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Mechanical Properties of High-Strength Concrete at Elevated Temperatures.

pdf icon Mechanical Properties of High-Strength Concrete at Elevated Temperatures. (8654 K)
Phan, L. T.; Carino, N. J.

NISTIR 6726; 102 p. March 2001.

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compressive strength; concretes; experiments; elastic modulus; explosive spalling; spalling; high strength concrete; temperature


This report describes results of NIST's experimental program on the effects of elevated temperature exposure on the mechanical properties of high strength concrete (HSC). Mechanical properties were measured by heating, with and without preload, the 100 mm x 200 mm HSC cylinders to different target temperatures, and loading them to failure while hot or after the specimens had cooled to room temperature. The specimens were heated at a slow heating rate of 5 deg C/min to prevent large thermal gradients. The maximum target temperature was 600 deg C. The test specimens were made of four HSC mixtures with water-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. Experimental results indicate that HSC with lower w/cm and with silica fume have higher relative residual strength after elevated temperature exposure than those with higher w/cm and without silica fume. The differences in relative modulus of elasticity are less significant. The tendency for explosive spalling, however, was greater in HSC specimens with lower w/cm. An examination of the internal heating characteristics of the cylinders indicted that the loss of capillary and chemically bound water was more restricted in the mixtures that had the higher tendency for spalling.