Influence of freeze-thaw cycles on capillary absorption and chloride penetration into concrete

Abstract

Combined mechanical and environmental actions reduce service life of reinforced concrete structures more than each of the participating actions alone. In this contribution, the influence of freeze-thaw cycles on capillary water absorption and chloride penetration into ordinary concrete with two different water-cement ratios and air-entrained concrete was investigated. Water profiles in concrete were quantified by neutron radiography. Capillary water absorption and chloride penetration are both slowed down considerably by air entrainment. Chloride ions dissolved in water are filtered out of the penetrating salt solution and remain concentrated near the surface. Capillary water absorption and chloride penetration into ordinary concrete are accelerated considerably by frost damage. After exposure to freeze-thaw cycles a damage gradient from the surface to the center of the samples was observed. Transport mechanisms were studied in some detail and the data obtained can serve as a basis for more realistic prediction of service life of reinforced concrete structures under the influence of combined freeze-thaw cycles and chloride penetration.