brief description

1. SPECIAL CONCRETES
Presenting a seminar on
“Ferro Cement”
Parikshit N H

2. INTRODUCTION
Ferro cement is a type of thin wall
reinforced concrete.
It is 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 material.

3.  Mortar provides the mass and wire mesh imparts
tensile strength and ductility.
 When building Ferro-cement structures the mortar is
applied to the reinforcing wire with a trowel, never
poured like common concrete work. Often a formwork
is used to provide the desiredshape.
 It is a super reinforced concrete. It differs from
conventional concrete in this there is a higher ratio of
steel to cement mortar. By altering the cement/steel
ratio to make ferrocement, we actually produce a
material, which exhibits properties, superior to either
steel or cement separately.

4. HISTORY
Ferrocement originated in 1840’s in
France. The inventors of ferrocement are
Frenchmen Joseph Monier and Joseph-
Louis Lambot.
In 1875 they constructed the first steel
and concrete bridge.

5. TYPICAL CROSS SECTION OF FERROCEMENT

6. MATERIALS USED IN FERRO
CEMENT
Cement mortar mix
Skeleton steel
Steel mesh reinforcement

7. CEMENT MORTAR MIX
ordinary Portland cement and fine aggregate
matrix are used
The matrix constitutes 95% cement mortar & 5%
wire mesh of the composite.
FA (sand), occupies 60 to 75% of the volume
of the mortar
Plasticizers and other admixtures are used

8.  Sand: cement ratio (by mass)1.5 to 2.5
 Water: cement ratio (by mass) 0.35 to 0.60
SAND
 confirming to zone-I or Zone-II
 free from impurities
WATER
 Free from salts and organicimpurities
 Minimum to achieve desiredworkability
 pH equal or greater than7

9. WIRE MESH
 Ferro cement is a relatively
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 and it is
spaced at 5mm to 10 mm.

11. SKELETON OF FERROCEMENT
ton of ferrocement

12. SKELETON STEEL
 It supportthe steel wire mesh
 3 to 8 mm steel rods areused
 Thickness varies from 6-20mm according toloading
condition
 Generally mild steel or Fe 415 or Fe 500 bars are used
 Used to impart structural strength in caseof boats etc.
 Reinforcement should be free from dust, rustand
other impurities.

13. STEEL MESH REINFORCEMENT
 Consists of galvanized steel wires of diameter
0.5 to 1.5 mm, 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.

14. DEVELOPMENT OF FERROCEMENT
 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.

15. CASTING TECHNIQUES
There are four methods of casting are
as given below :
a. Hand plastering
b. Semi-mechanised process
c. Centrifuging and
d. Guniting.

16. HAND PLASTERING
 In this method the control thickness is
difficult and the minimum thickness of
section that can be casted works out to be
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.

17. 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 machinery

19. CENTRIFUGING
 The centrifuging process is commonly
adopted for the fabrication of cylindrical
concrete units.
 Because of good compaction the
ferrocement pipe cast by centrifuging can
be used as pressure pipes.

21. GUNITING
 The process of guniting can be adopted
for applying the mortar to the wire mesh
system.
 This process applied with experienced
gunman, can give good compact and
uniform surface.
 This appears to be suitable process or mass
production of ferrocement prefabricated
units.

23. PROPERTIES
It is very durable, cheap and versatile material.
Low w/c ratio produces impermeablestructures.
Less shrinkage and low weight.
High tensile strength and stiffness.
Better impact and punching shearresistance.
Undergo large deformation before cracking orhigh
deflection.

24. Tensile Strength of Ferrocement
Load taken by the ferrocement depends upon
the number of reinforcing mesh layers used in
ferrocement.
 Increase in number of mesh layers also
improves ductility of ferrocement.
As the specific surface increases there is
increase in the tensile strength of ferrocement.
 Orientation of mesh its thickness and spacing
of mesh are the main factors that responsible
for the specific surface.

25. ADVANTAGES OF FERRO CEMENT
The main advantages of ferrocement are as
given below :
i. Simple to construct.
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.

26. DISADVANTAGES OF FERRO-CEMENT
 Low shear strength
 Susceptibility to stress rupturefailure
 It can be punctured by collision with pointed
objects.
 Corrosion of the reinforcing material due to
the incomplete coverage of metal bymortar.
 It is difficult to fasten to ferrocement with bolt,
screw, welding and nail etc.
 Tying rods and mesh together is especially tedious
and time consuming.

27. APPLICATIONS
 Ferro cement
has been
sucessfully used
for casting water
tanks .

28.  It is been used for
building boat .
 Ferro cement boat
is 14 meter long.
which is
comparatively
cheaper than
reinforced concrete
boats.
 It is also been
used for creating
man hole cover.

29.  Ferro cement is
also been used for
making roofs.
 It is also been
used for casting
benches , chairs
etc….
.

30.  A.E. Naaman, ―Ferrocement and Laminated
Cementitious Compositesǁ, Techno Press
3000, An Arbor, Michigan, USA, 2000.
 S. Wang, A.E. Naaman. and V.C. Li.,
“Bending response of hybrid ferrocement
plates with meshes and fibers,” Journal of
Ferrocement., Vol. 34 No.1, p. 275-288, 2004.
International Journal of Innovative Research
in Science, Engineering and Technology An
ISO 3297: 2007 Certified Organization Volume
3, Special Issue 4, April 2014
REFERENCES

31. Thank
You