At present, the polycarboxylate superplasticizer used in the market has high requirements on the quality and stability of raw materials, and is sensitive to cement adaptability, sand and gravel mud content, water absorption, stone powder content, sand and gravel grading, sand rate, coal ash loss and water requirement.
Therefore, it is particularly important to check the raw materials entering the site.
Good material stability promotes the stability of production control and greatly reduces the probability of quality accidents.
In the use process of polycarboxylate superplasticizer, technical service personnel and customers often reflect that polycarboxylic acid superplasticizer is more sensitive, and its sensitivity is mainly manifested in:
1. Dose sensitivity
When the content of polycarboxylate superplasticizer in concrete fluctuates slightly, the concrete mixture is easy to segregate, leak water or crack, which has adverse effects on the pumping performance, mechanical properties and durability of concrete.
2. Temperature sensitivity
When the temperature difference between morning and evening is large, the fluidity of concrete fluctuates greatly.
High ambient temperature in summer leads to great fluidity loss of concrete mixture.
When the ambient temperature is low in summer, the fluidity of concrete mixture increases with time, which leads to the problems of concrete delamination, stone aging, poor concrete inclusions, poor appearance and so on.
3. Sensitivity to water consumption
Because polycarboxylic acid system superplasticizer has higher dispersion than naphthalene system superplasticizer and aliphatic superplasticizer, the water reduction rate can reach more than 30%.
With the increase of the dosage, the sensitivity of unilateral water consumption becomes more prominent, and the concrete mixture may appear stratification, segregation, bleeding and other phenomena.
In the actual production process of mixing station, the water content in sand and gravel often fluctuates.
If the water content of sand and gravel is not correctly estimated, the actual amount of water mixed with concrete will change.
The application of polycarboxylic acid water reducer is sensitive to water consumption and can not meet the construction requirements.
4. Sensitivity to raw materials
The sensitivity to sand, cement, and admixtures mainly indicates that the content of polycarboxylic acid water reducer increases as the mud content of sand increases.
When the grade or batch of cement or admixture is changed, the fluidity of concrete mixture will also change significantly.
