Effect of Initial Curing on Surface Deterioration of Concrete Caused by Salt Diffusion and Crystallization Pressure

Abstract

Crystallization pressure under dry condition after absorption of salts contained in seawater or rainwater causes surface deteriorations of concrete. This deterioration is emphasized under repetition of wetting and drying by propagation of micro cracks. However the deterioration has been hardly researched on concrete. On the other hand, initial curing condition must play an important role in the deterioration because the deterioration starts from surface and the curing has a major affect on the quality of surface concrete rather than inside concrete. In this study, the influence of initial curing condition, the kind of salt, type of cement and concrete mix proportion on the surface deterioration caused by salt crystallization pressure has been investigated. The salts investigated in wetting and drying test were Na₂SO₄, K₂SO₄, MgSO₄, NaNO₃, KNO₃, Mg(NO₃)₂, NaCl, KCl and MgCl.