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本文研究负温养护、同条件预养护方式、含气量等对冬期施工不同强度等级混凝土强度的影响规律,确定冬期施工混凝土的临界强度。结果表明:混凝土在负温养护时强度发展缓慢,混凝土强度等级越高,混凝土抗冻性能越好;强度等级高,冬期同条件养护混凝土强度损失小,预养护有助于混凝土抗冻性能的提高;混凝土受冻临界强度随强度等级提高而增长;当含气量为3%时,C30混凝土R_(-7+28)/R_(28)的比值最高,为最佳含气量。将试验结果应用于天津117大厦混凝土冬期施工中,采取一定的养护措施保证了冬期施工混凝土强度正常发展。
In this paper, the influence of negative temperature curing, the same pre-curing mode and gas content on the strength of concrete with different strength grades in winter construction are studied, and the critical strength of concrete in winter is determined. The results show that the strength of concrete is slowed down during negative temperature curing. The higher the concrete strength grade, the better the frost resistance of concrete. The higher the strength grade, the less strength loss of concrete under the same conditions in winter. Pre-curing is helpful to improve the frost resistance of concrete The critical strength of frozen concrete increases with the increase of strength grade. When the gas content is 3%, the ratio of R_ (- 7 + 28) / R_ (28) of C30 concrete is the highest, which is the best gas content. The test results are applied to the concrete construction of Tianjin 117 Building in winter, and some curing measures are taken to ensure the normal development of concrete strength in winter.