● ●
● ●
● ●
● ●
Concrete density and compressive strength
test;
Steel tensile strength testing;
Petrography examination (water-cement
ratio, constituents of aggregate, cement-
aggregate bond, micro-crack, homogeneity
of concrete mix, etc.);
Thermoluminescence test (to determine
the burn degree).
The concrete carbonation depths for 16
selected reinforced concrete elements were
between 2mm to 25mm from the surface of the
concrete. It is noted that the depth of damage
caused by carbonation was not beyond the
concrete cover area.
From the compressive strength test, the
estimated in-situ concrete cube strength
for cores extracted from thirteen selected
reinforced concrete elements ranged between
15.0 N/mm 2 and 27.0 N/mm 2 with mean value
of 23.2 N/mm 2 and standard deviation of 3.55.
Meanwhile, the density measured from 13 cores
ranged between 2,279 kg/m 3 and 2,409 kg/m 3
and none of elements tested were below the
acceptable limit.
Rebound hammer tests were carried out on 26
randomly selected reinforced concrete elements.
The test results show that the rebound numbers
ranged between 25 and 45 with an average of 33.
Based on steel tensile test results obtained
from three mild steel bar samples and five high
yield steel bar samples, the yield stresses ranged
between 327.1 N/mm 2 and 342.9 N/mm 2 for
mild steel bars and b e t w e e n 368.5 N/mm 2
and 420.6 N/mm 2 for high yield steel bars. None
of the elements tested were below the acceptable
limit, 356.7 N/mm 2 for high yield steel, and 217.5
N/mm 2 for mild steel.
From the petrography examination of two core
samples, it was revealed that the top 35mm of the
concrete was estimated to have been subjected
to a temperature in excess of 300°C but not more
than 600°C. The concrete mass beyond the depth
of 35 mm was estimated to have been subjected
to a temperature of not more than 300°C. The
strength of the top 35mm of the concrete reduced
significantly.
The concrete thermoluminescence test of two
core samples showed that the samples had been
subjected to a temperature of between 400°C and
500°C. Significant loss of strength of concrete
commences at 300ºC.
It can be seen from the test results, the
estimated temperature reached during the fire
was not more than 600°C.
Conclusion
The relatively high concrete fire-resistance
means that fire-damaged concrete structures
are often capable of being repaired rather
than replaced. By using forensic engineering
techniques, one can assess the extent of
fire damage of structures. This can provide
substantial savings in capital expenditure and
also savings in consequential losses by repairing
rather than demolition. After assessment of the
structure based on the condition of damaged
concrete element, relevant repair techniques
can be applied. Current guidance for undertaking
assessment, design and repair of fire-damaged
concrete structures is available in Technical
Report No. 68 by The Concrete Society.
REFERENCE
Concrete Society. (2008). Technical Report No.
68 - Assessment and Repair of Fire-Damaged
Concrete Structures.
Ingham, J. (2009). Forensic engineering of fire-
damaged concrete structures. In Institution of
Civil Engineers’ Fourth International Conference
on Forensic Engineering (pp. 393–402). London:
Thomas Telford Ltd.
Mohd, M. F. (2018). Assessment of concrete
element subjected to elevated temperature.
Universiti Teknologi Malaysia.
Osman, M. H., Sarbini, N. N., Ibrahim, I. S., Ma, C.
K., Ismail, M., & Mohd, M. F. (2017). A case study
on the structural assessment of fire damaged
building. IOP Conference Series: Materials Science
and Engineering, 271, 12100.
37