开级配大粒径沥青碎石低温性能评价

Evaluation of Low Temperature Performance of Open-graded Large Stone Asphalt Mixes

摘要:

为了探讨小梁弯曲试验评价开级配大粒径沥青碎石（OLSM）低温性能的适用性，分析了试件截面与跨径对OLSM低温受力特征的影响，提出了OLSM低温性能评价方法；采用改进小梁弯曲试验的方法，评价了集料级配、沥青标号、沥青胶浆膜厚度、粉胶比和矿粉代替量等因素对OLSM低温性能的影响。结果表明，标准小梁弯曲试验未能真实反映OLSM低温受力特性，改进小梁弯曲试验适合评价OLSM低温性能；OLSM低温性能随着分形维数的增大先提高后降低，分形维数2.41～2.44下其低温性能较好；其低温性能随着沥青标号的增加而降低，随着粉胶比和水泥代替矿粉量的增大先提高后降低，低标号沥青、粉胶比1.0～1.2和水泥代替矿粉量10%-30%下其低温性能较好；其低温性能随着胶浆膜厚度的增大而提高，但厚度超过50μm后提高效果不明显。

Abstract:

In order to explore the applicability of small beam bending test in evaluating low temperature performance of Open-graded large stone asphalt mixes(OLSM), the effect of section size and span on temperature characteristics of it is analyzed，and the evaluation method of low temperature performance is put forward. And the effects of aggregate gradation, asphalt grade, asphalt mortar film thickness, ratio of filler to bitumen and cement substitution for powder on the low temperature performance of OLSM are analyzed based on the improved small beam bending test. Research shows that: standard small beam bending test fails to truly reflect the low-temperature stress characteristics of OLSM. However, the improved small beam bending test is suitable for evaluating the low temperature performance of it. The low temperature performance of OLSM increases first and then decreases with the increase of fractal dimension. And it has excellent low temperature performance when the fractal dimension range is 2.44 to 2.41. The low temperature performance of OLSM increases first and then decreases with the increase of powder-to-binder ratio and cement substitution for powder, and decreases with the increase of asphalt label. And it has excellent low temperature performance when the ratio of powder to binder range is 1.0 to 1.2 and the cement substitution for powder range is 10%-30%. The low temperature performance of it could be increased effectively by increasing amount of mortar. However, if the film thickness of mortar is more than 50μm, the effect is not obvious.