Durability of Concrete Made with Different Chemical Admixtures Under Marine Splash Environment

Abstract

A detailed investigation on the concrete specimens made with different chemical admixtures was carried out after 10 years of exposure in the marine splash environment. Chemical admixtures include air-entraining admixture (vinsol), water-reducing admixture (lingosulfonate group), various high-range water-reducing and air-entraining admixtures (naphthalene, melamine, polycarboxyl and amino-sulfonate group), and drying shrinkage reducing mixture (glycol ether plus amino alcohol derivatives). The specimens were tested for carbonation depths, chloride ingress, oxygen permeability, electrochemical and physical evaluations of corrosion of steel bars in concrete, porosity and mineralogy of the mortar portion, and SEM (Scanning Electron Microscopy) investigation of steel-concrete interface. Naphthalene group of high-range water-reducing and air-entraining chemical admixture shows relatively better performance with respect to the strength development and chloride ion ingress in concrete. The use of shrinkage reducing admixture shows no harmful effects after 20 years of exposure. The specially adopted method of casting concrete used in this study causes a formation of good steel-concrete interface that prevents the initiation of corrosion even for water soluble chloride concentration around 1.5% of cement mass.