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Date: Monday, May 20, 2019 Time: 3:00-4:00 pm Place: 1-131

Seminar from Sama

Abstract: Concrete is one of the most widely used construction materials; it is usually associated with Portland cement as the main component for making concrete. The cement industry alone is responsible for about 6% of all CO2 emissions, because the production of one ton of Portland cement emits approximately one ton of CO2 into the atmosphere. Cement is the product of the reaction between water and clinker. As a result, the main components formed from cement hydration reaction are calcium-silicate hydrate (CSH) and calcium hydroxide (CH). CSH is the main binding agent in cement and concrete. It progressively densifies as cement hardens and is ultimately responsible of concrete performances. CH’s presence is considered a weakness in cement as it might react with acids, and could be leached out leaving pore space. Over the years, researchers have looked at various replacements and additions to the cement aiming to add functionalities to the concrete and enhance its properties. In this study, Carboxyymethyl cellulose (CMC) is added to the cement. As a first observation, the viscosity of the mixtures change with addition of different molecular weights and concentrations, and hence, becomes harder to mix. As the hydration goes on, the gel solidifies and forms a hardened cement paste. Clearly, the presence of CMC modifies the volume fractions of CSH and CH, favoring the growth of the CSH phase, and we’ll see how this affects the mechanical properties through a series of indentation tests at different depths.