Durability of concrete exposed to sea water attack

Abstract

Key Words: Durability, compressive strength, salinity level, Red Sea Summary : Large numbers of concrete structures are in contact with marine environment, hence exposed to both physical and chemical detrimental effects during their service life. The aim of the thesis is to study the main factors affecting the behavior of concrete in marine environments such as the effect of cement content, cement type, using of silica fume as a mineral additive, exposure condition and salinity level of seawater on the behavior of concrete exposed to seawater attack. Fifteen concrete mixes were cast with three types of cements; ordinary Portland cement (OPC), sulfate resistant cement (SRC) and slag cement (SC), and three cement contents (i.e., 350, 400 and 450 kg/m3) were used. Ten percentage of silica fume was used as a mineral additive in some concrete mixes with cement content 400 and 450 kg/m3. After 28-days of water curing, the specimens were exposed to three exposure conditions (i.e., wet and dry, immersion and splash condition) in artificial Red and Dead Sea for 12 months and their properties were determined and compared with those of specimens immersed in tap water. It was found that as expected Dead Sea is more aggressive than Red Sea due to its higher salinity level. The highest reduction in the compressive strength was found in concrete mixes exposed to splash zone. Slag cement concrete mixes showed the lowest reduction in compressive strength after exposure to sea water attack, while ordinary Portland cement concrete mixes showed the highest reduction. Furthermore, the reduction in the compressive strength of concrete increased by the addition of silica fume to concrete