Protein gypsum retarder is an additive that reduces the hydration rate of gypsum and prolongs the setting time. It is mainly used for gypsum building materials such as plastering gypsum, bonding gypsum, gypsum putty, and gypsum products.

There are three main types of commonly used retarders: organic acids and their soluble salts, alkaline phosphates, and protein retarders. Here, the editor mainly talks about the characteristics of protein retarders.

Protein gypsum retarder

Characteristics:

The purpose of adding retarders to gypsum slurry is to prolong the hydration and hardening time of gypsum, so that the slurry can maintain plasticity for a longer time, thereby adjusting the setting time of the slurry.

Protein gypsum retarder

Usage:

(1) The addition amount is 0.2%-0.25% of the gypsum content.

(2) As the amount of gypsum retarder increases, the setting time is prolonged.

(3) As the temperature increases, the amount of gypsum retarder needs to be appropriately increased.

(4) Due to the different types and properties of gypsum, the effect of gypsum retarder may be different. Samples should be tested before use to determine the dosage.

(5) When used for plastering gypsum, gypsum retarder and 0.5% cement can effectively extend the retarding time.

Protein gypsum retarder

Precautions for use:

(1) Effect on strength: Excessive addition will cause the concrete to not solidify for 24 hours or even 72 hours, thereby affecting the early strength of the mortar and delaying the construction progress.

(2) Effect on shrinkage: When used in appropriate amounts, it has no obvious effect on its shrinkage. When used in excessive amounts, it will cause the mortar surface to dry out and shrink and shrink cracks due to excessive water evaporation.

(3) Effect on frost resistance: The frost resistance of mortar with retarder is similar to that of mortar without retarder.