Retarders

Set retarding additives are water soluble organic powders that delay of cement, when in solution, the retarder molecule is adsorbed onto the cement particle. The chemical bond that forms between the retarder and cement surface blocks and slows down the rate of initial hydration.

This mechanism slows down the development of hydration products, delaying the stiffening and hardening of cement. However, once the molecules are totally adsorbed then hydration commences and initial and final set occur without affecting early age strengths.

Retarder do not have an effect on other properties such as workability and water demand, however overdosing can lead to excessively long set times and Oscrete Performance Additives always recommend that retarders should be trialed in a formulation in order to determine optimum dosage rates.

Oscrete Performance additives supplies a range of manufactured retarder to suit all cement types.The type of cement used in a formulation will dictate as to which retarder is suitable for use.

For Portland cement based dry bagged mortars: Osperse RT01 and Osperse RT02 are recommended.

Osperse RT01

Click here to download Osperse RT01 Datasheet

Osperse RT02

Click here to download Osperse RT02 Datasheet

For High Alumina cements and High Alumina/Portland cement blends: Osperse D73 & Tartaric Acid are recommended.

Osperse D73

Click here to download Osperse D73 Datasheet

For Gypsum based dry bagged mortars: Osperse RT01 & Osperse RT02 are recommended.

Osperse RT01

Click here to download Osperse RT01 Datasheet

Osperse RT02

Click here to download Osperse RT02 Datasheet

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