Development of eco-friendly clay ceramics using rice husk ash as a secondary mineral source of quartz

Abstract

The study focuses on the sustainable reuse of waste ceramic materials, particularly rice husk ash (RHA), as a secondary mineral source in ceramics production. RHA's potential to replace primary raw clays in making ceramic blocks and bricks is explored. RHA is categorized as Class II-A non-inert waste, limiting its use to controlled applications like the ceramic industry due to environmental and health risks. The study assesses the feasibility of incorporating RHA into three different types of clay: yellow and black plastic clays (plastic) and sandy clay. Waste classification according to environmental and health risks follows ABNT NBR 10004/2004 guidelines. Various analytical techniques, including X-ray fluorescence, X-ray diffractometry, differential thermal analysis, and thermogravimetric analysis, were employed to characterize the materials. Laser diffraction measured the particle size distribution of the clays. In addition to the conventional ceramics industry standard formulation (STD), the study prepared five different mixtures with varying RHA and clay contents. These mixtures underwent evaluation for properties such as thermal shrinkage, density, porosity, water absorption, and diametral mechanical strength, with resistance reliability assessed using Weibull distributions. Results indicated that introducing over 15% RHA into clay ceramics led to excessive water absorption, rendering it unsuitable. Consequently, an 8.3% RHA content was chosen to manufacture hollow ceramic blocks for non-load-bearing masonry. This industrial test demonstrated favorable processing conditions compared to the STD, highlighting RHA's potential as an alternative raw material for the ceramic industry, contributing to sustainable development.