Reactive powder concrete – change in compressive strength and modulus of elasticity at high temperature

Abstract

This paper presents the results from an experimental study on the behaviour of Reactive Powder Concretes (RPC) at high temperature. The exposure to high temperature is related to the potential risk of fire. A previous study has shown that RPC is prone to spalling in such circumstances and for this reason polypropylene fibres were used in RPC concrete to prevent this occurring. The addition of PP fibres reduces the risk of spalling due to an increase in permeability, however it reduces the initial compressive strength of the RPC material by approx. 20 %. The results demonstrate that the strength of concrete along with the modulus of elasticity decrease with increasing temperature. Two experimental concretes were prepared and prismatic specimens, 40x40x80mm in size, were cast from each mixture and tested in compression after being submitted to the high temperature. The relative value of compressive strength course for both types of concrete shows a similar development. The change in modulus of elasticity with temperature was determined from the stress-strain relationship and compared with the dynamic modulus of elasticity determined with the use of a Pundit plus ultrasonic pulse velocity defectoscope.