Influence of RHA on strength and durability properties of alkali activated concrete

Abstract

The ever-increasing demand from the building sectors drives the production of cement, which in turn leads to a rise in carbon dioxide emissions and contributes to the acceleration of global warming. To reduce the amount of cement that is used, an alternative binder made from agricultural and industrial waste products like rice husk ash (RHA) and ground granulated blast furnace slag (GGBS) among others, has been selected. Alkali activated concrete (AAC) is prepared by mixing binder, coarse aggregate, fine aggregate with an alkali activator. The impact of RHA substitution on workability, compressive strength and durability of GGBS based AAC is evaluated in this study. The slump value reduces as increase in the percent of RHA in AAC mix. The increase in curing time enhances the compressive strength of GGBS-RHA based AAC. The durability parameter as water absorption testing was performed after 28 and 90 days of curing, while depth of carbonation and H2SO4 attack were evaluated after 28 days of curing. As per the test results, adding more RHA up to 10% enhances the strength and durability of GGBS based AAC. Although the strength was reduced by utilizing more than 10% RHA in the AAC mix, but still the compressive strength more than 45 MPa is attainable. The water absorption and depth of carbonation both increases by using higher substitution of RHA in AAC mix. According to the H2SO4 attack test results, substituting RHA at a lower replacement level results in improved durability properties while raising the acid curing gradually reduces the strength of AAC.