Ferro cement

Ferro cement technique, though of recent origin, have been extensively used in many countries, notably in U.K. There is a growing awareness about the advantages of this technique, all over the world. It is well known that conventional reinforced concrete members are too heavy, brittle, cannot be satisfactorily repaired if damaged, develop cracks and reinforcements are liable to be corroded. The above disadvantages of normal concrete make it efficient for certain types of work.

Ferro cement is a relatively new material, consisting of wire meshes and cement mortar. This material was developed by P.L.Nervi, an Italian architect and engineer, in 1940. It consists of closely spaced wire meshes, which are impregnated with rich cement mortar mix. The wire mesh is usually of 0.5 to 1.0mm dia wire at 5mm to 10mm spacing, and cement mortar is of cement sand ratio of 1:2 with water/cement ratio of 0.4 to 0.45. The ferrocement elements are usually of the order of 2 to 3cm in thichness with 2 to 3mm external cover, to the reinforcement.

The steel content varies between 300Kg to 500kg per cubic meter of mortar. The basic idea behind this material is that, concrete can undergo large strains in the neignbourhood of the reinforcement, and the madnitude of strains depends on the distribution and subdivision of reinforcement, throughout of the mass of concrete.

Ferrocement is widely accepted in UK as about building material. It has also found various other interesting civil engineering applications. The main advantages are simplicity of its construction, lesser weight of the elements due to their small thickness, its high tensile strength, less crack widths compared to conventional concrete, easy repairability, non-corrosive nature and easier mould ability to any required shape.

There is also saving in basic materials namely, cement and steel. This material is more suitable to special structures like shells, which have strength through forms and structures like roofs, silos, water tank and pipe lines.

The material is under active research in various countries, and attempts are being made to give a sound theoretical backing to establish the material behavior. This is a highly suitable material for precast products, because of its easy adaptability to prefabrication and lesser dad weight of the units cast. The development of ferro-cement depends on suitable casting techniques for the required shape. Development of proper prefabrication techniques for ferro-cement is still not a widely explored area, and gap needs to be filled.