Production of clay ceramics using agricultural wastes: Study of properties, energy savings and environmental indicators

Abstract In this study, agro-wastes were used as additive raw materials for the production of fired clay ceramics. The objectives of this study are to evaluate the impact of adding agro-wastes into clay body on the thermal and mechanical properties of ceramic materials, to determine the net energy consumption and to determine gas emissions during firing process. The clay and agro-wastes were characterized by chemical elemental analysis, thermogravimetric and differential thermal analysis (TGA-DTA). The fired clay ceramics were produced with clay and optimal proportions of wheat straw (WS) and olive core flour (OCF). The thermal and mechanical properties were evaluated by measuring thermal conductivity with hot-disk method and bending test respectively. The results showed that for clay incorporated OCF (4, 8 wt%) and WS (3, 7 wt%), thermal conductivity was decreased by 16 to 30%. However, the mechanical strength of the same samples has slightly decreased respectively. TGA-DTA provided an approach to estimate the heat required or released for both clay and agro-wastes thermal decomposition. The addition of agro-wastes into the clay body showed that energy consumption of fired clay ceramics production decreased to above 36% for clay incorporated 4 wt% OCF (C-4wt%OCF). The energy saving during the firing process was a tangible outcome. In order to determine the impact of the agro-wastes addition, the environmental indicators were discussed for the clay incorporated WS and OCF respectively. Total gas yield released were measured by Micro-GC after the combustion of clay incorporated OCF and WS in fixed bed reactor respectively. The analysis of gas emissions are related to the combustion of organic and inorganic compounds of agro-wastes and clay body, respectively. The CO 2 emissions coming from the combustion of agro-wastes reached up to 4.38% for C-8wt%OCF. However, the CO 2 emissions associated with decarbonatation of clay body decreased. Adding agro-wastes into the clay body results to improving thermal properties without negative impact on the mechanical properties of ceramic materials, also to a significant energy saving and decreasing of the inorganic CO 2 emissions related to the decarbonatation of clay body. The relevance of this work, pointed out in the data presented in regards to the state-of-the art is that the paper is focused on fired clay ceramic properties, on energy savings and on the evaluation of environmental indicators in the laboratory scale.