Preparation of innovative eco-efficient composite bricks based on zeolite-poor rock and Hen's eggshell

Abstract The growing demand for building materials, as well as environmental concerns associated with energy consumption and natural resource depletion, prompted an urgent search for sustainable alternatives for clay, including natural and waste materials, to conserve the fertile lands, save energy, and ensure the waste's safe disposal. This research investigates the potential utilization of zeolite-poor rock and eggshells to produce energy-saving ceramic bricks. The study examined the effect of composition, microstructure and sintering temperature on the physicomechanical properties of the composite ceramic bricks. Five groups of the samples were prepared with different zeolite-poor rock and eggshell compositions using uniaxial dry pressing. Eggshell powder (ESP) was used to partially substitute zeolite-poor rock. The substitution percentages were 0%, 5%, 10%, 15% and 20% by wt of zeolite-poor rock. The compacted specimens were burned at three different temperatures (950, 1050 and 1150 °C) at a heating rate of 60 °C/h. Mineralogical composition, phase identification, microstructural feature, chemical constituents, thermal analysis and particle size distribution were investigated using X-ray diffraction, scanning electron microscope, energy dispersive spectroscopy, thermal gravimetric analysis, differential thermal analysis and laser particle distribution analyzer. Moreover, the technical characteristics of the sintered composite ceramic bricks were evaluated. The findings revealed that the inclusion of 20% eggshell to the samples sintered at 950 °C generated composite bricks with the lowest density (1.4 g/cm3) and thermal conductivity of 0.27 W/mk, while the compressive strength was 10.5 MPa, demonstrating the manufacturing of energy-efficient zeolite-based ceramic bricks. All samples showed compressive strengths greater than the minimum specified by the standards for load-bearing ceramic bricks. The use of zeolite-poor rock and eggshell waste to produce composite ceramic bricks is a promising and cost-effective alternative for sustainable development while saving energy, reducing pollution and deterioration of the environment.