A study of carbonation-induced corrosion

Abstract

This study is concerned with measurements of corrosion in steel rods embedded at 4, 8, 12 and 20 mm from the exposed surface of concrete dried and carbonated uniaxially for 0·4, l·5 and 4 years. Corrosion was stimulated by exposing all specimens to a moist environment for a prescribed period prior to extraction and cleaning of the rods for gravimetric corrosion measurements. Corrosion was mainly controlled by the unneutralized remainder, i.e. the depth of reinforcement cover minus the depth of carbonation. Corrosion increased as the unneutralized remainder reduced from about +5 mm to −10 mm. The relationship between corrosion and the unneutralized remainder was not significantly affected by the depth of cover, the water/cement ratio, the period of curing or the exposure conditions during carbonation. However, corrosion seemed to be increased when there was 50% ground granulated blast-furnace slug in the cement; in contrast 30% pulverizedfuel ash or 5% ground limestone had little effect.