Evaluation of Reinforcement Corrosion in Cementitious Composites Modified with Water Treatment Sludge

Abstract

The water treatment sludge (WTS) is a residue composed of organic and inorganic matter in a solid, liquid, and gaseous state that has a variable composition concerning its physical, chemical, and biological characteristics. The irregular disposal of WTS can promote harmful changes to the environment, such as reduction of dissolved oxygen and increase in the concentration of aluminum and other metals in the receiving watercourses. To propose a suitable purpose for this residue, this work evaluated the physical and mechanical properties of the concrete and corrosion resistance of the reinforcement in a cementitious composite using WTS in replacement to the natural sand. A conventional concrete and a conventional mortar were used as a reference and a 3% WTS-content concrete, and a 3% WTS-content mortar were prepared to evaluate the WTS influence in mechanical properties and corrosion resistance. By electrochemical measurements, it was observed that the resistance of the cementitious matrix was not altered by WTS addition. Regarding steel resistance, the WTS may promote a higher susceptibility to frame corrosion, which can be correlated to the lower pH than reference medium (REF). The concrete reinforcement characterization indicates that concretes with WTS can be used as reinforced concrete structure in urban areas.