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ABSTRACT
Hot weather characterized by high ambient temperature and low relative humidity causes rapid cement paste and difficulties during concrete. Admixtures that retard rapid cement paste settings are necessary to prevent fresh concrete from the adverse effects of hot weather. However, in Nigeria the retarding admixtures are imported and also expensive. Jaggery as locally sourced admixture is another substitute that has been established to be a retarder, but its effects vary with cement's chemical composition. Therefore, this study assessed the role of Jaggery as a retarder on the properties of concretes made with Dangote, Ashaka, Bua, Sokoto and Elephant brands of Portland cement produced in Nigeria. It also looks at the concept of Housing delivery in Nigeria. Cement paste was prepared using 0.06%, 0.1% and 0% as control. Setting time tests were performed at two different temperatures; at normal laboratory temperature of 27oC and simulated hot ambient temperature of 43oC (similar to Sokoto, Birnin Kebbi, and Maiduguri, etc.). The results showed that the initial setting times of the control pastes made with Ashaka, Bua, Dangote, Elephant and Sokoto cements at 43oC was reduced by 51.85%, 38%, 45.94%, 24.73% and 40% respectively when compared with the control pastes at normal laboratory temperature of 27oC. The reduction effects were eliminated by the addition of 0.1% and 0.06% of Jaggery in all the cement brands at 43oC. Thus, significant increase in initial setting times was recorded. Similar trends were observed for the final setting time in all the brands of cement. The results revealed that the 0.1% addition of sugar proved to be optimum dosage for the cement pastes made with Ashaka, Dangote, Elephant and Sokoto cements. On the other hand, 0.1% as the optimum dosage. The research concluded that the use of Jaggery as a retarding admixture in cement paste made with the brands of cement enhanced the setting properties of concretes when an optimum dosage is used. It is recommended that, Jaggery can be used as retarder when concreting in hot dry weather regions in Nigeria.
Keywords: Cement brands, Hot weather, Jaggery, Setting time, Housing, Delivery
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