Sasobit温拌沥青的低温性能评价指标研究

Study on Low Temperature Performance Evaluation Indicator of Sasobit Warm Mix Asphalt

针对当前国内外在评价温拌沥青低温性能指标上的局限性,为更精准地评价温拌沥青的低温抗裂性能,将不同掺量的降黏类温拌剂Sasobit加入到基质沥青中制备温拌沥青,并分别进行旋转薄膜烘箱老化和压力箱老化来对温拌沥青的低温性能评价指标展开了研究。采用沥青弯曲梁流变试验来获得温拌沥青的劲度模量、劲度模量变化率,计算得到低温连续分级温度及k指标。另外,运用Burgers黏弹性模型对BBR试验数据进行参数拟合来获得Burgers模型的4个黏弹性参数,并构建了低温性能综合评价指标J。通过沥青混合料小梁弯曲试验得到温拌沥青混合料的低温弯曲应变能密度,将弯曲应变能密度与各评价指标进行了相关性分析和比选。试验结果表明:温拌剂Sasobit的加入削弱了沥青的低温抗裂性能,这表现为更高的劲度模量、更低的劲度模量变化率、更高的低温连续分级温度、更大的k指标和J指标;Sasobit掺量越高,低温性能削弱效果越显著;利用单一的劲度模量或劲度模量变化率m指标对温拌沥青的低温性能评价存在一定片面性,综合考虑沥青低温变形能力和应力松弛能力的低温连续分级温度、k指标及J指标能更加精确地评价温拌沥青的低温性能。

In view of the limitations of evaluating current low-temperature performance indicator of warm mix asphalt at home and abroad,in order to more accurately evaluate the low temperature crack resistance of warm mix asphalt,the viscosity-reducing warming agent Sasobit with different amounts are added into the matrix asphalt to prepare warm mix asphalt,and the RTFO-aging and PAV-aging are separately applied to study the low temperature performance evaluation indicators of the warm mix asphalt.The asphalt bending beam rheology(BBR)test is used to obtain the stiffness modulus and the stiffness modulus change rate of the warm mix asphalt,and the low temperature continuous grading temperature and k indicator are calculated.In addition,the BBR test data are fitted by using the Burgers viscoelastic model to obtain the 4 viscoelastic parameters of the Burgers model and construct the low temperature performance comprehensive evaluation indicator J.The low temperature bending strain energy density of the warm mix asphalt mixture is obtained by trabecular bending test of the asphalt mixture.The correlation between the bending strain energy density and each evaluation indicator is analyzed and compared.The test result shows that(1)the addition of the warming agent Sasobit weakened the low temperature crack resistance of the asphalt,which is characterized by a higher stiffness modulus,a lower stiffness modulus change rate,and a higher low temperature continuous grading temperature,larger k indicator and J indicator;(2)the higher the Sasobit content,the more significant the weakening effect of low temperature performance;(3)using a single stiffness modulus or stiffness modulus change rate to evaluate the low temperature performance of warm mix asphalt has a certain one-sidedness,while low temperature continuous grading temperature,k indicator and J indicator considering the low temperature deformation ability and stress relaxation ability of asphalt can more accurately evaluate the low temperature performance of warm mix asphalt.