Chemical Reactions in Pozzolanic Concrete

Volume 1 - Issue 4

Ash Ahmed¹*, John Kamau², Jonida Pone¹, Fraser Hyndman¹ and Heni Fitriani³

Received: May 31, 2019;   Published: June 10, 2019

DOI: 10.32474/MAMS.2018.01.000120

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Abstract

Cement is the most utilized construction material, and the second most consumed commodity in the world after water. Its demand has soared proportionately with the exponential rise in population in a bid to match the required development. The heavily energy-intensive processes that are involved in its production contribute to about 7 to 10 per cent (%) of the total global emissions, with potentially adverse environmental implications, and are also economically expensive. These processes, and generally those of the production of concrete consume heavily on natural resources such as sand, gravel, water, coal and crushed rock, 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 supplementary cementitious materials (SCMs) or pozzolans that require less process heating and emit fewer levels of carbon dioxide (CO₂). This paper elaborates on the different types of chemical reactions taking place in concrete containing pozzolans as a partial cement replacement. A pozzolanic material relies on the secondary reaction following the hydration of cement, whereby it reacts with the free calcium hydroxide to form the calcium silicate hydrates (C-S-H) phase which is the major contributor to strength in concrete; as a result there is usually long term strength development up to and beyond 91 days in pozzolanic concrete. Due to the depleted levels of calcium hydroxide, pozzolanic concrete impart superior sulfate resistance.

Keywords: Hydration of cement; Pozzolans; Pozzolanic reaction

Abstract| Introduction| Components of Concrete Mix| Conclusion| Acknowledgement| References|