Corrosion Sensing Properties of Carbon Black-Based Cementitious Smart Coatings

Abstract

This research explores the sensing capabilities of carbon black (CB)-based cementitious coatings for detecting deformations arising from reinforcement corrosion. The investigation focused on a chlorides-contaminated reinforced mortar element subjected to controlled accelerated corrosion. The objective is to utilize smart coatings’ sensing properties to establish a link between electrochemical attacks and the mechanical effects induced by corrosion. Differently from their more frequent application in the literature, this type of study focused on a chemical attack rather than physical. The sensors were employed to quantify the increase in internal stress and strain due to oxide formation and propagation within the matrix.

The sensors exhibit good sensitivity to corrosion progression identifying attack penetration on the reinforcement and crack formation on the surface. The research was initiated with the implementation of a protocol designed to efficiently accelerate corrosion in reinforced mortar beams, considering varying rebar exposure. Subsequently, a correlation was established between the electromechanical response of the smart coatings and the ongoing corrosion in the substrate, culminating in surface fracture development. Positioned transversally to the beam’s longitudinal direction, all sensors consistently provided accurate crack propagation measurements up to an average width of 116 ± 45 μm. Additionally, the sensors demonstrated the ability to provide crack development measurements also when positioned at varying distances from the directly affected rebar sections. This study expands the use of smart carbon-based coatings, positioning them as multifunctional systems beyond traditional structural applications.