Effects of urea on durability of reinforced concrete

Abstract

This Paper describes a laboratory investigation of the influence of urea on the mechanical properties of concrete and the corrosion of the reinforcing steel. The mechanical properties of concrete cubes, exposed to weekly cycles of drying and submersion in a variety of urea or salt solutions, were investigated by non-destructive and destructive monitoring at regular intervals. The microstructure of concrete was analysed by means of mercury intrusion porosimetry. The resistance to freezing and thawing of concrete prisms was studied by recording weight loss, dynamic modulus of elasticity and ultrasonic pulse velocity. The effects of urea on reinforcement corrosion were investigated by monitoring changes in the corrosion potentials and corrosion rates of steel electrodes, embedded at four depths of cover in concrete slab specimens exposed to various methods of treatment with urea or salt solutions.