Extending the use of supplementary cementitious materials in concrete

Concrete is the most used construction material in the world, and its production accounts for about 8% of human-generated CO2 emissions. In conventional concrete, the binder is Portland cement, which has the largest CO2 contribution of
all constituents. To improve the properties of concrete and reduce its carbon footprint, Portland cement can be partially replaced by Supplementary Cementitious Materials (SCMs), such as coal fly ash, blast furnace slag, or silica fume. These
traditional SCMs are industrial by-products and their use in concrete promotes circularity and reduces waste. However, due to the overall decarbonization of the industry, their availability is expected to decrease in the coming years. The concrete industry is therefore looking into alternative SCMs, which can ideally substitute even more Portland cement that traditional SCMs. In this respect, it is essential to evaluate the effect of SCMs on concrete durability, i.e. ensuring that concrete will remain in sufficiently good condition over the service life of a structure – typically 100-120 years for bridges.