Utilising under-burnt waste bricks from kilns as supplementary cementitious material

Abstract

This paper studies the pozzolanic performance of Crushed Brick Powder (CBP) obtained by grounding under- burnt waste bricks from a continuous brick kiln. Two different size fractions of CBP considered for cement replacement are CBP1 passing through 150 μm but retained on 75 μm and CBP 2 passing through 75μm. The compressive strength tests on mortar with CBP reveal that strength does not exceed the control; however, 10 - 15% cement replacement by CBP is optimum. A study of the presence of hydrate phases by XRD and quantification of portlandite in the paste samples by TGA up to 90 days confirms the action of pozzolanicity. Further, To determine the feasibility of CBP1 and CBP2 fractions in concrete, M25 grade concrete's strength and carbonation were studied by replacing 45% cement with a combined proportion of CBP1 (20%) and CBP2 (25%). This replacement reduced the concrete grade from M25 to M20 and increased the accelerated carbonation depth. Despite this, the projected natural carbonation coefficient with accelerated carbonation data is determined as low. The utilised CBP is cost-effective as it requires less mechanical processing and is without any chemical activation, and thus it can satisfactorily be used for low-cost housing construction and lower-grade structural and non-structural uses.