Defoamers are generally only used for model gypsum, gypsum for precision casting, self-leveling gypsum mortar, etc., which can reduce the pores on the surface of gypsum products. Common defoamers include n-butanol, polyethylene glycol, and tributyl phosphate.
During the construction, when the dry powder and water are stirred, air bubbles are often generated, which affects the aesthetics of the product. Appropriate amount of dry powder defoamer can effectively eliminate bubbles and pinholes in dry mortar products, and eliminate pores and cavities generated during blade coating and spraying, and improve the impermeability and strength of the product.
The dosage of dry powder defoamers is between 0.2% and 0.5%.
The mortar contains a proper amount of uniformly sealed small bubbles, which will greatly improve the freeze-thaw resistance, wear resistance, durability and resistance to shrinkage of the mortar. However, uneven or unstable bubbles will make the surface of self-leveling mortar rough and will greatly affect its strength and other properties. The selection of a suitable defoamers can accelerate the cracking and elimination of unstable large bubbles, make the bubbles uniform, and improve the performance of the mortar from the surface. This is because the defoamer is also a surfactant, which not only eliminates bubbles in the mortar, but also stabilizes the bubble. The dosage of such defoamers is preferably 0.5%.
After the defoamer is added to the gypsum-based self-leveling mortar system, the fluidity of the self-leveling mortar can be increased, the apparent state of the mortar after hardening can be improved, and the wet density of the mortar can be increased, Therefore, the compressive strength, the folding strength and the like after the self-leveling mortar is hardened are remarkably improved.
Post time: Nov-26-2019