Production of colored bi-layered bricks from stone processing wastes: Structural and spectroscopic characterization

Stone processing wastes, being inherently colored, present an attractive option to develop the building façade products. In this study, four different types of stone processing wastes are characterized using X-ray diffraction, FTIR & Raman spectroscopies, and their suitability is evaluated to develop the colored bi-layered bricks. The stone processing wastes are blended with ground granulated blast-furnace slag to produce colored geopolymer mortars, and their compressive strengths are compared. Incorporation of stone waste decreased the compressive strength of geopolymer mortars. Particularly, Ca-rich stone wastes decreased the compressive strength less as compared to Si-rich stone waste. However, the stone waste blended geopolymer mortars still attained a value greater than 10 MPa, while achieving the desired color property. This corroborates the high potential of stone waste for producing colored masonry bricks equivalent to class designation 10 fly ash bricks as per IS 12894. The bi-layered bricks are conceptualized to make them economically viable, and their manufacturability is demonstrated at the laboratory scale via a four-step process in an existing industrial set-up (used for conventional fly ash bricks). The economic viability of these colored bi-layered bricks is compared against conventional single-layered fly ash bricks. It is found that colored bi-layered bricks have tremendous potential for cost-saving of up to 35% of the overall cost (accounting for the cost of a finished brick surface). This study presents a first-of-its-kind detailed study to produce colored bi-layered bricks using stone processing wastes. These new bricks combine the desired features of aesthetics and durability, and therefore, show a great promise as a cost-effective alternative to conventional fly ash bricks.