Effect of Casting Temperatures and Curing Methods on Concrete Properties

Abstract

This study concentrates on the effects of curing methods and casting temperatures on concrete properties in cases of fresh and solid states. The targeted strength of the concrete mix is 25 N/mm2. An experimental work was performed at the laboratory of the Faculty of Engineering, University of Khartoum. Initially the tests on the basic materials (cement, fine aggregate, coarse aggregate) used. The program was testing the strength of concrete for a number of 80 samples of three cubes and test for absorption of water for 16 samples. These samples were casted at temperatures of 15, 25, 35 and 50 c0 and cured with four different methods. Methods of curing used are immersing the samples in water, cured through the winding sample with Hessian and sprinkled water, winding samples with plastic sheets to prevent evaporation of water or loss of water from the sample and paint samples with doofagard. In addition some samples were uncured. The samples were broken in three days, seven days, 28 days and 56 days. In the water absorption tests the samples were casted at different temperatures and different methods of curing except a coating sample with doofagard because the sample cannot absorption water. Also the workability tests for the samples casted at temperatures 15, 25, 35 and 50 c0 were performed. The find out of these experimental works showed that: (1) the compressive strength of cement concrete specimens increased with the period of curing (2) curing of concrete by immersion in water results in a high compressive strength than the other methods of curing (3) The concrete will gain low compressive strength if it is not cured at all after casting (4) The best degree of casting temperatures is 15 and 25 c0 that resulted in a good workability and high compressive strength; on the other hand casting concrete at high temperature reduce workability of fresh concrete.