养护剂对道床板现浇混凝土收缩开裂性能的影响

为解决道床板现浇混凝土养护难、易开裂的问题,研究了自制高效养护剂对道床板现浇混凝土的强度、塑性收缩变形和抗裂性的影响。结果表明,采用养护剂养护有利于提高混凝土的抗压强度,其早期(7d)抗压强度高于标准养护下的抗压强度,后期(28d和56d)抗压强度与标准养护下的抗压强度相近,但其7d和28d抗折强度略低于标准养护下的抗折强度。在混凝土浇筑成型后立即喷涂养护剂,可有效降低混凝土塑性收缩。72h后,TJ-A、TJ-B和C型3种养护剂分别降低混凝土塑性收缩率为42%、27%和27%,同时,这3种养护剂养护下的混凝土表面水分蒸发量比自然养护下分别降低了60%、54%、60%。养护剂养护有效地防止了混凝土早期裂缝的产生,提高了混凝土的抗裂性能。

Influences of Curing Agent on Shrinkage-cracking Property of Bed Slab Cast-in-situ Concrete

The influence of curing agent on the mechanical properties,plastic shrinkage and crack resistance are studied in order to solve the problem of hard providing effective curing ways for track bed cast-in-situ concrete which is easy to crack.The results indicate that curing agent can improve the compressive strength of concrete,and the compressive strength of concrete with curing agent is higher than that of concrete under the standard curing at early ages(before 7d),and it’s similar to that of concrete under the standard curing at later ages(28d,56d).But flexural strength of concrete with curing agent is slightly lower than that of concrete under the standard curing at ages of 7d and 28d.Spraying curing agent on concrete surface immediately after casting can effectively reduce the plastic shrinkage.Three kinds of curing agent(TJ-A,TJ-B and type C)can reduce 42%,27% and 27% of plastic shrinkage and reduce 60%,54%,60% of water evaporation value than that of concrete without curing agent after 72h.In addition,the result of cracking resistance test shows that curing agent can efficiently prevent the early cracking of concrete,and improve the anti-cracking ability of concrete.