Recyclability, Water Absorption and Durability of Unstabilized Clay Brick Reinforced with Straw

Abstract

Earth has been used as a construction material for centuries, starting with sun-dried mud and straw bricks, which had limited strength and durability. This evolved into fired clay bricks, which enabled large-scale production. However, with the building industry now accounting for 35% of global energy consumption, there is an urgent need to reduce energy use, construction costs, and reliance on nonrenewable resources—particularly in energy-scarce developing nations. This study explores Unstabilized Earth Bricks (UEBs) as a sustainable alternative, requiring 98% less energy than conventional bricks. The addition of straw as an eco-friendly additive not only addresses the disposal of 200 million tons of agricultural straw waste but also improves brick strength. Tests on 230 mm x 100 mm x 90 mm bricks with 1% and 2% straw content showed increased compressive strength, though strength declined in recycled samples. Both straw-reinforced and recycled UEBs demonstrated high durability in wire brush tests, underscoring their potential as cost-effective, sustainable building materials. However, recycled clay bricks exhibited significantly lower strength and are less suitable for structural applications.