Effects of Test Conditions and Mixture Proportions on Behavior of High-Strength Concrete Exposed to High Temperature.
Effects of Test Conditions and Mixture Proportions on
Behavior of High-Strength Concrete Exposed to High
Temperature.
(1034 K)
Phan, L. T.; Carino, N. J.
ACI Materials Journal, Vol. 99, No. 1, 54-66,
January/February 2002.
Keywords:
concretes; high temperature; high strength concrete;
spalling; compressive strength; elasticity; silica fume
Abstract:
Mechanical properties of high-strength concrete exposed
to elevated temperatures were measured by heating 100 mm
x 200 mm cylinders at 5 degrees C/min up to temperatures
of up to 600 degrees C/min. Heating was carried out with
and without a sustained stress, and properties were
measured at elevated temperatures as well as after
cooling to room temperature. Four mixtures with
water-cementitious material ratios (w/cm) ranging from
0.22 to 0.57, and room-temperature strengths ranging
from 51 MPa to 98 MPa, were used. Two of the mixtures
contained silica fume. Measured compressive strengths
and elastic moduli were normalized with respect to room
temperature values, and analysis of variance was used to
determine whether the test method, the value of w/cm, or
the presence of silica fume affected the results. The
influence of these variables on the tendency for
explosive spalling was also examined. Results indicate
that losses in relative strength due to high-temperature
exposure were affected by the test method and w/cm, but
there were significant interactions among the main
factors that resulted in complex behaviors. The presence
of silica fume does not appear to have a significant
effect. Measurements of temperature histories in the
cylinders revealed complex behaviors that are believed
to be linked to heat-induced transformations and
transport of free and chemically combined water.
