Performance of plain and blended cements in high chloride environments

Reduction in the useful-service-life of bridge decks in the USA and Europe and reinforced concrete structures in tropical countries due to reinforcement corrosion has been of major concern to the engineering community throughout the world. In both situations, the presence of chloride ions in sufficient quantities is the primary cause of the initiation of reinforcement corrosion. Chlorides are contributed by deicer salts in the bridge structures, while soils and groundwaters charged with high concentrations of salts in tropical countries contribute significant quantities of chloride ions. In the latter regions, the low precipitation and high evaporation rates result in high salinities in the soil and groundwater. In this investigation, cement paste, mortar and reinforced concrete specimens made with two plain cements, and three blended cements were placed in a 15.7% CI- (26% NaCl) solution. The performance of these plain and blended cements in resisting reinforcement corrosion was evaluated by monitoring the corrosion activity at regular intervals. The effect of high concentrations of chloride salts on the physical properties was monitored by measuring compressive strength reduction. Results indicate retrogression of strength in blended cement mortar specimens placed in the chloride solutions compared to those cured in potable water. This behavior was more pronounced in the silica fume cement. However, the resistance to reinforcement corrosion of the blended cements, particularly silica fume cement, was better than the plain cements .