Strength and Rheological Properties of High Strength Concrete Incorporating Rice Husk Ash and Metakaolin

Abstract

Concrete has one of the largest ecological footprints as cement production generates 7% of the global CO2 emissions. This led the concrete technologists towards the use of supplementary cementing materials. As the advent of modern structures have raised the strength and service life requirements for concrete, it has become a great concern to find suitably engineered supplementary cementing materials that enhance both and are economical. Thereby, this study presents an experimental investigation on blended cement mixtures constituting two series of 6 mixtures each. The first series prepared with partial replacements of 5% & 10% fine aggregate by RHA in combination with 5, 10 and 15% Metakaolin as a replacement for cement and a persistent water/binder ratio of 0.3 and its effect on strength and rheology of High Strength concrete (M90) up to 28 days after casting was studied. Whereas, the second series used both RHA & Metakaolin as combined replacement for cement content with same replacement percentages by weight. The results exhibited increased compressive strength for up to 15% Metakaolin + 10% RHA. Maximum 28-day strength was 113.6 N/mm2 with an increment of 15.40% over control mix. The optimum cement blend revealed by the study is 10%RHA+15%Metakaolin in order to produce concrete of high strength and durability.