Picture: Vox Media, 2021
A new and innovative way to build our cities: The use of sustainable cement.
By 2050, 80% of the world’s population is expected to live in cities.
However, the ability to construct engineering masterpieces such as the Millau Viaduct and the Burj Khalifa comes with a high environmental cost. Cement production alone (excluding other aspects of construction) accounts for around 8% of global CO₂ emissions, about half of which results from chemical reactions inherent in the production process. As other industries such as energy and agriculture reduce their share of emissions, cement production may account for nearly a quarter of all human-driven CO₂ emissions by 2050.
Many low-CO₂ cements have emerged as attractive, more sustainable alternatives to traditional Portland cement. Portland cement is produced by heating a mixture of limestone and other minerals to around 1,450°C, a process that results in chemical reactions that release large amounts of CO₂.
But other materials are also widely used in concrete, including those largely generated from industrial waste or by-products such as coal fly ash, blast furnace slag, calcined clays, finely ground limestone or silica fume. They are used either by blending with traditional cement, or as a binder (or “glue”) themselves, without any Portland cement.
Importantly, the way these materials are produced results in far lower CO₂ emissions than Portland cement. This can reduce CO₂ emissions by between 50% and 80%, depending on the technology used.
Using these materials in cement provides enhanced strength and durability, and also improves sustainability by reducing associated CO₂ emissions and recycling industrial wastes.
Source: World Economic Forum, 2021
