seminar report on
Jinesh K. Mehta
Prof. S. S.
Mr. R. P. Vasani
INSTITUTE OF TECHNOLOGY
Date of presentation: 05/08/2000
used for Ferrocement
procedure: with an example of “chabutara”
of making “chabutara”
design for column
mixing, placing, finishing & curing
and cutting of mesh
and tiding of mesh
preparation, application and finishing
constructions with special features
Ferrocement boat construction
Ferrocement coracle & water tank
Network to Promote Ferrocement Technology
(Ferrous products + cement)
Ferrocement is a highly versatile form of
reinforced concrete, constructed of hydraulic cement mortar
reinforced with closely spaced layers of continuous and relatively small
diameter mesh. The mesh may be made of a metallic or other suitable material.
Ferrocement is a type of concrete,
primarily differs from conventional reinforced or prestressed concrete by the
manner in which the reinforcing elements are dispersed and arranged.
It is the kind of material where the
filler material, usually brittle in nature, called matrix is reinforced with
fibers dispersed throughout the composite resulting in better structural
performances than that of individual one.
Thus it is a versatile form of a
composite material made of cement mortar and layers of wire mesh or similar
small diameter mesh closely bound together to create a stiff structural form.
This material which is special from reinforced concrete, exhibits a behavior so
different from conventional reinforced concrete in performance, strength and
potential application that it must be classed as a separate material.
Advantages of ferrocement construction
over R.C.C. construction
It is highly versatile and
can be formed into almost any shape for a wide range of uses
Advantageous in spatial
structures, has relatively better mechanical properties and durability than
R.C.C. within certain loading limits
Thin elements and light structures, reduction in self weight
Its simple techniques require a minimum of skilled labor
Reduction in expensive form work so economy & speed can be
Only a few simple hand tools are needed to build any structures
Structures are strong and have good impact resistance.
Structures are highly waterproof
Higher strength to weight ratio than R.C.C
20% savings on materials and cost
Suitability for pre-casting
Flexibility in cutting, drilling and jointing
Very appropriate for developing countries; labor intensive
ferrocement for smaller structures is its high density (2600
kg/m3), however for larger structures it is not a big problem.
The large amount of labor required for ferrocement constructions
used for Ferrocement
1 to 8% of the total structural volume.
Placed throughout the structure. No. of layers, thickness and spacing are
decided according to strength requirement.
TYPES OF METALLIC MESH FOR REINFORCEMENT
Thickness varies from 6-20mm according to loading condition
Generally mild steel or Fe 415 or Fe 500 bars are used
Spacing 7.5cm to 12m
Ordinary portland cement
Cement: Sand should be 1:1.5 to 1:2.5
W/C ratio should be 0.4 to 0.6
confirming to zone-I or Zone-II
free from impurities
Free from salts and organic impurities
Minimum to achieve desired workability
Standards for ferrocement:
Min thickness of member-
12.5 mm for impermeable
Construction procedure: with an example of “chabutara”
of making “chabutara” :
get feel of ferrocement & R.C.C.:
The total understanding of any material
you can achieve only when you work with it. So I have decided to prepare a “chabutara”
in which I have constructed a R.C.C. pillar and on that 4 ferrocement bases
are supported. Total work in
ferrocement is @ 4.0 m2 and in R.C.C. is 9000 cm3.
To satisfy need
This was essential because due to
constant harassment of cats the birds can not come to eat. So
to give the birds a better place to eat.
To use waste materials
I was having old wire meshes from my old
shop. They were woven meshes of 2mm diameter and 10mm spacing and chicken mesh.
So I found that it was quite suitable to use for ferrocement structure.
by step Construction procedure of “chbutara” :
Height (above G.L.): 2000 mm
height (below G.L.) : 360 mm
Diameter: 75 mm
For footing a circular pit of 360 * 75 mm
excavated and by applying rich concrete layer of 40 mm a solid base was made.
Then reinforcement bars were placed aligned and then hole pit is filled up by
rich cement mortar and a cement seal of 20 mm was provided on the top most
portion of the footing.
Re-bars: 3- 8 mm dia. Fe 415 bars
Lateral ties: 3mm dia steel wire @ 100 mm c/c.
: M30 (mix design according to I.S.
