Powder defoamer in dry mortar

Defoamers help release bubbles entrained or generated during mortar mixing and construction, improve compressive strength, and improve surface conditions. The powdered defoamers currently used in dry mortar are mainly polyols and polysiloxanes.

 

Defoamers help release bubbles entrained or generated during mortar mixing and construction, improve compressive strength, and improve surface conditions. The powdered defoamers currently used in dry mortar are mainly polyols and polysiloxanes.

Functions of defoamers

Bubbles are unstable systems with a tendency to automatically reduce the specific surface area and even develop into a bubble-free state. In recent decades, people have conducted a lot of research on the mechanism of action of defoamers and put forward some hypotheses. The more generally accepted view is that substances that are insoluble in the defoamed medium are defoamers when the invasion coefficient and expansion coefficient are both positive. But in fact, some substances also have a defoaming effect in a dissolved state; for this reason, some revised theories have been proposed.

Shcarur.L.T and Akers.W. studied the defoaming process of silicone grease in an oil system and proposed that substances with low concentrations and lower surface tension than the foaming liquid have a foaming effect if they can form a homogeneous phase with the foaming liquid; if they are in a supersaturated state and can be evenly dispersed in the foaming liquid, they have a defoaming effect. In the experiment, it was observed that bubbles attached to defoamer droplets would burst quickly because the surface tension of the local liquid film around the droplets was reduced.

Defoamers are surfactants that inhibit or eliminate foam.

Generally, they must meet the following conditions:

 (1) The surface tension must be lower than that of the defoamed medium;

(2) It must have a certain affinity and good dispersibility;

 (3) It must have good chemical stability.

An effective defoamer can not only quickly burst the foam, but also prevent the regeneration of foam for a considerable period of time. At present, there are many types of defoamers, such as silicone, polyether, fatty acid, phosphate, etc., but each defoamer has its own adaptability. Dry mortar is a strong alkaline environment, and a defoamer suitable for alkaline media must be selected.

The defoamer used in dry mortar is a water-soluble powdered additive that can reduce the unwanted bubbles generated during the preparation and construction of hydraulic adhesive construction products. It is suitable for both neutral and alkaline systems. It is compatible with most other additives, such as surfactants and water-soluble compounds such as cellulose derivatives, starch and starch ethers, and polyvinyl acetate.

 

Defoamer performance

Different defoamers have different properties. Example of defoamer performance (FS202).

Defoamer KDO 8802 product introduction:

KDO 8802 is a powder defoamer with modified polyether as the main component. KDO 8802 can be used in cement-based mortar, gypsum-based mortar or other mortar systems with high appearance requirements.

Product features: KDO 8802 has rapid foam breaking ability and long-term foam suppression ability. KDO 8802 can promote the fluidity of mortar in high-flow mortar systems and has good compatibility with other cement-based and gypsum-based additives.

Scope of application: 1. High-flow gypsum mortar; 2. High-flow cement-based mortar 3. Other cement or gypsum-based mortars

KDO 8802 powder defoamer is a non-ionic surfactant suitable for cement dry mortar. It can degas the microbubbles generated in the construction or production of building materials, and make the product have excellent durability and shear stability as well as increased strength.