Experimental and analytical study of bond behavior between recycled aggregate concrete and steel bars using a pullout test

Abstract

The paper presents the results of an experimental program carried out on 96 concrete pullout specimens prepared with natural and recycled aggregates using 10 and 12 mm diameter deformed steel bars. Steel rebars were concentrically embedded in pullout specimens with two embedded length of 5 and 10 times the rebar diameter. The present work includes six recycled concrete aggregate mixtures and two conventional concrete mixtures with C25/30 and C35/45 target class of compressive strength and S4 class of workability. For both series, specimens were fabricated with different incorporation ratios of fine and coarse recycled aggregates and only coarse recycled aggregates. Tensile load was applied gradually until the pullout failure occurred and the slip between the rebar and concrete was measured at the free and loaded ends for each loading level. Furthermore, systematic observations of failure surface have been made at both macroscopic and microscopic scales. Test results showed that for the same class of compressive strength the bond strength and related failure mechanisms remain very close and the obtained values are, at least, four times higher than the predicted values by Eurocode 2. The experimental results of this study, together with an extensive number of results reported in the literature, were used to describe the variation of bond strength with concrete compressive strength, embedded length, and concrete cover. In addition, an analytical bond‐slip relationship is proposed and the parameters of bond‐slip law were calibrated by an optimization algorithm.

Bond between steel and concrete made with ceramic waste aggregate

“…Siempu and Pancharthi (2017) evaluated the mechanical performance and bond strength between steel rebar and a concrete mixture where fine and natural coarse aggregates were completely replaced by aggregates from construction and demolition waste. Wardeh et al (2017) evaluated the bond between steel rebar and six different mixtures of concrete containing recycled concrete aggregate. In all these studies, the evaluation method of the bond between concrete and reinforcement bars was the pull-out test.…”

Mechanical and fracture properties of recycled aggregate concrete in design codes and empirical models

“…These wastes, which do not undergo any significant physicochemical changes, are often landfilled without recovery, resulting in environmental risks such as water and air pollution as well as the visual impact on the environment. In order to valorize the materials resulting from the deconstruction and also to limit the use of the natural resources, the complete recycling of the concrete seems the promising solution . For this reason, two complementary projects were carried out in France in the last 5 years: the RECYBETON National Project (2012–2017) and the ANR ECOREB Project (2013–2016).…”

“…For this reason, two complementary projects were carried out in France in the last 5 years: the RECYBETON National Project (2012–2017) and the ANR ECOREB Project (2013–2016). The first aims to increase the complete reuse of deconstructed concrete while the second aims to overcome fears for the use of recycled aggregates by providing the tools for predicting the strength of recycled aggregate concretes …”

“…An increase in the binder content is however necessary in order to maintain the class of compressive strength . Numerous studies showed that for the same strength class, the introduction of recycled aggregates induces a decrease in the elastic modulus, the tensile strength, and the fracture properties . Moreover, the incorporation of recycled aggregates induces an increase in the peak strain under uniaxial compressive loads …”

Bond behavior between steel reinforcing bars and concrete under dynamic loads

“…2,[9][10][11][12] Among these models, the most adopted ones in the analysis and design of RC structures are those models proposed by fib 13 and ACI codes. 14 In recent years, the investigations of bond behavior have been extended to some new scenarios, including corroded bars, 15 recycled concrete, 16 and others. 17 During their lifecycles, RC structures are inevitably subjected to dynamic loads (e.g., earthquakes, explosions, impact loads, etc.).…”