Long Term observations in an Experimental study on durability of a Sustainable Concrete Made with Sea-water and Sea-sand in Tidal Conditions

Providing aggregates for the vast scale of concrete usage is a global issue. Due to the environmental impacts of the inappropriate extraction of natural resources of sand, as the main ingredient in the concrete, seeking proper solutions is critical. Hence, dredged sediments of sea and oceans, which is necessary for harbours’ transportations, may also cause burdens by contaminating the environment, as they are left open in nature and transform into the dust and particles in the air after a short while. Despite the shortage of Freshwater (FW) and due to its massive consumption in the construction industry, Seawater (Sw) is an appropriate alternative if the required engineering parameters are met. The durability of concrete structures exposed to the marine environment is essential for safety, infrastructures sustainability, and strength. This research aims to provide sustainable-economical concrete made of Sw and dredged marine sand (DMS). The experiments include also using ground granulated blast furnace slag (GGBS) and applying specific experiments such as measuring the compressive strength, special electrical resistivity (ER) and carbonation depth. The results showed a significant effect of GGBS’s presence on reducing carbonation depth, improving electrical resistivity, and compensating for the loss of compressive strength of seawater sea-sand concrete (SWSSC). In marine environments, using a lower water to cement ratio (w/c) has effectively increased the corrosion resistance, compressive strength and durability of SWSSC; besides, combining the mix with pozzolans such as GGBS minimised the risk of corrosion.