PHYSICAL, MECHANICAL PROPERTIES AND INTERNAL STRUCTURE CHARACTERISTICS OF CEMENT-LOCUST BEAN POD WASTE ASH MORTARS
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Date
2019-03
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Nigerian Journal of Pure and Applied Sciences, Faculty of Physical Sciences and Faculty of Life Sciences, Univ. of Ilorin, Nigeria
Abstract
The need to reduce the environmental pollution resulting from agro-wastes and to source a material that
can be used to replace cement in order to reduce the pressure on its consumption necessitated this
research. This study was designed to investigate 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 Scanning Electron Microscope (SEM), Energy Dispersive Spectroscopy (EDS),
and X ray diffraction analysis (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. A decrease of about 98% in compressive strength occurred at
30% LBPA and after 14 days of curing and the highest increase in compressive strength was recorded at
15% LBPA after 28 days of curing. Maximum compressive strength ranged 38.3 and 65 MPa after 7 to 28
days curing. Microstructural analysis revealed less voids and pores, and the presence of dense Calcium-
Silicate-Hydrate (CSH) gels which helped to maintain the optimum compressive strength at 15% LBPA
cement replacement level of the mortar. The results indicated that LBPA is a reactive pozzolanic material
and can be used as a supplementary cementitious material for producing medium-strength concrete.
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Keywords
Compressive; crystalline; agro-waste; network; ash