Article
based on contribution by: Mr Saransh
Kataria & Mr Satyajeet
Harne , Civil
engineering Students, S.G.S.I.T.S, Indore
Introduction
A
fire in the English Channel tunnel in
1996, caused severe damage to tunnel rings owing to the spalling
of
concrete and resulted in injuries to eight people and a property loss
of £50
million. The spalling was attributed to the High Strength of the
concrete.
Starting
in the 1980s concretes with increasing compressive strengths started to
become
commercially available and primarily utilized in the construction of
high-rise
buildings. High-strength concrete (HSC) provides a high level of
structural performance,
especially in strength and durability, compared to traditional,
normal-strength
concrete (NSC).
.
Use
of HSC offered economic advantages because concrete column
size could be reduced, thus permitting more usable space. It also had
application in the construction of prestressed girders for bridge
construction
and other specialized applications like offshore structures and
infrastructure
projects in which high performance (e.g., low permeability) is
required.
Today
concretes having compressive strengths up to 140 MPa and above can be produced,
with strengths of 172 MPa and above
attainable through use of special
fabrication procedures.
Generally,
concrete structural members perform well under fire situations. Studies show,
however, that the performance of HSC differs generally from that of NSC
and may
not exhibit good fire performance. Spalling under fire conditions is
one of the
major concerns with HSC.
References: 1.
"Fire Performance of High-Strength
Concrete Structural Members" by V.K.R.Kodur 2.
"The effect of fire-Concrete
Spalling" from http://www.promat-tunnel.com