Ceramic light-weight aggregates production from petrochemical wastes and carbonates (NaHCO3 and CaCO3) as expansion agents

This work shows the production of a ceramic light-weight aggregate (LWA) from mixtures of petrochemical wastes (oily wastes and oil sludge), a conventional clay and two different carbonates (NaHCO3 and CaCO3) used as expansion agents. The novelty of this study is the valorization of an important hazardous waste for the synthesis of a potential material for construction. All these feedstock where characterized by elemental, proximate and TG/DTG analyses and also by XRF for determining the inorganic composition. The LWA were produced from two different mixtures: i) clay and oily waste (CW) and ii) clay and oil sludge (CS), by using different proportions of both NaHCO3 and CaCO3 (0, 20 and 40 wt%). Additionally, the influence of sintering temperature (900, 950 and 1000 °C) on the particle density was also evaluated. Although TG/DTG analysis suggests a higher CO2 release with CaCO3 and hence, a higher bloating phenomena; there also appears an influence of the petrochemical waste composition. In addition, the particle density varied from 1.394 to 2.227 g/cm3, and from 1.226 to 2.571 g/cm3, for mixtures using CaCO3 and NaHCO3, respectively, and the lower the sintering temperature, the lower the particle density. The lowest density (1.223 g/cm3) was obtained when oily waste and NaHCO3 at 40 wt% are used (CW_NaHCO3_40). For this mixture, the synthesis process is prompted not only by the NaHCO3 addition, but also by the reaction among different elements of clay and oily waste. The resulting aggregate exhibited a foam-like structure with rounded cavities, suggesting the bloating phenomenon occurrence.