高温和重载对DCLR改性沥青混合料抗变形能力的影响

为了评价煤直接液化残渣(DCLR) 和复合DCLR改性沥青混合料在高温和重载下的抗变形能力, 对级配为AC-20的2种沥青混合料进行多温度(50℃、60℃、70℃)、多荷载(0.7、0.8、0.9、1.0 MPa) 条件下的三轴重复荷载试验, 并对试验数据进行非线性拟合, 提出了能够在高温和重载条件下评价2种沥青混合料抗变形能力的指标, 并利用方差分析法研究了温度和荷载对沥青混合料抗变形能力的显著性影响。研究结果表明: 2种沥青混合料的永久变形随温度和荷载的增大而增大, 流动数、非线性拟合指数分别与温度和荷载呈负相关与正相关, 说明流动数和非线性拟合指数均能反映沥青混合料的抗变形能力, 但2种沥青混合料的流动数的三维曲面在温度为65℃~70℃和荷载为1.0 MPa处有交叉, 说明流动数在高温和重载条件下不能有效区分DCLR和复合DCLR改性沥青混合料的抗变形能力; 在0.05显著性水平下, 2种沥青混合料的抗变形能力对温度的敏感性均高于荷载, 因此, 温度为影响2种沥青混合料抗变形能力的主要因素, 荷载为次要因素; 温度和荷载的非线性拟合指数、流动数分别在0.013和0.113显著性水平下对2种沥青混合料的抗变形能力有显著性影响, 因此, 在试验温度和荷载范围内非线性拟合指数比流动数更适合作为评价DCLR与复合DCLR改性沥青混合料抗变形能力的指标。 

Effect of high temperature and heavy load on deformation resistance of DCLR modified asphalt mixture

To evaluate the deformation resistance of coal direct liquefaction residue (DCLR) modified asphalt mixture and compound DCLR modified asphalt mixture under high temperature and heavy load, the tri-axial repeated load test was carried out on two asphalt mixtures with the gradation of AC-20 under multi-temperatures (50 ℃, 60 ℃, 70 ℃) and multi-loads (0.7, 0.8, 0.9, 1.0 MPa) conditions, and the test data were nonlinearly fitted. An index for evaluating the deformation resistances of the two asphalt mixtures under high temperature and heavy load was proposed, and the variance analysis method was used to investigate the significant influences of temperature and load on the deformation resistance of asphalt mixture. Research result shows that the permanent deformations of two asphalt mixtures increase as temperature and load increase. The flow number and nonlinear fitting index have negative and positive correlation with temperature and load, respectively, indicating that both nonlinear fitting index and flow number can reflect the deformation resistance of asphalt mixture. However, the flow number three-dimensional surfaces of the two asphalt mixtures have intersects when temperature varies from 65 ℃ to 70 ℃ and load is 1.0 MPa, demonstrating that flow number cannot effectively distinguish the deformation resistances of DCLR modified asphalt mixture and compound DCLR modified asphalt mixture under high temperature and heavy load. The sensitivity of two asphalt mixtures to temperature is higher than to load at a significant level of 0.05. Therefore, temperature is the main factor that affects the deformation resistances of the two asphalt mixtures, and load is the secondary factor. The nonlinear fitting index and flow number of temperature and load have significant influences on the deformation resistances of two asphalt mixtures when the significant levels are 0.013 and 0.113, respectively, reporting that the nonlinear fitting index is more suitable than the flow number for evaluating the deformation resistances of DCLR modified asphalt mixture and compound DCLR modified asphalt mixture within test temperature and load conditions.