Strength Investigations of Processed High Volume Fly-ash based Cement Concrete

摘要

The demand for fly-ash in construction industry is increasing due to high cost savings and improved durability properties. However, high volume fly-ash addition in cement concrete has to be carefully designed so as not to decelerate the rate of setting. The present study deals with the high volume fly-ash addition for cement replacement upto 50% (by weight of cement) with water to binder ratio of 0.3, 0.4, 0.5 and fine aggregate to coarse aggregate (F/C) ratios of 0.5 and 0.6. The effect of using finer variety of fly ash can enhance the performance of hardened concrete. The experimental test results indicated that with higher replacement level upto 50% processed fly-ash showed a slight reduction in the compressive strength of 25.59 MPa and 44.67 MPa at 7 and 28 days compared to control concrete. The inclusion of processed high volume fly-ash in concrete as a substitute cementing material showed enhanced mechanical properties in concrete and contributed towards development of high performance concrete. However, the effect of less w/b ratio with addition of polycarboxylate ether based superplasticizer contributed towards strength improvement and improved quality of high volume fly-ash concrete. The quality of concrete was also tested for ultrasonic pulse velocity test and it was showing consistent values in the range of 3300 to 4630 m/sec which is revealing a good quality of concrete.