Study On Mix Design And Pavement Performance Of Cold-repaired Asphalt Mixture

The cold-repaired asphalt mixture has been studied abroad as early as the 1920s,and more cold-repaired asphalt mixture has been developed in China,which has been applied to the actual pavement repairing and achieved certain results.However,there is no uniform design method of mix proportion of cold-repaired asphalt mixture and a set of performance evaluation methods suitable for cold-repaired asphalt mixture,which results in the uneven quality of cold-repaired asphalt mixture products in the market and makes it difficult to choose in maintenance management.In this paper,two kinds of cold-repairing additives,Ward brand and PR-JW03A brand,and cold-repairing asphalt liquor of Tuan'an finished product were selected.According to the preliminary mix ratio provided by the producer,two cold-repairing additives selected in this paper are prepared into cold-repairing asphalt mixture and their performance tests are carried out;the mix ratio design of cold-repairing asphalt mixture is carried out by using modified Marshall test method and empirical formula method,and the two design methods are optimized.Through the road performance test of cold-repairing asphalt mixture,the liquid phase pair of self-made cold-repairing asphalt mixture is verified.The performance of cold-repairing asphalt liquor and the method of mix design of cold-repairing asphalt mixture are discussed.The results show that the performance of PR-JW03A cold-compensating asphalt solution is the best,and its optimum proportion is additive:base asphalt:diluent:1.8:100:25,followed by Ward brand and finished cold-compensating asphalt solution.The optimum asphalt dosage determined by modified Marshall test method and empirical formula method is different.The optimum asphalt dosage of finished and self-made cold-repairing asphalt mixtures determined by empirical formula method is 4.5%.The optimum asphalt dosage of finished cold-repairing asphalt mixtures determined by modified Marshall test method is 5.1%,and the optimum asphalt dosage of self-made cold-repairing asphalt mixtures is 4.8%.Compared with the modified Marshall test method,the initial strength and moulding strength of cold-repaired asphalt mixture determined by empirical formula method are larger,the initial strength is above 2 KN,and the moulding strength is about 2 times of the initial strength;the water stability test results are not different under the two asphalt dosage design methods,and the ratio of stability and freeze-thaw splitting strength is full.The high temperature stability is better,but the dynamic stability of cold-repaired asphalt mixture is lower under the two asphalt dosage design methods.The low temperature performance is good,and the damage strain meets the requirements of the specification.The pavement performance of self-made cold-repaired asphalt mixture is equivalent to or better than that of finished cold-repaired asphalt mixture,and is basically equivalent to that of ordinary hot-mix asphalt mixture except for high temperature performance.The performance of self-made cold rehydration is better than that of finished product cold rehydration.Its pavement performance is similar to that of ordinary hot mix asphalt mixture and can be used for pavement repair.The performance of cold-repaired asphalt mixture designed by empirical formula method is better.This paper recommends using empirical formula method to design the mix proportion of cold-repaired asphalt mixture,and using paper trace test,workability test and Marshall stability test to modify.