Effect of defoamer on mortar performance

During the mixing process of dry-mixed mortar with water, the introduced air is wrapped by the wet mortar to form bubbles. At the same time, admixtures such as water reducers, redispersible polymer?powders and cellulose ethers have hydrophilic groups, which can reduce the surface tension of the liquid, cause bubble aggregation, and increase the stability of the bubbles. The microbubble gas content of 3% to 6% is the best in mortar products (such as self-leveling mortar, waterproof mortar, etc.). Uniform and stable small bubbles help improve the workability of mortar, enhance the frost resistance and other durability of mortar, etc. The increase of large bubbles will increase the porosity of mortar and reduce the mechanical properties of mortar. Especially for mortar products with waterproof requirements, it is inevitable to suppress and defoam the mortar.

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1. Effect of defoamer on wet density of mortar

Defoamer can inhibit the formation of bubbles in mortar and destroy the bubbles that have been formed. Therefore, adding defoamer to mortar products can reduce the gas content of mortar and increase the wet density of mortar. There are some differences in the effects of different types of defoamers, but within a certain range, the wet density of mortar increases with the increase of defoamer dosage; when the defoamer dosage reaches a certain value, the wet density of mortar tends to be stable.

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2. Effect of defoamer on mortar fluidity

Defoamer can improve the initial fluidity of mortar, and different types of defoamers have different effects on improving fluidity. Effective defoamer can not only quickly burst bubbles, but also prevent bubbles from regenerating for a considerable period of time.

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3. Effect of defoamer on mechanical properties of mortar

Defoamer improves?the compressive and flexural strength of mortar by eliminating harmful bubbles in mortar, reducing mortar porosity and improving the pore structure of cement, but they will no longer increase after reaching a certain value.

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Defoamers are used to eliminate harmful bubbles inside cement-based materials and have a wide range of application value in concrete and mortar. In dry-mixed mortar, defoamers are mainly used in self-leveling mortar to eliminate bubbles introduced by admixtures such as dispersed latex powder and water reducer during the mixing process, so as to make the hardened floor material smooth and flat, reduce the porosity on the surface of the material, and improve durability.