预拌碎石对GMA浇注式沥青混凝土高温性能的影响

Effect of Pre-mixed Gravel on High Temperature Performance of GMA Cast Asphalt Concrete

为研究预拌沥青碎石对钢桥面铺装结构高温抗车辙性能的影响,依据港珠澳大桥钢桥面铺装实体工程,开展GMA浇注式沥青混凝土的高温性能室内试验研究。首先设计GMA10和SMA13级配沥青混合料,然后制备不同预拌沥青种类(AH70#,SBS)、不同预拌沥青掺量(0.2%,0.4%,0.6%,0.8%)、不同粒径(5~10 mm,10~15 mm,15~20 mm)的单级配碎石,分析不同粒径、撒布量、撒布方式、预拌沥青种类与掺量对单层GMA浇注式沥青混凝土和组合结构(SMA+GMA)高温性能的影响。结果表明:预拌碎石撒布可显著提高GMA浇注式沥青混合料的高温性能;在其他相同条件下,撒布粒径10~15 mm的预拌碎石对提高GMA浇注式沥青混合料的高温性能最为明显,高达30%左右;随着预拌碎石撒布量的增加,GMA浇注式沥青混合料的高温改善作用逐渐增强,撒布量在10~12 kg/m2改善效果最佳;碎石撒布方式和预拌沥青的类型对提高浇注式沥青混合料的车辙动稳定度影响较小;随着预拌沥青掺量的增加,GMA浇注式沥青混合料高温性能改善作用先增强后减弱,预拌沥青掺量0.2%~0.6%较为合理;干拌碎石在浇注式沥青混合料中的的隔热效果优于预拌沥青碎石的;预拌沥青碎石的撒布改善了组合结构的高温抗车辙性能,车辙深度降低10%左右,车辙动稳定提高25%左右;组合结构70℃车辙动稳定度指标更能真实反映南方湿热高温环境下钢桥面铺装结构的高温抗车辙性能。

In order to study the effect of pre-mixed asphalt gravel on the high-temperature anti-rutting performance of steel bridge deck pavement structure, the indoor test of high-temperature performance of GMA cast asphalt concrete is conducted based on the project of steel deck pavement of Hong Kong - Zhuhai - Macao Bridge. First, the GMA10 and SMA 13 graded asphalt mixtures are designed. Then, the single graded gravels of different kinds of pre-mixed asphalt （ No. AH70, SBS）, different contents of pre-mixed asphalt （0.2%, 0.4%, 0.6%, 0.8%）, different particle sizes （5-10 mm, 10-15 mm, 15-20 mm） are prepared. At last, the effect of different particle sizes, spreading amounts, spreading modes, pre-mixed asphalt types and contents on the high temperature performance of GMA cast asphalt concrete and SMA ＋ GMA composite structure are analyzed. The result shows that （ 1 ） the spreading of pre-mixed gravel could significantly improve the high temperature performance of GMA; （2） under the same condition, the improvement of the high temperature performance is more reasonable with 10 - 15 mm particle gravel, at the top about 30% ; （3） with the increase of the spreading amount of pre-mixed gravel, the high temperature performance improvement of GMA is gradually enhanced, the spreading amount is the best in the range of 10- 12 kg/m2; （4） the gravel spreading mode and the type of pre-mixed asphalt have less effect on the rut dynamic stability of cast asphalt concrete; （5） the improvement of high temperature performance of GMA is enhanced and then weakened with the increase of the pre-mixed asphalt content, and it is reasonable with the pre-mixed asphalt content of 0.2% - 0. 6% ; （ 6 ） the heat insulation effect of dry-mixed gravel in cast asphalt concrete is better than that of pre-mixed asphalt; （7） the spreading of pre-mixed asphalt gravel improved the anti-rutting performance of the composite structure, the rutting depth is reduced by about 10%, and the rutting dynamic stability is improved by about 25 % ; （8） the index of 70 ~C rutting dynamic stability of the composite structure could reflect the high temperature anti-rutting performance of the steel bridge pavement structure more really in the hot and rainy south environment.