Surface Swelling Characteristics in Concrete under Salt Frost Exposure

Abstract

Salt scaling is a commonly observed durability issue in concrete exposed to a combined salt and frost attack. This damage is restricted to a very thin surface region causing the removal of mortar flakes. This study demonstrates the surface-swelling characteristics of different concrete mixes. Significant paste swelling of the embedded fine silica sand peripherally occurs around the coarse aggregate particles in concrete mixes having a high water/cement ratio or insufficient air entrainment. Localized scaling is observed in concrete mixes with a denser matrix. The severity of this phenomenon is related to the magnitude of cryogenic suction governed by the permeability of the paste. Surface scaling is proposed to be the generator of bulging stress due to confined expansion from ice growth.