Polyurethane based road 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 a roadway, the method comprising:
providing a reclaimer-stabilizer machine,
wherein the reclaimer-stabilizer machine is configured to pulverize an in situ soil and to combine at least one polyurethane precursor into the pulverized in situ soil;
pulverizing the in situ soil using the reclaimer-stabilizer machine;
combining the pulverized in situ soil with the at least one polyurethane precursor using the reclaimer-stabilizer machine,
wherein the combining forms a polyurethane filled soil material,
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
compacting the polyurethane filled soil material using the reclaimer-stabilizer machine, wherein the compacting forms a layer of the roadway.
2. The method of claim 1 , wherein the layer of the roadway is a wear layer.
3. The method of claim 1 , wherein the layer of the roadway is impermeable to water after curing the polyurethane filled soil material.
4. The method of claim 1 , further comprising adjusting a moisture content of the pulverized in situ soil using the reclaimer-stabilizer machine, wherein the adjusting comprises adding water into the pulverized in situ soil or removing water from the pulverized in situ soil.
5. The method of claim 1 , wherein the at least one polyurethane precursor comprises a first polyurethane precursor and a second polyurethane precursor, wherein the first polyurethane precursor comprises isocyanate and wherein the second polyurethane precursor comprises polyol.
6. The method of claim 5 , wherein the first polyurethane precursor and the second polyurethane precursor are mixed using the reclaimer-stabilizer machine prior combining with the pulverized in situ soil.
7. The method of claim 5 , wherein the first polyurethane precursor and the second polyurethane precursor are individually dispensed and are mixed together while being combined with the pulverized in situ soil using the reclaimer-stabilizer machine.
8. The method of claim 5 , wherein the first polyurethane precursor and the second polyurethane precursor are at least partially mixed during dispensing of the first polyurethane precursor and the second polyurethane precursor and before combining the first polyurethane precursor and the second polyurethane precursor with the pulverized in situ soil using the reclaimer-stabilizer machine.
9. The method of claim 1 , wherein the at least one polyurethane precursor comprises one of isocyanate or isocyanate-containing prepolymer, and wherein substantially no polyol is dispensed into the pulverized in situ soil.
10. The method of claim 1 , further comprising adding a reinforced component into the pulverized in situ soil, wherein the reinforced component comprises a material selected from the group comprising basalt fibers, silica fibers, glass fibers, and polypropylene fibers.
11. The method of claim 10 , wherein the reinforced component comprises basalt fibers.
12. The method of claim 10 , wherein the reinforced component is added as a part of the at least one polyurethane precursor.
13. The method of claim 10 , wherein the reinforced component is added separately from the at least one polyurethane precursor.
14. The method of claim 10 , wherein the reinforced component further comprises a dispersing agent, the dispersing agent comprises one of sand or fumed silica.
15. 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.
16. The method of claim 1 , wherein the layer of the roadway comprises between 1% and 10% by weight of polyurethane.
17. The method of claim 1 , wherein the at least one polyurethane precursor has a viscosity of between 20 centipoise and 2000 centipoise at 78 degrees Fahrenheit.
18. The method of claim 1 , wherein the layer of the roadway has a thickness of between 0.5 inches and 15 inches.
19. The method of claim 1 , wherein a water content in the polyurethane filled soil material is between about 5% and 20% by weight.
20. The method of claim 1 , wherein the at least one polyurethane precursor comprises between about 5% and 50% of naphthenic and aromatic process oils.