Sand : zone II
Aggregates: crushed angular and washed(free from dust)
Approx. load carrying
capacity: 25KN (250 Kg)
Self wt. Of column: 9.8KN (98 Kg)
Net load bearing capacity: 152 Kg
design (According to IS method)
Reference: hand book on concrete mixes ( SP 23: 1982)
concrete strength required in field at 28- days
size of aggregate
20 mm( angular)
0.8 compacting factor
of quality control
Test data for materials
O.P.C. ; Sidhee 53 Grade; satisfying the requirements of IS : 269 – 1976
gravity of cement:
gravity of coarse aggregate
gravity of fine aggregate
surface dry condition of aggregates
analysis : sand conforming to zone-II
Target mean strength of concrete
for a tolerance factor of 1.65 and using
fck = 30 + 6*1.65= 39.9 Mpa
Selection of water cement ratio
from fig –47, W/C ration required for
39.9 Mpa is 0.43. (E- curve for 53 Mpa)
this is lower than the max. value of 0.65
prescribed for mild exposure (see table 23)
Selection of water and sand content
from table –42, for 20 mm M.S.A. and
sand conforming to zone –II
water content / m3 of
concrete = 186 Kg
sand content as percentage of total
aggregate by absolute volume = 35%
water content %
sand in total aggregate
decrease in W/C ratio by
no change in C.F.
final water content w= 186 Kg/m3
final sand content p = 35
- 3.4 = 31.6%
Determination of cement content
= 186 Kg
= 186/0.5 = 372 Kg
cement content is adequate for mild exposure condition (see table 23)
Determination of coarse and fine aggregate content
table 41, for M.S.A. –20 mm , the amount of entrapped air = 2%.
this in to account and applying eq. 2 and 3
2 -- 0.98 = [ 186 + 372/3.15 + 1/ 0.316* fa/2.6]* 1/1000=> fa= 555.32 Kg
3 -- 0.98 = [ 186 + 372/3.15 + 1/ 0.684* Ca/2.6]* 1/1000=> Ca= 1202.03 Kg
mix proportion then becomes:
the mix is 0.43 : 1.0 : 1.5 : 3.23
pipes of 75mm diameter were used as
formwork. The pipe of different lengths(0.2m-0.6m) was used and concreting was
done in five stages, after each stage two lateral bars are placed horizontally
for support of ferrocement base. Thus whole 2m height was achieved.(see
reinforcement bars were tied up with stirrups at 100 mm c/c. Burnt oil was
applied on the inner side of the pipe thoroughly such that no concrete stick
with the pipe.
Weigh batching was done for the whole concreting process. There
might be little bit error due to use of simple weighing balance as a weigh
A proper attempt was made to achieve SSD condition before weigh
batching was done.
Hand mixing was done for at least 3.0 min for each batching.
Proper mixing was achieved in the case of hand mixing also because
total quantity for each batching was not more than 2500 cm3 i.e. 5.5 Kg in any
Concrete placing was done with the hands by wearing the gloves.
To achieve better compaction 20 blows of tamping rod were applied 3
times in each stage.
The formwork pipes are removed after 24 hours of placing. Then the
potholes, occurred due to very much confined structure or improper hand
compaction and also at the joints of 4 stages at lateral bars, were filled with
Curing was done for 14 days by simple application of water.
graph on the left page shows removal of formwork pipe after last stage of
8 mm diameter Fe 415 bars (for topmost base) and 6 mm diameter Fe
250 bars( for 2nd , 3rd and 4th base), were
provided as skeleton steel. These were the lateral bars inserted in the column
At each base two bars were provided length of
which are corresponding to diameter of that base.
mesh (wire mesh):
Two types of meshes were available and each stage single layer of
wire mesh was provided because here impermeability was not a desired criterion.
Then also from four bases in two base complete permeability is achieved at 9 mm
One was woven mesh of 2 mm thick and 10 mm spacing total
available size of which was 1.2 m * 2.5 m.
The other was chicken mesh of 1mm thick and 5 mm spacing and size
available was 1 m * 2 m.
Cement : sand = 1 : 1.5
Cement : Sidhee 53 Grade
Sand : ZoneII
Thus there are total four bases made up
of ferrocement for birds to alight and eat food. The all four bases are
basically circular and of different diameter and with different shapes as
The topmost base
Chinese roof shape
The second base 600 mm
Circular plate type
The third base
Circular plate type
The fourth base 800 mm
Circular bowl type
The top three bases are provided with
exposed, sharp, and upward projected wire mesh to stop the cats to climb on it.
and Cutting of mesh
The sizes of the base were decided considering convince of birds,
aesthetics and availability of material. Markings were done in such a way that
optimum utilization of available roll would be achieved.
