Combination of Palm Kernel Husk Ash (PKHA) and Free Lime (CaO) as an Admixture in Concrete Production
Almost all admixtures used in concrete construction in Nigeria are imported. In this study, various proportions of free Lime (CaO), Palm Kernel Husk Ash (PKHA) and Ordinary Portland Cement (OPC) were mixed and the setting times of various mix proportions were determined and compared with that of only OPC. The compressive strength of cement mixed with various proportions PKHA was also determined. This was with a view to establishing the use of PKHA as an admixture while still retaining the compressive strength of such cement PKHA combinations. A previous study by the main author studied the suitability of PKHA alone as an admixture, while still retaining the compressive strength characteristics. Results revealed that the setting time of the mixture of the PKHA and OPC cubes decreased as the percentage of the PKHA increases as compared to the setting time of pure OPC cubes which was the control test. Also, the cubes obtained by mixing various percentages of the PKHA and OPC showed reduced compressive strength for the 7 and 28 days compressive strength tests respectively relative to those made with 100% OPC which also served as the control test. In this recent study, setting time of the combination of PKHA/CaO and OPC decreased as the percentage of the PKHA/CaO increases. The compressive strength of the cubes of the combination of PKHA/CaO and cement were higher for the 7 and 14 days strength test but reduced drastically to values below that of OPC alone for the 28 days cube strength test.