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This research intended to investigate the influence of rice husk ash (RHA), green glass cullet (GGC) and local white clay (LWC) in Thailand on the physical properties of fired clay tiles. Utilization of RHA and GGC were the main objectives. Proportion of RHA varying from 10-60% by weight was conducted. Specimens of mixture formulation were sintered at 950 °C. The results revealed that the formula no. A7 containing 70% GGC and 30% LWC can develop greenish color. In addition, scanning electron microscopy was carried out to characterize microstructure and found the glassy phase in fired specimen. Moreover, nepheline (Na2Al2Si2O8) and wollastonite (CaSiO3) were detected by the X-ray diffraction technique. These phases can promote the strength of fired clay tiles. Meanwhile, the specimen of formula no. B13 comprising 60% GGC, 30% LWC and 10% RHA can develop the mullite phase (3Al2O32SiO2). Effect of utilizing RHA in this formula can develop greyish color of ceramic tiles. Physical properties of formula no. A7 and B13 can achieve 30.15, 24.54 MPa of bending strength and 1.91, 11.72% of water absorption. They all can pass Thai Industrial Standard (TIS 2508-2555). The result of this study can be employed to manufacture environmentally friendly fired clay tiles.

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This paper aimed at studying the influence of additive material boric acid in eco-friendly fired clay tiles. It is used as additive material by mixing with rice husk ash (RHA), brown glass cullet (BGC), local clay (LC), and sediment soil (SS). Effects of boric acid on the physical properties of ceramic bodies were investigated. The texture of specimen by utilizing waste materials was also studied. Mixture formulations consisted of 60% BGC, 10% RHA, 0-30% LC, and 0-30% SS with varying boric acid addition of 0-2%. Specimens were formed by uniaxial pressing with 100 bars, fired at 850 and 900°C, heating rate 100°C/h, and soaked for 1 h. The results showed that adding boric acid up to 2% had increased the flexural strength and decreased the water absorption of these specimens when fired at 850°C. On the contrary, the effects of adding boric acid fired at 900°C had decreased flexural strength and increased water absorption that showed the phenomenon of expanding specimens. However, the optimal formula of these clay tiles both fired at 850 and 900°C have passed the Thai Industrial Standards (TIS 2508-2555); Type BIII. Scanning electron microscope should they that microstructure characterization was in the glassy crystalline phase was found in high flexural strength specimens. In summary, exploiting boric acid can improve the physical properties of specimens with a low firing temperature, and fired clay wall tiles can be developed in this study. They can be identified as an environmentally eco-friendly building product.

The paper presents an experimental study on the production of non-fired ceramic tiles from rice husk ash (RHA) and green glass cullet (GGC) composites as a novel eco-friendly material. Eighteen mixture formulations were constructed as compared to control formula, specimens were uniaxially pressed at 10 MPa and then cured at room temperature for 7 and 28 days. Non-fired tiles (formula A4, B11, and C17) containing 20% GGC were mixed with 0%, 5%, and 10% RHA. The modulus of rupture can be increased by 87.23%, 48.8%, and 19.4%, respectively, at 28 days of curing as compared to control formula. These results were also coherent with microstructure characterization by scanning electron microscopy (SEM). Furthermore, formula A4 and C17 were selected to compare energy costs with wall tiles fired at 950°C. They were the same amount of energy-saving costs by 5.19 USD/m2. From these results, the new eco-friendly products can produce with a combination of RHA and GGC wastes which can enhance the physical properties due to the pozzolanic reaction. Moreover, the proposed non-fired ceramic tiles can conserve energy and reduce manufacturing costs.