Residual mechanical strength of concrete exposed to high temperatures – international standardization and influence of coarse aggregates

Abstract

The exposure of concrete to high temperatures affects its mechanical properties, reducing its compressive strength, tensile strength and modulus of elasticity. The reduction factors of these properties have been the target of several studies over the years, producing conflicting results. This article addresses the key factors related to such disparity, highlighting the influence of standardization and types of coarse aggregates, as well as an overview of the study of the mechanical properties of concrete exposed to high temperatures in the last years, foregrounding research in several countries and Latin American experience. This article also shows results from a Brazilian experimental study concerning the residual mechanical strength of concrete (NSC and HSC) exposed to temperatures from 100 to 900 °C at 1 °C/min, with or without preheating, in which three types of coarse aggregates—basaltic, granitic and limestone—were used, as well as RILEM recommendations. There is no precedent in Latin America for a study conducted for this purpose and which has applied such international recommendations. Through comparison with bibliographic references and statistical analysis, the effects of the type of coarse aggregate, preheating of samples and types of addition being used were evaluated, contributing to the structural analyses of burning structures.