20 Despite centuries of faithful service, concrete now displays an environmental footprint demanding a radical change. But does this mean it should be replaced entirely? Not if innovation can transform it into a more sustainable material. Used for over 2,000 years, concrete is currently the most consumed material in the world after water, according to the Global Cement and Concrete Association. However, its environmental footprint is very high: it accounts for nearly 8% of global CO2 emissions according to the think tank Chatham House. UNRIVALED PROPERTIES Faced with population growth and rapid urbanization, it seems difficult to do without concrete. There are very few other candidates capable of surpassing its strength, especially for large-scale construction, heavy industrial construction, and infrastructure. Many structures built with this material have been standing for at least a century. In this regard, concrete is undeniably durable. Concrete is also highly resistant, both to fire and natural disasters. Another advantage is its high thermal inertia. This thermal mass makes it capable of storing heat or coolness, gradually releasing it and reducing the need for air conditioning in summer. In this sense, it is superior to wood, for example. CONSTRUCTION CHEMICALS FOR DECARBONIZATION The main criticism of concrete stems primarily from the environmental footprint of its main ingredient: cement. Preparing concrete requires gravel, sand, cement, and water. Cement, or more precisely one of its components, clinker, is obtained by mixing crushed limestone and clay, which are then heated to very high temperatures. It’s this step that emits CO2 and consumes a considerable amount of energy, ultimately being largely responsible for concrete’s carbon footprint. That’s why research is focusing on reducing clinker usage in concrete. Several options exist. Firstly, by attempting to reduce energy consumption related to the calcination of raw materials, whether through renovating industrial processes or installing more efficient kilns. It’s also possible to operate them using cleaner energy sources, Reinventing CONCRETE SPoTLIGHT
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