Durability of Mortar and Concrete with Composite Cements Containing Novel SCMs

The simplest way to reduce global CO₂ emissions linked to cement productions is to reduce the amount of clinker by partially replacing it with supplementary cementitious materials (SCMs). The availability of the most common used SCMs (e.g. fly ash), is, however, expected to decrease in the coming years. Extensive research is conducted to find new alternatives and ensuring long-term durability of concrete incorporating new materials is crucial for implementation. The impact of novel SCMs from Nordic countries on fresh and hardened properties as well as durability performance in mortar and concrete was studied. The composite cements analysed had a composition of 78 wt.% Portland cement, 18 wt.% SCM and 4 wt.% limestone. The investigated SCMs include natural materials such as clays and volcanic rocks (rhyolite and hyaloclastite), and industrial products such as fly ash, slag, oil shale ash, bio-fuel ash or bio-coal fly ash. All SCMs except oil shale ash had comparable performance to fly ash in terms of resistance to carbonation and chloride ingress, resistance to freeze-thaw scaling and mitigation of ASR. Concretes prepared with oil shale ash had considerably higher chloride ingress and no mitigating effect on ASR expansion.