Effects of sugar as admixture on setting times and compressive strength of concrete

Abstract

This study aims to examine the influence of sugar as a retarding admixture on setting times and compressive strength of concretes produced with 2-different brands of Dangote and Sokoto cements produced in Nigeria. The samples of cement paste and concrete cubes were prepared with the percentage addition levels of sugar of 0%, 0.06% and 0.1% by mass of cement. The setting times test was conducted under room temperature and simulated 43^oC temperature using vicat apparatus. A mix ratio of 1:2:4 with water-cement ratio of 0.5 was adopted in the experiment and the compressive strength of hardened concrete specimens was investigated at 3, 7, and 28 days. The outcomes of the setting time test at a 43^oC temperature revealed that the control paste (0% addition of sugar) exhibited significant decrease in both initial and final setting times when compared with the results at a room temperature. However, with addition of sugar in both cement brands significant improvements in the setting times were recorded especially at 0.06% addition level. Furthermore, the results of compression test at 28 days revealed that control had 30.1 N/mm² while Dangote and Sokoto cements had maximum compressive strength at 0.06% addition of sugar of 33.4 N/mm² and 32.1 N/mm², respectively which represents 9.9% and 6.2% increase over the control specimen. The study therefore concluded that when an optimum percentage of 0.06% of sugar is added in the cement brands, it has the potential to increase the setting time and strength of concrete especially when concreting in a hot weather environment.