Fire Performance of High-Strength Concrete: A Report of the State-of-the-Art.
Fire Performance of High-Strength Concrete: A Report of
the State-of-the-Art.
(5839 K)
Phan, L. T.
NISTIR 5934; 115 p. December 1996.
Available from:
National Technical Information Service
Order number: PB97-132153
Keywords:
building technology; compressive strength; concretes;
elastic moduli; spalling; fire tests; high strength
concrete; test methods; thermal behavior; codes;
temperature
Abstract:
A review is presented of experimental and analytical
studies on the performance of concrete when exposed to
short-term, rapid heating as in a fire. Emphasis is
placed on concretes with high original compressive
strengths, that is, high-strength concretes (HSC). The
compiled test data revealed distinct difference in
mechanical properties of HSC and normal strength
concrete (NSC) in the range between room temperature and
about 450 deg C. The differences decreased at
temperature above 450 deg C. What is more important is
that many test programs, but not all, reported that HSC
experienced explosive spalling during the fire tests.
The spalling is theorized to be caused by the buildup of
pore pressure during heating. HSC is believed to be
more susceptible to this pressure build up because of
its low permeability compared with NSC. However, no
explanations were found for why spalling did not occur
in all HSC specimens. Analytical models for predicting
the buildup of internal pressure during heating are also
reviewed. The report also includes a comparison of test
results with existing code provisions on the effects of
fire on cocnrete strength. It is shown that the
Eurocode provisions and the CEB design curves are more
applicable to NSC than to HSC. In fact, these provisions
are unsafe when compared with HSC test results. The
review showed a lack of experimental data for
lightweight HSC heated under a constant preload to
simulate the stress conditions in HSC columns. The
report concludes with an outline of a research plan to
gain an understanding of the failure mechanisms in fire
exposed HSC. The ultimate goal of the research is to
develop tools for predicting the performance of HSC when
exposed to fire.
Building and Fire Research Laboratory
National Institute of Standards and Technology
Gaithersburg, MD 20899