基于国内外试验方法的橡胶沥青性能测试

Performance test of rubber asphalt based on domestic and abroad test methods

为统一橡胶沥青性能试验的评价指标,分别采用不同胶粉掺量对70#和90#的基质沥青进行改性,基于中国规范中的针入度、延度、软化点和弹性恢复试验以及Superpave中的动态剪切流变试验、布氏旋转粘度试验和弯曲梁流变试验等对橡胶沥青进行了性能评价。研究结果表明:胶粉的添加能显著改善沥青的高温性能,显著降低沥青的温度敏感性,但增大了沥青的高温粘度,增加了沥青混合料的拌和与压实难度;胶粉的溶胀作用会导致针入度的试验结果出现较大误差,因此,不建议采用针入度试验来评价橡胶沥青的性能;软化点可作为橡胶沥青高温性能的一个评价指标,对于90#基质沥青,胶粉掺量分别为10%、15%、20%和25%时的软化点比未掺胶粉时的软化点分别提高了11.23、11.97、15.18、21.10℃,对于70#基质沥青,胶粉的添加则使其软化点分别提高了4.02、8.18、12.83、14.45℃,因此,胶粉对70#基质沥青软化点的影响效果要大于对90#基质沥青的影响效果;胶粉对沥青低温性能的改善效果会随着温度的下降而降低,在研究胶粉对沥青低温性能的影响程度时,弯曲梁流变试验的结果比低温延度试验的结果更加明显,且由于橡胶沥青的低温延度较小,试验过程中容易产生较大误差,因此,建议采用弯曲梁流变试验评价橡胶沥青的低温性能。

To unify the performance evaluation indicators of asphalt rubber, 70 % and 90% base asphalts were modified with different rubber powder contents. The performance tests of rubber asphalts were conducted by Chinese specific tests such as penetration test, ductility test, softening point test and elastic recovery test, and Superpave methods such as dynamic shear rheology（DSR） test, Brookfield rotary viscosity test, and bending beam rheology（BBR） test. Analysis result shows that the addition of rubber powder can improve the high-temperature performance and reduce the temperature sensitivity of asphalt,but increase the viscosity of asphalt at high temperature and increase the difficulties in asphalt mixing and compaction. The swelling of rubber powder would lead big error in penetration test, so it is not recommended to apply penetration test in evaluation of rubber asphalt performance. Softening point can be regarded as one of evaluation indicators for high-temperature performance of rubber asphalt. For 90＂ base asphalt, its softening point increases by 11.23, 11. 97, 15. 18 and 21. 10 ℃ when the rubber powder content is 10%, 15%, 20% and 25% respectively. For 70% base asphalt, its softening point increases by 4.02, 8. 18, 12.83 and 14.45 ℃ when the rubber powder content is 10%, 15 %, 20% and 25 % respectively. It is also found the influence of softening point caused by rubber powder is larger on 70% base asphalt than on 905 base asphalt. The improvement of rubber powder on the low-temperature performance of asphalt would decease with the decrease of temperature. To test the improvement of rubber powder on the low-temperature performance of asphalt, BBR test is more significant than low- temperature ductility test. Besides, big error will produce in low-temperature ductility test process because of its small value. Therefore, it is recommended to apply BBR test for the low-temperature performance evaluation of rubber asphalt. 8 tabs, 7 figs, 21 refs.