When used, polycarboxylate superplasticizer may have a sudden change in quality. If it is not properly understood, it will easily cause serious quality problems of concrete.
Reasons for the sudden change in the properties of polycarboxylate superplasticizer and cautions for its use
The mutagenicity of polycarboxylate superplasticizer is as follows:
1. Abrupt change in water reduction rate.
When the water reduction rate suddenly becomes large, then the dosage in the original mix ratio is too large, which will cause serious bleeding, segregation, setting and hardening of concrete after a large area of cracking and other problems;
When the water reduction rate suddenly changes, the water consumption will increase, the water-binder ratio will become larger, the strength will decline, and the concrete working performance will decrease.
Therefore, in addition to the admission of each batch of water reducer for the overall inspection, but also to strengthen the quality control in the production process, once the above situation, to quickly find out the reason, adjust the amount of water reducer.
2. The content and variety of air entrainment in polycarboxylate superplasticizer change suddenly.
This situation may lead to excessive air content in concrete, which may lead to a substantial decline in concrete strength.
Low gas content and poor workability of concrete.
Engineers should frequently test the air content or bulk density of concrete and notify the admixture supplier to make adjustments if there is a significant change.
3, polycarboxylate superplasticizer added in the protection of slump component occurred suddenly change.
It may cause the concrete slump time loss is too large to meet the construction requirements.
4. The variety and dosage of retarded components in polycarboxylate superplasticizer change suddenly.
It may cause concrete setting time too long or too short, and may also cause concrete slump loss to become larger, unable to meet the construction requirements, affecting the early mechanical properties of concrete, and so on.
Response measures: Concrete setting time and slump loss are frequently detected.
