| At present, studying the technology of asphalt pavement recycling is only a start. Studying of Cold Recycled mix performance, gradation design method, construction technologies and so on should to be study more.The path scene cold regeneration, after is under the normal temperature passes through stave processing the old road surface, with the regenerant, the new stabilizer, the new aggregate and so on mixes up the blend according to certain proportion, can satisfy certain road and lays with the performance in the road surface one whole set craft.Joins the stable material is in order to enhance the breeder material the intensity, the stable material may use the cement, the emulsified bitumen, the froth asphalt generally and so on.Mixes adds the cement to take the stabilizer, the regeneration obtains the blend takes the road surface the basic unit use.At present, the domestic cold regeneration uses this kind of plan, the cement content general control between 3%～6%.Mixes adds the emulsified bitumen or the froth asphalt takes the stabilizer, the regeneration obtains the blend may take under the oil coated stone basic unit or the asphalt the surface layer use.The emulsified bitumen is the asphalt, the water and the emulsifier mixture.The use emulsified bitumen advantage is its viscosity is low, easy sprays the installment with the regenerative equipment in liquid to increase, after the breeder material and the emulsified bitumen mix up, the emulsified bitumen emulsion breaking, the moisture content separates from the asphalt, the moisture content is squeezed out in the roller compaction process the basic unit or evaporates in the keeping in good health time, the residual asphalt has the high viscosity, thus enhanced the old material cohesiveness.The froth asphalt is the high temperature asphalt (140℃above) meets the cold waterdrop (ambient temperature) to produce.Use asphalt for ordinary penetration level asphalt, like AH-70 number ordinary asphalt.When the water meets the high temperature asphalt, has the thermal transmission, the volunteer fire brigade rapid evaporation, the asphalt frothing, the volume expansion to original 10 to 20 times.The froth asphalt increased the asphalt volume and the surface activity greatly, in the foaming process, the asphalt viscosity obviously reduces, thus enables the asphalt to proliferate in fully the aggregate.Because carries on the reuse to the old material, in the construction process, the road surface geometry linear and thickness can obtain maintains well.Compares with other road surface repair technology, the scene cold regeneration also can reduce the continual traffic interruption to a certain extent the phenomenon. Summarizes, the path scene cold regeneration has the following merit:①Reduces the construction cost.The scene cold regeneration does not need to transport the material the mixing plant, then ships back again the cold breeder material the job location, saved the cartage expense and the delaying work time;②Saves the aggregate and the bituminous cement;③Maintenance old route surface geometry characteristic;④Protection environment;Saves the energy;⑥Reduced user's delay.Moreover, the road surface regeneration may needs to choose the different regeneration depthand the different stabilizer according to its destruction situation and the structure.This topic uses the WR2500 cold regenerative equipment which German Wirtgen Corporation produces.This equipment full use original road surface material, and joins the ration the stabilizer, disposable completes the material under the natural condition the mill to dig continuously, stave, mixes up, spreads paving and crafts and so on roller compaction.According to the result of investigating old pavement and deflection test, the recycling depth is ascertained. Then three schemes are decided. They are full depth reclamation with cement stabilized, full depth reclamation with foamed asphalt stabilized and the reclamation of old asphalt pavement with foamed asphalt stabilized. After studying the present situation of cold recycling, the method of how to choose the optimum content of stabilizers is confirmed. And the gradation design method of cold recycled mixture is put forward. After paving the test road, construction technologies and quality control methods are concluded. There is three times of road testing and techno-economic analysis of cold recycling.1. Through determines its test sample to the cement entire depth regeneration and the froth asphalt entire depth regeneration the non-side to limit the compressive strength and the elasticity coefficient, determined the stabilizer the best dosage is feasible; Uses Marshall's testing method to determine the blend the froth asphalt best amount used also is feasible.The regeneration blend gradation may through join the right amount new aggregate to enhance its structural strength, considered the construction factor, new aggregate Yi Guoduo, do not surpass again the crude material quality 60% for suitably.2. This topic carried on to 90 asphalt became spongy the experiment, the foaming temperature took 160°C, the water consumption took 2.5%, the expansion rate is 15 times, the half-life is 10 seconds.3. The recommendation cement entire depth cold regeneration mixture ratio design standard is: Limits a compressive strength generation of tabular value without the side to be bigger than 1.5MPa, the elasticity coefficient mean value is bigger than 1000MPa.4. The recommendation froth asphalt entire depth cold regeneration mixture ratio design standard is: Limits a compressive strength generation of tabular value without the side to be bigger than 1.2MPa, the elasticity coefficient mean value is bigger than 1500MPa.5. Uses Marshall regarding the surface layer froth asphalt cold regeneration mixture ratio design method to experiment, discovers with the greatest stability, in the greatest density and the goal percentage of voids the value correspondence three froth asphalt amount used, asks its mean value, obtains the best froth asphalt amount used starting value, the generalized analysis obtains the best froth asphalt amount used.6. The topic-based group did to the froth bituminous mixture added 1% cement and does not add the cement two group of contrast experiments, finally indicated, added 1% cement the froth bituminous mixture intensity to be higher than obviously does not add the cement, the latter passed stably lowly, did not give the use.7. The water content indicated to the froth bituminous mixture stability influence experiment that,The water content is higher, the froth bituminous mixture stability is lower.But the water content and the construction workability are proportional, water content low.Unifies the Wirtgen recommendation the empirical formula, this topic water content control about 5%.8. The froth bituminous mixture density is about 2.200g/cm3, compares approximately with ordinary bituminous mixture 2.400g/cm3, slightly low.This is because the froth asphalt is by granulated adheres in the aggregate surface, but the ordinary bituminous mixture such asphalt completely wraps the aggregate likely.This causes the froth bituminous mixture cleavage strength to be very bad, the water stability is also bad, therefore the froth asphalt regeneration zone all must use the ordinary asphalt concrete surface coating.This topic has performed the freezing and thawing split test to the froth bituminous mixture, the test result full proof above conclusion.9. The froth bituminous mixture not easy compaction, surface layer froth asphalt regeneration test section compactness is approximately 90%.When construction should increase the compaction merit suitably. |
