Thermal stability of different siliceous and calcareous aggregates subjected to high temperature

Abstract

The goal of this study is to improve the knowledge of the deterioration of aggregates subject to high temperature phenomena and to characterise the physical and chemical transformations they undergo. Twenty one (21) aggregates of different mineralogical composition were exposed at temperatures up to 750 ◦ C. The behaviour of siliceous and calcareous aggregates undergoing high temperature has been examined with respect to the evolution of physical, chemical and mineralogical properties. Aggregates constitute about 60% to 70% of the volume of concrete. This suggests that concrete properties are very likely influenced, if not dependant by those of the constituting aggregates. When a concrete structure is subject to high temperature as a building fire, it is required that people can leave safely before the structure's collapse. The single recommendation of the Part 1-2 of Eurocode 2 (1) concerning aggregates is a distinction between siliceous and calcareous aggregates. The National Union of Aggregates Producer (UNPG) is a French professional organization that represents companies producing aggregates for building industry and public works. The aggregate's quality is a paramount criterion for concrete durability. Aggregate's quality is deteriorated by extraction processes in addition to the occurrence of original cracks or impurities due to rock geological heritage. The goal of this study is to improve the knowledge of aggregate's deterioration phenomena. The results will be useful to explain the aggregate's behaviour and their contribution to the concrete spalling during fire exposure.