CHAPTER II

LITERATURE REVIEW

2.1 Definition of Ferrocement/Ferrogrout

As the material ‘ferrocement’ was used for a long time in boat building and

similar allied structures rather than in structural applications, a rigorous engineering

definition of ferrocement was not followed. Within ACI Committee 549, a

considerable discussion on its definition evolved and it was agreed to group together

various available definitions from many sources to come up with a concise and

accurate definition that may be acceptable to the engineering profession. Some

definitions considered by the committee are presented here.

Bigg (1968) has discussed the problem of definition in detail. He pointed out

that according to the American Bureau of Shipping it is:

“A thin, highly reinforced shell of concrete in which the steel

reinforcement is distributed widely throughout the concrete, so that

the material under stress acts approximately as a homogenous

material. The strength properties of the material are to be determined

by testing a significant number of samples....”

Although at first glance, the above definition seems an acceptable one, it

brought about a number of questions on the words italicised therein, which may have

different meanings of ferrocement to different people. Bigg went on to discuss

various aspects of ferrocement, suggests various ways of defining it, such as a

composite material and points out how the available engineering approach for

composites of fiber reinforced concrete may be used to come up with a definition of

ferrocement.

As a two-component composite, made up of reinforcement and mortar

(matrix), Bezukladov (1968) defined it in terms of the ratio of the surface area of

reinforcement to the volume of, the composite. In this manner, ferrocement is

separated from the conventional reinforced concrete. Somewhat arbitrarily, he

assigned the specific surface greater than 2cm2/cm3 to ferrocement which then

behaves more or less as a homogenous material. Less than 2cm2/cm3 is considered

reinforced concrete.

Shah (1974) in discussing different materials of construction, defined

ferrocement in a manner similar to Bezukladov. He called it a composite made with

mortar and a fine diameter continuous mesh as reinforcement, with which has higher

bond due to its smaller size and a larger surface area per unit volume of mortar.

Accordingly, this ratio may be as mush as ten times that which is observed in

conventional reinforced concrete; this results in failure of ferrocement in tension by

the actual breaking of wire mesh and a much higher cracking strength in the matrix.

As a composite, certain characteristics of ferrocement may thus be

summarised as follows:

a. Since the wire mesh (reinforcement) is much stronger in tension compared to

the matrix (mortar), the role of the matrix is to properly hold the mesh in

place, to give a proper protection and to transfer stresses by means of

adequate bond.

b. Compression strength of this composite is generally a function of the matrix

(mortar) compressive strength, while the tensile strength is a function of the

mesh content and its properties.

c. It follows from (b) above that the stress-strain relationship of ferrocement in

tension may show either a complete elastic behaviour (up to fracture of

reinforcing mesh) or some inelasticity depending upon the yielding properties

of the mesh.

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d. Since the properties of this composite are very much a function of orientation

of the reinforcement, the material is generally anisotropic and may be treated

as such in the theoretical analysis.

The above discussion indicates the variety of approaches that have been made

in a structural definition of ferrocement. It became apparent to the ACI Committee

549 that the first task should be to define Ferrocement as a construction material.

Accordingly, the following definition was adopted:

"Ferrocement is a type of thin wall reinforced concrete commonly

constructed of hydraulic cement mortar reinforced closely spaced

layers of continuous and relatively small wire diameter mesh. Mesh

may be made of metallic or other suitable materials."

The above definition implies that although ferrocement is a form of

reinforced concrete, it is also a composite material. Hence the basic concepts

underlying the behaviour and mechanics of composites materials should be

applicable to ferrocement.

2.2 History of Ferrocement/Ferrogrout

The use of ferrocement was first started as early as in 1848. It took the form

of a rowing boat constructed by Jean Louis Lambot. The boat, still in a remarkably

good condition, is on display in a museum at Brigholes, France. Since then,

ferrocement was mainly used in the marine environment.

