Improper use of polycarboxylate superplasticizer. It causes concrete to leak. The reason why polycarboxylate superplasticizers cause concrete leakage is simple: the quality of the aggregate fluctuates. In the process of concrete production, quality problems of sand aggregates are often encountered, such as bleeding problems such as changes in mud content, fluctuations in water content, changes in aggregate gradation, and changes in sand fineness modulus.
Polycarboxylate superplasticizers are sensitive to ambient temperature and have slow-release properties. Compared with other water reducing agents, the water reducing performance and water retention performance of polycarboxylate superplasticizers are greatly affected by temperature. When the temperature is high in summer and the temperature drops suddenly, the polycarboxylate superplasticizer with good water retention performance may collapse.
Add and reduce the water agent twice to adjust the slump. When polycarboxylate superplasticizer is used for secondary addition adjustment, sometimes its dosage cannot be reasonably controlled. When the amount of water reducing agent exceeds the theoretical requirement, the excess water reducing agent will still work after the concrete is poured, so it is a part of the concrete moisture analysis.
When mixing polycarboxylate superplasticizer, retarder cannot be used correctly. In order to obtain good concrete protection performance, a certain amount of retarder is usually added to the combination of polycarboxylate superplasticizer. When the amount of the retarding component is too large, or the temperature of the mixed polycarboxylate superplasticizer drops suddenly, the excessive retarding component will slow down the hydration of the cement and cause the concrete to ooze out.