Effects of nano sized sesame stalk and rice straw ashes on high-strength concrete properties

Abstract

Nano sesame stalk ash (NSSA) and rice straw ash (RSA) are by-products of bioenergy production. The aim of this paper was to investigate the effects of using NSSA with RSA on high-strength concrete (HSC) properties. The properties of NSSA and RSA were evaluated using scanning electron microscopy with energy dispersive X-ray spectroscopy, thermogravimetric analysis with differential thermal analysis and X-ray diffraction. Ordinary Portland cement ratios were replaced by different ratios of NSSA (0%, 2.5%, 5%, 7.5% and 10%) with RSA (10%, 20% and 30%) to prepare 16 concrete mixtures. The properties of HSC-containing NSSA and RSA were evaluated by slump test immediately after casting, compressive strength at 7, 14, and 28 days, furthermore indirect tensile strength, flexural strength, and modulus of elasticity were tested at 28-days. Microstructure tests showed that ash treatment improved HSC properties by removing carbon and unburned organic matter. The increase in ash replacement rate led to a decrease in workability. The mixtures containing (20% RSA and 2.5% NSSA) and (20% RSA and 5% NSSA) achieved the highest compressive strengths of 88.9 and 90.7 MPa, respectively. Furthermore the mixtures containing (20% RSA and 2.5% NSSA) achieved the highest splitting tensile strength, flexural strength, and elastic modulus values of 7.3, 10.7, and 38600 MPa, respectively.