In the early 1940s, Pier Luigi Nervi resurrected the original ferrocement

concept when he observed that reinforcing concrete with layers of wire mesh

produced a material possessing the mechanical characteristics of an approximately

homogeneous material and capable of resisting impact. After the Second World

War, Nervi demonstrated the utility of ferrocement as a boat-building material. His

firm built the 165-ton motor sailor Irene with a ferrocement hull about 36mm thick.

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Ferrocement gained wide acceptance only in the early 1960s in United

Kingdom, New Zealand, and Australia. In 1965, an American-owned ferrocement

yacht built in New Zealand, the 16m Awahnee, circumnavigated the world twice

without serious problems, although it encountered several mishaps.

Nervi built a small storehouse of ferrocement in 1947 which was

approximately 10.7m 21.3m. This was the first time ferrocement concept in the

applications to building. Later he covered the swimming pool at the Italian Naval

Academy with a 15m-diameter dome and then the famous Turin Exhibition Hall – a

roof system spanning 91m. In both cases, ferrocement served as permanent forms

for the structural system including the main support ribs.

In 1958, the technology then spread to Russia with the construction of a

number of structures. Examples of these were a ferrocement vault of 17.0m spans in

one of the metro stations in Leningrad and the interior of a hall covered with

ferrocement elements.

The more recent ferrocement structures include the Sydney Opera House,

built in 1973. Ferrocement tiles were used as surfacing on the vaults of the Opera

House, a major arts centre in Sydney. Similar beautiful buildings and mosque were

built in India and Indonesia using ferrocement.

2.3 Advantages of Ferrocement/Ferrogrout

Ferrocement is particularly suited to developing countries for the following

reasons:

Its basic raw materials are available in most countries.

It can be fabricated into almost any shape to meet the needs of the user;

traditional designs can be reproduced and often improved.

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For properly fabricated, it is more durable than most woods and cheaper than

imported steel, and it can be used as a substitute for these materials in many

applications.

The skills required for ferrocement construction are quickly acquired, and

include many skills traditional in developing countries. Ferrocement

construction does not need heavy plant or machinery; it is labour intensive.

Being labour intensive, it is relatively inexpensive in developing countries.

Except for sophisticated and highly stressed designs, as those for deepwater

vessels, a trained supervisor can achieve the requisite amount of quality

control using fairly unskilled labour for fabrication.

In case of damage, it can be repaired easily.

The beauty of ferrocement was that it could appear in any shapes. Only

imagination could limit the forms and shapes of this beautiful and cheap material.

Further unskilled labour could be employed to construct the structure. The material

and labour required are plentiful in the developing countries, especially in rural

areas. These factors make it a very appropriate material for national developments.

2.4 Constituent Materials

Ferrocement can be divided into two main components: the matrix and the

reinforcement.

2.4.1 Matrix

The matrix is a hydraulic cement binder, which may contain fine aggregates

and admixtures to control shrinkage and set time, and increase its corrosion

resistance. The binder is itself a composite material consisting of a hydrated cement

paste and an inert filler material.

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2.4.1.1 Cement

The cement commonly used is Portland cement possibly blended with

pozzolan. The cement should comply with ASTM C 150-85a, ASTM C 595-85, or

an equivalent standard. The cement should be fresh, of uniform consistency and free

of lumps and foreign matter. It should be stored under dry conditions and for a short

duration as possible. Cement factors are normally higher in ferrocement than in

reinforced concrete.

Mineral admixtures, such as fly ash, silica fumes or blast furnace slag may be

used to maintain a high volume fraction of fine filler material. Filler material is

usually well-graded sand and this classifies the binder material as a mortar. Since the

matrix represents approximately over 95% of the resulting ferrocement volume, its

physical properties and microstructure, which depend upon the chemical composition

of the cement, the nature of the inert filler, the water-cement ratio and the curing

regime, have a great influence on the final properties of the product.

Rice Husk Ash (RHA) cement can be economically used as partial

replacement of cement in mortar mixes. When RHA does not exceed 35% by weight

of the blended cement, the compressive strength at 28 days is similar to that of Type

I Portland Cement Mortar.

