Nondestructive assessment of corrosion of reinforcing bars through surface concrete cracks

Abstract

Degradation of reinforced concrete (RC) structures is a serious safety problem affecting all industrialized countries, and the economical aspect of this problem cannot be neglected. One of the main reasons for the degradation of RC is the corrosion of steel reinforcing bars as a result of concrete cover cracking and reduction in bar cross section. As a consequence, the structural capacity of RC elements decreases progressively as degradation develops. Nondestructive testing and/or analytical formulation represent high-quality rapid methods for evaluating the corrosion penetration of bars and provide useful parameters for designing retrofits. This paper presents an additional tool that can be used to evaluate and assess the vulnerability of existing structures in terms of the determination of bar cross section lost. Using simple charts and formulas, this can be accomplished by calculating reinforcing bar cross section loss due to corrosion by measuring external crack widths in the concrete cover. Predictions were obtained by using two analytical models developed. These predictions have been satisfactorily compared with both the literature and new experimental results, as well as with previous empirical models available in the scientific literature. The experimental results were obtained by corroding real-scale concrete specimens reinforced with smooth and ribbed bars (according to old and modern building codes) using 3.5 wt% sodium chloride solution and an applied current

Experimental response and fiber‐reinforced cement composites strengthening of real reinforced concrete columns with poor‐quality concrete

“…Many of the existing reinforced concrete (RC) structures built between the 1960s and 1970s are vulnerable to earthquake loads due to poor material properties, lack of transverse reinforcement, degradation of the structural materials, corrosion of longitudinal reinforcements, cover spalling and reduction of the bearing load capacity . This increases the need to develop reliable assessment procedures and efficient and sustainable repair/retrofit interventions for existing RC buildings …”

“…Many of the existing reinforced concrete (RC) structures built between the 1960s and 1970s are vulnerable to earthquake loads due to poor material properties, 1-5 lack of transverse reinforcement, degradation of the structural materials, corrosion of longitudinal reinforcements, cover spalling and reduction of the bearing load capacity. [6][7][8] This increases the need to develop reliable assessment procedures and efficient and sustainable repair/retrofit interventions for existing RC buildings. [9][10][11] Nowadays, available guidelines and standards 12,13 allow the use of nondestructive tests (NDTs), in conjunction with destructive tests (DTs), to assess the uniformity of materials and to characterize the concrete compressive strength.…”

Structure, performances, and formation mechanism of cement composites with large‐scale regular microstructure by distributing uniformly few‐layered graphene oxide in cement matrix

“…The mainly reason is that cement hydration products are disordered resulting in forming lots of cracks and pores in the cement composites, which affect mechanical properties and durability of cement composites . Therefore, the formation of highly compact and regular microstructure is very important for strength and durability of cement composites . The cement will carry out a complex chemical reaction and produce many complex products in forming cement composites, which are summarized in Table .…”

Experimental evaluation of the residual compression strength and ultimate strain of chloride corrosion‐induced damaged concrete

“…Past studies showed cracking in the concrete cover plays important role in inelastic buckling behavior of longitudinal steel reinforcement of RC columns . Bossio et al presented a relationship between external cracks width and bar section loss due to reinforcement corrosion.…”