Design & development of alkali-activated walling materials using waste foundry sand
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landfills. It is produced at a rate of around 0.6 tons per 1 ton of foundry industry production. Conventional clay brick manufacturing is highly energy-intensive, primarily due to the high-temperature kiln firing process, resulting in substantial fossil fuel consumption and associated greenhouse gas emissions. The current work describes the development of one-part alkali-activated walling materials utilizing waste foundry sand (WFS) to provide a sustainable solid waste management solution and reduce the embodied energy of the manufactured bricks. Fly ash (FA) and blast furnace slag fine powder (BFSFP) were found to be regionally accessible materials for experiments, along with anhydrous sodium metasilicate (ASS) as the activator. WFS was utilized as a full replacement for natural fine aggregate, serving as a sustainable alternative in the granular matrix of the alkali-activated binder system. To create alkali-activated waste foundry sand bricks (AFSB), FA and BFSFP were combined in varying amounts with ASS (8% and 10% of the binder). The binder-WFS proportions were 1:1, 1:2, and 1:3, whereas the water-to-binder ratio was adjusted to maintain constant consistency. AFSB were divided into three classes according to their compressive strength (which ranged from 4 to 18 MPa) following an evaluation of their various physico-mechanical characteristics, following IS 3495 (Part 1- 3), 1992. It was observed that the produced bricks had an average density of 2015–2057 kg/m 3 and a 4-6% water absorption rate. AFSB's thermal conductivity was between 0.32 and 0.40 W/(m.K). In comparison to burnt clay bricks and fly ash bricks, the embodied energy utilized to create AFSB was determined to be about 50% and 10% lower, respectively. Experimental analysis validated the high performance and sustainability of the developed low-carbon, energy-efficient alkali-activated modular walling materials, manufactured using industrial byproducts, demonstrating enhanced mechanical strength, durability, and a significantly reduced carbon footprint.