In modern concrete and mortar systems, polycarboxylate superplasticizers (PCE) are widely used due to their excellent water-reducing and dispersing performance. However, during mixing, PCE may introduce air into the system, leading to increased bubbles that can negatively affect the density and strength of the material. Therefore, the proper use of defoamers becomes essential for improving system stability.

Polycarboxylate superplasticizers act as surface-active agents. While dispersing cement particles, they reduce surface tension, making it easier for air to enter the system and form stable bubbles. Excessive bubbles may lead to several issues:

Adding a suitable defoamer can effectively break these bubbles and reduce air content, improving overall performance.

In practical production and laboratory testing, the dosage of defoamers should be adjusted based on the specific formulation. The typical reference range is:

generally 0.1% – 0.5% of the solid content of PCE

recommended starting point around 0.2%

typically 0.1% – 0.3%

It should be noted that different types of defoamers (silicone-based, mineral oil-based, or polyether-based) may show different effects. The final dosage should be determined through testing.

For better compatibility and system stability, the following procedure is recommended:

Dilute the defoamer with a small amount of water to improve dispersion.

Slowly add the diluted defoamer into the polycarboxylate superplasticizer solution while stirring.

Stir for about 10–20 minutes to ensure uniform distribution.

Before large-scale production, perform tests to evaluate flowability, air content, and workability.

In practical applications, compatibility depends on raw materials, cement type, and environmental conditions. Laboratory testing is strongly recommended when adjusting formulations to ensure system stability and reliable performance.

A well-balanced combination of polycarboxylate superplasticizer and defoamer can effectively reduce bubbles and improve both workability and final construction quality.