基于BBR试验的沥青低温性能差异性分析

Variation analysis of low temperature performance of asphalt based on BBR test

BBR试验是一种常用于评价沥青低温性能的测试方法,利用相应的PG分级来区分不同类型沥青低温性能之间的差异性。然而此方法存在一定的不足,即不能准确评价处于同一PG分级上沥青之间低温性能的差别。因此,为研究处在同一PG低温分级温度档上不同沥青低温性能之间的差异性,研究选取三种进口沥青作为研究对象并分别进行基本指标检验和BBR试验,同时根据BBR试验结果引入PG连续分级温度Tc、沥青低温柔量k和沥青小梁跨中挠度δ三种指标来评价处于同一PG分级上的不同沥青之间低温性能的差异。研究表明:利用PG低温连续分级温度Tc、基于S(t)和m指标建立的沥青低温柔量k和沥青小梁跨中挠度δ来评价的所选三种沥青低温抗裂性能得到的结果具有一致性;这说明三种评价指标具有比较高的置信度和合理性,在工程中可以采用,能准确区分出同一PG分级上不同种类沥青的低温性能,弥补了PG低温分级的不足,为实际道路施工提供了理论支持,尤其是对于寒区道路建设具有较大的参考意义。

BBR test is commonly used to evaluate the low temperature performance of asphalt. The corresponding PG grade is used to distinguish the difference of different types of asphalt. However, this method has some shortcomings, that is, it cannot accurately evaluate the difference of low temperature performance of different asphalts in the same PG grade. Therefore, to study the difference of low temperature performance of different asphalts in the same PG low temperature classification temperature range, three kinds of imported asphalt were selected as research object and the basic index test and BBR test were conducted respectively. According to BBR test results, PG continuous grading temperature Tc, asphalt low tenderness k and asphalt trabecular mid-span deflection δ were introduced to evaluate the difference of low temperature performance among different asphalts in the same PG grading. The results show that the low temperature cracking resistance of the selected three asphalts evaluated by using the PG low temperature continuous grading temperature Tc, the asphalt low temperature temperature k established based on the S(t) and m indexes, and the midspan deflection δ of the asphalt trabeculae are consistent. This shows that the three evaluation indicators have relatively high confidence and rationality, and can be used in engineering. These three evaluation indicators can accurately distinguish the low-temperature performance of different types of asphalt on the same PG classification, make up for the deficiency of PG low-temperature classification, and provide theoretical support for actual road construction, especially for road construction in cold regions.