Introduction of Ferro Cement

• Ferro cement is a form of reinforced concrete using closely spaced multiple layers of mesh and/or small diameter roads completely infiltrated with, or encapsulated in, mortar.
• When building Ferro-cement structures the sand/cement mortar is applied to the reinforcing wire with a trowel, never poured like common concrete work. Often a form is used to provide the desired shape.
• Ferro cement is a form of reinforced concrete using closely spaced multiple layers of mesh and/or small diameter rods completely infiltrated with, or encapsulated in motor.
• Ferro cement is a type of thin wall reinforced concrete, commonly constructed of hydraulic cement mortar, reinforced with closely spaced layers of continuous and relatively small size wire mesh. The mesh may be made of metallic or other suitable materials.

Techniques of manufacturing

• Hand plastering
• Semi-mechanised process
• Centrifuging and guniting

Material used in Ferro cement

• Cement mortar mix
• Skeleton steel
• Steel mesh reinforcement or fibre-reinforced polymeric meshes

Chemical Admixture in Ferro Cement

• Water reduction, with strength and reduces permeability.
• Air entrainment, which increases resistance to freezing and thawing.
• Suppression of reaction between galvanized reinforcement and cement.

Cement Mortar Mix

• Ordinary Portland cement and fine aggregate matrix is used.
• The matrix constitutes 95% cement mortar & 5% wire mesh of the composite.
• Sand, occupies 60 to 75% of the volume of the mortar.
• Plasticizers and other admixtures are used.

Steel Mesh Reinforcement

• Consists of galvanized steel wires of diameter 0.5 to 1.5mm, spaced at 6 to 20mm centre to centre.
• Welded wire mesh has hexagonal or rectangular openings.
• Expanded-metal lath is also used made from carbon, glass etc.

Properties of Ferro Cement

• It is a very durable,  cheap and versatile material.
• Better impact and punching shear resistance.
• Undergo large deformations before cracking or high deflection.
• Low w/c ratio produces an impermeable structures.
• Less shrinkage, and low weight.
• High tensile strength and stiffness.

Cost effectiveness

• Depends on type economic system and applications.
• Relative cost of labor.
• Doesn’t need heavy plant or machinery.
• Low cost construction materials are used.

Advantages of Ferro-Cement

• 20% savings on materials and cost.
• Suitability for pre-casting.
• Flexibility in cutting, drilling and jointing.
• Very appropriate for developing countries, labor intensive.
• Good impermeability.
• Fabricated into any desired shape.
• Ease of construction, low weight and long lifetime.
• Better resistance against earthquake.

Disadvantages of Ferro Cement

• Corrosion of the reinforcing materials due to the incomplete coverage of metal by mortar.
• It is difficult to fasten to Ferro cement with bolts, screws, welding and nail etc.
• Large no of labors required.
• Cost of semi-skilled and unskilled labors is high.
• Tying rods and mesh together is especially tedious and time consuming.
• Low ductility.
• Susceptibility to stress rupture failure.
• It can be punctured by collision with pointed objects.

Applications

• Boats, fishing vessels, barges, cargo tugs, flotation buoys.
• Water tanks, sedimentation tanks, swimming pool linings, well casings, septic tanks, etc.
• Grain storage bins, silos, canal linings, pipes, shells for fish and poultry farms.
• Houses, community centers, precast housing elements, corrugated roofing sheets, wall panels, etc.
• Biogas digesters, biogas holders, incinerators, panels for solar energy collectors, etc.
• Mobile homes, Kiosks, wind tunnel
• Silos and bins
• Bus shelters
• Pedestrian bridges
• Soil stabilization
• Chemical resistant treatment
• Precast Ferro cement structures

Conclusion

• Ferro-cement is used often because the construction made from it are more resistance to earthquakes. It has a wide range of other uses including sculpture and prefabricated building components.