Tips of application of polycarboxylate high-performance water reducer(V)： The Dosage of Polycarboxylate Superplasticizer
Polycarboxylate Superplasticizer shows high water reduction rate and good slump retention at low dosage. However, the following issues may arise during application:
① The dosage is sensitive when the water-cement ratio is low, and it exhibits a higher water reduction rate. However, when the water-cement ratio is large (above 0.4), the water reduction rate and its variation are not that obvious. This may be related to the mechanism of Polycarboxylate Superplasticizer. Its dispersing and retaining effects are based on the steric hindrance effect formed by the molecular structure. When the water-cement ratio is large, there are already enough water molecules in the cement dispersion system to form the space hindrance effect, so the steric hindrance effect of polycarboxylate molecules naturally becomes smaller.
② The dosage has a more significant impact when the amount of binder material is large. Under the same conditions, the water reduction effect is smaller when the total amount of binder material is less than 300 kg/m3 than when it is greater than 400 kg/m3. Moreover, when the water-cement ratio is large and the amount of binder material is small, there will be a superposition effect.
Polycarboxylate Superplasticizer is developed for high-performance concrete, so its performance and price are more suitable for high-performance concrete.
