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本文研究了起始养护时间对混凝土早期收缩的影响。研究结果表明,对不掺减水剂的混凝土,虽然起始养护时间对收缩的影响百分率也很大,但由于总收缩较小,因此从早期收缩开裂的角度来说,起始养护时间影响较小。而对掺减水剂的混凝土,由于初凝后8h内的收缩急剧增加,不加养护的收缩值可高达500×10-6m/m以上,远远超过混凝土的开裂极限。但初凝时即开始早期养护,早期收缩很小,远远小于混凝土的开裂极限。初凝后8h再开始养护的早期收缩值与不养护差别很小,起不到任何裂缝控制的效果。因此,不同起始养护时间对混凝土早期收缩影响十分显著。对掺减水剂的混凝土,必须从初凝前即采取养护措施,才能有效控制混凝土的早期收缩裂缝。
This paper studies the impact of initial curing time on concrete early shrinkage. The results show that although the influence of initial curing time on shrinkage is also great for concrete without water-reducing admixture, the initial curing time is more affected by the early shrinkage cracking because of the smaller total shrinkage small. As for the concrete with water-reducing admixture, the shrinkage without curing can reach as high as 500 × 10-6m / m due to the rapid increase of shrinkage within 8h after initial setting, far exceeding the cracking limit of concrete. However, initial setting begins early conservation, early contraction is small, far less than the cracking limit of concrete. 8h after initial setting and then start curing conservation value of the early contraction and no difference is small, can not achieve any effect of crack control. Therefore, different initial curing time on concrete early shrinkage is very significant. Concrete admixture water-reducing agent must be taken before the initial coagulation measures to effectively control the early shrinkage cracks in concrete.