Method of producing a road making material and to a road made therefrom

Abstract

A method of producing a road making material includes the steps of heating plastics and bitumen and mixing 5%-25% by weight of plastics with bitumen. The heated plastics/bitumen mixture is then mixed with aggregate to form a bitumous compound which may then be used to lay a road (pavement) surface. Alternatively, the heated plastics and bitumen is mixed directly with aggregate to form a bitumous compound. The plastics used is, preferably, waste plastics that is collected, cleaned and shredded, or the plastics may be pelletised or in the form of microbeads.

Claims

1. A method of producing a road making material comprising the steps of: 1. heating plastics and bitumen; and 2. mixing the heated plastics and bitumen with aggregate to form a plastics/bitumen/aggregate mixture; wherein the plastics/bitumen/aggregate mixture of step 2 is used to form a road surface, and wherein the road surface is formed by laying the material of step 2 at a temperature in the range of 70 C. to 160 C. and subsequently rolling the material so that it is compacted, wherein a rolling weight is up to approximately 10,160 kg (10 ton).

2. The method as claimed in claim 1, wherein step 2 includes the steps of: (a) mixing the heated plastics and bitumen to form a plastics/bitumen mixture, and (b) mixing the mixture of step (a) with aggregate to coat said aggregate with plastics/bitumen.

3. The method as claimed in claim 1, wherein in step 1, the plastics is heated to between 120 C.-180 C.

4. The method as claimed in claim 1, wherein the plastics is heated to approximately 165 C. and the bitumen is heated up to approximately 160 C.

5. The method as claimed in claim 1, wherein in step 1, a ratio of plastics to bitumen is 5%-25% by weight of plastics to bitumen.

6. The method as claimed in claim 1, wherein a grade of bitumen is one of 40/60, 60/70, 80/100 or 100/150.

7. The method as claimed in claim 1, wherein a grade of bitumen is 40/60 for a heavily trafficked road.

8. The method as claimed in claim 1, wherein the aggregate has a mesh size in the range 1 mm-55 mm.

9. The method as claimed in claim 1, wherein the aggregate has a mesh size of 10 mm or 14 mm.

10. The method as claimed in claim 2, wherein, in step (b), a ratio of the plastics/bitumen mixture to the aggregate is approximately 4%-10% by weight.

11. The method as claimed in claim 1, wherein, in step 1, waste plastics is collected, cleaned and shredded to 1 mm-50 mm to be heated and mixed with bitumen.

12. The method as claimed in claim 1, wherein plastics microbeads of 5 m to 1 mm or pelletised plastics in the range 1 mm to 10 mm are used.

13. The method as claimed in claim 1, wherein, in step 2, a ratio of the heated plastics and bitumen to the aggregate is approximately 4%-10% by weight.

14. The method as claimed in claim 1, wherein the plastics/bitumen/aggregate mixture is a bitumous compound.

15. A method comprising the steps of: 1. heating waste plastics and bitumen; 2. mixing the heated plastics and bitumen with aggregate to form a plastics/bitumen/aggregate mixture; 3. laying the material of step 2 at a temperature in the range of 70 C. to 160 C.; and 4. subsequently rolling the material so that it is compacted, wherein a rolling weight is up to approximately 10,160kg (10 ton), thereby forming a road surface.

Description

(1) The invention will now be described, by way of example, with reference to the accompanying drawing, in which:

(2) FIG. 1 shows a flow chart of a method of producing a road making material and to a road made therefrom.

(3) This invention preferably uses waste plastics that is collected from landfill sites, dumps, garbage trucks, school collection programmes, or by purchase from waste buyers/collectors, although it is to be understood that the improved road making material of this invention is not dependent upon the use of waste plastics since it is possible that plastics material from a chemical plant may be utilised.

(4) Referring to FIG. 1, in step 1 waste plastics material is collected from the forementioned landfill sites, etc. The collected waste plastics is sorted, if required, and cleaned by, for example, washing and cut to a size of 1 mm-55 mm using a shredding machine in step 2. Alternatively, plastics microbeads of 5 m to 1 mm or pelletised plastics in the range 1 mm to 10 mm are used.

(5) The shredded plastics is then heated in step 3 to a temperature of 120 C.-180 C., preferably 165 C. It has been found that the plastics softens at 120 C. and there is no gas evolution in the range 120 C.-180 C. The bitumen is similarly heated, usually in a separate furnace up to 160 C. in step 3.

(6) In step 4, the plastics are mixed with the bitumen at a rate of 5%-25% by weight of plastics to the weight of bitumen. A mixing plant is used to control the temperature of the plastics and bitumen which are mixed together so as to provide a substantially uniform coating of plastics on the bitumen.

(7) The bitumen used may have grades 60/70, 80/100 or 100/150, but for heavily trafficked roads is, preferably, 40/60 grade.

(8) In step 5, the heated plastics/bitumen mixture is mixed with aggregate where the plastics/bitumen mix is 4%-10% by weight to aggregate. The aggregate is typically 1-55 mm, preferably 10 mm or 14 mm and has stone dust and lime as a filler. The aggregate may, preferably, be granite stone or may be ceramics or other suitable material. The plastics/bitumen, when mixed with the aggregate, produces a bitumous compound which is aggregate coated with plastics/bitumen and the compound may be transported to a laying machine where it is laid on a pre-prepared surface, the road laying temperature being between 70 C.-160 C. in step 6. The surface is then rolled by a roller having up to an 10,160 kg (10-ton) capacity, for example.

(9) Alternatively, steps 4 and 5 are combined in step 7 where the heated plastics and bitumen are mixed with aggregate whereby the plastics and bitumen mixture coats the aggregate.

(10) It is believed that using plastics with bitumen to coat aggregate for a road making material has the following advantages over currently produced bitumised road surfaces: 1. A stronger road with increased Marshall stability valueroad strength increased by approximately 100%, leading to maintenance intervals being doubled. It is estimated that using this invention will produce a road that will last up to ten years before maintenance is required, and may even last four or five times longer. 2. Improved resistance towards rain water penetration and water stagnation. 3. Reduced stripping and production of potholes. 4. Increased binding and improved bonding of the mix. 5. Reduced pores in aggregate with consequential reduction in rutting and ravelling. 6. No leaching of plastics. 7. Improved UV protection. 8. Increased load withstanding, thereby satisfying present day needs with heavier road vehicles and increased vehicle density. 9. Decrease in cost of road construction. 10. Useful utilisation of waste plastics 11. When using pellets or microbeads, the particle size is completely uniform meaning that the mixing time after the pellets are added is consistent and can be minimised to increase the efficiency of the asphalt plant. Producing microbeads and pelletising requires consistency of the ingredients in order to work and as such quality control is entrained into the production of the microbeads or pellets, further increasing the efficiency of asphalt plants and minimising any contamination of the down stream product. This is because the formation of a microbead or pellet is only possible if there is no contamination as any contaminants tend to block the filters in the pelletising machines.

(11) Many variations are possible without departing from the scope of the present invention as defined in the appended claims.