向佳瑜,李 曦,蒋 震,冷 政,寇建岭,曾 维
冬季超高层泵送混凝土力学性能研究
向佳瑜,李 曦,蒋 震,冷 政,寇建岭,曾 维
摘 要:根据长沙国金中心混凝土400m以上超高层泵送冬季施工情况,通过改变胶凝材料组分及含量,设计九组不同的配合比制备高性能混凝土,分别对其工作性能、力学性能、水化产物等方面进行分析,并结合工程应用,得出混凝土冬季环境下工作性能、力学性能变化的相关规律。结果表明,硅灰在超高层泵送混凝土中掺量为3%~5%比较适宜,对混凝土工作性能指标改善明显,压力泌水率保持在20%以内,扩展度达到700mm以上无泌水现象;硅灰具备火山灰效应及填充作用,可提高混凝土的强度;采用热水生产法、罐车保温法、泵管保温法、配合比优化法等方法后,在5℃左右养护温度下,C50混凝土构件实体抗压强度在浇筑后36h达到25MPa,72h后达到38MPa,拥有较高的早期强度,满足冬季施工进度要求。
Abstract: According to changing the composition and content of cementitious materials, 9 kinds of concrete samples with different mix proportions were prepared for Changsha international financial centre above 400m super high pumping. The work performance, mechanical performance and hydration products were analyzed, and the research was combined with winter construction, some related rules of concrete work and mechanical performance under winter condition were obtained. Experimental results showed that the proper content of silica fume in super high pumping concrete was 3%~5% which had a promoting effect on the work performance. The pressure bleeding rate was less than 20% and expansion up to 700mm without bleeding. The concrete strength increased as the density rise by volcanic ash and filling effect of silica fume. The compressive strength of C50 concrete after pouring 36h reached 25MPa and 72h reached 38MPa at temperature about 5℃, which had high early strength to meet the requirements of winter construction schedule with hot water production, concrete delivery tanker insulation, pump tube insulation and mix optimization.
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