Experimental study on chloride penetration into concrete after carbonation under wet and dry cycle mechanism

The part above the sea water of marine concrete structures will be subjected to chloride penetration and carbonation over a long period of time.Compared with the concrete structures in the general atmosphere,marine concrete structures are more susceptible to reinforcement corrosion.In this paper,experiment of chloride penetration into concrete after carbonation under wet and dry cycle mechanism was carried out.Effect of concrete carbonization on chloride diffusion was deeply studied through analysis of the distribution of chloride ions,chloride diffusivity coefficient and microstruction of the concrete.The results showed that free chloride ion content in concrete was enhanced after carbonation,the decay of chloride ion concentration was slowed down.After carbonation,chloride diffusivity coefficient of concrete with low water-binder ratio was reduced,and chloride diffusivity coefficient of concrete with high water-binder ratio was increased apparently.And the microstruction of the concrete was deteriorated by carbonation.Both the density and chloride ion penetration resistance of concrete could be increased by reducing the water-binder ratio.