In this article, we will discuss the causes of excessive loss of concrete slump during the testing process and how to avoid such situations.

Concrete construction pouring site

Polycarboxylate superplasticizers, as a new type of water reducer, have the characteristics of low dosage and high water-reducing rate. With the development and application of functional polycarboxylate superplasticizers, their application has become more widespread. However, polycarboxylate superplasticizers are sensitive to water content, dosage of admixtures, and sand and aggregate quality. Some abnormal phenomena may occur during the use of polycarboxylate superplasticizers, such as improper operation leading to excessive loss of concrete slump.

High efficiency water reducing agent storage device

Causes of the issue:

Polycarboxylate superplasticizers are more sensitive to temperature compared to other water reducers. When the temperature of cement exceeds 50°C, abnormal slump loss may occur. Additionally, mismatching polycarboxylate superplasticizers with admixtures or mixing them with other high-efficiency water reducers can reduce the effectiveness of polycarboxylate superplasticizers. Moreover, the compatibility between polycarboxylate superplasticizers and cement may deteriorate.

concrete slump testing

Experimental recommendations:

Preferably choose cement with lower initial temperature, and maintain communication with the admixture manufacturer, especially in summer.
(1) Provide training to production personnel, emphasizing that naphthalene-based and polycarboxylate superplasticizers should not be mixed. If both types of water reducers are used, they should be stored separately with clear labeling and should not be mixed.
(2) During normal concrete production, strive to maintain a slump greater than 200mm and a slump flow greater than 550mm to ensure the workability of the concrete at the construction site.
(3) When producing concrete with a slump less than 200mm and slump flow lower than 550mm, carry an appropriate amount of the same type of water reducer as a backup in the mixing truck.

For a new batch of materials, thorough testing before construction is necessary to determine the optimal mix ratio and construction methods, fundamentally addressing the issue of excessive loss of concrete slump.

We hope this article has been helpful to you. Concrete admixtures are a discipline where the quality of purchased materials is crucial. Various issues need to be addressed during subsequent testing and usage. Choose Fuluorui, and we will provide comprehensive solutions to any problems you encounter.