Mechanical Properties of High-Strength Concrete at Elevated Temperatures.
Mechanical Properties of High-Strength Concrete at
Phan, L. T.; Carino, N. J.
NISTIR 6726; 102 p. March 2001.
Available from: National Technical Information Service
(NTIS), Technology Administration, U.S. Department of
Commerce, Springfield, VA 22161.
1-800-553-6847 or 703-605-6000;
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Order number: PB2002-101495
compressive strength; concretes; experiments; elastic
modulus; explosive spalling; spalling; high strength
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.