Engineering Properties of Industrial Wood Waste Ash-Concrete

Abstract

This study investigated the use of industrial wood waste ash (IWWA) as partial replacement of Portland cement in the production of concrete. The IWW was incinerated in controlled environment in a kiln at a temperature of 550^oc-600^oc.The resulting ash was cooled and further ground using a Disk mill (FFC 15) with a sieve size of 0.66mm in it. X-ray fluorescence method was used to characterize the oxide composition of the resulting ash. By using absolute volume method of 1:2:4 concrete mix with a water/cement ratio of 0.55, concrete cubes measuring 150mm x 150mm x 150mm were made from five different concrete mixes prepared by using IWWA to replace 0%, 5%, 10%, 15% and 20% of Portland cement by mass. The workability of the fresh concrete mixes was evaluated using the slump test and the compressive strength of the concrete cubes was evaluated at 1, 7, 28, 56 and 90 days. Test results indicate that IWWA is pozzolanic, workability of the concrete mix decreases with an increase in replacement percentage of cement with IWWA. Compressive strength of IWWA-OPC concrete increases with age of curing and it decreases with increasing IWWA replacement. The compressive strength of IWWA concrete was lower at early stage compared to the control sample but improved significantly up to 90 days. The optimum compressive strength is 21.19N/mm²obtained at 20% replacement of cement with IWWA at 28 days. The maximum compressive strength at all ages of testing was obtained at 90 days for 5% (31.40N/mm²) replacement of cement with IWWA. A regression analysis using Minitab statistical software indicates that the variation of concrete compressive strength is significantly dependent on the variations of IWWA content and age of curing. The model R² coefficients, residual and normality plots averaged about 90% showing adequate prediction of the model.