Development of a Nonconventional First-Class Fly Ash Brick and Evaluation of Its Mechanical and Durability Properties

The present study focuses on the development of nonconventional first-class fly ash brick (NFFB) using predominantly available industrial waste materials such as fly ash and ground granulated blast furnace slag (GGBS) through geopolymerization. By optimizing material composition under ambient curing conditions, the research aims to enhance brick quality while reducing the use of natural resources. The mix constituents for NFFB have been optimized by varying the molarity of NaOH, the ratio of sodium silicate to sodium hydroxide (S/H ratio), and the amount of cement. The experimental results revealed that the optimized NFFB, consisting of 45% fly ash, 22.5% GGBS, 30% sand, 2.5% cement, with an 8 M NaOH solution and a 1.0 S/H ratio, meets the performance requirement of a first-class brick in terms of strength. Additionally, the developed NFFB showed low water absorption, reduced linear shrinkage, minimal efflorescence, and optimal initial rate of absorption showing better durability as compared to conventional burnt-clay bricks and fly ash bricks. These findings demonstrate that the developed NFFB meets Indian standards for first-class bricks and offers a sustainable alternative to conventional bricks in construction applications.