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 one-and-a-half decade.
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 reduction.
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 generations.

'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.