Magnesium cement-based concrete
Portland cement has been a critical component of structural concrete for 200 years, providing solid foundations for the development and steady growth of modern society since the Industrial Revolution. The need for rapid construction grew over time, reaching unsustainable production levels as of today. During the production of 1 ton of Portland cement, approx. 725 kg of CO2 gas is released into the atmosphere. A smaller part (~30%) originates from the combustion fuels needed to heat the rotary kiln to 1450°C, where the thermal decomposition (calcination) of limestone generates calcium oxide and the remaining majority (~70%) of CO2 emissions. As calcium oxide constitutes an integral part of Portland cement, this raw constituent cannot be easily substituted during production. Due to technological limitations and the inherent geogenic emissions from limestone calcination (507 kg of CO2/tone of cement), a further significant reduction in CO2 emissions from Portland cement production cannot be expected in the future. Hence, there is a need to search for alternative materials that could replace this widely used binder in the building industry. This is a challenging task, as the newly developed binder needs to be available worldwide in massive quantities and offer at least comparable performance to Portland cement to be accepted into common building practice.
Here we focus on the development of magnesium cement-based concrete. Once the production of magnesium oxide, the binding block for this material, is implemented on a large scale, it will potentially offer a CO2-free alternative to calcium oxide used for Portland cement production. This project focuses on developing a suitable concrete mix design based on magnesium cement, which is applicable to structural concrete. We characterize the rheological behavior of the fresh mix and the subsequent development of mechanical properties and durability indicators. Our goal is to provide a verified mix composition that fulfills the contemporary requirements for structural concrete and delivers a building material with a negligible CO2 footprint.
Contact: Michal Hlobil, Frank Winnefeld
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