Brine sludge activated ground volcanic pumice-based alkali activated binder

Commercially available alkaline activators are commonly used to activate alumino-silicious solid waste materials for the production of alkali-activated binders (AABs). The reliance on these commercial activators not only increases the production cost but also significantly impacts the environment. This study presents a novel approach of using brine sludge (BS), an alkaline solid waste produced during the chlor-alkali manufacturing process, as an alternative to the commercial alkaline activators, specifically replacing sodium hydroxide (SH), aiming to lower expenses and mitigate environmental impact. The total quantity of alkaline activator and the ratio of sodium silicate (SS) to BS were varied to effectively activate ground volcanic pumice (GVP), ensuring adequate workability and strength. Furthermore, suitable quantity of GVP was replaced with silico-manganese fume (SMF), blast furnace slag (BFS), and ordinary Portland cement (OPC) to improve the properties of the resulting binder. About 100 kg/m³ of BS quantity with a SS/BS ratio of 2.5 proved effective in achieving excellent workability and a maximum compressive strength of around 10 MPa. The inclusion of 30 % SMF and 30 % BFS resulted in a binder with a compressive strength of 48.15 and 33.87 MPa, respectively, after 28 days of room temperature curing. Further, a notable improvement in the microstructure was observed with the inclusion of these industrial by-products. The predominant reaction products in the 30 % SMF incorporated binder were Potassium Feldspar and Nchwaningite while calcium-aluminosilicate phases were identified in the 30 % BFS mix. This research lays the groundwork for further investigations into the potential of utilizing alkaline solid waste material to activate other industrial by-products, thereby offering technological, economic, and environmental advantages of using alkaline activated binders.