多种湿法橡胶改性沥青的综合性能评价与改性机理研究

Comprehensive Performance Evaluation and Modification Mechanism of Various Wet Rubber Modified Asphalt

本工作拟对普通橡胶沥青、Terminal Blend(TB)橡胶沥青和脱硫橡胶沥青三种橡胶沥青的高温抗车辙、中温抗疲劳、低温抗裂以及流动施工性能进行综合评价,并从化学官能团和流变特性角度研究其改性机理。采用车辙因子、零剪切粘度、不可恢复蠕变柔量等指标,从增粘和增弹两个角度对沥青的高温性能进行评价;采用时间扫描试验和线性振幅扫描试验对沥青的中温抗疲劳性能进行评价;采用低温弯曲流变仪和135℃布氏粘度对沥青的低温抗裂性能与施工和易性进行评价;最后,基于模量-温度扫描试验、改进的Arrhenius方程拟合和红外光谱试验,从流变和化学角度对不同橡胶沥青的改性机理进行了研究。研究表明:普通橡胶沥青中的橡胶分子团聚最明显,弹性与力学性能最优,但粘度也最大,普通橡胶沥青在高温下展现出明显的橡胶态平台区和非牛顿流体行为。TB橡胶沥青中的橡胶颗粒降解度最高,橡胶分子与沥青分子完全混溶,粘度接近基质沥青,低温性能优异。脱硫橡胶沥青所采用的胶粉降解程度介于两者之间,改性效果较为均衡,是具有前景的废旧轮胎固废回收利用手段。

This work aimed to comprehensively evaluate the high-temperature anti rutting, medium-temperature anti fatigue, low-temperature anti cracking and flow-construction performances of these three kinds of rubber modified asphalts, conventional crumb rubber modified asphalt(CRMA), Terminal Blend rubber asphalt(TBRA) and desulfurized rubber asphalt(DRA), and discussed their modification mechanism from the perspective of chemical functional groups and rheological properties. Using rutting factor, zero-shear viscosity and irrecoverable compliance, the high-tempe-rature performance of asphalts was evaluated from the perspectives of viscosity and elasticity;the time sweep test and linear amplitude sweep test were conducted to evaluate the fatigue resistance of asphalts at medium temperature;the low-temperature bending rheometer test and 135 ℃ Brookfield viscosity test were used to evaluate the low-temperature crack resistance and construction workability of asphalts;finally, based on the modulus-temperature sweep test, Arrhenius model fitting and infrared spectroscopy test, the modification mechanism of different rubber asphalts was studied from the perspective of rheology and chemistry. The results show that the rubber molecules in CRMA have the most obvious agglo-meration, which translates to the best elasticity and mechanical properties, but also the largest viscosity. CRMA exhibits an obvious rubbery platform and non-Newtonian fluid behavior at high temperatures. The rubber particles in TBRA have the highest degradation rate, the rubber molecules are completely miscible with the asphalt molecules, and thus the viscosity is close to that of the base asphalt. The degree of degradation of the DRA is between the two, and the modification effect is more balanced. DRA is a promising means of recycling solid waste of waste tires.