The reaction of Portland cement and water results in formation of hardened

cement paste. The ranges of mix proportions recommended for common

ferrocement applications are sand-cement ratio by weight, 1.5 to 2.5, and water-

cement ratio by weight, 0.35 to 0.5. Fineness modulus of sand, water-cement ratio

and sand-cement ratio should be determined from trial batches to insure a mix that

can infiltrate (encapsulate) the mesh and develop a strong and dense matrix. Water

reducing admixtures may be used to enhance mix plasticity and retard initial set, as

with conventional concretes. The behaviour of mortar is similar to that of plain

concrete. The major distinction is the size of the aggregate used. In general a good

quality mortar is stronger and more durable than good quality concrete; however,

their basic response to the environment is essentially the same.

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2.4.1.2 Fine Aggregates

Normal weight fine aggregate (sand) is the most common aggregate used in

ferrocement. It should be clean, hard, strong, and free of organic impurities and

deleterious substances and relatively free of silt and clay. It should be inert with

respect to other materials used and of suitable type with respect to strength, density,

shrinkage and durability of the mortar made with it. Grading of the sand is to be

such that a mortar of specified proportions is produced with a uniform distribution of

the aggregate, which will have a high density and good workability and which will

work into position without segregation and without use of a high water content. The

fineness of the sand should be such that 100% of it passes standard sieve No. 8.

Table 2.1 gives some guideline on desirable grading.

Table 2.1: Guideline on desirable sand grading

Sieve Size Percent Passing

No. 8 80-100

No. 16 50-85

No. 30 25-60

No. 50 10-30

No. 100 2-10

2.4.1.3 Admixture

Chemical admixtures used in ferrocement serve one of the following four

purposes: water reduction, which increases strength and reduces permeability; air

entrainment, which increases resistance to freezing and thawing; and suppression of

reaction between galvanised reinforcement and cement.

2.4.2 Reinforcement

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The reinforcement of ferrocement is commonly in the form of layers of

continuous mesh fabricated from an assembly of continuous single strands filaments.

Specific mesh types include woven and welded mesh, expanded metal lath and

perforated sheet products. There is a wide variety in mesh dimensions, as well as in

the amounts, sizes and properties of the materials used.

2.4.2.1 Wire Mesh

Wire mesh is one of the essential components of ferrocement. Different types

of wire meshes are available almost everywhere. These generally consist of thin

wires, either woven or welded into a mesh, but the main requirement is that it must

be easily handled and, if necessary, flexible enough to be bent around sharp corners.

The function of the wire mesh and reinforcing rod in the first instance is to act as a

lath providing the form and to support the mortar in its green state. In the hardened

state its function is to absorb the tensile stresses on the structure, which the mortar on

its own would not be able to withstand. A structure is subjected to great deal of

pounding, twisting and bending during its lifetime resulting in cracks and fractures

unless sufficient steel reinforcement is introduced to absorb these stresses. The

degree to which this fracturing of the structure is reduced depends on the

concentration and dimensions of the embedded reinforcement. The mechanical

behaviour of ferrocement is highly dependent upon the type, quantity, orientation and

strength properties of the mesh and reinforcing rod. Figure 2.1 shows the common

type of wire mesh used in ferrocement industry.

The ACI committee 549 on Ferrocement concluded that the definition of

ferrocement could not be limited to steel reinforcing only. The ACI definition of

ferrocement included the statement “Mesh may be made of metallic material or other

suitable materials.” This definition allows bamboo mesh and mesh made of other

materials to be used for ferrocement structures.

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Figure 2.1: Mesh types commonly used in ferrocement.

2.4.2.2 Skeletal Steel

Skeletal steel as the name implied is generally used for making the

framework of the structure upon which layers of mesh are laid. Both the longitudinal

and transverse rods are evenly distributed and shaped to form. The rods are spaced

as widely as possible up to 300mm apart where they are not treated as a structural

reinforcement and are often considered to serve as spacer rods to the mesh

reinforcements. In some cases skeletal steel is spaced as near as 75mm centre-to-

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centre thus acting as a main reinforcing component wire mesh in highly stressed

structures, for example boat, barges, tubular sections, and others.

