ROAD MAKING MATERIAL, A METHOD OF PRODUCING A ROAD MAKING MATERIAL AND A ROAD MADE THEREFROM

Abstract

The present invention relates to a road making material comprising aggregate, bitumen, and a plastics material, wherein: (a) when the road making material is 10 mm stone mastic asphalt, the bitumen comprises at least 4.7% but no more than 5.69% by weight of the aggregate, bitumen, and plastics material mix; (b) when the road making material is 6 mm, 10 mm, or 20 mm asphaltic concrete, the bitumen comprises at least 3.1% but no more than 4.09% by weight of the aggregate, bitumen, and plastics material mix; (c) when the road making material is hot rolled asphalt, the bitumen comprises at least 4.9% but no more than 5.89% by weight of the aggregate, bitumen, and plastics material mix; or (d) when the road making material is heavy duty 32 mm, the bitumen comprises at least 2.4% but no more than 3.39% by weight of the aggregate, bitumen, and plastics material mix.

Claims

1. A method of producing a road making material comprising: (a) heating aggregate; (b) heating bitumen; (c) mixing aggregate and bitumen to form an aggregate and bitumen mixture; (d) after mixing the aggregate and bitumen, adding plastics material to the aggregate and bitumen mixture; and (e) mixing to incorporate the plastics material with the aggregate and bitumen; wherein the plastics material comprises high density polyethylene (HDPE) or low density polyethylene (LDPE).

2. The method of claim 1, wherein the aggregate is heated to 130° C.-180° C.

3. The method of claim 1, wherein the bitumen is heated to 130° C.-180° C.

4. The method of claim 1, wherein the aggregate is heated to 165° C.

5. The method of claim 1, wherein the bitumen is heated to 165° C.

6. The method of claim 1, wherein the plastics material is at ambient temperature when added to the aggregate and bitumen mixture.

7. The method of claim 1 further comprising heating the plastics material to 120° C.-180° C. before mixing with aggregate and bitumen.

8. The method of claim 1, wherein the plastics material is heated to 165° C.

9. The method of claim 1, wherein the aggregate, bitumen, and plastics material are mixed for at least 30 seconds.

10. The method of claim 1, wherein the aggregate, bitumen, and plastics material are mixed for at least 45 seconds.

11. The method of claim 1, wherein the plastics material is a blend comprising high density polyethylene (HDPE) and low density polyethylene (LDPE).

12. The method of claim 11, wherein said blend comprises 50% high density polyethylene (HDPE) by weight and 50% low density polyethylene (LDPE) by weight, with no other plastics materials or contaminants present in the blend.

13. The method of claim 1, wherein the plastics material is a blend comprising polyvinyl butyral (PVB).

14. The method of claim 1, wherein the plastics material is a blend comprising styrene isoprene styrene (SIS).

15. The method of claim 1, wherein 3 kg of the plastics material is present per 1 tonne of roadmaking material.

16. The method of claim 1, wherein: (a) the road making material is 10 mm stone mastic asphalt, the bitumen comprises at least 4.7% but no more than 5.69% by weight of the aggregate, bitumen, and plastics material mix; (b) the road making material is 6 mm, 10 mm, or 20 mm asphaltic concrete, the bitumen comprises at least 3.1% but no more than 4.09% by weight of the aggregate, bitumen, and plastics material mix; (c) the road making material is hot rolled asphalt, the bitumen comprises at least 4.9% but no more than 5.89% by weight of the aggregate, bitumen, and plastics material mix; or (d) the road making material is heavy duty 32 mm, the bitumen comprises at least 2.4% but no more than 3.39% by weight of the aggregate, bitumen, and plastics material mix.

