Effect of Defoaming Agents on the Self-Leveling Performance of Gypsum
Release Time:
2020-05-22
Source:
Effect of Defoaming Agents on the Self-Leveling Performance of Gypsum
Defoamer is a product specifically designed for powder coatings, cement-based dry-mix mortars, and gypsum-based dry-mix mortars. It is formulated through the reaction of multiple organic polymer compounds with surfactants, combined with a specialized carrier, and manufactured using advanced production processes and equipment. This defoamer features easy dispersibility, rapid defoaming, high stability, broad adaptability, excellent compatibility, and low dosage requirements. It effectively eliminates microbubbles generated during the construction or manufacturing of building materials, resulting in a smooth, even finished surface, a dense internal structure, and enhanced product performance. Additionally, it imparts outstanding long-term durability and shear stability while increasing strength.
During construction, the mixing of dry powder materials with water often generates air bubbles, which can detract from the aesthetic appearance of the product. The appropriate addition of a dry-powder defoamer in dry-mix mortar formulations effectively eliminates air bubbles and pinholes, as well as voids and cavities that arise during troweling or spraying, while also enhancing the product’s impermeability and increasing its strength.
Advantages of dry powder defoamers:
1. Excellent defoaming performance, effectively suppressing bubble formation during mixing.
2. Excellent diffusivity and penetrability, rapid defoaming, resulting in a smooth and even finished surface, a dense internal structure, and a significant enhancement of product performance.
3. Excellent compatibility and strong adaptability with other admixtures.
4. Chemically stable, it does not alter the fundamental properties of the foaming system and imparts excellent long-term stability and shear stability to the product, while also enhancing the strength of the finished product.
5. Exhibits significant defoaming (or foam-suppressing) performance, requires a low dosage, and reduces production costs.
6. High safety; not classified as a hazardous material.
The presence of an appropriate number of small, uniformly distributed, closed, and stable air bubbles in mortar can significantly enhance its freeze–thaw resistance, wear resistance, durability, and resistance to drying shrinkage. However, non-uniform or unstable air bubbles not only result in a rough and unsightly surface on self-leveling mortar but also severely compromise its strength and other performance characteristics. The selection of a suitable defoaming agent can accelerate the rupture and removal of unstable large air bubbles, thereby promoting uniform bubble distribution and improving the overall performance of the mortar. This is because defoaming agents are also surfactants; in mortar, they not only eliminate air bubbles but also act as foam-stabilizing agents to maintain bubble stability.
The addition of a defoamer to gypsum-based self-leveling mortar systems can increase the flowability of the mortar, improve its surface appearance after hardening, and enhance its wet density, thereby significantly improving its compressive and flexural strengths upon hardening. Currently, powdered defoamers used in mortar products are predominantly imported composite formulations; moreover, different brands of defoamers exhibit varying degrees of compatibility with the same mortar formulation, leading to differences in the resulting mortar performance. Therefore, selecting an appropriate defoamer for mortar applications is crucial for substantially enhancing the overall performance of the mortar.
