Reflective crack relief layer that is permeable
View Patent ↗A design method for making a bituminous mixture that is used to form a vapor-permeable layer of pavement is provided. This design procedure includes preparing one or more bituminous mixture test specimens, measuring the performance of these specimens, and selecting a desirable bituminous mixture for paving that is vapor-permeable based on the performance of the specimens. Another aspect of the present invention is the selected bituminous mixture, which includes aggregate and a bituminous binder. The aggregate should be selected such that no more than about 5% by mass of the aggregate and preferably no more than about 3.5% by mass of the aggregate is able to pass through a 75 μm sieve. The selected bituminous mixture should have an Air Permeability Value that is at least about 8 cm 2 so as to reduce its propensity for blistering during and after construction. Still further, the selected bituminous mixture should have desirable fatigue resistance and should be substantially water-impermeable.
1. A bituminous mixture comprising:
a mixture formed by mixing aggregate and a bituminous binder,
said aggregate having no more than 5% passing through a 75 μm screen and at least 70% passing through a 2.36 mm screen,
said binder being at least 7% of the mixture, and
said mixture having a dust to asphalt ratio of less than 09.
2. The bituminous mixture of claim 1 wherein said bituminous mixture has an Air Permeability Value that is at least 8 cm 2 .
3. The bituminous mixture of claim 1 wherein said bituminous mixture has an Air Permeability Value that is at least about 10 cm 2 .
4. The bituminous mixture of claim 1 wherein said bituminous mixture has a Flexural Beam Fatigue of at least 5000 cycles at 2000 microstrains, 10 Hz, and 20° C.
5. The bituminous mixture of claim 1 wherein said bituminous mixture has a Flexural Beam Fatigue of at least 35,000 cycles at 2000 microstrains, 10 Hz, and 20° C.
6. The bituminous mixture of claim 1 wherein said binder has a film thickness that is at least about 7 μm.
7. The bituminous mixture of claim 1 wherein said bituminous mixture has at least about 3% air voids.
8. The bituminous mixture of claim 1 wherein more than 85% of said aggregate is able to pass through a 2.36 mm sieve.
9. The bituminous mixture of claim 1 Wherein no more than 7% of said aggregate is able to pass through a 150 μm sieve and least 90% is able to pass through a 9.5 mm sieve.
10. The bituminous mixture of claim 1 wherein said bituminous mixture has at least 5% air voids.
11. The bituminous mixture of claim 1 wherein said bituminous mixture has no more than 70% voids filled with bitumen.
12. The bituminous mixture of claim 1 wherein no more than 25% of said aggregate is able to pass through a 600 μm sieve
13. The bituminous mixture of claim 1 wherein said bituminous mixture has at least 18% VMA.
14. A method for making a bituminous mixture comprising:
mixing aggregate with bitumen with the aggregate having no more than 5% passing through a 75 μm screen and at least 70% passing through a 2.36 mm screen and with the binder being at least 7% of the mixture and the mixture having a dust to asphalt ratio of less than0.9%.
15. The method of claim 14 wherein said bituminous mixture has an Air Permeability value that is at least 8 cm 2 .
16. The method of claim 14 wherein said bituminous mixture has an Air Permeability value that is at least 10 cm 2 .
17. The method of claim 14 wherein said bituminous mixture has a Flexural Beam Fatigue of at least 5000 cycles at 2000 microstrains,10 Hz, and 20° C.
18. The method of claim 14 wherein Said bituminous mixture has a flexural beam fatigue of at least 35,000 cycles at 2000 microstrains,10 Hz, and 20° C.
19. The method of claim 14 wherein said binder has a film thickness that is at least 7 μm
20. The method of claim 14 wherein said bituminous mixture has at least 3% air voids.
21. The method of claim 14 wherein more than 85% of said aggregate is able to pass through a 2.36 mm sieve.
22. The method of claim 14 wherein no more than 7% of said aggregate is able to pass through a 150 μm seive and at least 90% is able to pass through a 9.5 mm sieve.
23. The method of claim 14 wherein said bituminous mixture has at least 5% air voids.
24. The method of claim 14 wherein said bituminous mixture has no more than 70% voids filled with bitumen
25. The method of claim 14 wherein no more than 25% of said aggregate is able to pass through a 600 μm sieve.
26. The method of claim 14 wherein said bituminous mixture has at least 18% VMA.
27. A method of selecting a bituminous mixture for making a layer for a roadway, comprising:
providing aggregate wherein no more than 5% by weight of the aggregate passing through a 75 μm screen and at least 70% by weight of the aggregate passing through a 2.36 mm screen;
providing at least one bituminous mixture comprised of a bituminous binder and said aggregate, said binder being at least 7% of the mixture and said mixture having a dust to asphalt ratio of less than 0.9% ;
performing at least one of a fatigue test and a permeability test on said at least one bituminous mixture; and
selecting a bituminous mixture for said layer after performing the at least one of said fatigue and permeability tests based on at least one or fatigue and permeability performance of said at least one bituminous mixture, wherein aggregate in said selected bituminous mixture is sufficiently large so as to create at least 3% air voids in said bituminous mixture and allow for substantial permeability in said mixture.
28. The method of claim 27 wherein at least 90% by mass of said aggregate in said selected bituminous mixture is able to pass through a 9.5 mm sieve, and substantially all of said aggregate in said selected bituminous mixture is able to pass through a 12.5 mm sieve.
29. The method of claim 27 , further comprising:
determining amount of voids filled with bitumen in said at least one bituminous mixture before said selection step and selecting said bituminous mixture based on said determination.
30. The method of claim 27 , further comprising:
determining amount of air voids in said at least one bituminous mixture before said selection step and selecting said bituminous mixture based on said determination.
31. The method of claim 27 , further comprising:
determining dust/bitumen ratio of said at least one bituminous mixture before said selection step and selecting said bituminous mixture based on said determination.
32. A fatigue-resistant and vapor-permeable layer of roadway, comprising a mixture of:
aggregate, wherein no more than about 5% by mass of said aggregate is able to pass through a 75 μm sieve and more than about 70% is able to pass through a 2.36 mm sieve; and
a bituminous binder, said binder being at least 7% of said layer and said layer having a dust to asphalt ratio of less than 0.9% ; and
wherein said layer as an Air Permeability value of at least 8 cm 2 and has a Flexural beam Fatigue of at least 5000 cycles at 2000 microstrains, 10 Hz, and at 20° C in the first 24 hours after being placed.
33. The layer of claim 32 wherein said bituminous mixture has no more than 70% voids filled with bitumen.
34. The layer of claim 32 wherein said layer has at least 18% VMA.