AN EXPERIMENTAL STUDY ON THE COMPRESSIVE STRENGTH OF CONCRETE AND BOND STRENGTH BETWEEN STEEL BARS AND CONCRETE EXPOSED TO ELEVATED TEMPERATURES UP TO 700℃

摘要

The bond between concrete and reinforcement is the most important property on emerging reinforced concrete. By means of this property, concrete and reinforcement resist together against the load applied to the reinforced concrete structural members and act to complement each other. It is known that, when exposed to elevated temperatures as a result of fire, load carrying capacity and resistance to the external effects of structural members decrease. In this reduction, it is important to know the proportion of the bond between concrete and reinforcement and the effect of temperature difference to the bond strength.In this study, concrete-reinforcement bond and concrete compressive strength are investigated on the samples which are exposed to elevated temperatures up to 700℃. For this study, deformed steel bars of 8 mm diameter are embedded in to concrete blocks with embedment length of 16 cm; and unreinforced specimens are also produced for strength evaluation. Pull-out and compressive strength tests are carried out on the specimens and the effects of elevated temperatures on the bond strength and compressive strength are investigated by comparing the results against unheated specimens. Increases in both bond and compressive strength are observed for temperatures up to 150℃, however, there is decrease in the bond and compressive strength for all other temperatures.