Technological and microstructural perspective of the use of ceramic waste in cement-based mortars

•Replacing up 10% of natural sand with ceramic waste resulted in better physical and mechanical properties. The construction sector is constantly growing and, consequently, the increase in the use of building materials. In view of this, the red ceramic industry is responsible for a large amount of waste, through failures in its process and thus generating defective parts. Therefore, this work aims to reuse these wastes generated by the red ceramic industry in mortars, as a partial substitute for natural sand. The ceramic waste was ground in a crusher mill-type crusher for one hour. Mortars were made, in the mix proportion 1:6 (cement: sand) in mass, replacing the sand with ceramic waste in replacing of 10, 20 and 30% and the mixture reference (0%), using the ordinary portland cement. The mortars were subjected to tests of workability, water retention, density, incorporated air content, density in the hardened state, water absorption, flexural strength in bending and compressive strength. Soon after, microstructural characterization techniques were performed in mixtures, such as isothermal calorimetry, mercury intrusion porosimetry and X-ray diffraction. The results show that the mixture with 10% improved the flexural strength in bending and compressive strength, indicating a lower coefficient of capillarity, as they have fewer pores and a greater amorphous halo. The ceramic waste caused an increase in density in the fresh and hardened state and a decrease in the content of incorporated air. In the mixtures with 20% and 30% of ceramic waste, there was a loss in the properties, mainly in the strength. Therefore, the most satisfactory mixtures were with 10% ceramic waste.