Ferrocement for future generations
The most significant contribution of ferrocement is that
most of the structures made of steel can also be constructed in ferrocement,
claims J.A. Desai, Managing Director, J.A. Desai Ferrocements Pvt. Ltd
Corrosion is the phenomena which causes deterioration of
steel. The menace of corrosion has been increasing along with the increasing use
of steel for various purposes such as building and construction, automobiles,
shipbuilding, transmission line and telecommunication towers, substation
structures, bridges and jetties, irrigation structures like gates, water supply
lines and pipes. This is a negative aspect of the use of steel. However, there
being no other alternative, the same has been accepted with the provision of
corrosion resistant treatment such as painting, galvanising, epoxy powder
coating application etc. Steel is being used so widely that mineral resources
are depleting fast.
As a remedy, a wide range of corrosion protection systems have been developed.
These are not permanent and have to be applied again and again, causing
recurring expenditure. In India, the cost of prevention of corrosion and
management is estimated at Rs 1.5 lakh crore every year. In spite of these
anti-corrosive treatments, corrosion does take place and basic structures have
to be replaced at certain intervals of time. Similarly, the cost of corrosion in
USA is estimated at $276 billion every year.
Against all these odds, a material called ferrocement has been developed, and it
helps prevent corrosion. The most significant contribution of ferrocement is
that most of the structures that are made of steel can also be constructed in
ferrocement. Structures constructed in ferrocement will resist corrosion fully
with nil/negligible maintenance. Ferrocement section in form of 'I', tee channel
or angle as in case of steel can be manufactured with many added advantages.
Even ferrocement anticorrosion treatment can be carried out effectively on
existing steel structure surfaces. Such coating done in the UK has lasted over
Ferrocement structures, as alternatives to steel structures, will resist urban
polluted atmosphere to a large extent. Where there is severe acidic atmosphere,
low-cost treatment should be sufficient. There are instances of ferrocement
structures lasting for about eight decades or more without any maintenance.
Ferrocement is also an environment-friendly material.
Ferrocement structurals are just the replacements for steel structurals used in
industrial structures for pharmaceuticals, chemicals, warehousing, refinery,
thermal power, irrigation, treatment plants and other industries. Steel used in
marine structures such as boats, ships, barges, tugs and docks can also be
replaced with ferrocement structurals. Regarding marine structures such as
boats, the United National Industrial Development Organisation praised
ferrocement in its publication 'Ferrocement Boats' as early as 1972. In short,
wherever steel is used in civil engineering and other industries, ferrocement
structurals can be used with great advantage with regard to corrosion and cost
Ferrocement has been in use for about 50 years for construction of boats, ships,
roofs, irrigation structures like gates and other allied structures as well as
houses, swimming pools, bridges, walkways, jetties and water storage tanks.
Lakhs of square feet of ferrocement plates have been constructed and used in
water storage structures, roofing etc. Ferrocement structurals such as RSJ,
channels and I section have been used in construction.
Use of ferrocement will result in saving in cement and steel to the extent of 50
per cent in building and other allied industries. At the same time, the
structures constructed with ferrocement will be more efficient, durable, strong
and maintenance free. This will be an added saving in the economy in addition to
saving in huge cost of corrosion management and prevention. Ferrocement
structures last much longer than similar steel structures.
The use of ferrocement will reduce the requirement of raw materials such as iron
ore for steel and limestone etc., for cement. Ferrocement can also contribute in
light of the recent debate on banning the export of iron ore, which is depleting
very fast. Cement manufacture is also being modified so as to use less
limestone. As such, ferrocement will be a boon to the nation as well as future
'Best alternative to RCC and steel'
— J.A. Desai, Managing Director, J.A. Desai
Ferrocements Pvt. Ltd
What is ferrocement?
Ferrocement is a thin section material precast/cast insitu and fabricated in the
form of panels or appropriate shapes and sizes consisting of light structural
steel, wire mesh layers, high quality cement matrix, admixtures, super
plasticizers, fibres etc. The high quality cement matrix has a ratio of 1:2 to
1:2.5 or so. The cost of ferrocement is not expressed in per tonne as it is not
powder like cement nor is it expressed in per cubic metre; it is expressed as Rs
2,500-5,000 per surface area or Rmt of column or beam. Ferrocement can be
described as a modified form of reinforced cement concrete with elimination of
coarse aggregate, large-size reinforcement, sometimes shuttering, but having
quite different properties with increased strength.
Ferrocement is the best alternative to RCC and steel. It is strong, durable,
waterproof, corrosion preventive and fireproof up to 750° C for long periods,
say, 48 hours, which can be extended. Apart from rainwater harvesting, there are
many applications. For instance, it can be used for insulation cost reduction
and as a very effective material for disaster prevention and management.
How does ferrocement prevent corrosion?
Ferrocement surfaces have wire mesh layers. This wire mesh prevents crack
formation at the surface of the ferrocement and travels further deep into the
material. Ferrocement has a crack-arrest mechanism and is a denser material
compared to concrete with hard surface. Structures like ferrocement pools,
walkways and jetties are constructed using ferrocement footings, beams, columns,
floors, walls, roofs, decks, railings etc., and a lot goes into the manufacture
of beams, columns, floors etc.
In terms of cost, how does it compare with steel and cement?
It can be said that ferrocement is generally costly, but sometimes on job-to-job
basis, it turns out cheaper. Ferrocement is competitive considering the
lifecycle cost with least maintenance. Being a structural material, it should be
compared with structures like reinforced cement concrete, prestressed concrete
structures or steel structures.
How does ferrocement help lower the requirement of raw materials, as in iron
ore for steel and limestone etc., for cement?
Ferrocement is a strong material and so a small quantity of ferrocement replaces
a large quantity of RCC. Ferrocement structures consist of less steel and
high-quality cement matrix with certain manufacturing techniques. As a result,
the requirement of steel is reduced considerably but the end result and
durability is same. There is also saving in mineral ores. I anticipate that
existing steel plants producing structural steels like joists, channels and
angles will be modified to ferrocement structural producing plants in future,
say, in five to 10 years.
If ferrocement has so many advantages, why is it not popular in construction?
We have come across a large number of engineers and architects who also wanted
to know that if ferrocement had advantages, then why it was not replacing steel
and cement to a large extent. Our answer was that if they were convinced about
this material then they should adopt it in actual practice. But they have not
done so. There are also some professionals who, without a proper study of the
product, have said that ferrocement was not a good material. The main reason is
that they compare ferrocement to RCC.
[May 19-25, 2008]