Investigation of compressive strength and thermal properties of corn cob ash cement concrete

Abstract

Corn cob is an agricultural waste obtained from maize or corn. Previous studies considered the conversion of corn cob into useful materials by incorporating its ash as partial replacement for cement in concrete. However, there is paucity of information on the thermal properties of Corn Cob Ash (CCA) concrete. Therefore, the thermal properties of CCA concrete were examined in this study. The chemical composition of the CCA was determined. A total number of 105 concrete cubes of size 150 mm with varying percentage by weight of CCA to Ordinary Portland Cement (OPC) replacement order of 0, 5, 10, 15 and 20% were cast using mix ratio 1:2:4 with water/cement ratio of 0.55. Slump and compacting factor were carried out for workability test. The concrete cubes were tested for compressive strength at 7, 14, 28, 56 and 90 days and thermal properties at 28 and 90 days. Obtained results were subjected to Analysis of Variance (ANOVA). The CCA possessed combined silica, alumina and ferric oxide of 65.41%. The slump and compacting factors ranged from 87–105 mm and 0.92–0.97, respectively. Compressive strength of CCA concrete at 90 days ranged from 26.50 to 17.00 N/mm2 at 0 to 20% CCA. Thermal conductivity, heat capacity and thermal diffusivity of the CCA concrete at 90 days ranged from 1.283–1.012 W/m·K, 3.927–2.632 mJ/(m3k) to 0.867–0.407 mm2/s, respectively as CCA increased from 0 to 20%. OPC concrete incorporating CCA has insulating property. CCA can be used when compressive strength is required but not more than 10% replacement.