1. Mud content of sand
When the mud content of sand is high, the water reduction rate of polycarboxylate superplasticizer is obviously reduced, and the change is not obvious when the content of polycarboxylate is increased.
Solution: apply this batch of sand to low-grade ordinary concrete;
Strictly control sand silt content, the requirement of mud content at least less than 2 %.
2. Sand does not dissolve with polycarboxylate superplasticizer
When the sand gradation, mud content, mud content meet the requirements of the case, but with polycarboxylate efficient superplasticizer does not dissolve, there is a chemical composition of sand and polycarboxylate efficient superplasticizer composition conflict, stirred concrete has no fluidity.
Solution: For each batch of sand entering the site, if the physical indicators are qualified, the concrete construction mix ratio shall be retested and the insoluble sand shall be removed from the site.
3. Concrete slump loss fast
Solution measures: water-reducing agent manufacturers by adding slump protection agent, and then using on-site raw materials for mix ratio retest, in order to adjust the slump loss, meet the requirements of construction.
4. Concrete grouting
On rainy days, C50 concrete was poured and discharged from the tank truck in good condition. However, after the concrete was shaken, there was bleeding and segregation.
Solution: reduce the water consumption, lengthen the mixing time, reduce the content of 0.1%, vibrate the concrete no longer lactation, make the concrete specimen standard raise the compressive strength of 28 days to reach the design strength.
