CONCRETE-TECHNOLOGYPresenting a seminar on “Ferro Cement”

Civil 6th semDhruvil .y. patel

FERRO CEMENT “ Ferro cement is a composite material which is used in building or sclupture with cement, sand, water and wire mesh material often called a thin shell “

MATERIAL OF FERRO CEMENTWIRE MESH & CEMENT MORTAR

Ferro cement is a relatively new material consisting of wire meshes and cement mortar.

Wire mesh In figure many types of wire

mesh are shown……. The wire mesh is usually of

0.5 to 1.0 mm dia wire at 5 mm to 10 mm spacing and cement mortar.

Cement mortar

Cement mortar is of cement sand ratio of 1:2 or 1:3 with water/cement ratio of 0.4 to 0.45.

The ferrocement elements are usually of the order of 2 to 3 cm in thickness with 2 to 3 mm external cover to the reinforcement

The steel content varies between 300 kg to 500 kg per cubic meter of mortar.

AIM The basic idea behind this material

is that concrete can undergo large strains in the neighbourhood of the reinforcement and the magnitude of strains depends on the distribution and subdivision of reinforcement throughout of the mass of concrete.

ADVANTAGES OF FERRO CEMENT The main advantages of ferrocement are

as given below :

i. Simplicity of its construction,ii. Lesser dead weight of the elements

due to their small thickness,iii. Its high tensile strength,iv. Less crack widths compared to

conventional concrete,v. Easy repairability, noncorrosive nature

and easier mouldability to any required shape

PROPERTIESThickness – 10mm to 60mmSteel – 5 to 8%Steel cover – 1.5mm to 5mm.Ultimate tensile strength – 34.5

N/mm²Allowable tensile strength – 10

N/mm²Compresive strength – 27.5 to 60

N/mm²

APPLICATIONFerro cement

has been sucessfully used for casting water tanks .

It is been used for building boat .

Ferro cement boat is 14 meter long. Which is 300% cheaper than reinforced concrete boats.

It is also been used for creating man hole cover.

Ferro cement is also been used for making roofs.

It is also been used for casting benches , chairs etc….

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DEVELOPMENT OF FERRO CEMENT

This is a highly suitable material for precast products, because of its easy adaptability to prefabrication lesser dead weight of its units cast.

The development of ferrocement depends on suitable casting techniques for the required shape.

CASTING TECHNIQUES There are four methods of casting are

as given below :

a. Hand plasteringb. Semi-mechanised processc. Centrifuging andd. Guniting.

HAND PLASTERING In this method the control of thickness

is difficult and the minimum thickness of section that can be cast works out to about 2cms.

The strength obtaind by this system will be lower compared to other methods .

However the units can be cast by this process and used in siuations where for other improved methods do not exist.

These units can be used for pipes , storage structures and gasholder units.

SEMI –MECHANISED PROCESS This system is termed as semi-

mechanised because the mould can be rotated to facilitate dashing of mortar.

This system is better than the earlier system as better compaction .

The uniformity of this system is also better than the earlier system.

The advantages of this system are that it does not require any sophisticated equipment or electricity.

CENTRIFUGING

The centrifuging process is commonly adopted for the fabrication of concrete cylindrical units.

Because of good compaction , the ferrocement pipe cast by centrifuging can be used as pressure pipes.

GUNTING

The process of guniting can be adopted for applying the mortar to the wire mesh system.

This process applied with experinced gunman can give good compact and uniform surface.

This appears to be suitable process for mass production of ferrocement prefabricated units.

Thank You