静水作用下板式无砟轨道CA砂浆力学性能变化

Studies on Mechanical Changes of CA Mortar for Slab Track Under Hydrostatic Effect

水泥乳化沥青砂浆(简称CA砂浆)是高速铁路板式无砟轨道的关键功能材料,位于轨道板与底板之间,起支承、调整、减振的作用。文章通过试验,研究了水作用下不同配合比CA砂浆的力学性能变化,并对其原因进行了分析。结果发现长时间浸泡将显著降低CA砂浆的抗压强度,且沥青含量越高,降低幅度越大;但长时间浸泡作用下CA砂浆并未出现沥青流失现象;研究还发现CA砂浆存在干湿循环后脆化的现象,其中低弹模CA砂浆6轮干湿循环后折压比由0.70降低至0.51,电子扫描显微镜(SEM)的分析结果表明沥青膜脱水收缩以及水泥持续水化是导致该现象的原因。

Cement and emulsified asphalt mortar（ CA mortar）,a kind of material composed of cement,emulsified asphalt,sand and admixtures,is widely used in high-speed railway track structure. In CRTS（ China Railway Track System） I-type track systems,CA mortar is cast between the concrete bed plate and the track slab,providing a function of leveling and supporting track slab. Mechanical changes of different CA mortar under hydrostatic effects were studied in this paper. Results show that the compressive strength of CA mortar was decreased largely when immersed in the water for 12 months. The more asphalt content,the larger of the compressive deceased. The effluence of the asphalt could not be seen when the CA mortar was immersed for a long time. Results also show that CA mortar embrittlement occurs after wetting-drying cycle test,and the bend- press ratio of the low elastic CA mortar was decreased from 0. 70 to 0. 51 after six wet- dry cycles. The SEM analysis show that the asphalt film losing dehydration and contraction as well as the Portland cement continue hydrating might be the reasons of the brittleness changing.