Rheological properties, compressive strength, hydration products and microstructure of seawater-mixed cement pastes: Fid-Bau Portal

Rheological properties, compressive strength, hydration products and microstructure of seawater-mixed cement pastes

Wang, Junjie / Xie, Jianhe / Wang, Yuli / Liu, Yongliang / Ding, Yahong

Abstract The application of seawater as the mixing water in concrete production could mitigate the increasing demand for fresh water in concrete production associated with the continuously increasing offshore infrastructures. Understanding the key factors that influence the properties of seawater-mixed cementitious materials could promote the application of seawater during concrete preparation. A comprehensive investigation was carried out to assess the effects of the water/cement ratio (w/c), the partial replacement of ordinary Portland cement (OPC) with supplementary cementitious materials, and the salt concentration in seawater on the rheological properties (plastic viscosity (η), dynamic yield stress (τ d), thixotropic area (A thix)), compressive strength (f c), hydration products and microstructure of cement pastes. The results show that there was an increase in η, τ d, A thix and f c in all seawater mixes compared to deionized (DI) water mixes, and the increase in strength was more significant in the pastes with a lower w/c. The increase in salt concentration in the seawater did not linearly increase f c; instead, the early age strength increased initially and then decreased. This result was due to the combined effects of the increased chloride and Na⁺ ions on the strength development with the increase in salt concentration in the seawater. Interestingly, it was found that there was a good correlation between the results of η and f c for the seawater mixes in this study, and the same η value indicated a higher f c in the seawater mix than in the DI water mix.

Highlights • Effects of w/c, SCMs and salt concentration on properties of seawater-mixed cement pastes were investigated. • The correlation between the rheological properties and the compressive strength of the cement pastes was discussed. • Advantages of seawater on properties of the cement pastes were compared with the results of DI water mixes.