多聚磷酸SBS复合改性沥青混合料低温流变特性及本构关系研究

On Rheological Properties and Constitutive Relationship of Polyphosphoric Acid-SBS Composite Modified Asphalt Mixture at Low Temperature

基于小梁弯曲蠕变试验和直接拉伸应力松弛试验,采用蠕变速率、松弛时间、松弛模量等流变学指标,对比分析了在不同低温条件下,多聚磷酸(PPA)-SBS复合改性沥青混合料和SBS改性沥青混合料的低温流变特性,同时结合损伤力学和黏弹性力学理论,建立了蠕变损伤模型与六单元广义Maxwell应力松弛模型.结果表明:不同低温条件下,PPA-SBS复合改性沥青混合料进入蠕变稳定期的时间早于SBS改性沥青混合料,其累积变形量和蠕变速率均大于SBS改性沥青混合料;以Burgers模型为基础,结合损伤力学建立的蠕变损伤模型能够较好地反映蠕变损伤3阶段的变形特性;10℃时2种沥青混合料的应力松弛能力几乎相同,而0、-10、-20℃时PPA-SBS复合改性沥青混合料的应力松弛能力要优于SBS改性沥青混合料,且温度越低效果越明显;采用六单元广义Maxwell模型能够较好地描述低温条件下的沥青混合料应力松弛特性.

Based on the trabecular beam bending and creep test and direct tensile stress relaxation test,the creep rate,relaxation time,relaxation modulus and other rheological indicators were used to compare and analyze the polyphosphoric acid(PPA)-SBS composite modified asphalt mixture and SBS modified asphalt mixture under different low temperature conditions.Through the low-temperature rheological properties of modified asphalt mixture,combined with damage mechanics and viscoelastic mechanics,a creep damage model and a six-element generalized Maxwell stress relaxation model were proposed.The results show that the PPA-SBS composite modified asphalt mixture enters the creep stability period earlier than the SBS modified asphalt mixture under different low temperature conditions,and its cumulative deformation and creep rate are greater than that of the SBS modified asphalt mixture;based on the Burgers model,the creep damage model established in combination with damage mechanics can better reflect the deformation characteristics of the three stages of creep damage.The stress relaxation ability of the two asphalt mixtures is almost the same at 10℃,while the stress relaxation ability of PPA-SBS composite modified asphalt mixture at 0℃,-10℃and-20℃is better than that of SBS modified asphalt mixture,and the lower the temperature,the more obvious the effect;the six-element generalized Maxwell model can be used to better describe the stress relaxation characteristics of asphalt mixture under low temperature conditions.