Study On Aging Resistance Of Biochar Modified Asphalt And Its Mixture

pavement construction Promote the national overall traffic,but the asphalt production with high pollution,high consumption,high carbon emissions and other shortcomings,has certain influence on the ecological environment,and on the surface of the asphalt aging is the pavement performance,the important reason for decline in the service time,therefore,in this paper,using biochar modified asphalt,studies the performance of modified asphalt and mixture performance,It is beneficial to reduce the economic cost and make the national construction better develop towards the green and sustainable direction.Firstly,modified asphalt with different biochar content(0%,3%,6%,9%,12%)was prepared,and its physical properties(three indicators)and rheological properties(Brinell rotational viscosity,DSR,BBR)were tested.The results showed that,The addition of biochar increases the softening point of asphalt by 1.3 ℃～4.1℃,the maximum viscosity by 60.4%,the complex modulus,rutting factor,critical failure temperature,and the elongation and phase Angle of asphalt decrease.It is verified that biochar can increase the viscosity of asphalt and decrease the temperature sensitivity.Infrared spectrum analysis showed that the modification mechanism of biochar did not change the chemical composition of asphalt,but was a physical modification.BBR test showed that biochar reduced the low temperature performance of asphalt.Secondly,the aging performance of biochar modified asphalt was studied,and the aging indexes(residual penetration ratio,softening point increment,viscosity,complex modulus and phase Angle aging index)of biochar modified asphalt were analyzed.The results showed that the anti-aging performance of biochar modified asphalt was better than that of base asphalt.Multi-stress repeated creep recovery test(MSCR)shows that biochar can reduce the stress sensitivity of asphalt.When the biochar content is more than 9%,the traffic load grade of biochar modified asphalt increases from general load grade to heavy traffic load grade.Infrared spectrum analysis showed that the sulfoxide index(SI)and carbonyl index(CI)of biochar modified asphalt decreased significantly after aging compared with base asphalt.The sulfoxide index and carbonyl index of 12%biochar modified asphalt decreased by 13.57%and 10.54%after short-term aging.BBR test results show that after short-term aging,the PG low temperature grade of biochar modified asphalt decreases from-22℃ to-16℃ with 12%content.Therefore,the biochar content should not exceed 12%.Finally,biochar modified asphalt mixture was configured,and its water stability and high temperature performance were analyzed through freeze-thaw splitting test and uniaxial penetration test.The test results showed that the addition of biochar had no effect on the water stability of the mixture,and the high temperature performance of biochar modified asphalt mixture was improved by 4.27%to 15.64%.The aging test of asphalt mixture shows that the asphalt mixture modified by biochar has certain aging resistance.