Study On Material Composition Design And Pavement Performance Of Ultra-high Modulus Asphalt Concrete

High modulus asphalt concrete(HMAC)is one of the effective measures to prevent rutting of asphalt pavement under high temperature and heavy load.Although HMAC overcomes the hidden danger of rutting to some extent,hard bitumen cracks easily due to its poor low-temperature performance,which cause the potential risk of fatigue cracking increasing.This study designed an Ultra-high modulus asphalt concrete(UHMAC)considering three aspects included mixture binder,gradation type and aggregates.The material composition design and construction technology have been studied and optimized according to the material composition characteristics.In this paper,high viscosity asphalt was prepared by crosslinking reaction,and its high-temperature and low-temperature characteristics were studied based on the principle of rheology.The high viscosity asphalt and Pen.30#original asphalt were selected as the binder.According to different gradation design methods in France and China,mixtures were prepared with different gradations(EME-14,AC-13 and SMA-10),and their molding temperature and optimal asphalt content were determined.The factors affecting the dynamic modulus of UHMAC were analyzed and the pavement performance of UHMAC was evaluated.The detailed research contents and conclusions are as follows:(1)The optimum ratio of high viscosity asphalt is 70#matrix asphalt:SBS:X-additive:graphene=1:0.05:0.05:0.0004,which has good storage stability and adhesion class 5.MSCR and BBR test results show that the high viscosity asphalt has good high temperature performance and better low temperature performance than hard asphalt.The fluorescence microscopy and Fourier infrared spectroscopy test results showed that the modifiers were well distributed in the asphalt phase with good compatibility and dominated by physical co-blending.(2)Three gradation curves of EME-14 and AC-13 and SMA-10 were designed.The molding process and compaction temperature of the three gradations were determined,and the optimum asphalt dosage was determined according to the calculation method of abundance coefficient and Marshall test.(3)The dynamic modulus value of UHMAC increases with the increase of frequency and decreases with the increase of temperature;the dynamic modulus value of UHMAC prepared by each type of gradation is ranked as AC>EME>SMA;macadam has a positive effect on the dynamic modulus value;and the more the amount of admixture,the higher the dynamic modulus value of UHMAC.When high viscosity asphalt is used and 100%macadam is mixed,the dynamic modulus value of UHMAC is the highest.(4)The results of rutting test,low temperature bending test,water immersion Marshall test and freeze-thaw splitting test show that UHMAC has excellent high temperature performance and water stability,and the highest dynamic stability reaches 8549 times/mm;the use of hard asphalt and macadam has a negative effect on the low temperature performance of UHMAC.