Effect of using sugar and gypsum as a retarder on concrete properties in Omani weather

This study deals with the retardation of cement setting time and workability in hot weather such as in Sultanate of Oman. Combination of sugar and gypsum was used as retarders. The aim of this study was to investigate the effect of retarders on consistency, setting time of ordinary Portland cement (OPC) paste and compressive strength of concrete cubes after 7 days of curing. OPC paste with a water cement ratio 0.4 to 0.5 was prepared by mixing 500 grams of ordinary Portland cement, a fixed amount of sugar of 0.02% by weight of cement with a combination of different gypsum of 1, 2, 3, 4, and 5% by weight cement and water. Sugar has a strong retarding effect, and this effect, controlled by Gypsum, can shorten the long setting time caused by sugar. The setting time of cement paste was reduced from 5.5 hours to 3 hours with an increase in Gypsum at a fixed amount of sugar. At a constant sugar content, increasing the gypsum content reduced the compressive strength from 31.5 MPa to 30.92 MPa.