Evaluation of the effect of marine salts on urban built infrastructure

This paper presents the results of a study that evaluated the effects of marine salts on built infrastructures at the Port city of Chittagong in Bangladesh. Specimens made from five different types of mortars (normally used as external renders in built infrastructures such as buildings and bridges) with varying cement contents were exposed to atmospheric environment at 12 sampling stations scattered around the metropolitan area of Chittagong. The performance of the specimens was evaluated based on marine salt deposition and resistance to marine salt penetration. The study also monitored the deposition of chlorides and sulfates in wet candle sensors located at 12 stations. The type and amount of salts captured in powdered samples extracted from the mortar specimens as well as from wet candle sensors were determined using ion chromatography. The study showed that the marine salt deposition is significant up to a distance of about 200 m from the seashore. The analysis of deposition and subsequent penetration of marine salts in exposed specimens identified the mortar types that are more resistant to the aggressive potential of the region's marine aerosol. The results of this study can be very useful for local authorities engaged in selecting protective measures (in terms of external renderings) to improve the durability of infrastructures exposed to marine salts. (c) 2008 Elsevier Ltd. All rights reserved.