Effect of slightly cadmium-enriched kenaf straw on the mechanical and thermal properties of cement mortar

Abstract

The purpose of this paper is to discuss the application of kenaf straw as a building material for phytoremediation of heavy metal-contaminated soil. The kenaf straw core (KSC) content, kenaf fibre content and KSC particle size were used as factors to study the effects of a slightly cadmium-enriched kenaf straw on the mechanical and thermal properties of cement mortar. XRD, thermogravimetry and SEM were also carried out to study the microstructure of the cement mortar. The safety and reliability of the slightly cadmium-enriched kenaf straw in the cement mortar was evaluated by a heavy metal leaching test. The results show that the compressive and flexural strengths of the cement mortar decreased with increasing KSC content, but the 28-day strength of the cement mortar with a maximum KSC content of 8% can still meet engineering requirements. In addition, the cement mortar demonstrated good thermal insulation performance, the thermal conductivity and dry density of the mortar were significantly reduced, and the bond strength and crack resistance of cement mortar were also improved. The cadmium enriched in kenaf straw did not affect the strength of cement mortar, and the leaching concentration of the heavy metal was far below the prescribed safety limit.