Of polycarboxylic acid superplasticizer applying in question
Greatest disadvantage of polycarboxylic acid superplasticizer for high air, add defoamer methods currently used in Defoamers disperse negative issues can cause fluctuations in gas eventually will cause the fluctuation of concrete strength.
Almost every kind of polycarboxylic superplasticizer defoamer is needed to avoid unnecessary air entrained, polycarboxylic series of superplasticizer and Defoamers poor compatibility, always separated from the water defoaming agents floating on the surface.
Another problem is difficult to prolong the setting time, choose the suitable retarder is present, we must solve the problem.
Last question is its shrinkage-reducing effect is not good, concrete shrinkage-reducing admixture dosage above 0.5% to be effective, shrinkage-reducing effect is about 10%~20% and polycarboxylic acid total effective volume is about 0.3%~0.5%, shrinkage-reducing effect is not too big, the theoretical value can reach 5%~10% it is very good.