Cutting was the most
tedious task. To cut all the wire mesh in circular shape only chisel and hammer
were used and no other mechanical instrument, so it became a tedious job.
photograph on the left page shows cutting of mesh with the help of chisel and
To make the basic circular shape for all four bases the wire meshes
were cut in D- shapes. In each D-shape a half-circular portion was cut to mesh
it properly with column.
second photograph on the left page shows cut wire mesh for three bases.
and tiding of mesh
The wire mesh in this case were placed only above the lateral bars,
while generally at the both the side of skeleton steel wire mesh are provided to
achieve better impermeability and strength.
shown in the photograph the two Ds were placed at each stage in such a way that a full
circular shapes were achieved and inner sides properly flush with column.
Then the wire meshes were tied with lateral bars with the help of
binding wire at @ 80 mm c/c spacing
The binding wire used was 1.5 mm dia. wire.
photograph on the left side shows tiding of wire mesh at stage 2.
As no. of supports were relatively less at each stage better
strength of the ferrocement base was required and so the cement : sand
proportion is 1: 1.5 was maintained.
Water cement ratio was 0.5.
Green color pigments were added during preparation of mortar to
achieve the base color of green.
Thorough mixing of cement, sand and color were done after it water
was added and then hand mixing was done for three minutes.
The wire meshes were washed and made clean before application of
mortar. Plastering was done with the help of hand by wearing gloves.
As shown in photograph mortar was taken in hand and then pressed on
mesh from both the side if possible, and by the similar way it was applied on
all four bases.
For 2-3 layers of mesh mortar should be applied from both the sides
and that may be done with one-stage technique, two-stage technique or sectional
on the left side shows application of mortar on stage 2.
For this type of structures there is no need of providing finishing
layer because high smoothness is not required.
Small holes were filled with rich mortar before setting of in place
Here in this structure mortar was applied from single side only and
so most of the skeleton steel remain out of mortar. So care should be taken to
see that proper mortar should be applied from lower side at joints of wire mesh
and skeleton steel.
Curing was done for 14 days by normal moist curing method.
Here due to application of mortar from single side only most of the
portion of the skeleton steel remained exposed, so painting of that bars with
red oxide was essential to protect from adverse effect of environment.
Also the binding wires were painted properly which were remained
Here ferrocement bases were of green color due to adding of pigment
in cement so there was no need of painting ferrocement bases, but the outer
periphery of them were put exposed and projected upwards, these sharp ends were
also painted with red oxide.
Concrete column was also painted with red oxide to give a tree stem
color, a try was made to give the structure look of
a tree and only due to this reason green color was added in to the
on the left page shows painting of exposed bars, periphery of base and column.
Costing of “chabutara”
Costing of column
Steel bars (8mm-dia)
3 * 8ft
Cement (siddhi 53)
Sand (zone- III)
to 12.5 mm)
Pipes & oil charges
147Rs. (excluding labor)
for four bases of ferrocement:
Woven wire mesh
8 * 3 ft
Labor for cutting
5 * 3 ft
Steel bars (6 mm dia)
30 Rs. (2.15 kg)
40 kg 20Rs.
550Rs. (excluding labor)
If all three base are made
of conc. Then it will cost 1200 Rs.
And weight increases 5
times of present weight.
of ferrocement with
Ferrocement's features such as resistance
to fracture, fatigue and impact, high tensile resistance and easy availability
of material make it useful in a wide range of applications such as:
concrete road repair
food and water storage containers
In its final cured stage, ferrocement is
somewhat flexible and can be bent slightly without developing cracks.
