Page 92 - ICJ Jan 2023

POINT OF VIEW COLLECTOR’S EDITION

in higher porosity, lower strength, and more DURABILITY CANNOT BE ACHIEVED
vulnerability to cracking under stress. Thus, when WITHOUT A HOLISTIC APPROACH.....
a structure or a part of the structure is subject A PARADIGM SHIFT IS NEEDED FROM
to extreme weathering and loading cycles, an PRESCRIPTIVE TO PERFORMANCE-
extensive network of internal microcracks may BASED STANDARD SPECIFICATIONS
develop. Under these conditions, the presence
of even a few apparently disconnected surface FOR MATERIALS
cracks of narrow dimensions can pave the way
for penetration of harmful ions and gases into the • The belief that society is being well served
by high-speed construction is questionable
interior of concrete.
due to dramatic changes during the 20th
century. Globally, we do not have a labour
HIGH-EARLY STRENGTH CONCRETE shortage, but we do face a serious problem
MIXTURES ARE MORE CRACK-PRONE of man-made climate change which brings
AND DETERIORATE FASTER IN into the limelight the construction materials
like steel and concrete that are being
CORROSIVE ENVIRONMENTS produced at a great cost to the environment.
Therefore, conservation of materials, not

PARADIGM SHIFTS NEEDED IN THE the construction speed, should be the new
CONSTRUCTION PRACTICE emphasis of the concrete industry in the
21st century.
It is a myth that durable and sustainable concrete
structures can be built according to current practice • The belief that the higher the strength
when the materials and mixture proportioning of concrete, the more durable will be the
are correctly specified and the specifications structure, is not supported by field experience.
are meticulously followed. This is because the High-early strength concrete mixtures are
materials and the construction practice in the 20th more crack-prone and deteriorate faster in
century, developed primarily to meet the need for corrosive environments. Codes should be
high-speed construction, have generally proven amended to stress this point adequately.
harmful to the durability of concrete structures • Many reductionistic or narrow solutions
exposed to severe environmental conditions. We to concrete durability problems have been
have reached a point in time when some sacrifice
in the speed of construction seems to be necessary tried in the past without much success.
if it is important to pursue the goal of durable and We must recognise the fact that durability
environmentally sustainable concrete structures. cannot be achieved without a holistic
This, obviously, will require a change in the approach. In its report, ACI Committee 201,
mindset of owners, builders, and designers. Some Durability of Concrete, does not consider
of the badly needed paradigm shifts in the current the cracking-durability relation, because
construction practice are briefly discussed below. cracking is not a part of the mission of this
committee. Concrete cracking happens to

The Indian Concrete Journal | November 2018 93