upper bearing surface 14 for contacting the under side 16 of a railway rail 18, and a lower surface 20 for contacting a sleeper 22 or the like. A worm screw secures the rail to the pad and sleeper upon which the pad is disposed therebetween. When a train travels over the rail on surface 24, the pad 10 is deformed under the tensile and / or pressure loading but owing to the resi I iently deformable properties of the pad, the pad absorbs some of the associated vibrations and the worm screw is less likely to be displaced over time by repeated loading and unloading of the rail. Thus the working like of the arrangement is prolonged when compared to known arrangements.

Claims

1. A composition comprising elastomer particles having an average particle diameter of less than 8mm wherein the elastomer particles are derived from rubber tyres.

2. A composition as claimed in claim 2 wherein the tyres are aircraft tyres.

3. A composition as claimed in claim 2 or 3 wherein the elastomer particles are derived from vulcanised rubber.

4. A composition as claimed in any one of claims 1 to 3 wherein the average particle size is 0.001 -1mm.

5. A composition as claimed in claim 4 wherein the average particle size is less than 200 - 300pm.

6. A composition comprising asphalt, concrete and / or bitumen, said composition comprising:a) elastomer particles having an average particle diameter of less than 8mmb) Asphalt, bitumen and / or concrete7. A composition as claimed in claim 1 wherein the elastomer particles comprise rubber, natural rubber, polyurethane, polybutadiene, neoprene and / or silicone.

8. A composition as claimed in claim 2 wherein the elastomer particles are vulcanised.

9. A composition as claimed in any one of the preceding claims wherein the elastomer particles comprise highly unsaturated diene elastomers, for example, polybutadienes (BR), polyisoprenes (IR), natural rubber (NR), butadiene copolymers, isoprene copolymers and mixtures of these elastomers.

10. A composition as claimed in any one of claims 1 to 3 wherein the elastomer particles comprise rubber elastomers that are copolymers and include, for example, butadiene-styrene copolymers (SBR), butadiene-isoprene copolymers (BIR), isoprene-styrene copolymers (SIR) and isoprene-butadiene-styrene copolymers (SBIR) and mixtures thereof; natural rubber, synthetic cis-1,4 polyisoprenes and mixtures thereof.

11. A composition as claimed in any one of the preceding claims wherein the elastomeric particles comprise less than 10% (by weight) of the repair composition.

12. A composition as claimed in claim 6 wherein the elastomeric particles comprise less than 5% (by weight), less than 2.5% (by weight), less than 1.25% ( by weight) or less than 1.0 % ( by weight) of the repair composition.

13. A composition as claimed in any one of the preceding claims wherein the average particle size of the elastomeric particles is less than 6mm14. A composition as claimed in any one of the preceding claims wherein the average particle size of the elastomeric particles is less than 4 mm.

15. A composition as claimed in any one of the preceding claims wherein the average particle size of the elastomeric particles is 0.001 - 1mm.

16. A composition as claimed in any one of the preceding claims comprising an aggregate stone mastic asphalt material.

17. A composition as claimed in any one of the previous claims for repairing a road surface.

18. A road surface repair composition comprising a composition as claimed in any one of claims 1 to 17.

19. A water based composition for covering a substrate, said composition comprising water and organic solute, wherein the organic solute is derived from a composition as claimed in any one of claims 1 to 18.

20. An under rail pad comprising an elastomeric body having an upper surface adapted to underlie the undersurface of a rail being deformable to dampen rail vibration when the rail is loaded wherein the elastomeric body comprises a composition as claimed in any one of claims 1 to 18.

21. A sheet material derived from a composition as claimed in any one of claims 1 to 18.

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