Ferrocement can be used in such compound-curved structures as
Compound curvature adds to the strength,
stiffness, and impact resistance of these structures, which can be built over a
minimum of internal forms. The examples of these type of structures can also be
constructed very satisfactorily with thin-walled ferrocement are:
Round or conical tanks
Other areas where ferrocement is being
tried to a limited scale in India are:
Large span roofs (including shells and folded plates)
Cattle feeders, water troughs and vats for fish ensilage
Grain and copra drier
Pipes and irrigation conduits
Timber treatment enclosures
Architectural panels and finishes
Components of furniture
boats have by now been built in almost every Asian country. In India it is in
still developing stage but in countries like china ferrocement boats have been
introduced on a large scale.
construction of a conventional ferrocement boat can be subdivided into the
Drawing of the frames in
Bending and welding of
Setting up of frames
Applying rods and mesh
Plastering and curing
one analysis is given for a 25 gross tons 18m coastal fishing boat (Korea)
designed in may –1969 by a local
concrete pile manufacturer, who incidentally had never built a boat not dealt
with ferrocement before. So one can understand it is very easy to adopt this
material with some care.
in table-1 comparison of three material is shown for the this boat, the money is
estimated according to current rates of year 2000.
ferrocement has been used mainly as a construction material for boats longer
than 10m length because the minimum thickness which could be achieved when
skeletal steel is used as a reinforcement is about 19cm (3/4in). when
ferrocement of this thickness is used for boats of smaller length, it results in
very much heavier boat than when using any other construction materials.
problem was resolved by using a ferrocement material that has only wire mesh as
reinforcement, without skeletal steel, but having the required strength. This
was possible with this type of ferrocement constructed with a thickness of 13 cm
(1/2in) which led to the design of 23ft boat comparable in weight when
constructed with timber. The ferrocement used in this construction is reinforced
by 9mm * 9mm in woven wire mesh of 0.8-1.0 mm dia. The cement, sand and water
ratio is 1:1.5:0.45
is a common type of county craft made of split bamboo covered with buffalo skin,
used by local people to cross rivers for fishing in rivers and reservoirs. An
attempt was made to fabricate the same in ferrocement. This attracted much
attention and now it is proposed to build a few more such craft for use in the
fisheries Department, Madras. The main intention is to popularize them among the
ferrocement water tank
is an important characteristic of ferrocement in its use for water retention.
is giving serious attention towards evolving convenient designs of ferrocement
water tank of capacities ranging from 200 to 5,000 gallons. Factory produced
tanks can be designed for conventional handling with simple equipment.
analysis of the cylindrical ferrocement water tank was carried out in two parts
by linear elastic theory. The first part dealt with the cylindrical shell wall
an the second part with the base plate. The total solution for the entire tank
was obtained by imposing appropriate boundary condition at the junction of the
base plate and wall.
important factors were considered before a decision was made on the dimensions
and amount of reinforcement required for a prototype water tank. Then a
tank 8-ft in dia and 8.5-ft in height was selected. The wall and base thickness
adopted were 1.25 in. and 2.25 in. respectively. From the analysis it was found
that the max. hoop stress governs the design of the cylinder which was
proportioned with a safety factor against the development of cracks. In this
design the estimated cracking stress and max. hoop stress are 335psi and 126psi
cement :sand :water ratio was 1:1.5:0.4 used for the mortar. The admixtures
accelerators are also used. For the skeletal steel 6in * 6in BRC weld mesh of
0.2 in. in diameter was used to form the cylinder and base plate, rigid enough
to carry the weight of the reinforcement and wet mortar. Wire mesh used was 9mm
* 9mm woven wire mesh of 0.8-1.0 mm
dia. Three layers of wire mesh, two layers of BRC weld mesh and 3/8 in. mild
steel bars were used for the base plate and for the cylindrical walls.
Particular care was taken at the junction between the cylindrical wall and base
plate by weaving the vertical wire mesh through the reinforcement of the base
tank was filled with water and observed for more than 3 months and there was no
leakage even without any waterproofing coating. Cost comparison was made and it
was found that ferrocement water tank is cheaper by about 30 % in comparison
with steel tank of the same capacity based on local cost.
case study :1(Philippines)
prototype 3-bedroom residence with carport, whose shell is made up of
ferrocement was built in lligan city an industrial center, Philippines. The
ferrocement shell consists of a
roofing system complemented by exterior wall panels. The shell normally accounts
for the major cost of any dwelling structure. Although executed in ferrocement
the shell turned out to be comparatively cheaper than a similar dwelling using
the conventional corrugated GI or asbestos sheets for roofing supported by
wooden framing complete with ceiling and enclosed by and exterior 6” hollow
made the use of ferrocement more economical than that of a conventional
materials was the application of the following.