Steel rods of different kinds are used in ferrocement construction. Their

strength, surface finish, protective coating and size affect their performance as

reinforcing members of the composite. In general, mild steel rods are used for both

longitudinal and transverse directions. In some cases high tensile rods and

prestressed wires and strands are used. Rod size varies from 4.20mm to 9.5mm

whereas 6.35mm is the most common. Ferrocement panels with longitudinal and

transverse rods of this size are about 25mm. A combination of different rod sizes

can be used with smaller diameter rod in the transverse direction.

2.4.2.3 Substitute Materials

Some of the substitute materials include bamboo mesh and bamboo skeletal

reinforcement. Chembi and Nimityongskul (1989) investigated the use of bamboo

mesh to replace steel wire mesh in ferrocement water tank. A bamboo cement tank

of 6m3 capacities was constructed in 1983. The tank was kept alternatively full and

empty of water to simulate actual field condition and was monitored regularly. After

5 years, they found that the tank has not shown structural defects. Bamboo

reinforcement 0.3 m from the top of the tank was investigated and found in good

condition.

Meanwhile, Venkateshwarlu and Raj (1989) investigated the use of bamboo

to replace skeletal steel in ferrocement roofing elements. Slabs reinforced with

bamboo strips as skeletal reinforcement and chicken wire mesh were subjected to

monotonically increasing uniformly distributed load to study the load deflection

behaviour and to determine its serviceability limit (span/deflection). The

investigation showed that by using bamboo, the cost of roofing elements comes to

about 50% of reinforced concrete and 70% of ferrocement elements. The slabs can

be prefabricated in the factory or can be produced at the site manually. The

serviceability limit was suggested as 150 and it was observed, that at deflections up

to 10mm, no cracking occurred. Hence, roofing elements can be produced up to a

maximum span of 1.5m and can be used in multiples to cover longer span.

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2.4.3 Other Materials

2.4.3.1 Water

Water used in the mixing is to be fresh and free from any organic and harmful

solution, which will lead to deterioration in the properties of the mortar. Salt water is

not acceptable but chlorinated drinking water can be used. Potable water is fit for

use as mixing water as well as for curing ferrocement structures.

2.4.3.2 Coating

In general, ferrocement structures need no protection unless they are

subjected to strong chemical attack that might damage the structural integrity of their

components. A plastered surface can take a good paint coating. In terrestrial

structures, ordinary paint is applied on the surface to enhance the appearance.

Marine structures need protection against corrosion and vinyl and epoxy coatings

were found to be the most successful organic coatings.

2.5 Properties

Ferrocement, often regarded as just another form of reinforced concrete, is

quite unique with respect to material behaviour and suitability for structural

applications. Ferrocement possesses a degree of toughness, ductility, durability,

strength and crack resistance that it is considerably greater than that found in other

forms of concrete construction. These properties are achieved in structures with a

thickness that is generally less than 25mm, a dimension that is nearly unthinkable in

other forms of concrete construction, and a clear improvement over conventional

reinforced concrete. Some of the properties of ferrocement such as tension,

compression, flexure, shear, fatigue, impact and fire resistance, durability, corrosion,

and water retaining capacity had been investigated and are listed as below.

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2.5.1 Tensile Behaviour

Unlike reinforced concrete, tensile behaviour of ferrocement is considerably

different. This is mainly because the reinforcement is spaced closer and uniformly

than in reinforced concrete and its smaller diameter results in a larger specific surface

area. This in turn affects cracking behaviour (finer and more number of cracks) in

ferrocement.

Naaman and Shah’s (1974) work indicated that the stress level at which the

first crack appeared and the crack spacing were a function of the specific surface of

reinforcement. The ultimate load of the ferrocement specimen was the same as the

load carrying capacity of the reinforcement in that direction. This should be

expected since the load is carried by the reinforcement itself after the mortar is

cracked.

