Combination of rice husk ash, bagasse ash, and calcium carbonate for developing unglazed fired clay tile

Abstract

This research aims at developing unglazed fired clay tiles by utilizing industrial wastes; rice husk ash (RHA), bagasse ash (BGA), calcium carbonate (CC), and fly ash (FA). Brown glass cullet (BGC) has been mixed with these waste materials for reducing firing temperature. In addition, local clay is also used for facilitating specimens' plasticity. Work pieces are molded by uniaxial pressing at 100 bars with dimensions 50 x 100 x 7 mm and fired at 850 and 950 °C. Formulation mixtures of the experiment are divided into 4 groups. Calcium carbonate (CC), residue from sugar mill plant mixing with local materials, LBC and LWC (Local ball clay and local white clay) have been utilized in group 1. After testing the physical properties of fired specimens, a high bending strength of formula in group 1 has been selected. It is further employed as the basic formula of the next three groups by mixing RHA, BGA, and FA, respectively. The results found that the optimal ratios containing 5% RHA, 5-10% BGA, and 5% FA of group 2, 3, and 4 which fired at 950 °C can achieve Thai Industrial Standard (TIS 2508-2555 type BIII) in terms of bending strength and water absorption. Clarifying the color of selected formulas is determined by CIELAB color coordinate. In addition, analyzing the microstructure of selected specimens by scanning electron microscopy (SEM) and X-ray diffraction (XRD) has been conducted. Glassy phase and wollastonite crystal are found in the specimens providing high bending strength.