Ferrocement or Ferro-cement is a system of construction using reinforced mortar or plaster (lime or cement, sand, and water) applied over an “armature” of metal mesh, woven, expanded metal, or metal-fibers, and closely spaced thin steel rods such as rebars.
Mortar offers a mass and wire mesh offers a tensile strength and flexibility.
Here we will learn about ferrocement, its properties, merits & demerits!
Introduction to ferrocement:
Ferrocement is much thinner than reinforced concrete and the mesh can be formed to any shape without a conventional form, then plastered or mortared by hand.
Ferrocement is a brilliant reinforced concrete, it differs from conventional concrete and has a higher ratio of cement mortar to steel.
By altering the cement / steel ratio to make ferrocement, we really produce a material that reveals properties which might be superior than steel or cement.
Properties of Ferrocement:
- Ferrocement has high tensile strength and stiffness.
- It improves the influence and punching shear resistance.
- Undergo massive deformation earlier than rupture or high deflection.
- It is Light weight.
- A low w/c ratio produces impermeable structures.
- It is a very durable, inexpensive, and versatile material.
material used in Ferrocement:
The particle size of sand should not more than 2.36mm and less than 1.18mm.
More than 2.36mm particle can make the mortar porous and particles less than 1.18mm requires more water to the impermeable structure.
Sand occupies 60- 75% mortar volume.
Reinforcement are effectively used in ferrocement & they are further classified as follows:
A. Skeleton Steel:
The skeleton steel frame is made conforming exactly to shape of the structure and the geometry.
The steel rods are spaced at 70 to 100 mm apart and diameter may vary from 3 to 8 mm.
This is used for holding the wire mesh in the shape of the structure.
In the case where higher stresses may occur, the mild steel bars are used.
B. Wire Mesh:
The wire mesh consists of galvanized wire spaced at 6 to 20 mm centre to centre and 0.5 to 1.5 mm in diameter.
The wire mesh may be of the shape as welded wire mesh or square is woven wire mesh, hexagonal wire or mesh expanded metal, etc.
The yield strength of plain wires used in fabric should not be more than 415 MPa and 500 MPa for deformed wires.
The metal content might vary between 300 kg to 500 kg per cubic meter of mortar.
Ferrocement manufacturing process:
1. Hand plastering:
In this method, control thickness is hard and the minimum thickness is a stream that is 2cms.
The strength achieved by this technique shall be lower than different methods.
Units can be inserted in this process and used if various higher methods are not present.
These items can be utilized for pipes, storm buildings, and gas holder units.
2. Semi mechanized process:
This system also is known as semi-mechanized because the mold can be rolled to facilitate the dynamic to the mortars.
The consistency of this system may be greater than the earlier system.
Better compaction can be obtained using a straight edge pressed against the inner mould in this method.
Local, un-skilled people can handle this process.
The gun-running process can be adapted to apply the mortar to the wire mesh system.
This is the most suitable process for the large-scale construction of ferrocement prefabricated units.
If this process is utilized with a skilled gunner, it can provide a compact and uniform surface.
4. By Centrifuging:
Centrifuging courses are often adopted for the development of solid cylindrical units.
Ferro cement pipes are cast by centrifuging and it is used as tension pipes.
Advantages of Ferrocement:
- Ferrocement can be fabricated in any desired shape, hence it is more suitable to a special structure like shells, roofs, water tank, etc.
- It is a highly suitable material for precast merchandise.
- It has high ductility and resistance to crack.
- Also has favorable tensile properties.
- It has low maintenance.
- They are environmentally friendly.
Disadvantages of Ferrocement:
- Ferrocement is sensitive to stress failure.
- They have low shear strength.
- It can be perforated by hitting sharp objects.
- Corrosion in the reinforcing materials as a result of incomplete protection of metallic by mortar.
Also read: Hydraulic Cement & Pozzolana Portland cement
Uses of ferrocement:
Boats, fishing vessels, barge, cargo tugs, and flotation buoys are the main criteria for marine applications.
Water supply and sanitation:
Water tanks, sedimentation tanks, swimming pool linings, well coverings, septic tanks, etc.
Houses, community centers, precast housing elements, corrugated roofing sheets, wall panels, etc.
Rural energy biogas digesters, biogas holders, incinerators, panels for solar energy collectors, etc.
Mobile homes, kiosks, wind tunnels, silos and cans.
Also read: Quick Setting Cement & White Portland Cement
Ferrocement is often used in the constructions for resistant against earthquakes.