Material Behavior

Effect of Extreme Temperatures on the Coefficient of Thermal Expansion for Ultra-High Performance Concrete

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Abstract

During the last decade, ultra-high performance concrete (UHPC) has been used in highway bridge connections due to its superior strength and durability. Specifically, UHPC shear keys have been used to reduce joint cracking and enhance transverse load transfer between high strength concrete (HSC) girders of adjacent box-girder bridges. In the calculation of thermal stresses between UHPC and HSC components, the thermal expansion coefficients of the materials are required. In current analysis/design of bridge structures with normal strength concrete, the coefficient of thermal expansion (CTE) is assumed to be constant for temperatures between 32 and 140°F (0 to 60°C). However, recent field analysis of an adjacent box-girder bridge with HSC girders connected using UHPC shear keys has shown that the actual temperature range experience by the UHPC-HSC was 14 to 100.4°F (-10 to 38°C). Furthermore, according to the bridge design procedure specified by AASHTO, temperature ranges between -55 to 125°F (-48.3 to 51.6°C) should be used in the analysis/design of bridges depending on their geographic location within the United States. The main objective of this study was to establish thermal expansion-temperature curves for UHPC and HSC for temperatures ranging from -76 to 140°F (-60 to 60°C). The data was obtained using the Ohio CTE testing method so that the thermal strain could be measured in the air-dry condition. The experimental results revealed the CTE of UHPC tested in this study to be constant for the temperature range considered, with an approximate value of 9.4 x 10-6/°F (16.9 x 10-6/°C). Also, the CTE of HSC is approximately linear in the temperature range from 35 to 70°F (1.7 to 21.1°C), and constant for temperature changes outside this range. An average value of HSC CTE was determined to be 6.0 x 10-6/°F (10.8 x 10-6/°C). The findings of this study are expected to be useful in the design/analysis of bridges to calculate the thermal stresses between UHPC and HSC composite structures.

Keywords: thermal strain, coefficient of thermal expansion, CTE

How to Cite:

Steinberg, E. P., Hussein, H. H., Walsh, K. K. & Sargand, S. M., (2016) “Effect of Extreme Temperatures on the Coefficient of Thermal Expansion for Ultra-High Performance Concrete”, International Interactive Symposium on Ultra-High Performance Concrete 1(1). doi: https://doi.org/10.21838/uhpc.2016.108