Development of Sustainable Hybrid Cementitious Concrete Using Rice Husk Ash, Quartz Powder, and Bentonite Clay.

This study investigates the performance of hybrid cementitious concrete (HCC) made with rice husk ash (RHA), quartz powder (QP), and bentonite clay (BC). Four concrete mixes, including a control and three HCC mixes containing different proportions of RHA, QP, and BC, were prepared and tested. The properties of the developed concrete were evaluated through slump, density, compressive strength, failure pattern, split tensile strength, water absorption, X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX). The results indicated that the RHA, QP, and BC reduced workability, with a 13 to 19% reduction compared with the control mixture. Furthermore, the ternary blend HCC-R20-Q20-B20 achieved the highest 28-day compressive strength of 44.6 MPa (22.1% increase compared with the control). Similarly, the highest split tensile strength of 4.56 MPa was obtained by HCC-R30-Q20. Also, the HCC-R30-Q20 exhibited the lowest water absorption value, with a 23.1% reduction. Although the RHA, QP, and BC resulted in a slight decrease in density, all mixes remained within the normal-weight concrete range (2380 to 2408 kg/m3). The SEM revealed a denser microstructure, refined pore structure, and improved ITZ. Furthermore, EDX analysis indicated variations in the elemental composition, with variations observed in the Ca/Si and Al/Si ratios.