17. A road making material comprising aggregate, bitumen, and a plastics material, wherein: (a) when the road making material is 10 mm stone mastic asphalt, the bitumen comprises at least 4.7% but no more than 5.69% by weight of the aggregate, bitumen, and plastics material mix; (b) when the road making material is 6 mm, 10 mm, or 20 mm asphaltic concrete, the bitumen comprises at least 3.1% but no more than 4.09% by weight of the aggregate, bitumen, and plastics material mix; (c) when the road making material is hot rolled asphalt, the bitumen comprises at least 4.9% but no more than 5.89% by weight of the aggregate, bitumen, and plastics material mix; or (d) when the road making material is heavy duty 32 mm, the bitumen comprises at least 2.4% but no more than 3.39% by weight of the aggregate, bitumen, and plastics material mix.

18. A method for making a road surface, the method comprising laying a road making material to form a road surface, wherein the road making material comprises aggregate, bitumen, and a plastics material, wherein: (a) when the road making material is 10 mm stone mastic asphalt, the bitumen comprises at least 4.7% but no more than 5.69% by weight of the aggregate, bitumen, and plastics material mix; (b) when the road making material is 6 mm, 10 mm, or 20 mm asphaltic concrete, the bitumen comprises at least 3.1% but no more than 4.09% by weight of the aggregate, bitumen, and plastics material mix; (c) when the road making material is hot rolled asphalt, the bitumen comprises at least 4.9% but no more than 5.89% by weight of the aggregate, bitumen, and plastics material mix; or (d) when the road making material is heavy duty 32 mm, the bitumen comprises at least 2.4% but no more than 3.39% by weight of the aggregate, bitumen, and plastics material mix.

19. A method for making a road surface, the method comprising producing a road making material and laying the road making material to form a road surface, wherein the step of producing comprises: (a) heating aggregate; (b) heating bitumen; (c) mixing aggregate and bitumen to form an aggregate and bitumen mixture; (d) adding a plastics material to the aggregate and bitumen mixture; and (e) mixing to incorporate the plastics with the aggregate and bitumen; wherein the plastics material comprises high density polyethylene (HDPE) or low density polyethylene (LDPE); and wherein: (a) when the road making material is 10 mm stone mastic asphalt, the bitumen comprises at least 4.7% but no more than 5.69% by weight of the aggregate, bitumen, and plastics material mix; (b) when the road making material is 6 mm, 10 mm, or 20 mm asphaltic concrete, the bitumen comprises at least 3.1% but no more than 4.09% by weight of the aggregate, bitumen, and plastics material mix; (c) when the road making material is hot rolled asphalt, the bitumen comprises at least 4.9% but no more than 5.89% by weight of the aggregate, bitumen, and plastics material mix; or (d) when the road making material is heavy duty 32 mm, the bitumen comprises at least 2.4% but no more than 3.39% by weight of the aggregate, bitumen, and plastics material mix.

Description

EXAMPLES

[0094] LDPE/HDPE Performance Table

[0095] Independent UKAS accredited tests were carried out on 3 standard products used in the United Kingdom. The products used were 20 mm asphaltic concrete (AC20), 10 mm Stone mastic asphalt (SMA) and Hot Rolled Asphalt (35 14 HRA). The tests shown are for a replacement of 6% of the bitumen content (equivalent to a reduction of 3 kg of bitumen per tonne of asphalt, and 3 kg of plastics material present per tonne of asphalt) with a plastics material blend comprising a 1:1 by weight blend of HDPE and LDPE.

TABLE-US-00001 Result with 6% Control replacement of bitumen Material Test Result with plastics material AC20 Stiffness (ITSM) 7827 MPa 11600 MPa AC20 Water sensitivity 93.6% 99.7% AC20 Wheel tracking 3.6 mm 1.5 mm SMA Stiffness (ITSM) 1823 MPa 5438 MPa SMA Water sensitivity 94.8% 99.5% SMA Wheel tracking 3.1 mm 1.3 mm SMA 4 Point bending 100 143 HRA Stiffness (ITSM) 3568 MPa 4313 MPa HRA Wheel tracking 2.8 mm 1.2 mm HRA Marshall Flow 1.7 2.1 HRA Marshall stability 8.2 7.0

[0096] PVB Performance Table

[0097] Independent UKAS accredited tests were carried out on 2 standard products used in the United Kingdom. The products used were 20 mm asphaltic concrete (AC20) and 10 mm Stone mastic asphalt (SMA). The tests shown are for a replacement of 6% of the bitumen content (equivalent to a reduction of 3 kg of bitumen per tonne of asphalt, and 3 kg of plastics material present per tonne of asphalt) with 100% PVB plastics material.

