Determination of the Pozzolanicity of Cocoa Pod Ash at Different Temperatures

Abstract

Pozzolans are siliceous or aluminous materials which possess little or no cementing property but chemically react with calcium hydroxide at ordinary temperature to form compounds possessing cementitious properties. There is paucity of information on the pozzolanicity of Cocoa Pod Ash (CPA). Hence, this study investigated the pozzolanicity of CPA. Cocoa pods were obtained from selected farms in Egba Odeda, Ogun State Nigeria. The Cocoa pods were washed, sundried and calcinated to ashes in a furnace between 600° C to 1000° C at Science Laboratory Technology Department, Federal Polytechnic Ilaro, Ogun State. Chemical analyses and X-ray Crystallography were carried out on the CPA to determine the types of oxides present and their varying percentages. The oxides were Silica (SiO,), Ferric (Fe,O,), combined percentages of Ferric and Aluminum oxides (Fe,O, and Al,O,), Calcium (CaO), Magnesium (MgO) and Sulphur (SO,). The moisture content and the Loss of Ignition (LOD) of the CPA samples were also determined.The oxides of Silicon, Ferric, Aluminium, Calcium and Magnesium oxide ranged between 6.39-8.00; 0.78 – 0.89; 1.74- 2,29; 7.15-8.42 and 4.38-5.16% respectively. Sulphur trioxide and LOI ranged 3.51- 3.78 and 27.2- 32.0%, respectively. The Xray crystallography showed that the total percentage composition of SiO, Al,O, and Fe,O, in CPA varied from 14.87-24.21%. The study showed that CPA did not satisfy the minimum 70% requirements stipulated by ASTM C618 (2005) for a pozzolan after the analysis of the oxides but it satisfied all the requirements for LOI, hence CPA is a weak pozzolan