Near-to-surface properties affecting bond strength in concrete repair

Abstract

Abstract:One of the main processes for repairing concrete structures is patch repair.Efficiency and durability of a repaired system depends on the bond between concrete substrate and repair material. By increasing the surface roughness, the surface treatment of concrete substrate can promote mechanical interlocking that is one of the basic mechanisms of adhesion. Nevertheless, some problems may arise from "co-lateral" effects of the treatment, especially due to the development of microcracks inside the substrate. In the presented paper, the effect of concrete substrate surface preparation has been characterized by roughness measurement, description of microcracking in the near-to-surface layer and a pull-off cohesion test. After repair, pull-off bond strength has been evaluated. It is concluded that selection of a suitable surface treatment technique should be preceded by the analysis of its aggressiveness in relation to the concrete substrate strength. A procedure for bond strength estimation using multiple regression approach, based on parameters describing surface quality really generated from various roughening techniques, is then proposed.

On the evaluation of interface quality in concrete repair system by means of impact-echo signal analysis

“…SRI and fhs, two parameters whose statistical significance was already demonstrated by Courard et al [19], have been introduced into the correlation model. As a result multiple regression correlation coefficients R increased up to 0.70 for Group A and 0.85 for Group B respectively, as presented in Table 5.…”

“…The effect of surface quality on impact-echo signal was investigated for two groups of concrete substrates ( Table 1). Effect of near-to-surface properties on bond strength for those groups was discussed in previous paper by Courard et al [19].…”

“…4), resulting from different surface preparation techniques. In [19] it was concluded that surface tensile strength is an accurate parameter characterizing the quality of substrate prior to repair and is easier to evaluate than density of microcracks.…”

“…3) [19] and surface tensile strength (f hs ) defined in EN 1504-10 and measured according to EN 1542 (Fig. 4), resulting from different surface preparation techniques.…”

Performance of Cement-Based Patch Repair Materials in Plain and Reinforced Concrete Members

“…The treatment of a concrete substrate is commonly used for cleaning, removing the laitance layer, and roughening the surface. However, it can induce micro cracking if it is not well operated with regard to the quality and strength of concrete (Courard et al 2006;Courard et al 2014;Garbacz et al 2005;Liu et al 2014;Qian et al 2014).…”