Polyurethane based roadway forming
Provided herein are roadways containing polyurethane materials. A roadway includes a base layer of a compacted in situ material and/or a wear layer disposed on the base layer. One or both of these layers may include the polyurethane material to bind other components in the layers and to form more robust and durable roadway structures capable of withstanding operating loads of the roadway. In some embodiments, the polyurethane material is added to the wear layer by mixing in situ soil and/or foreign aggregate with polyurethane material or by dispensing the polyurethane material over the existing partially formed wear layer. The base layer may or may not include a polyurethane material. The type, concentration, distribution, and processing of the polyurethane material in the wear layer may be the same or different than that in the base layer.
1. A method of forming one of a road, a walkway, a base for railroad tracks, or a parking lot, the method comprising:
providing a soil;
combining the soil with at least one polyurethane precursor,
wherein combining the soil with the at least one polyurethane precursor forms a polyurethane filled soil material,
wherein the polyurethane filled soil material comprises the soil and the at least one polyurethane precursor,
wherein a concentration of the at least one polyurethane precursor in the polyurethane filled soil material is between about 2% by weight and 20% by weight; and
pressing the polyurethane filled soil material.
2. The method of claim 1 , wherein the polyurethane filled soil material is pressed onto a paving foundation.
3. The method of claim 2 , wherein pressing the polyurethane filled soil material onto the paving foundation forms one or more layer of the one of the road, the walkway, the base for railroad tracks, or the parking lot.
4. The method of claim 3 , further comprising sealing the one or more layer of the one of the road, the walkway, the base for railroad tracks, or the parking lot using a polyurethane material thereby forming a sealing layer over the one or more layer of the one of the road, the walkway, the base for railroad tracks, or the parking lot.
5. The method of claim 1 , wherein combining is performed using a pug mill.
6. The method of claim 1 , wherein the soil is a foreign aggregate comprising at one of sand, gravel, or crashed rock.
7. The method of claim 1 , further comprising, after pressing the polyurethane filled soil material onto the paving foundation, curing the polyurethane filled soil material using at least one of air streams or heat.
8. The method of claim 1 , further comprising adjusting a moisture content of the soil prior to combining the soil with the at least one polyurethane precursor.
9. The method of claim 1 , wherein the at least one polyurethane precursor comprises a first polyurethane precursor and a second polyurethane precursor and wherein the first polyurethane precursor and the second polyurethane precursor are combined while combining the soil with the at least one polyurethane precursor.
10. The method of claim 1 , wherein the at least one polyurethane precursor comprises one of isocyanate or isocyanate-containing prepolymer, and wherein the polyurethane filled soil material is substantially free from polyol.
11. The method of claim 1 , further comprising adding a reinforced component into the polyurethane filled soil material, wherein the reinforced component comprises a material selected from the group comprising basalt fibers, silica fibers, glass fibers, and polypropylene fibers.
12. The method of claim 1 , wherein the at least one polyurethane precursor comprises a heat stabilizer selected from a group consisting of aluminum hydroxide, magnesium hydroxide, antimony trioxide, antimony pentoxide, sodium antimonite, zinc borate, zinc stannate, zinc hydrostannate, red phosphorous, ammonium polyphosphate and combinations thereof.
13. The method of claim 1 , wherein the least one polyurethane precursor comprises diphenylmethane-diisocyanate.
14. The method of claim 1 , wherein providing the soil comprises pulverizing an in situ soil.
15. The method of claim 14 , wherein combining the soil with the at least one polyurethane precursor is performed while pulverizing the in situ soil.
16. The method of claim 14 , wherein the in situ soil is a cured asphalt concrete composite.
17. The method of claim 1 , wherein a layer formed after pressing the polyurethane filled soil material has a soil compaction of at least about 90%.
18. The method of claim 1 , wherein the at least one polyurethane precursor comprises a polyester polyol.
19. The method of claim 18 , wherein the polyester polyol comprises a hydroxyl-terminated reaction product of a polyhydric alcohol, and wherein the polyhydric alcohol comprises at least one of ethylene glycol, propylene glycol, diethylene glycol, 1,4-butanediol, neopentylglycol, 1,6-hexanediol, cyclohexane dimethanol, glycerol, trimethylolpropane, or pentaerythritol.
20. The method of claim 1 , wherein the at least one polyurethane precursor and the soil are combined at a site of pressing the polyurethane filled soil material onto the paving foundation.