(1) Applicability investigation
The hot-in-place recycling technology is mainly used to repair the surface layer of asphalt pavement. The regeneration depth is usually limited to about 4cm. It is only suitable for the base layer with good bearing capacity, and the disease only occurs in the middle and upper layers of the road.
1. The overall strength of the original road surface meets the design requirements;
2. The original pavement diseases are mainly concentrated on the surface layer;
3. The 25℃ penetration (0.1mm) of the original road asphalt is not less than 20.
(2) Detailed investigation
Investigate the types and locations of various pavement diseases;
1. Survey on the quality of old pavement materials.
2. Old asphalt performance test: detect the penetration, ductility, softening point and other indicators of old asphalt;
3. Old asphalt mixture gradation test: Determine the old asphalt mixture gradation.
(3) Mixing ratio design of recycled mixture
1. Old asphalt recycling test
2. Determination of technical standards for recycled asphalt
Select regenerant, add regenerant to old asphalt in different proportions, measure its penetration, softening point, 135°C viscosity and other indicators, determine the amount of regenerant, and test the anti-aging performance of regenerated asphalt.
3. Mix ratio design test
(a) If the gradation of the old asphalt mixture is available, add the amount of rejuvenating agent determined according to the asphalt regeneration test into the old asphalt mixture, and do a Marshall test to see if new asphalt needs to be added to determine the optimum asphalt ratio of recycled asphalt.
(b) If the gradation of the old asphalt mixture is not available, determine the gradation of the new asphalt mixture to be added and the ratio of the new mixture, and determine the optimal asphalt ratio through the Marshall test.
4. Performance inspection of recycled asphalt mixture
The hot-in-place recycled mixture should meet the relevant requirements for hot-mix asphalt mixtures in the current "Technical Specifications for Highway Asphalt Pavement Construction" (JTG F40).