Performance assessment of eco-efficient concrete with ternary blended cementitious materials considering the effect of binder component fineness

The production of concrete and especially of cement clinker is associated with significant CO2 emissions. In order to reduce these emissions, various measures have been introduced in recent years, including energy efficiency, the use of alternative fuels, and the replacement of Portland cement clinker by supplementary cementitious materials (SCM). Here, the performance and the environmental impact of so-called eco-efficient concretes with a strongly reduced clinker content as low as 20 wt% of cement, blended with limited contents of slag - reflecting the fact that also slag is a limited resource - and high contents of limestone powder are discussed. In addition, the fineness of the slag in the ternary blended cements was systematically varied. The properties in the fresh state, the mechanical and durability properties as well as the environmental impact of these eco-efficient concretes are determined. Results show that the fineness of the binder components, in this case the slag fineness, has a significant effect on the hydration kinetics and the resulting mechanical performance as well as the durability properties of eco-efficient concretes. Finer grinding of the slag significantly improves the performance of clinker-efficient cements. Concretes with clinker contents in the cement as low as 30 wt% and high limestone powder contents of up to 40 wt% proofed to be suitable for structural concrete. The CO2 footprint is reduced because the replaced clinker compensates the additional emissions (higher energy consumption) associated with grinding. This enables efficient use of the binder while reducing the clinker content and replacing it with less reactive and lower-emission materials.