低温沥青混合料在长隧道路面中的应用

Application of Low-temperature Asphalt Mixture in Long Tunnel Pavement

摘要:

针对城市地下长隧道路面使用的需求，对上海市北横通道东段隧道内路面所用的新材料AC-20C的低温复合改性沥青混合料，从原材料、配合比设计、施工混合料气体排放、现场实体检测方面进行研究。根据不同级配、不同油石比分别确定其最佳混合料级配和最佳油石比，通过残留稳定度、动稳定度、冻融劈裂强度比、低温弯曲破坏应变试验评价沥青混合料的水稳定性、抗车辙能力和抗裂性能，同时通过对比低温和传统热拌沥青混合料生产能源消耗、排放的气体，分析节能减排情况。结果表明：此次配合比设计最佳油石比为4.2%，动稳定度≥2 400 次/mm，残留稳定度、冻融劈裂强度比、低温弯曲试验破坏应变以及现场压实度、渗水各项指标均符合设计要求，工程应用效果良好；拌和楼每生产1 t低温沥青混合料可节约0.9 m3天然气，且相关气体排放降低率均超40%，充分展现了低温环保改性沥青节能减排的理念。

Abstract:

In view of the needs of urban underground long tunnel pavement， the new material AC-20C low-temperature composite modified asphalt mixture used in the tunnel pavement of the east section of Beiheng Passage is studied from the aspects of raw materials， mix proportion design， gas emission of construction mixture， and on-site physical detection. The optimal mixture gradation and optimal asphalt-aggregate ratio are determined according to different gradations and different asphalt-aggregate ratios. The water stability， rutting resistance and crack resistance of asphalt mixture are evaluated through the residual stability， dynamic stability， freeze-thaw splitting strength ratio and low-temperature bending failure strain test. At the same time， by comparing the energy consumption and gas emissions of low-temperature and traditional hot-mixed asphalt mixtures， the situation of energy conservation and emission reduction is analyzed. The results show that the optimal asphalt-aggregate ratio of this mix proportion design is 4.2%， the dynamic stability is ≥2 400 times/mm， and the residual stability， freeze-thaw splitting strength ratio， low-temperature bending test failure strain， as well as on-site compaction degree and water seepage indicators all meet the design requirements， and the physical application effect is good. At the same time， for every ton of low-temperature asphalt mixture produced by the mixing plant， 0.9 cubic meters of natural gas can be saved， and the reduction rate of relevant gas emissions can reach more than 40%， which fully demonstrates the concept of energy conservation and emission reduction of low-temperature environmentally friendly modified asphalt.