Techniques of modular
coordination with the use of standardized building components to allow mass
fabrication and easier/faster construction method.
Design of a structural
configuration which yields a stiff roofing system and framed thin-shell section
of exterior wall panels, yet is functional in shape and pleasing, although the
roof is revolutionary in appearance.
Formulation of mortar
mixture that is impermeable without the use of expensive additives but still
adopts proper curing methods.
mix proportion of the mortar used in the module is 1:2 cement: sand. From
0.4-0.6 parts of water is added to get a workable mix. It takes about 1cu.ft of
cement to cast one roof module.The roof surface of the module is covered by sack
and continuously cured for seven days. Then the column drain hole is plugged to
allow ponding of water for some time, to test for possible leaks.
reinforcement assembly of the roof module is shop fabricated and installed in
place on the forms at site. The main steel are welded to each other and the
galvanized wires are meshed by hand in a weaving loom-like space pattern,
conforming with the configuration of the finished roof module. Five roof modules
can be cast in six working days by a crew of eight men including a foreman.
light weight precast panels measures 0.825 * 2.10 meters. Its overall thickness
is 0.025 meters, and it is bound on its periphery with stiffening ribs whose
section is 0.05 by 0.1 m. it is reinforced with 1/4th in. steel bars
and GI wires, adequately placed and made to protrude for joining provision with
adjacent panels. The casting forms are made such that during manufacture open
spaces for windows can be obtained or their overall dimensions can be altered,
if used for perimeter fencing panels of the lot or septic vault sidings.
all precast columns have been erected and joined to the in-situ footing, the
collapsible roof module form supported by movable scaffolding is installed in a
one column unit. The pre-assembled steel and wire mesh reinforcements are
properly positioned on the aligned module form and then the ferrocement roof is
cast in place. The clearance between monopods eventually become sealed
ferrocement joints through which electrical conduits pass.
Ferrocement secodary roof slab:
study 2: (Singapore)
many high rise building in singapore, a secondary roof is provieded for thermal
insulation of flats in the top floor. The use of ferrocement slabs is
investigated as a substitute.
slab is 3*3 ft. and 1-in. thick, selected in consideration of weight in regard
of handling problem and economical use of the wire mesh. The final design
consists of two layers of 0.5* 0.5in. wire mesh with
0.0639 in. dia. And one layer of 6*6 in. BRC weld mesh with 0.125 dia. The
preliminary observation shows that the ferrocement slab is satisfactory in terms
of crack resistance and economy. The strength is much more then required.
Construction of house
fig on the left hand side shows a prototype ferrocement house which contains
ferrocement roofs, lintels, cornice, door panels, chair & table etc.
ferrocement being a highly versatile form of composite material made up of
cement mortar and layers of wire mesh having large no. of application. Also it
is a boon for countries like India where large no. of manpower is easily
available. So different ferrocement products can replace easily conventional
products by achieving economy as well as durability. Also up to 20% addition of
fly ash in ferrocement improves its properties and so it is also environment
friendly. Thus we engineers should welcome this type of material and try to make
maximum use of it. With the help of ferrocement very high strength structure can
also be constructed but for that proper design of reinforcement should be done.
Ferrocement, versatile construction
its increasing use in Asia
(691.31 PAM 09306)
Papers refered are:
Ferrocement reseach and development in tamil nadu, india(coracle)
Ferrocement roofing research in the philippines (house)
Ferrocement developments and applications in india
Ferrocement research and development at university of singapore
The potentials of ferrocement and related
Materials for rural Indonesia.
(691.31 PAM/PHR 9305)
Some of the Web sites visited:
GAS-L: ferrocement gasifier info
Technologies - Sustainable Livelihoods and DA
International Network to Promote
The International Ferrocement Information Centre (IFIC) at the
Asian Institute of Technology (AIT) was established in 1976 to ensure the
transfer of ferrocement technology.
A Ferrocement Information Network (FIN) was established in 1985 to
facilitate and accelerate the flow of information among ferrocement users in
IFIC's efforts in promoting ferrocement technology, including
providing training and providing information, have resulted in applying the
technology in some 50 countries. IFIC has also established relationships with
more than 200 universities in 60 countries to teach ferrocement technology. In
addition, more than 100 ferrocement reference centers have been established
throughout the world.
FC news group provides all types of information about ferrocement
by giving links for different books different papers presented on ferrocement.