Prediction of Cover Thickness Based on Long-Term Chloride Penetration in a Marine Environment

Abstract

Chloride-induced corrosion is one of the main causes of deterioration of reinforced concrete structures in marine environments. In the last decades many investigations have been concluded to determine the parameters affecting the deterioration of concrete structures. Prediction of long-term chloride penetration is necessary to be established based on the results of long-term exposure tests under a marine environment. This paper presents an experimental investigation for predicting long-term chloride content in concrete. The experimental results on specimens with 0%, 7.5%, and 12.5% silica fume (SF) and 10% natural zeolite (NZ) replacement, located in southern Iran for 7 years, showed that both the concrete cover and concrete quality requirements stated in the present codes need to be increased so that an acceptable service life can be achieved. Use of 0–12.5% SF and 10% NZ can reduce the required concrete cover thickness up to 20%–40% and 10%–20%, respectively. Also, the increase of water to cementitious material ratio from 0.40 to 0.50 can increase the cover depth up to 36%. In this regard practical graphs for design and analysis of concrete structures in marine environments have been derived based on long-term results of concrete samples in the investigating site.