Al-Noury and Huq (1988) had proposed expressions for predicting the first

crack strength and modulus of elasticity of ferrocement in the uncracked and cracked

range. It was found that the first crack strength of ferrocement in tension might be

predicted on the basis of the strain at the limit of proportionality of mortar and the

uncracked modulus of ferrocement. The modulus of elasticity of ferrocement in the

cracked range could be predicted on the basis of the behaviour of an equivalent

composite model aligned wires. Beyond first crack, the crack formation mechanism

in ferrocement in the cracked range is related to the matrix-wire interfacial bond.

2.5.2 Compression Strength

The high compressive strength of mortar contributes primarily to the

compressive strength of the ferrocement composite. Although the reinforcement

may have some influence on the compressive strength, but this is limited to certain

types of reinforcement. For example, the use of welded wire mesh would increase

compressive strength due to the lateral restraint provided by the welded transverse

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wires, while the hexagonal mesh or expanded metal may weaken the composite due

to longitudinal splitting.

Kameswara Rao and Kamasundra (1986) investigated the stress-strain curve

and Poisson’s ratio of ferrocement in axial compression. It was found that the

specific surface is the only factor, which controls the behaviour of ferrocement in

axial compression. Equations developed for predicting the increase in strength,

strain and modulus of elasticity by regression analysis were used to generate the

stress-strain curve of ferrocement under axial compression. They have found that

ferrocement behaves linearly up to 50-60% of the ultimate strength in compression;

beyond this limit the behaviour becomes non-linear. The value of ultimate strength,

strain at ultimate strength and Young’s modulus increase with increasing of specific

surface area.

2.5.3 Flexural Strength

In some application, ferrocement may be subjected to flexural stress. In such

cases, one must consider the method and manner in which its behaviour in flexure

may be predicted. Needless to say that compared an average reinforced concrete

beam (which is generally under-reinforced), the ferrocement beams due to several

layers of wire mesh tend to be over reinforced. It is therefore important to insure that

indeed ferrocement will not fail similarly to an over-reinforced concrete beam.

Analytical and experimental evaluations were reported by Johnston and Mowat

(1974), Logan and Shah (1973), Balaguru et al (1976) and Pama et al (1978).

Mansur and Paramasivam (1986) proposed a method to predict the ultimate

strength of ferrocement in flexure based on the concept of plastic analysis where

ferrocement is considered as a homogenous perfectly elastic-plastic material. Simple

equations are derived for direct design of a cross-section. An experimental

investigation was also conducted to study the behaviour and strength of ferrocement

in flexure. It was found that the ultimate moment increase with increasing matrix

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grade (decreasing water cement ratio) and increasing volume fraction of

reinforcement.

2.5.4 Shear

Venkata Krishna and Basa Gouda (1988) performed testing on ferrocement

beams with different volume fraction of reinforcement in transverse shear. It was

found that the shear strength depends upon mortar, strength of wire mesh, volume

fraction and shear span. Theoretical expressions were developed for predicting the

shear strength at first crack and collapse of ferrocement beams with different type of

wire meshes namely hexagonal, woven and welded.

2.5.5 Fatigue Resistance

Fatigue strength plays an important role in restricting the use of ferrocement

in structures subjected to such a loading as in bridges. The fatigue strength of the

wire, as tested in air, is the primary factor affecting fatigue of the composite.

Balaguru et al (1977) investigated the flexural fatigue properties of ferrocement

beams reinforced with square woven and welded meshes. Their finding is the

relationship between the stress range in the outermost layer of steel mesh and the

number of cycles to failure.

Singh et al. (1986) investigated the influence of the reinforcement on the

fatigue behaviour of ferrocement. They conducted fatigue tests on ferrocement slabs

with different types of mesh reinforcement, studying the effect of the size of wire,

galvanising of the wire and placing of wire mesh in layers to the fatigue strength of

ferrocement. Samples of the wires were also fatigue-tested in air and a relationship

is developed between the fatigue strength of each type in air and in the composite. It

was found that the fatigues of the wire in air and in ferrocement are related. Most

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fatigue failures occurred by fracture of the wires and the range of repeated stress in

the wires gave the greatest on the fatigue strength of ferrocement.

