低热大体积混凝土微应变特性分析

Analysis of Micro-strain Characteristics of Low-heat Mass Concrete

为减少锚碇大体积混凝土结构内外产生较大温差而引起的混凝土收缩开裂,将粉煤灰与自主研制的水化热抑制剂掺入混凝土中,探究水化热抑制剂对水泥流动度与凝结时间及不同掺量的粉煤灰与水化热抑制剂对大体积混凝土温缩变形性能的影响。结果表明:大体积混凝土早期水化温度随粉煤灰与水化热抑制剂掺量的增加而降低,且水化温度峰值出现后移现象;大体积混凝土的微应变随粉煤灰与水化热抑制剂掺量的增加而降低,且水化热抑制剂在较低掺量时对水化的抑制效果更明显;未掺粉煤灰的混凝土7 d龄期的收缩值已超过180 d龄期的70%,而掺粉煤灰的混凝土在7 d收缩值仅占180 d龄期的50%左右,在28 d才达到180 d收缩值的70%,在此基础上复掺水化热抑制剂的混凝土要达到180 d的收缩的70%需要45 d。综合作用效果与成本考虑,推荐采用内掺40%粉煤灰与外掺0.2%的水化热抑制剂进行锚碇大体积混凝土的配制。

In order to reduce the temperature stress caused by the large temperature difference inside and outside the anchorage mass concrete structure, the fly ash and the self-developed hydration inhibitor were mixed into the concrete. The effects of hydration inhibitor on the temperature-shrinkage deformation of mass concrete were investigated. As a result, the hydration inhibitor can effectively reduce the loss of cement fluidity and prolong the setting time of cement by more than 4 hours. The early hydration temperature of mass concrete decreases with the increase of the content of fly ash and hydration inhibitor, and the peak value of hydration temperature moves backward. The micro-strain of mass concrete decreases with the increase of fly ash and hydration inhibitor, and the inhibition effect of hydration inhibitor on hydration is more obvious at lower content. The shrinkage value of concrete without fly ash in 7 d has exceeded 70% of the age of 180 d, while the shrinkage value of concrete with fly ash in 7 d is only about 50% of the age of 180 d, and the shrinkage value of 180 d is 70% in 28 d. On this basis, it takes 45 d for concrete with hydration inhibitor to reach 70% of the shrinkage of 180 d. Considering the comprehensive effect and cost, it is recommended to use 40% fly ash and 0.2% hydration inhibitor to prepare anchorage mass concrete. 40% fly ash and 0.2% hydration inhibitor to prepare Anchorage mass concrete.