Mechanical and Structural Characteristics of Cement Mortars Blended with Locust Bean Pod Ash

Abstract

This study looks at the effect of cement replacement with locust bean pod ash (LBPA) as a supplementary cementitious material on compressive strength of mortars. The fresh properties (workability, initial and final setting times), compressive strength at 7, 14, 21 and 28 days and microstructural analysis (SEM, EDS and XRD) were evaluated. LBPA were considered at replacement levels of 0, 10, 15, 20 and 30% of cement mass for preparation of the mortar samples. Workability of the cement mortars reduced as the content of LBPA increases while initial and final setting times increased in relation to increase in LBPA content in the matrix. An increase of about 79% in compressive strength at 7 days, 100% at 14 days, 147% at 21 days and 136% at 28 days were recorded with LBPA content of 15% LBPA being the optimum level when compared to control mix. Maximum compressive strength ranged between 38.3 and 65MPa after 7 to 28 days curing. Microstructural analysis revealed less voids and pores, and the presence of dense CSH gels which helped to maintain the optimum compressive strength at 15% LBPA cement replacement level of the mortar.