TABLE-US-00002 Result with 6% Control replacement of bitumen Material Test Result with plastics material AC20 Stiffness (ITSM) 7827 MPa 9133 MPa AC20 Wheel tracking 3.6 mm 1.9 mm SMA Stiffness (ITSM) 1823 MPa 4539 MPa SMA Water sensitivity 94.8% 96% SMA Wheel tracking 3.1 mm 1.5 mm SMA 4 Point bending 100 198

[0098] SIS Performance Table

[0099] Independent UKAS accredited tests were carried out on 2 standard products used in the United Kingdom. The products used were 20 mm asphaltic concrete (AC20) and 10 mm Stone mastic asphalt (SMA). The tests shown are for a replacement of 6% of the bitumen content (equivalent to a reduction of 3 kg of bitumen per tonne of asphalt, and 3 kg of plastics material present per tonne of asphalt) with 100% SIS plastics material.

TABLE-US-00003 Result with 6% Control replacement of bitumen Material Test Result with plastics material AC20 Stiffness (ITSM) 7827 MPa 10387 MPa AC20 Wheel tracking 3.6 mm 2.9 mm SMA Stiffness (ITSM) 1823 MPa 3746 MPa SMA Water sensitivity 94.8% 97.9% SMA Wheel tracking 3.1 mm 2.5 mm SMA 4 Point bending 100 398

[0100] Comparative Data

[0101] The table below demonstrates the reduction in bitumen content that can be achieved by the present invention when compared to standard comparable products. These are non-limiting examples and a person skilled in the art would readily be able to apply the teaching of the present invention to any of the many varieties of asphalt produced globally.

TABLE-US-00004 Standard Minimum Minimum bitumen content bitumen content possible with plastics possible material added Product (% by weight) (% by weight) 10 mm Stone mastic 5.7 4.7 asphalt 20 mm Asphaltic 4.1 3.1 concrete Hot rolled asphalt 5.9 4.9 35 14 Heavy duty 32 mm 3.4 2.4

[0102] Plastics Material Tests

[0103] Several plastics materials were tested for their suitability for use in the present invention. Plastics materials were prepared wherein blends comprised at least 60% of the specified plastic material, and preferably 100% pure plastics materials were used (i.e. with no contaminant or other plastics). The plastics materials were then utilised in the method according to the invention. The table below shows five failures and reasons why these plastics materials are unsuitable for the present invention. HDPE, LDPE, PVB, and SIS have no such problems and were selected as being suitable for use in the present invention and are individually preferred and can be used in combinations with one another.

[0104] Additionally, whilst the five plastics listed below were not suitable for the present invention when comprising at least 60% of the plastics material, the plastics listed below may comprise up to 10% by weight in total of the plastics material with no significant adverse effects.

TABLE-US-00005 Products tested Reason for failure Polyvinyl Recycled PVC has very high variability in melting point chloride (PVC) (from 100° C. to 260° C.) and there are multiple grades of recycled PVC available which means that guaranteeing full melt is difficult. Polyethylene The melting point of recycled PET proved too high for terephthalate asphalt production. (PET) Polypropylene When mixed with recycled polypropylene the asphalt (PP) became too dry and brittle meaning the resultant asphalt is difficult to lay and may not have longevity. Polystyrene There is a high variability of recycled polystyrene grades (PS) which means that consistency of product is difficult to guarantee. Polycarbonate Using recycled polycarbonate, a full melt is difficult to (PC) achieve at 160° C. degrees in asphalt mixing plant.