Gypsum retarder | A good partner for gypsum mortar
It is an additive that reduces the hydration rate of gypsum and prolongs the setting time. It is mainly used in gypsum building materials such as plastering gypsum, adhesive gypsum, gypsum wall putty, and gypsum products.
There are three main types of commonly used retarders: organic acids and their soluble salts, alkaline phosphates, and protein-based retarders.
Gypsum retarding agent
Characteristics
The purpose of adding a retarding agent to gypsum slurry is to prolong the hydration and hardening time of gypsum, so that the slurry can maintain its plasticity for a longer period of time, thereby regulating the setting time of the slurry.
Gypsum retarding agent
Usage
(1) The addition amount is 0.2%-0.25% of the gypsum content.
(2) As the amount of gypsum retarding agent increases, the setting time is prolonged.
(3) As the temperature increases, the amount of gypsum retarding agent should be increased appropriately.
(4) Due to differences in the type and properties of gypsum, the effect of gypsum retarding agents may vary. Before use, test samples should be tested to determine the amount to be added.
(5) When used for plastering gypsum, gypsum retarding agent can be mixed with 0.5% cement to effectively prolong the setting time.
Gypsum retarding agent
Precautions for use:
(1) Effect on strength: Excessive addition will cause the concrete to remain unhardened 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 significant effect on shrinkage. Excessive use may cause surface cracking and shrinkage cracks due to excessive moisture evaporation.
(3) Effect on freeze-thaw durability: The freeze-thaw durability of mortar mixed with a retarder is similar to that of unmixed mortar.