2.5.6 Impact Resistance

Impact strength is a useful parameter in applications related to offshore

structures and boats. Reports attesting the favourable characteristics of ferrocement

in collisions involving boats with each other or with rocks are numerous. The main

attributes include resistance to disintegration, localisation of damage, and ease of

repair. However, due to experimental complexity associated with measurement of

impact resistance, little quantitative or comparative data exist.

Impact strength was defined as the energy absorbed by the specimens when

struck by a swinging pendulum dropped from a constant height. The damage was

measured by the relative flow of water through the specimen surface for a fixed

energy absorbed which is 600lb-in (66.7kN-mm).

Shah and Key (1972) tested 9in2 (5625mm2) and ½in (12mm) thick

ferrocement slabs using an impact tester. From the test, it indicated that the higher

the specific surface of the meshes and the higher the strength of the mesh, the lower

the damage due to impact loading.

2.5.7 Fire Resistance

A problem unique to ferrocement is potentially poor fire resistance because of

the inherent thinness of its structural form and the abnormally low cover given to the

reinforcement.

Basanbul et al. (1989) studied the fire resistance of ferrocement load bearing

sandwich panels. The fire resistance of the ferrocement wall was found to be

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encouraging for designers of ferrocement buildings. Though the thin shell nature of

ferrocement has raised questions about its fire resistance, it was found that

ferrocement retains much of the load bearing qualities of reinforced concrete. Its

heat transmission qualities are not as good as those of reinforced concrete, which

would be just under four hours, but this latter consideration is more dependent on the

mass of the wall. Limited problems of spalling of the front face sheets occurred

during the early portion of the test but this spalling was not severe enough to cause

serious structural damage during the period in which the wall satisfied the ASTM E-

119 performance criteria.

2.5.8 Durability

When ferrocement is exposed to aggressive environment, its successful

performance depends to a great extent on its durability against the environment than

on its strength properties. The external causes may be physical, chemical or

mechanical. They may be due to weathering, occurrence of extreme temperatures,

abrasion, electrolytic action, and attack by natural and industrial liquids and gases.

The extent of damage produced by these agents depends largely on the quality of the

mortar, although under extreme conditions any unprotected mortar will deteriorate.

The internal causes are alkali-aggregate reaction, volume changes due to the

differences in thermal properties of aggregate and cement paste, and above all the

permeability of mortar. The permeability of mortar largely determines the

vulnerability of the mortar to external agencies, so that in order to be durable the

mortar must be relatively impervious.

Although the measures required to insure durability in reinforced concrete

also apply to ferrocement, three other factors which affect durability are unique to

ferrocement. First, the cover is small and consequently it is relatively easy for

corrosive liquids to reach the reinforcement. Second, the surface area of the

reinforcement is unusually high, so the area of contact over which corrosion

reactions can take place, and the resulting rate of corrosion, are potentially high.

Third, although many forms of reinforcement used in ferrocement are galvanized to

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prevent corrosion, the zinc coating can have certain adverse effects bubble

generation. All three factors have varying importance depending on the nature of the

exposure condition. However, in spite of these unique effects, there is no report of

serious corrosion of ferrocement not associated with poor plastering or poor matrix

compaction. To insure adequate durability in most applications, a fully compacted

matrix is necessary. A protective coating may also be desirable.

2.5.9 Corrosion

Corrosion is the deterioration of metals or alloy due to interaction with its

surroundings. The most common example of corrosion is the rusting of steel.

Corrosion is normally a fairly slow but complex process; however, due to presence

of certain conditions, it may occur very rapidly. Many of these can occur in

ferrocement and avoiding them is one of the biggest problems. All ferrocement

marine structures, by virtue of their marine environment are liable to corrosion

attack. The danger of corrosion is enhanced in ferrocement by the extreme thinness

of the cover of mortar over the steel reinforcement. The corrosion process is often

difficult to recognise until extensive deterioration has occurred. The severity of the

attack on structure will depend basically on how well it has been designed and built,

the materials used and what happens to it when in and out of use.

