Study On Durability And Development Of Granulated Crumb Rubber Asphalt Mixture

Granulated crumb rubber granular asphalt pavement is a kind of high elasticity self stress anti-ice pavement paving technology.Under the action of vehicle load,the rebound deformation of the high elastic pavement leads to the stress concentration phenomenon in the ice layer,which can inhibit the condensation of the ice layer.However,the mixture of rubber particles weakens the contact state between mineral aggregates and the durability of the mixtures is insufficient.Based on the provincial and ministerial key projects of Qinghai Provincial Transportation Department,the paper studies the operation safety technology of long and steep slope and snow section of Zamalong to Daotang River Highway,in the light of the durability of granular crumb rubber asphalt mixture,the optimization design of mixture ratio,water stability,fatigue performance and anti-sliding durability are studied.The main contents and conclusions of the thesis are as follows:?1?Analysis the special material composition structure of rubber granular asphalt mixture,select skeleton dense type gradation.The modified CAVF method and the equal volume replacement method are used to design the gradation composition.According to the standard Marshall Test,the optimum asphalt content of rubber granular asphalt mixture is calculated and the road performance is tested.The results show that when the content of rubber particles is 3%,the optimum asphalt dosage is6.3%.With the blending of rubber particles,high temperature stability and low temperature crack resistance have a certain degree of improvement,but the water stability has decreased.?2?Analysis on the mechanism of water damage of rubber granular asphalt pavement,the evaluation method of water stability of asphalt mixture is discussed.Three-factor three-level orthogonal design was used to test the freeze-thaw splitting,and the primary and secondary relationship and significance of rubber granular content,mineral aggregate type and asphalt dosage on the water stability of rubber granular asphalt mixture were studied.The results show that the content of crumb rubber has a significant effect on the splitting strength compared with TSR value,among which the A₂B₁C₂ water stability is the best,and the TSR value is 85.7%with the combination of limestone as coarse aggregate and rubber particle content of 3%.With granite as coarse aggregate and rubber particle content of 5%,the A₃B₃C₂ water stability was the worst and the TSR value was 76.4%.The scheme A₂B₁C₂ up by 9.3%compared to the TSR value of the scheme A₃B₃C₂.?3?The strain control model is selected to carry out four-point bending beam fatigue test for rubber granular asphalt mixtures.Setting the test temperature 15?,using 10 Hz partial sine wave to load,respectively,under the strain level of 500?,550?and 600?,according to the variation of fatigue life,the phase angle change and the decay law of material stiffness modulus,the influence of void ratio and rubber granular content on the fatigue performance of asphalt pavement is compared.The results show that:The skeleton dense rubber granular asphalt mixture XJ-13-1 has better fatigue performance under low strain condition and stronger resistance to fatigue cracking damage.However,the fatigue life was attenuated with the increase of strain level.Under high strain condition,the fatigue performance of SMA-13 asphalt mixture is better than that of skeleton dense rubber granular asphalt mixture.Among them,the XJ-13-2 of large pore rubber granular asphalt mixture has the weakest fatigue performance under three strain conditions.?4?The effect of rubber granular content and asphalt dosage on the resistance to sliding durability of the mixture was evaluated by using indoor accelerated polishing test.The results show that the decay rate of BPN is slowed down with the increase of rubber granular content.The influence of asphalt dosage against sliding durability is also obvious,the asphalt dosage is too low to cause the mixture adhesion performance is not enough,and the fine aggregate shedding in abrasion causes the anti sliding decay rate to increase.Therefore,under the optimum asphalt dosage,the rubber granular asphalt mixture can effectively improve the durability of the road surface antiskid.