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冬期混凝土施工中,为尽量减少冻害影响和强度损失,以下三个问题最为突出:一是确定达到抗冻临界强度的时间或拆模时间;二是选择经济有效的施工措施;三是选用与施工环境相适宜的化学外加剂。一、临界成熟度的确定按惯例,是通过测定试块强度来决定结构混凝土是否达到允许受冻或拆模的临界强度。这样做工作量大,且试块很难与结构保持同样温度,又由于测试中存在误差,试块强度难以准确反映结构混凝土的实际强度。国内外实践证明,采用成熟度(温度与时间乘积)来推断已知配合比的混凝土强度是可行的,据此来规定混凝土养护初期允许受冻或拆
In winter concrete construction, in order to minimize the impact of freezing damage and strength loss, the following three problems are most prominent: First, determine the time to reach the critical strength of frost resistance or the time for demoulding; Second, select the economic and effective construction measures; Third, select and construction Suitable chemical additives for the environment. I. Determination of Critical Maturity According to common practice, it is determined by determining the strength of the test block to determine whether the structural concrete reaches the critical strength that allows freezing or mold removal. The workload is large, and it is difficult for the test block to maintain the same temperature as the structure. Because of the errors in the test, the strength of the test block is difficult to accurately reflect the actual strength of the structural concrete. Practice at home and abroad has proved that it is feasible to use the maturity (temperature and time product) to infer the concrete strength of the known mix ratio, and to specify that the concrete can be frozen or removed at the initial stage of curing.