Low clinker cement as a sustainable construction material

Portland cement is the world's most widely used manufactured material and underpins modern infrastructure like no other. Global production of Portland cement clinker stands at a little over 3.5 billion tonnes, and consequently the global cement industry is responsible for 6–7% of anthropogenic carbon dioxide emissions. The industry recognises the need to reduce its carbon dioxide emissions, and there have been a number of technological advances in recent years that have helped to reduce the carbon footprint of cement production. Amongst these, one of the most popular and effective methods has been to reduce the clinker factor, that is, replace cement clinker with supplementary cementitious materials (SCMs). This chapter reviews the chemical and mineralogical properties of many of the most popular SCMs, considers their impact on cement hydration and concrete performance, and then summarises their impact on concrete durability. Finally, the chapter reviews the environmental footprints of the SCMs themselves and considers their long-term future as a vital constituent of modern Portland cements.