7. Air-entraining agent
Air-entraining agent, also known as foaming agent. It is mainly used in gypsum dry-mixed building materials such as gypsum insulation compound and plaster plaster. Air-entraining agents (foaming agents) help improve workability, crack resistance, frost resistance, and reduce bleeding and segregation. The dosage is generally 0.01% to 0.02%.
Defoamers commonly uses in gypsum self-leveling mortar and gypsum caulking putty. It can improve the density, strength, water resistance and cohesiveness of slurry. The dosage is generally 0.02% to 0.04%.
9. Water reducer
Water reducing agent can improve the fluidity of gypsum slurry and the strength of gypsum hardened body. Usually used for gypsum self-leveling mortar and plaster plaster.
At present, domestically produced water reducers are ranked according to their fluidity and strength effects: polycarboxylate retarded water reducers, melamine high-efficiency water reducers, tea-based high-efficiency retarded water reducers, and lignosulfonate water reducers.
When using water reducing agents in gypsum dry-mix building materials, in addition to considering water consumption and strength, attention should also be paid to the setting time and fluidity loss of gypsum building materials over time.
10. Waterproofing agent
The biggest defect of gypsum products is poor water resistance. Areas with high air humidity have higher requirements for water resistance of gypsum dry-mixed mortar. Generally, the water resistance of hardened gypsum is improved by adding hydraulic admixtures.
In the case of wet or saturated water, adding hydraulic admixtures can make the softening coefficient of the gypsum hardened body reach above 0.7. So as to meet the product strength requirements. Chemical admixtures can also be used to reduce the solubility of gypsum (that is, increase the softening coefficient), reduce the adsorption of gypsum to water (that is, reduce the water absorption rate) and reduce the erosion of gypsum hardened body (that is, water isolation).
Gypsum waterproofing agents include ammonium borate, sodium methyl siliconate, silicone resin, emulsified paraffin wax, and silicone emulsion waterproofing agent with better effect.
11. Active stimulator
Activation of natural and chemical anhydrites imparts adhesiveness and strength for the production of gypsum dry-mix building materials.
Acid activator can accelerate the early hydration rate of anhydrous gypsum, shorten the setting time, and improve the early strength of gypsum hardened body. Alkaline activators have little effect on the early hydration rate of anhydrous gypsum but can significantly improve the later strength of gypsum hardened body. Moreover, part of the hydraulic gelling material can be generated in the hardened gypsum body, effectively improving the water resistance of the hardened gypsum body.
The use effect of the acid-base compound activator is better than that of a single acidic or basic activator.
Acid stimulants include potassium alum, sodium sulfate, potassium sulfate, etc. Alkaline activators include quicklime, cement, cement clinker, calcined dolomite, etc.
12. Thixotropic lubricant
Thixotropic lubricants uses in self-leveling plasters or plasters. It can reduce the flow resistance of gypsum mortar, prolong the open time, and prevent the delamination and settlement of slurry. So that the slurry has good lubricity and workability. While making the structure of the hardened body uniform, it increases its surface strength.