超缓凝大体积混凝土配合比优化及温控技术

结合嘉鱼长江公路大桥10#主墩承台大体积混凝土的温控防裂施工,研究了缓凝剂种类、粉煤灰与矿渣粉复合矿物掺合料掺量和聚丙烯腈纤维对混凝土凝结时间、工作性、力学性能、绝热温升和耐久性的影响,优化配制了一种具有超缓凝和低水化热温升的C40承台混凝土;采用Midas FEA有限元仿真计算软件分析了承台大体积混凝土的温度场和应力场,通过降低混凝土浇筑温度、合理设置冷却水管和保温保湿养护等一系列温控措施,确保了承台大体积混凝土施工各项温度指标均符合温控标准要求,拆模后未出现有害温度裂缝.

Mix Proportion Optimization and Temperature Control Technology for Super Retarding Pile Cap Mass Concrete

The effects of retarder type, content of fly ash-slag powder composite mineral admixture and PAN fiber on concrete setting time, workability, mechanical properties, adiabatic temperature rise and durability were systematically investigated through the construction of temperature and crack control of 10# main pier pile cap mass concrete in Jiayu Yangtze river highway bridge.Additionally, a kind of C40 pile cap concrete with super retarding and low hydration heat has been successfully cast.Then, Midas FEA finite element method was employed to calculate and analyze the temperature field and stress field of pile cap mass concrete.And a sequence of efficient temperature control measurements including reducing the pouring temperature of concrete, setting up cooling water pipe in a reasonable way and heat and moisture preservation were adopted.It turn out that no harmful cracks occurred in the pile cap mass concrete and its temperature control index met all the requirements of the temperature control standards.