Study on the Durability of Fly Ash Concrete Under Multi-Salt Attack and Dry-Wet Cycles

The deterioration law of fly ash concrete under multi-salt corrosion and dry-wet cycles was investigated. Three kinds of concentration of multi-salt solution including Na2SO4, NaHCO3 and NaCl were prepared. Tests of multi-salt immersion and dry-wet cycles were carried out on fly ash concrete and normal concrete. The results indicate that the damage of concrete in multi-salt solution is more severe than in water. The mass loss rate of concrete increases in the early period then decreases gradually, while the relative dynamic elastic modulus increases at first and decreases later. Through the analysis of micro-structure of concrete and energy spectrum, concrete corrosion caused by multi-salt and dry-wet cycles includes both the chemical corrosion and multi-salt crystallization damage. Under the action of multi-salt attack and dry-wet cycles, the corrosion resistance of fly ash concrete is better than that of normal concrete.