Experimental Characteristics Impact on Bond Strength at Elevated Temperatures: A Literature Review

Abstract

Evaluating structure strength characteristics post-fire or when subjected to prolonged periods of elevated temperature is essential, as these conditions degrade concrete strength, specifically bond strength between rebar and concrete. Residual bond strength can be determined through direct pull-out or beam tests. Several factors influence bond strength at normal temperatures, including the properties of the concrete and the rebar, the specimens' characteristics, the concrete cover, and the stress state of the specimen during testing. The situation becomes more complex at higher temperatures as heating introduces additional variables. In this context, the bond is influenced by the heating characteristics of the specimen, such as the heating rate and cooling process. While researchers acknowledge these factors, the degree of their impact is still a subject of debate. This paper aims to review the existing literature on bond strength at elevated temperatures and to explore how various factors influence this strength under such conditions. The study gathers data to examine the bond-slip curve at high temperatures, the effects of experimental variables on bond strength, and the residual bond strength after exposure to elevated temperatures. Key experimental characteristics considered in this paper include the heating procedure, heating rate, heating duration, cooling regime, properties of the rebar, properties of the specimen, and the relationship between concrete strength and bond strength.