-3℃养护下等强度混凝土强度增长的影响因素

摘要

为研究冻土区桥梁钻孔灌注桩混凝土在低、负温养护环境下强度增长规律, 各因素对混凝土在-3℃养护下达到等强度过程中对强度增长的影响, 负温养护条件下等强度混凝土宏观结构与微观结构之间的关系;综合考虑水胶比、含气量、矿物掺合料等因素设计混凝土配合比, 在标养 (20℃) 和恒定负温 (-3℃) 下养护混凝土试件并测试不同龄期混凝土抗压强度, 同时测试-3℃下养护达到等强度混凝土的孔隙特征.结果表明:水胶比对-3℃养护下混凝土各自达到等强度的时间影响不是很明显;矿物掺合料和含气量都会影响-3℃养护下混凝土达到等强度的养护时间, 且含气量对混凝土强度的影响程度要大于矿物掺合料;通过延长养护龄期达到等强度的混凝土, 宏观上的"等强度", 并没有达到微观上的"等孔结构".%In order to study the strength growth law of bridge bored pile concrete in permafrost region under low and negative temperature curing environment, the influence of various factors on the strength growth of concrete in the process of reaching equal strength under-3℃curing, and the relationship between macrostructure and microstructure of equal strength concrete under negative curing temperature, the concrete specimens were cured at standard curing temperature (20℃) and constant negative temperature (-3℃) and the compressive strength of concrete at different ages was tested.At the same time, the pore characteristics of concrete under the curing condition of-3℃were tested.Results show that water-binder ratio does not have significant effect on the time for the concrete to reach the equal strength under-3℃curing, mineral admixtures and air content affect the curing time for the concrete to achieve equal strength under-3℃curing, and air content has more significant effect on the strength of concrete than mineral admixture.The equal strength of concrete achieved by extending the curing age is only macroscopic"equal strength"and it does not reach the microscopic"equal pore structure".