基于响应曲面法的PCB/WCF改性沥青混合料优化设计

Optimization Design of PCB/WCF Modified Asphalt Mixture Based on Response Surface Methodology

为改善废轮胎热解炭黑(PCB)改性沥青混合料的水稳定性,利用废弃鸡羽毛(WCF)的羊毛状纤维有益于沥青混合料水稳定性提升的特点,制备了AC-13 PCB/WCF改性沥青混合料。首先通过激光粒度仪,扫描电子显微镜与能谱仪分析了PCB与WCF的微观形貌与表面化学元素分布。然后基于响应曲面法(RSM)设计了PCB掺量、WCF掺量以及油石比对沥青混合料AC-13的空隙率、马歇尔稳定度以及冻融劈裂抗拉强度比影响的试验方案。最后通过方差分析(ANOVA)方法研究了3个自变量及其交互作用对沥青混合料的空隙率、马歇尔稳定度以及冻融劈裂抗拉强度比的影响,并建立了PCB/WCF改性沥青混合料AC-13性能预测模型。结果表明:PCB的粒径分布集中在197~358 nm,表面灰分会降低PCB与沥青的相容性;WCF羽轴两侧的羽片呈扇状分布,主要化学元素为碳、氮、氧、硫。由优化模型获得的PCB/WCF改性沥青混合料AC-13最佳优化参数为,PCB掺量0.52%,WCF掺量0.36%以及油石比5.5%;对应预测值为空隙率3.85%,马歇尔稳定度11.79 kN以及冻融劈裂抗拉强度比84.56%;基于最优参数配合比制备的PCB/WCF改性沥青混合料AC-13验证试验结果为空隙率3.69%,马歇尔稳定度11.6 kN以及冻融劈裂抗拉强度比84.9%,且都在95%置信区间内,表明模型具有较好的预测能力;优化设计的PCB/WCF改性沥青混合料AC-13的预测值和试验验证值均满足中国改性沥青混合料的性能要求。

In order to improve the water stability of waste tire pyrolysis carbon black(PCB)modified asphalt mixture,by using the wool fiber of waste chicken feather(WCF),which is beneficial to the improvement of water stability of asphalt mixture,PCB/WCF modified asphalt mixture with gradation AC-13 is prepared.First,the microstructure and surface chemical element distribution of PCB and WCF are analyzed by using a laser particle size analyzer,scanning electron microscope and energy dispersive spectrometer.Subsequently,an experimental plan based on the response surface methodology(RSM)is designed to investigate the effects of PCB content,WCF content and asphalt-aggregate ratio on the porosity,Marshall stability and freeze-thaw split tensile strength ratio of asphalt mixture AC-13.Finally,the impact of 3 independent variables and their interactions on the asphalt mixture’s porosity,Marshall stability and freeze-thaw split tensile strength ratio is studied by using analysis of variance(ANOVA),and a predictive model for the performance of PCB/WCF modified asphalt mixture AC-13 is established.The result shows that.The particle size distribution of PCB is concentrated in the range of 197-358 nm,and the surface ash content reduces the compatibility between PCB and asphalt.The feathers on both sides of the WCF shaft are distributed fan-shaped with the main chemical elements of carbon,nitrogen,oxygen and sulfur.The optimal parameters obtained from the optimization model for PCB/WCF modified asphalt mixture AC-13 are PCB content of 0.52%,WCF content of 0.36%and asphalt-aggregate ratio of 5.5%.The corresponding predicted values are porosity of 3.85%,Marshall stability of 11.79 kN and freeze-thaw split tensile strength ratio of 84.56%.The validation experiments for AC-13 PCB/WCF modified asphalt mixture prepared based on the optimal parameters result in porosity of 3.69%,Marshall stability of 11.6 kN and freeze-thaw split tensile strength ratio of 84.9%,all within a 95%confidence interval,indicating that the model has good predictive capability.The predicted values and experimental verification values of the optimized design for PCB/WCF modified asphalt mixture AC-13 meet the performance requirements for modified asphalt mixtures in China.