ABSTRACT
In this research three different ashes were used separately as partial replacement in concrete, these are rice husk ash (RHA), palm oil Husk ash (POHA) and coconut husk ash (CHA). These waste materials were obtained on burning of husk of each of the three materials. Chemical composition, sieve analysis, consistency, setting time, Specific gravity tests were carried out on the paste with and without ashes and workability on fresh concrete containing the three ashes (RHA,POHA and CHA) to ascertain the compressive strength properties of concrete and mortar containing ashes as partial replacement for cement. Concrete mixes were prepared i.e. 100% OPC as control, three mixes each of RHA, POHA and CHA at cement replacement of 15%, 20% and 25%. Compressive strength test was carried out on mortar and concrete for 7, 21 and 28days. It has been found that coconut husk ash has compressive strength close to control in mortar on 7days of 15% and palm oil Husk has compressive strength close to control in concrete at 28days of 20%. More so, the compressive strength of palm oil Husk ash in concrete on 28days of 20% is close to control which is 0% in concrete. The results obtained and the observation made clearly demonstrate that the partial replacement of cement by coconut husk ash and palm oil Husk ash is advantageous, particularly for mortar and concrete at 15% and 20% respectively without any chemical additive