EXPERIMENTAL INVESTIGATION ON THE EFFECT OF COMPRESSIVE STRENGTH OF CONCRETE DUE TO DELAY IN POURING CONCRETE

The compressive strength of concrete is the important property that should be known in the construction of reinforced concrete structures. The cube test is the method to determine the compressive strength of the concrete. The 28th -day test result shows the characteristic strength of the concrete to be prepared and used in the construction work. It is obvious to have delays in casting after the completion of preparing the concrete for several reasons beyond the existing ability on the site. The present investigation was to find the effect on the compressive strength of M25 grade concrete due to time delay in casting and re-mixing. The concrete mixtures were left after completion of the mixing process for a different period of time for 30 minutes, 1:30 hour, and 2 hours then returned the mixing process and placed in its moulds. Results were compared to those samples cast in the mould with time delay of 30 minutes and analyzed. Some 45 standard cubes were cast to measure the concrete compressive strengths at 3, 7, 14, 21, and 28 days. The results thus obtained showed that the compressive strength of re-mixing concrete with 1.30 hr and 2 hr time delay was lower than concrete prepared with a time delay of 30 minutes. The reduction in 28 days compressive strength was up to 28.28% when compared with the concrete prepared with 30 minutes delay in time.