Effects of Aggregate Mineralogy on the Thermal Expansion Behavior of Concrete

Abstract

The coefficient of thermal expansion (CTE) of concrete is greatly influenced by thermal behavior of aggregates due to their large volume proportion in concrete. In order to understand the effect of coarse and fine aggregate on the thermal behavior of concrete, the average CTE of concrete with granite and dolomite as coarse aggregate and granite-originated manufactured sand and alluvial natural sand as fine aggregate were measured. The results showed that concretes composed of high stone volume of granite with manufactured sand (MS) have the lowest CTE value (4.44μe>/°F) whereas those composed of low stone volume of granite with siliceous natural sand (NS) have the highest CTE value (5.42μe/°F). Testing results demonstrate that the effect of fine aggregate in concrete mixture is more dominant while using granite as coarse aggregate rather than dolomite. In addition, this study characterized the microstructure and chemical composition of both coarse and fine aggregates by utilizing petrographic analysis tools. Testing results were used to identify minerals showing varied thermal behavior and also to correlate with the measured CTE values of the concrete specimens so that better understanding of thermal expansion behavior of concrete could be made.