Effect of Calcination Method of Shea Nut Shell on its Pozzolanicity and Compressive Strength of Concrete

Abstract

The search for alternatives to cement owing to enormous negative environmental impacts that characterized its production and usage, has led to the adoption of ashes from various agricultural residues a replacement for cement. This study therefore investigated effect of ashing methods on the pozzolanicity of sheanut shell ash and its replacement of cement on the strength of concrete. Shea-nut shells were calcined using controlled open–burning (COB) and controlled burning under five different temperatures at intervals of 50 ℃ in the range 500 to 700 to obtain six (6) different ash specimens which were characterized using X-Ray Fluorescence to determine its oxides composition. The most reactive amongst the ashes was used to replace cement at 0, 5, 10, 15 and 20% to produce five concrete specimens: SSA-00, SSA-05, SSA-10, SSA-15 and SSA-20 using 1:2:4 mix proportion and 0.5 water cement ratio (WCR). The weight, density and compressive strength of the cubes were determined at 28th day. The concrete specimens of the control sample and test specimen with the most enhanced compressive strength were subjected to Scanning Electron Microscopy (SEM) with Energy Dispersive Spectrum (EDS). The combined percentage compositions of SiO2, Al2O3 and Fe2O3 for the best ash was 50.29% with controlled open burning as the best method. The optimum concrete compressive strength at 28 days curing period was 19.11 N/mm2 for 5% replacement level which is recommended for use in concrete production for any structural elements.