Tailor-made blended cement for sustainable concrete in Ghana

Abstract

Concrete is the most widely used construction material in the world compared to other known construction materials including steel, glass, aluminium and timber. The reason for its wide usage is because of its low embodied energy, an indicator of carbon emissions into the environment. However, since the volume of concrete used globally is very huge, the environmental impact is great and hence any little improvement on concrete ingredients will have real impact. A possible improvement of concrete is a good focus on Portland cement since embodied carbon dioxide in concrete is a function of cement content in the mix. In this work two sets of mortars were formulated; one with clay pozzolans and water reducers and the other was the pozzolans containing no water reducers. The performance of the two sets of mortars were evaluated based on their strength properties which were performed in accordance with the ASTM C109 standards. In the work, Portland cement was replaced by the clay pozzolan between 10% and 40% by weight. The clay pozzolan used was from waste crushed bricks obtained. The results of the blended cement mortars were compared with the unblended cement mortars. The results of the study indicated that for the mortars containing pozzolan and the water reducers, the optimum cement replacement was 30 wt.% of the pozzolan. For the mortars containing only the pozzolans, the strength values recorded a progressive reduction with the increasing content of the pozzolan in the cement matrix. The study recommended that 30 wt.% replacement of cement and the addition of water reducers could be used to formulate 42.5 grade cement whereas between 20-30 wt.% of only pozzolan content could be fit for a 32.5 grade of cement. � 2019 International Committee of the SCMT conferences. All rights reserved.