What is Ferrocement?
Ferrocement is a composite material which is prepared by using closely spaced one or multiple layers of mesh and small diameter rods which is completely covered by cement mortar. it is a highly versatile material with many engineering properties such as flexural strength, toughness, fatigue resistance, impact resistance and crack resistance. It was developed by an Italian Architect P.L.Nervi in 1940. Further, it is defined by ACI (American Concrete Institute) in 1980 in ACT- 549.
Properties of Ferrocement
1. Ferrocement which is especially advantageous in special structure. has relatively better mechanical properties.
2. It has better durability than ordinary reinforced concrete.
3. Within the certain loading limit. it behaves as homogeneous elastic material and these limits are wider than for normal concrete.
4. The uniform distribution and high surface area to volume ratio (specific surface) of its reinforcement results in better crack arrest mechanism that is the propagation of cracks are arrested resulting in high tensile strength of the material.
5. it is a very durable, cheap and versatile material.
6. Low water-cement ratio produces an impermeable structure.
7. Less shrinkage and low weight.
8. Better impact and punching shear resistance.
9. undergo large deformations before cracking or high deflection.
Material Used In Ferrocement
- Cement Mortar Mix
- Steel Mesh reinforcement or fibre-reinforced polymeric meshes
Cement Mortar Mix
- OPC and the fine aggregate matrix is used.
- Sand cover 60 to 75% of the volume of the mortar.
- Plasticizers and other admixture are used.
- Mortar ratio = 1:5 to 2:5 (Cement : Sand)
- Water-cement ratio = 0.35 to 0.60
6 to 8 mm steel rods are used to form the skeleton of the structure. Used in the form of tied reinforcement or welded wire fabric.
- MS wire of 2 to 6 mm dia at 100 to 150 mm interval in a grid form.
- Chicken mesh (GI hexagonal mesh of 10 to 20 mm made of wire of 0.5 to 1 mm dia)
- Welded wire mesh has a hexagonal or rectangular opening.
Uses of Ferrocement
1. It saves cement and steel in the construction of structures so it is used in residential building.
2. It is used for casting domestic overhead water tanks. The tank is lightweight and can be transported easily. The tank will be cheaper than any other competitive materials. The tank can be made with hopper shaped bottom with a simple arrangement for drawing the grains.
3. It is a container can be used in a gas holder unit in “Bio-Gas” plants.
4. With a few modifications, Ferro cement tanks can also be used as septic tank units.
5. It is used for boat building.
6. It is used in the manufacturing of manhole cover.
7. It is a popular material for prefabricated roof units.
8. It is a suitable material for pressure pipes.
9. Ferrocement is a suitable material for casting curved benches for parks, garden and open-air cinema theatre.
Advantages of Ferrocement
1. Ferrocemnt structures are thin and light. Therefore a considerable reduction in the self-weight of the structure and hence in foundation cost can be achieved. A 30% reduction in deadweight on supporting structure 15% saving in steel consumption and 10% in roof cost has been estimated in USSR.
2. Ferrocement is suitable for manufacturing the precast units which can be easily transported.
3. The construction technique is simple and hence does not require highly skilled labour.
4. Partial or complete elimination of formwork is possible.
5. Ferrocement construction is easily amenable to repairs in case of local damage due to abnormal loads (such as impact).
Disadvantages of Ferrocemnt
The disadvantage of Ferro cement construction is the labour-intensive nature of it, which make it expensive for industrial application in the western world.
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