Research On Application Of Direct Coal Liquefaction Residue Modified Asphalt Mixture In Pavement Engineering

The Direct Coal Liquefaction Residue(DCLR)is the by-product which is about 30% of the origin coal produced during the direct coal liquefaction production.Along with the development of coal liquefaction in China,too much DCLR has become the barrier of industry progress.DCLR has the potential to be developed as road asphalt modifier so that this research focused on the properties of DCLR modified asphalt mixture to discuss the possibility of applying DCLR in road industry.Firstly,the preparation and basic property of DCLR modified asphalt and mixtures have been researched.The optimum dosage of DCLR is 10%.Based on the property of DCLR modified asphalt,optimum preparation of compound DCLR modified asphalt was found.The addition of DCLR will hurt the low-temperature property of asphalt and compound DCLR was used to fix the negative influence.Four kind of asphalt mixture was prepared and tested.The high temperature and anti-moisture property of DCLR modified asphalt can meet the requirement except for its low-temperature property.The high-temperature,low-temperature and anti-moisture property of compound DCLR modified asphalt mixture can reach the level of SBS modified asphalt mixture.Secondly,the design parameters of DCLR modified asphalt mixture were tested.Using the uniaxial compression test,the compression resilience moduli of DCLR/ compound modified asphalt mixture was obtained.Also the dynamic modulus under different temperature of four asphalt mixture was tested.The master curves of the asphalt mixtures were show,and dynamic and viscoelastic behaviors of asphalt mixtures were described using the Christensen-Anderson-Marasteanu(CAM)model.The results showed that DCLR and compound DCLR modified asphalt mixture has better elastic property.Based on the viscoelastic parameters of CAM models of the asphalt mixtures,the high-and low-temperature performance of DLCR and compound DCLR modified asphalt mixtures are obviously better than the SK-90 and SBS modified asphalt mixtures.Thirdly,the anti-rutting performance of DCLR modified asphalt mixture was discussed by the multiple temperature and tire pressure rutting test.It was found that the compound DCLR modified asphalt mixture could still maintain very high anti-rutting performance even in the worst situation.The creep parameters of DCLR and compound DCLR modified asphalt mixture were fitted by the Origin software using creep model.A validation model was constructed in ABAQUS,the results of simulation was so close to test results that the creep parameters could be used in theoretical calculation.Lastly,the temperature field and rutting estimation model were constructed to analyze the rutting behavior of pavement structure contained DCLR and compound DCLR modified asphalt mixture.Based on the models,temperature of each layer during any season was obtained.The most dangerous time that prone to occur rutting is rush hour in summer.The result shows that the DCLR and compound DCLR modified asphalt mixture have better anti-rutting performance compared with SK-90 asphalt mixture.The rutting depth of pavement structure can be reduced 63% and 49% by compound DCLR modified asphalt mixture and DCLR modified asphalt mixture.In addition,the tensile stress under middle layer has been diminished.Also,the economy and social benefits of DCLR modified asphalt mixture were discussed.Applying DCLR and compound DCLR modified asphalt mixture can save the engineering budget and solve the problem of redundant DCLR.