Performance of ground clay brick in ASR-affected concrete: Effects on expansion, mechanical properties and ASR gel chemistry

The effects of ground clay brick (GCB) on alkali-silica reaction (ASR) expansion as well as on mechanical properties of ASR-affected concrete are investigated. Crushed red clay brick originated from demolished masonry was ground in a laboratory ball mill and replaced for portland cement at levels of 15% and 25% by weight in concrete mixes produced with alkali reactive sand. ASR expansion, compressive strength, flexural strength, and modulus of elasticity of the concrete mixes were evaluated. Effect of GCB on ASR gel chemistry was also studied on Pyrex glass-paste specimens using SEM/EDS (scanning electron microscope equipped with energy dispersive X-ray spectroscopy). The results indicate that GCB effectively reduces ASR expansion in concrete: associated cracking and loss on mechanical properties are also significantly reduced. SEM study suggests that GCB alters alkali silica gel chemistry thus resulting in a less expansive product.