High-strength concrete containing RHA and nano-CaCO3

Abstract

The properties of high-strength concrete (HSC) containing rice-husk ash (RHA) and nanocalcium carbonate (nano-CaCO3) is evaluated. For this purpose, various HSC samples containing 0-20% RHA and 0-1.5% nano-CaCO3 were prepared and investigated for the slump, compressive strength, absorption, electrical resistivity, chloride penetration depth and sulphuric acid (H2SO4) attack resistance. Results indicated that by a ternary combination of Portland cement (PC) + 10% RHA + 0.5% nano-CaCO3, it is able to produce HSC with 28 days compressive strength of 101.7 MPa, which was 15% higher than that of estimated for plain HSC. Additionally, substituting optimum level of nano-CaCO3 in HSC containing RHA could improve the electrical resistivity and reduce the water absorption and chloride ion penetration depth compared with binary use of PC + RHA. A lower mass loss has been determined for the ternary combination of PC + RHA + nano-CaCO3 at all immersion times in 5% H2SO4 solution as compared with plain HSC. Moreover, considering HSC samples exposed to H2SO4 solution at the age of 84 days, it can be seen that the presence of nano-CaCO3 in HSC containing RHA did not necessarily contribute to a significant reduction in the crushing load loss percentage compared with the binary use of PC + RHA.