Seawater cement paste: Effects of seawater and roles of water film thickness and superplasticizer dosage

Abstract

In some remote areas or islands, the shortage of freshwater inspires the consideration of using seawater for making concrete. However, the use of seawater is not common and relatively little research has been done on seawater concrete. In this research, the influences of seawater on the fresh and hardened properties of seawater cement paste were investigated and the concept of water film thickness (WFT) was extended to seawater cement paste. To compare the various properties of seawater and freshwater cement pastes, and find out how the WFT affects the fresh properties of seawater cement paste, a series of seawater and freshwater cement paste mixes with varying water to cement (W/C) ratio and superplasticizer (SP) dosage were made and tested. It was found that at the same SP dosage and W/C ratio, seawater cement paste has lower workability and flowability, higher adhesiveness, lower packing density and slightly higher cube strength than the freshwater cement paste. Lastly, statistical correlation analysis revealed that the WFT and SP dosage are the key factors governing the fresh properties of seawater cement paste. Hence, the WFT theory is proven to be applicable also to seawater cement paste.