Viability of using Corncob Ash as a Pozzolan in Concrete

Cement is the most utilised construction material, its global consumption only seconding that of water. Its demand has soared proportionately with the exponential rise in population to match required development. The heavily energy-intensive processes that are involved in its production contribute to about 7% (per cent) to 10% of the total global carbon dioxide (CO2) emissions, with potentially adverse environmental implications and are economically expensive. These processes, and those of the production of concrete consume heavily on natural resources such as sand, gravel, water, coal and crushed rock, the mining of which mars the environment. It is however possible, that energy and cost efficiency can be achieved by reducing on the amount of clinker, and in its place utilizing pozolanic materials that require less process heating and emit fewer levels of CO2. This study investigated the viability of corncob ash for use as a pozzolan in concrete. Tests were carried our by replacing cement by weight in concrete mixes with corncob ash at 5%, 7.5%, 10%, 15% and 20%steps at the point of need. The results were compared with a control specimen that was made with 100% cement (0% CCA). Durability was tested using the sulfate elongation test on specimens that were immersed in a 5% sodium sulfate (Na2SO4) solution. From the results, all replacements achieved impressive compressive strengths that were suitable for structural applications, while the sulfate elongation tests showed that CCA could be used in Na2SO4 aggressive environments with an advantage. The findings also showed good repeatability and highlighted the potential of CCA to be used as an effective pozzolan in concrete.