Abstract
The purpose of this study was to evaluate the benefits of replacing Ordinary Portland Cement (OPC) with Corncob Ash (CCA) blended cements. The cement industry contributes considerable amount of Carbon Dioxide (CO2) emissions into the atmosphere. The main contribution of CO2 emissions from cement production results from the process of creating Calcium Oxide (CaO) from limestone (CaCO3) commonly known as the calcination process. Blending OPC with a pozzolanic material will assist in the reduction of CO2 emissions due to calcination as well as enhance the quality of OPC. There are various pozzolanic materials such as fly ash, rice husk, silica fume and CCA that could be promising partial replacement for OPC. In this study, CCA will serve as the primary blending agent with OPC. An experiment was performed to designate an appropriate percentage replacement of CCA that would comply with specific standards of cement production. The experimental plan was designed to analyze compressive strength, workability and thermal performance of various CCA blended cements. The data from the experiment indicates that up to 10% CCA replacement could be used in cement production without compromising the structural integrity of OPC. In addition, it was found that the compressive strength and workability of the resulting concrete could be improved when CCA is added to the mixtures. Furthermore, it was shown that the introduction of 10% CCA can lead to significant reduction in thermal conductivity of the mixture.
Highlights
CO2 emissions are becoming an extremely distressing issue that continues to negatively impact the environment
The increase of global temperature leads to melting polar ice caps and depleting the construction was responsible for 2,236 million metric tons of CO2 emissions, approximately 39% of total CO2 emissions (Gorkum, 2010)
The compressive strength results reported in this study confirm the results found by (Adesanya and Raheem, 2009b) which showed that compressive strength began to increase with the increase of Corncob Ash (CCA) replacement from zero up to 10% regardless of the curing age
Summary
CO2 emissions are becoming an extremely distressing issue that continues to negatively impact the environment. Other researchers studied the effects of kinetics on fly ash blended cements hydration at different curing temperatures. Pozzolanic cement blends have significant effects on corrosion and compressive strength compared to that of OPC (Guneyisi et al, 2005). Over 100 million tons of fly ash are available as waste from thermal power plants in India alone (Singh and Garg, 2007) As such several researchers developed a variety of blends and tested them for compressive strengths after 28 days curing age. High strength plaster could be developed from fluorogypsum waste with a mixture of chemical activators such as Ca(OH), CaCl2 and Na2SO4 They found that 15-20% lime sludge could be added to the binder to economize production without sacrificing compressive strength (Singh and Garg, 2009). Use the flow table test to observe the change of workability as a function of time for the blended cements
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