EVALUATION OF THE 1:2.5:5 CONCRETE MIX WITH SUPERPLASTICIZER

Concrete is a composite material that consists essentially of a binding medium of which approximately 10-30% is made up of cement in most cases. With concrete mix ratio of 1:2:4 and a water/cement ratio of 0.5, using Grade 42.5 cement under controlled condition, one is likely to get compressive strength of 25MPa at 28 days. But this presents a challenge of high requirement of cement material in the concrete constituent and in turn high production cost. This project was aimed at determining what strength could be obtained by using a mix proportion of 1:2.5:5 and a water/cement ratio of 0.5. Laboratory tests such as sieve analysis and compressive tests on samples of fine aggregate and coarse aggregate were carried out and these were compared with BS882 requirements. Two concrete mix ratios of 1:2:4 and 1:2.5:5 were considered for this research, using the same water/cement ratio of 0.5. From the experiments carried out, it was obvious that with good quality control 1:2.5:5 mix proportion at 0.5 water/cement ratio can give concrete with more than 25MPa at 28days and a cost saving of 8% over the 1:2:4 mix proportion.