Lowering carbon foot print of Portland cement by class F fly ash substitution in mortar mixture in terms of workability and strength properties

Abstract

In the experimental work, recycling by inclusion of class F fly ash in mortar was investigated in terms of workability and strength of mortar to fabricate an environment friendly construction material. For this aim, class F fly ash were used as cement replacement at 10%, 30%, 50% and 70% ratios in mortar. Water-binder ratios were 0.40, 0.45 and 0.50. A total of 15 different mortar mixtures including control Portland cement and fly ash mortar were produced. Workability of fresh mortar was measured using mini flow testing. Flexural and compressive strength of hardened standard sized samples were measured after completion of their specified curing time at 1d, 3d, 7d 28d, 3m and 6m. Experimental results showed that inclusion of fly ash in mortar improved workability with respect to control Portland cement mortar. Recycling low amount of fly ash in mortar did not show detrimental but beneficial influence on strength properties of mortar. However, employing high amount of fly ash in mortar reduced flexural and compressive strength at early ages, however, the reduction in flexural and compressive strengths were remedied due to pozzolanic reaction of fly ash at longer curing time compared to control Portland cement mortar. It was concluded that current fly ash was a suitable pozzolanic material to be recycled by replacement with Portland cement in mortar to manufacture clean construction material in terms of workability and strength concern.