Assessment of the durability and environmental impact of seawater-activated portlandite-calcined clay binder

This study investigated the performance of seawater-cured calcined clay-portlandite binder as a potential alternative to ordinary portland cement (OPC) for marine concrete applications. The samples for the investigation were prepared by mixing calcined kaolinite and bentonite clays in different ratios with portlandite. Seawater served as both the mixing and curing agent while acting as an activator due to its chloride and sulfate ion contents. The process involved three sequential steps: evaluating the changes in the mechanical performances, assessing the microstructural features, and estimating the environmental impacts. The results showed that the bound and total chloride content was significantly higher in the calcined clay mixes than in the OPC. The higher kaolinite enhanced the mechanical properties, and the strength-providing phases were Friedel’s salt, C-A-S-H, ettringite, and zeolites. It was concluded that this novel binder has the potential to reduce global warming by 85–90% more than OPC.