Role of supplementary cementitious materials on chloride binding behaviors and corrosion resistance in marine environment

Chloride attack in the marine environment adversely affects the durability of Portland cement materials, leading to the premature failure of marine engineering structures. In this research, different supplementary cementitious materials (SCMs) were added to cement to form a binary system, and the characterization and adsorption behavior of chloride ions were investigated. Additionally, the effects of different SCMs on the setting time, fluidity, mechanical properties, drying shrinkage, chloride binding capacity, and hydration process of cementitious composites in marine environments were systematically researched. The obtained results revealed that the incorporation of SCMs increased the chloride ion binding capacity of the matrix by 7.7 %-22.3 %. Metakaolin (MK), granulated blast furnace slag (GGBS), and fly ash (FA) enhanced chloride ion binding capacity mainly due to the formation of more Friedel's salt (Fs), whereas silica fume (SF) promoted the formation of more C-S-H that adsorbed chloride ions. SF and MK exhibited the strongest chloride binding capacities and significantly inhibited SO42-and Mg2+ induced corrosion. Moreover, the addition of SCMs promoted early hydration of the cementitious composites shortened the setting time, increased early strength, and had no adverse effect on the 28 d compressive strength. These findings are expected to advance the design of highly durable cementitious materials for use in marine environments.