Experimental Study On Properties Of SiC Nano-Modified Asphalt And Its Mixtures

In recent years,nano modified asphalt pavement has gradually been a research focus of asphalt pavement materials w:ith the development of material science.After comparison and selection among different kinds of nano materials,nano SiC was selected as a single modifier to study both physical performance and aging performance of nano-SiC modified asphalt,of which the development mechanism was also analyzed from a microscopic perspective.The improvement effect of nano-SiC on the pavement performance of asphalt mixture was also evaluated.Generally speaking,the test achieve goal as expected,has laid the certain foundation for the nanometer SiC modified asphalt research and the application.Firstly,Comparative study of nano-SiC modified asphalt with different particle size and different dosage of nano SiC was conducted.The three index result was showed as follows:With the increase of nano SiC content,the high temperature performance of modified asphalt continually increases but the low temperature performance gradually decreases,And 100nm SiC has the maximum penetration index and optimum temperature susceptibility.Also,in order to assure the thermal storage stability of modified asphalt,it is suggested that the maximum dosage is 6%.From the three aspects of residual penetration ratio,softening point increment and coefficient of variation of Brookfield viscosity,it is shown that the optimum selection of 100nm particle size and 6%dosage of nano-SiC can maximize the anti-aging performance of asphalt.From the DSR test on original asphalt and aged asphalt,we can know:the rutting factor of asphalt with nano SiC dosage of 6%and the particle size of 20nm SiC was significantly increased,which can improve the anti-aging performance of asphalt and extend its life.From the BBR test on asphalt both before and after TFOT test,it was showed that nano SiC had a detrimental effect on low temperature cracking resistance of asphalt,which can make the creep stiffness increase and the creep rate decrease slightly.Therefore,it could be proved by the above analysis that the optimum particle size of the modified asphalt with 6%nano SiC dosage was 100nm.Then,from a microscopic point of view,SEM test showed that nano SiC particles disperses uniformly in asphalt with a tinier particle size,which formed a bond between them and good dispersion effect was achieved.Infrared spectroscopy test showed that there were a few small peaks appearing in nano SiC modified asphalt spectra,which indicated that there were new chemical groups in asphalt with a small content.That proved that there was a weak chemical action between matrix but they co-existed in a physical way.Finally,the Marshall specimens were prepared perspectively with 3%and 6%content of 100nmSiC at the optimum asphalt aggregate ratio,and their pavement performance was evaluated.Rutting tests show that 6%dosage of nano-SiC can improve the high temperature performance of the mixture to the greatest extent.The low temperature bending tests showed that both 3%and 6%dosage of 100nmSiC can make modified asphalt mixture of flexural strength and flexural strain decrease slightly but contributes little to the low temperature crack resistance.Immersion Marshall test showed that modified asphalt mixture with 6%dosage of 100nmSiC has better water stability.The results of freeze-thaw cleavage test showed that asphalt mixture with 6%dosage of 100nmSiC has the best anti-water damage effect.