Research On The Influence Of Freezethaw Cycle On The Performance Of Largevoid Asphalt Mixture

The rise of sponge cities has greatly promoted the development of large void asphalt pavements in China,and OGFC asphalt pavement is currently the most widely used large void asphalt pavement.Frequent freeze-thaw cycles will inevitably affect the performance of OGFC asphalt pavement,and the existing research involves less on the frost resistance of OGFC asphalt pavement.Therefore,this paper studies the performance decay of OGFC asphalt mixture under the action of freeze-thaw cycles.The law provides a certain reference for the use of OGFC asphalt pavement in frozen areas.The main research and conclusions carried out in this article are as follows:1.In order to obtain a cementitious material with excellent low-temperature performance,the low-temperature performance of SBS+HVA composite modified asphalt and SBS+ rubber powder composite modified asphalt was compared through the force measurement ductility test,and the compounding of SBS+HVA composite modified asphalt The ratio was studied.The test results show that the toughness ratio of SBS+HVA composite modified asphalt is much greater than that of SBS+ rubber powder composite modified asphalt.SBS+HVA composite modified asphalt has better flexibility at low temperatures and better low-temperature performance;compared to SBS+HVA composite The research on the ratio of modified asphalt shows that the mixing amount of SBS is 4% and the amount of HVA is 10%,and the low temperature performance of composite modified asphalt is the best.2.In order to study the change law of the splitting performance of OGFC asphalt mixture under the action of freeze-thaw cycles,through Marshall freeze-thaw splitting test,the splitting of mixtures with different oil-stone ratios and different design void ratios under different freeze-thaw cycles Performance was studied.The test results show that the splitting strength of OGFC asphalt mixture attenuates significantly under the action of the first 4 freeze-thaw cycles,and then with the increase of the number of freeze-thaw cycles,the decreasing trend of splitting strength slows down and gradually stabilizes.The mixture with the best oil-stone ratio(4.5%)has the highest splitting strength under each freeze-thaw cycle and the largest residual strength ratio.The greater the design porosity of the mixture,the more significant the effect of freeze-thaw cycles on the splitting performance of the mixture,and the worse the resistance of the mixture to freeze-thaw damage.3.In order to study the flexural and tensile performance changes of OGFC asphalt mixture under the action of freeze-thaw cycles,the trabecular bending test was carried out on the flexural and tensile performance of mixtures with different oil-stone ratios and different design porosities under different freeze-thaw cycles.Researched.The test results show that the bending tensile strength,bending tensile strain,and bending stiffness modulus of the mixture decrease faster under the action of the early freeze-thaw cycles,and then with the increase in the number of freeze-thaw cycles,the bending tensile strength,bending tensile strain and The downward trend of bending stiffness modulus slowed down and gradually stabilized.Research on the oil-stone ratio shows that an appropriate increase in the oil-stone ratio can improve the frost resistance of the mixture.The greater the design porosity of the mixture,the weaker its ability to resist freeze-thaw damage.If the design porosity is too large,the frost resistance and flexural properties of the mixture will be significantly lost.4.In order to study the effect of freeze-thaw cycles on the high-temperature performance of OGFC asphalt mixtures,through high-temperature rutting tests,the hightemperature performance of mixtures with different oil-stone ratios and designed porosity under different freeze-thaw cycles was studied.The test results show that the mixture with the best oil-stone ratio has the best high-temperature performance.Increasing and decreasing the oil-stone ratio will reduce the dynamic stability of the mixture;as the oilstone ratio increases,the dynamic stability loss rate of the mixture decreases.The design porosity increases,the dynamic stability of the mixture shows a trend of first increasing and then decreasing,and the dynamic stability loss rate increases.A comprehensive analysis shows that an appropriate increase in the oil-stone ratio can improve the frost resistance of the mixture;the design porosity of the OGFC asphalt mixture should not be too large.In this study,the 21% design porosity of the mixture should be split,bent and stretched and high temperature The performance is relatively good,and relatively speaking,it also shows better frost resistance;too large design porosity will seriously reduce the frost resistance of the mixture,and should be avoided in actual engineering applications.