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Mechanical Properties of High-Strength Concrete at Elevated Temperatures



Long T. Phan, Nicholas J. Carino


This report describes results of NIST's experimental program that focuses on effects of elevated temperature exposure on mechanical properties of hing strength concrete (HSC). Mechanical properties were measured by heating, with and without preload, the 102 mm x 204 mm HSC cylinders to steady state thermal conditions at a target temperature, and loading them to failure while hot or after the specimens had cooled to room temperature. The test specimens were made of four HSC mixtures with water-to-cementitious material ratio (w/cm) ranging from 0.22 to 0.57, and room-temperature compressive strength at testing ranging from 51 MPa to 93 MPa. Two of the four HSC mixtures contained silica fume. The specimens were heated to a maximum core temperature of 600 degrees C, at a heating rate of 5 degrees C/min. Experimental results indicate that HSC with lower w/cm and with silica fume retain more residual strength after elevated temperature exposure than those with higher w/cm and without silica fume. The differences in modulus of elasticity are less significant. However, the potential for explosive spalling increased in HSC specimens with lower w/cm. An examination of the specimen's heating characteristics indicate that the HSC mixtures which experienced explosvive spalling had a more restrictive process of capillary pore and chemically bound water loss than those which did not experience spalling.
NIST Interagency/Internal Report (NISTIR) - 6726
Report Number


building technology, compressive strength, concrete, elastic modulus, experiment, explosive spalling, fire, high-strength concrete, temperature


Phan, L. and Carino, N. (2001), Mechanical Properties of High-Strength Concrete at Elevated Temperatures, NIST Interagency/Internal Report (NISTIR), National Institute of Standards and Technology, Gaithersburg, MD, [online], (Accessed July 13, 2024)


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Created March 1, 2001, Updated February 19, 2017