High temperature behaviour of a wide petrographic range of siliceous and calcareous aggregates for concretes

• Twenty-one aggregates of various mineralogical compositions are exposed to heating.
• For siliceous aggregates, quartz crystallinity has an influence on spalling sensitivity.
• Thermal expansion of siliceous aggregates is related to quartz content, especially after 450 °C.
• Thermal expansion of calcareous aggregates varies between 1 and 1.33% at 750 °C.
• Decarbonation occurs for dolomite at a lower temperature than for calcium carbonate.

This study aims to characterize the physical and chemical transformations of aggregates undergoing high thermal solicitation in order to better understand their deterioration in this context. Twenty one (21) aggregates of various mineralogical compositions are exposed to heating/cooling cycle up to 750 °C. The thermal behaviour of siliceous and calcareous aggregates depends on several parameters related to mineralogical structure including granular texture, crystallinity of minerals, porosity and density. Thermal properties like expansion and weight loss related to chemical reactions show important variations among the siliceous aggregate category. The thermal behaviour of aggregate is dependant of its mineralogical and chemical compositions.