Effects of chloride ion in sea sand on properties of fresh and hardened concrete incorporating supplementary cementitious materials

This study aims to explore the applicability of non-desalted sea sand (NSS) for concrete production by investigating the effects of chloride ion on properties of fresh and hardened concrete incorporating fly ash (FA) and ground granulated blast furnace slag (BFS). All mixtures were prepared with a constant water-to-cementitious materials ratio of 0.50. The results showed that chloride ion in NSS had no effect on the slump loss and air content reduction of fresh concrete for 60 min after mixing. Thermal analysis and pore structure results clarified that chloride ion accelerated the pozzolanic reactivity of FA and hydraulicity of BFS at early ages. The presence of chloride ion also contributed to the increase in the mechanical properties and durability (permeability and sorptivity) of concrete at later ages. The outcomes of this study could validate the potential application of NSS for concrete incorporating supplementary cementitious materials as the alternative fine aggregate at coastal areas.

Automated summary

This study found that the use of non-desalted sea sand as fine aggregate in concrete can improve the mechanical properties and durability of concrete by accelerating the pozzolanic reactivity and early hydraulicity of supplementary cementitious materials. This validates the potential application of non-desalted sea sand for concrete production in coastal areas.