Potential Use of Parkia Biglobosa Husks Ash as Partial Replacement of Cement in Concrete Production

Purpose: This paper discusses the setting time of pastes, workability of concrete mix and compressive strength of concrete cubes prepared with the cement content partially replaced with parkia biglobosa husks ash (PBHA). Design/Methodology/Approach: The blends of the cement and ash by weight were in the proportions of 100%, 95%, 90%, 85% and 80% cement to 0%, 5%, 10%, 15% and 20% ash and denoted as C100A0 (control specimen), C95A5, C90A10, C85A15 and C80A20 (experimental specimen) respectively. Blends of cement/ash pastes and concrete mixes were prepared for each replacement level and tested for the setting time using the Vicat Apparatus and workability using the slump cone respectively. Twelve number cubes were prepared from each mix from which three cubes were randomly chosen from each replacement level and tested for compressive strength by crushing at four curing phases (7, 14, 28 and 90 days). Findings: Test results of the cement/ash paste and concrete mix showed a steady increase of setting time and a decrease in slump respectively with increased ash content. In all replacement levels, the compressive strength increased with curing time and decreased steadily with increased ash contents in the cement up to 10% replacement level in all curing periods. However, at the 15% replacement level, compressive strength increased and dropped again at the 20% cement/ash replacement level in all curing periods. Though the short-term strength development is low, the long-term strength development is very encouraging with a maximum value of 35.18N/mm2 obtained at the 15% ash content as the optimum cement/ash percentage replacement. Practical Implication: The Parkia Biglobosa Husks ash (PBHA) is a potential supplementary cementitious material that can be used to partially replace cement for concrete production. Originality and value: The presence of the ash (PBHA) in the cement tends to reduce the flash setting of concrete produced in windy and hotter climates.