基于后掺法的混凝土坍落度恢复技术研究

Technology Research About Recovery of Concrete Slump Loss Based on Superplasticizer Later Added

通过水泥对减水剂的吸附、水泥浆溶液Zeta电位、净浆流动度和混凝土坍落度等试验,分析了后掺聚羧酸减水剂量和添加时间对水泥净浆流动性、混凝土工作性能的影响及其相互关系,在此基础上提出了恢复混凝土坍落度的技术方法。结果表明:后掺法通过降低水泥颗粒对减水剂的吸附和减小颗粒的Zeta电位,能够有效避免早期水化产物对减水剂的吸附包裹,提高减水剂的有效分散能力;减水剂后掺的量与时间的合理匹配,可在一定时间内恢复混凝土坍落度,当先掺80%、后掺20%的减水剂时,在2h内可以显著地改善坍落度损失。

By studying the adsorption behavior, the zeta potential, the fluidity of the cement paste and concrete slump, we clarified the effect that later added amount and time of superplasticizer on performance of concrete and cement paste, as well as their mutual relations. And on base of which the measures to resume the slump of concrete were put forward. The experimental results show that later added method could reduce the adsorption effect of PC on cement particles and decrease the zeta potential of particles, effectively avoiding adsorption and coat of water reducer on early hydration pro- duction, improving effectively the dispersing ability of PC. Concrete slump can be restored within a certain time if later added amount and time of PC match reasonable, when added 80% of PC first and 20% second, the slump loss of concrete can be significant improved.