Property of multiple admixture-concrete in multi-salt soaking under wetting-drying and freezing-thawing cycles

Multiple admixtures (e.g. Fly ash, silica fume, slag, expansion agent, air-entrained water reduce agent (AEWRA) and cementitious capillary crystalline waterproofing material (CCCWM)) were added in concrete. Five groups concrete mix was designed, and experiments were conducted to study the damage, mass loss rate, dynamic elastic modulus, erosion-resistance coefficients, with multi-salt soaking and wetting-drying cyclic and freezing-thawing. The microstructure corrosion mechanisms were revealed by SEM, EDS and XRD. The results show that a limitation in improvement of erosion resistance is only for mixing with fly ash and silica fume. Nevertheless, it is significant to improve the erosion resistance of the fly ash and silica fume mixture in which certain amount of expansion agent are added. The dynamic elastic modulus is above 80%, and the erosion-resistance coefficients are above 0.9 after 11 cycles in multi-salt soaking and wetting-drying cyclic and freezing-thawing. CCCWM mixed into concrete can reduce the erosion resistance, the dynamic elastic modulus is below 60%, and the erosion-resistance coefficients are reduced from 1.0 to 0.3 after 4 cycles of multi-salt soaking and wetting-drying cyclic and freezing-thawing. The corrosion products for ettringite and calcium carbonate are found that multi-salt soaking under wetting-drying and freezing-thawing cycles will accelerate corrosion of the concrete, using microscopic mechanism analysis.