多聚磷酸改性沥青的路用性能及机理分析

Road performance and mechanism analysis of polyphosphoric acid modified asphalt

为研究多聚磷酸改性沥青性能、改性机理及其混合料路用性能,制备了不同含量的多聚磷酸改性沥青和改性沥青混合料,采用3大指标(针入度、延度和软化点)、黏度(60℃和135℃)、马歇尔稳定度、流值和残留稳定度等,对多聚磷酸的改性和路用效果进行评价,结合傅里叶红外光谱与荧光显微镜分析其改性作用机理.结果表明,多聚磷酸改性沥青的软化点和黏度增幅较大,针入度显著降低,5℃延度相似;掺入改性剂的质量分数为1%的沥青混合料,高温性能提升幅度较大,但水稳定性没有明显改善;对比基质沥青与改性沥青红外光谱图,发现未形成新的吸收峰,多聚磷酸均匀分布于沥青.由改性沥青及其混合料的测试结果可知,多聚磷酸能改善沥青的高温性能,但未能改善低温性能,多聚磷酸的最佳质量分数为1%;多聚磷酸改性沥青为物理改性过程.

In order to investigate the effect of polyphosphoric acid on the performance and modification mechanism of modified asphalt and road performance of its asphalt mixture,different dosages of polyphosphoric acid modified asphalt and its mixture are prepared. Three physical property indexes（penetration,ductility and softening point）,viscosity（60 ℃,135 ℃）,stability and residual stability are tested to evaluate the polyphosphoric acid modification and road performance. Infrared spectroscopy and fluorescence microscopy are used to analyze modification mechanism. The results show that the softening point and viscosity of polyphosphoric acid modified asphalt increase greatly,the penetration decreases obviously and the ductility at 5 ℃ does not change. The performance of asphalt concrete with 1% modifier is greatly improved at high temperature,but no significant change happens to the water stability. By comparison of IR spectra between matrix asphalt and modified asphalt,no new absorption peak is formed. Fluorescence microscopy images show that polyphosphoric acid is evenly distributed in asphalt. Based on thetest results of modified asphalt and modified asphalt mixture,the polyphosphoric acid improves the high temperature performance of the asphalt while the low temperature performance does not change,and the optimal content of the polyphosphoric acid is 1%. Bitumen modified by polyphosphoric acid is a physical modification process.