Research On Road Performance Of Rubber Asphalt And Mixture In Seasonally Frozen Region

The duration of spring and autumn is short of frozen region, winter is long and cold, summer is hot and rainy. According to the special climate characteristics of frozen region, with the penetration, softening point, ductility, elastic recovery and viscosity as control index, researches the change rule of every technical indicator of rubber asphalt with the change of mixing temperature, rubber powder fineness, rubber powder content.Takes the volume index of VMA, Voids in coarse aggregate and the asphalt saturation as reference, and makes design of mix proportion of the mixture in different factors, at last, we get the influence law of gradation, powder fineness, crumb rubber content on the volume index. Then makes comparative analysis of the road performance of mixture under different factors, analyses the the level range of factorsof rubber asphalt mixture that is suit for Heilongjiang province. Based on the characteristics of big temperature gap between day and night in frozen area of Hei longjiang province, using the freezing and thawing experiment in 24 hours for a freezing and thawing cycles, taking the tensile strain, splitting strength and stiffness modulus as control index,researches the attenuation law of rubber asphalt mixture performance in different number of freeze-thaw and under the condition of different porosity. The results of the study are as follows:1.Rubber asphalt performance shows a parabolic variation with the temperature increasing.When temperature is on the high side, the elasticity of the rubber asphalt is poorer, there is the best temperature in the reaction process of rubber powder and asphalt; The Powder particle size is big, Rubber asphalt tensile properties at low temperature is poor, With the decreasing of the particle size, Rubber modified asphalt performance increase gradually, but the performance increase amplitude decreases gradually; Rubber asphalt with high content of rubber powder has lower elastic recovery, high viscosity, which causes the difficulty in mixture compaction, The effect is poorer on the performance with low content of rubber powder.2. Using five kinds of ordinal gap graded from coarse to fine, the results showes that with the increase of the fine aggregate mixture coarse aggregate clearance increases gradually, in order to make the coarse aggregate formation skeleton structure of embedded crowded, there is the highest limit of key mesh (2.36 mm) pass rate, but the rough big void in mineral aggregate grading, the corresponding asphalt content is on the high side. Along with the increase of powder particle size and rubber powder dosage, mixture of asphalt content also increased, powder particle size has small effect on the change of the mixture ratio,. oil-stone ratio of mixture is smaller.3.The road performance of rubber asphalt mixture increases with the oil-stone ratio, the fineness of powder, powder content increases, but it existed a turning point with the increase of rubber powder content, that the mixture of high temperature and low temperature performance, there; the performance declines beyond the turning point; with the increasing of fine aggregate, the mixture of high temperature performance, low temperature performance and water stability performance improve. Rubber asphalt mixture performance of the matrix asphalt mixture has increased greatly, dynamic stability is about 2 times higher than the matrix asphalt mixture.4.For the freezing and thawing, the study found that:Mixture specimen of void fraction increases and strength gradually decreased with the increase of number of freezing and thawing,cleavage; With the increase of void fraction,the mixture performance attenuation rate is accelerated,, the intensity attenuation amplitude can be as high as 50%, in view of the season frozen zone, in order to prevent freezing and thawing of diseases, the mixture of void ratio at scene should be avoided falling in freeze-thaw damage area.