Study On The Attenuation Law Of Long-term Skid Resistance Of Asphalt Pavement With Limestone And Basalt Mixed Aggregates

The deterioration of the skid resistance of asphalt pavements can cause the overall skid resistance of the pavement to be inadequate,posing a significant risk to driving safety.Based on the science and technology project of Zunyi Highway Bureau in Guizhou Province,the thesis uses limestone and basalt in Zunyi area as the research object,and selects the representative limestone and basalt mixes from several types of limestone for skid resistance and abrasion resistance test and asphalt mix ratio design;using the asphalt mix friction characteristics tester,from different basalt mixing ratios(basalt mixing 0%,35%,40%,45%,100%),to different asphalt mixes with different friction characteristics.The accelerated loading wear test was carried out in three aspects: different basalt blending ratios(0%,35%,40%,45%,100%),different loadings(75kg,100 kg,150kg,200kg)and different temperature conditions(10℃,25℃,40℃)to obtain data on the skid resistance evaluation indexes of asphalt pavement under different conditions;the Asymptotic model was selected to simulate the decay law of the skid resistance evaluation indexes with wear time.Based on the fitted equations,the linear normalization method was used to establish the relationship between the skid resistance evaluation indexes and the wear time,and the skid resistance decay law of asphalt pavement under different basalt blending ratio,different loading and different temperature conditions was investigated.Finally,relying on the asphalt pavement project of G243 Suiyang section in Zunyi City,Guizhou Province,accelerated loading experiments were conducted on the sampled specimen plates by friction characteristic tester to establish the relationship between the number of runs of the asphalt mixture friction characteristic tester and the number of design axle loads,so as to make a skid resistance life prediction for the asphalt mixture with mixed aggregate of limestone and basalt.The main research findings are as follows:(1)Through a comprehensive comparison and analysis of the crushing,abrasion and polishing properties of various limestones with mineral composition and angularity,the crushing value of Jiangbei limestone is 19.1%,the abrasion value is 18.0% and the polishing value(PSV)is 45,which is the best overall performance among 10 limestones,so Jiangbei limestone and basalt are selected as the raw materials for the mix ratio design and the study of the decay law of anti-slip properties.(2)For the intermixing of basalt and limestone,under the same load,the crushing value shows a negative correlation with the basalt admixture;under the same basalt admixture,the crushing value shows a positive correlation with the applied load;under the same wear rpm,the wear value shows a negative correlation with the basalt admixture.(3)With the increase of wearing time,the decay rate of each anti-slip performance index shows the law of rapid decline first and then tends to level off,i.e.,the rapid decline stage and stable decline stage of anti-slip performance;for asphalt mixes with different basalt blending ratios,the decay rate of anti-slip performance in both stages is smaller than that of limestone grading,and the decay rate is slowest in the stable decline stage when the basalt blending is 45%;when ambient temperature is high,with the increase of temperature,the decay rate of pavement antiskid performance will increase,making the antiskid performance worse;when the ambient temperature is at 10℃ and25℃,the influence of ambient temperature on the antiskid performance of asphalt pavement is smaller;with the increase of load,the distinction point between the rapid decline stage and the stable decline stage of antiskid performance of asphalt mixes with mixed aggregates of limestone and basalt is advanced.(4)By establishing the relationship between the number of runs of the asphalt mixture friction characteristic tester and the number of design axle loads,the skid resistance service life of the limestone and basalt mixed-aggregate asphalt mixture in this test section was predicted to be about 17-18 years.