A Durable Concrete Mix Design Approach using Combined Aggregate Gradation Bands and Rice Husk Ash Based Blended Cement

Abstract

This study proposes a new concrete mix design procedure that incorporates durability as an integrated design parameter. Rice husk ash (RHA) was used as supplementary cementitious materials (SCM) with pozzolanic characteristics to enhance durability. Moreover, utilization of RHA as SCM also solves the problem of its disposal in rice producing countries. Two combined aggregate gradation bands were used to develop the proposed mix design since those were proved to perform well in the mix and the resulting concrete exhibited insignificant variation in fresh and hardened properties. It was found that RHA incorporation within cement significantly reduced the permeability of resulting concrete. Consequently, concrete mixes with intended durability could be designed through addition of RHA. A number of contour plots, representing correlations between different design parameters, were generated to be used in different steps of the proposed mix design. Finally, concrete mix prepared following the new mix design approach showed satisfactory validation with respect to targeted design parameters. Thereby, the uniqueness of the proposed mix design of this study lies in the fact that it uses improved aggregate band gradations, utilizes RHA as SCM, takes durability as a mix design parameter and provides sustainable solution to concrete construction in rice producing developing countries like Bangladesh.