Effect of gypsum type on properties of cementitious materials containing high range water reducing admixture

• Effect of gypsum type on properties of cementitious materials was investigated.
• Two different types of cement, which prepared from the same clinker, were used.
• However, cements were contained calcium sulfate hemihydrate or dihydrate as retarder.
• Fresh properties of mixtures were negatively affected when cement-containing hemihydrate was used.
• However, hemihydrate utilization had a positive influence on the early compressive strength.

In this study, the effect of cement gypsum type on properties of the properties of cement paste, mortar and concrete mixtures containing high range water reducing admixture (HRWR) was investigated. Two different types of cement prepared from the same clinker but containing either calcium sulfate hemihydrate or dihydrate as retarder were used. The fresh and hardened (compressive strength and drying-shrinkage) properties as well as static and dynamic rheological behavior of the mixtures were investigated. Compared to the mixtures containing dihydtate, the fresh and rheological properties of mixtures were negatively affected when cement-containing hemihydrate was used. However, hemihydrate utilization had a positive influence on the early compressive strength. The adverse effects on fresh properties were more significant in paste mixtures. These negative effects decreased in the mortar and concrete mixtures. The presence of hemihydrate in cement was found to increase the drying-shrinkage.