2.5.10 Water (or Liquid) Retaining Capacity

Another special property to be noted is that of water retention when

application of ferrocement is considered in liquid storage tanks. The important

aspect here is small crack widths so that leakage may be minimal. Shah and Naaman

(1977) indicated that crack widths in ferrocement for the same steel stress are smaller

than in reinforced concrete by order of magnitude. This making it a better choice on

material for water retaining structures. Tests were conducted on cylindrical vessels

with internal water pressure to investigate this impact. The results showed that the

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crack width in ferrocement is much smaller than allowable. Naaman and Sabins

(1978) also provided some recommendations on using ferrocement for water tanks.

2.6 Construction Procedure

Ferrocement construction unlike other sophisticated engineering construction

requires minimum of skilled labour, utilises readily available materials and most of

the tools for construction are intended for conventional concrete construction. The

skills for ferrocement construction techniques are easily acquired and requisite

quality control can be achieved using fairly unskilled labour for the fabrication under

the supervision of a skilled foreman.

There are several means of producing ferrocement. All methods require

high-level quality control criteria to achieve the complete encapsulation of several

layers of reinforcing mesh by a well-compacted mortar of concrete matrix with a

minimum of entrapped air. The most appropriate fabrication technique depends on

the nature of the particular ferrocement application; the availability of mixing,

handling and placing machinery; and skill and cost of available labour.

The four major steps in ferrocement construction are:

Placement of wire mesh in proper position,

Mortar mixing,

Mortar application, and

Curing.

The objective of all construction methods is to thoroughly encapsulate a

layered mesh system with a plastic Portland cement matrix. The mortar must be

thoroughly compacted during placing to ensure the absence of voids around

reinforcement and in the corners of any framework. Ferrocement structures are to be

properly cured once the mortar has taken its first set (which occur 3 to 4 hours after

mortar application). The set mortar or concrete is to be kept wet for a period

dependent on the type of cement used and the ambient conditions.

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2.7 Applications

2.7.1 Housing Applications

Ferrocement has found widespread applications in housing particularly in

roofs, floors, slabs and walls. Ferrocement is considered as a suitable housing

technology for developing countries attested by the increasing number of easily built

and comfortable ferrocement houses. Ferrocement houses utilising local materials

such as wood, bamboo or bush sticks as equivalent steel replacement have been

constructed in Bangladesh, Indonesia and Papua New Guinea.

Precast ferrocement elements have been used in India, the Philippines,

Malaysia, Brazil, Papua New Guinea, Venezuela and the Pacific for roofs, wall

panels and fences. In Sri Lanka, a ferrocement house resistant to cyclones has also

been developed and constructed. A pyramidal dome over a temple in India and

numerous spherical domes for mosques in Indonesia have been constructed with

ferrocement. The choice was dictated by low self-weight, avoidance of formwork

and availability of unskilled labour. Figure 2.2 shows one of the examples of the

houses built using ferrocement structures.

Figure 2.2: A typical ferrocement house

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2.7.2 Marine Applications

Ferrocement has been adapted to traditional boat designs in Bangladesh,

China, India, Indonesia and Thailand due to timber shortages. In China, 600

ferrocement boat-manufacturing units produce annual capacity of 600,000 to 700,000

tonnages. Ferrocement boats are divided into four categories according to usage:

farming boats, fishing boats, transport boats and working boats.

In countries like Hong Kong, Korea, India, Malaysia, Philippines, Sri Lanka

and Thailand, ferrocement boats generally conform to western standards. In Hong

Kong, India and Sri Lanka, most of the ferrocement crafts constructed are used as

mechanised fishing trawlers while in Korea, as fishing boats. In addition, the

Southeast Asian Fisheries Development Centre, Philippines, has used ferrocement

tanks for prawn brood stock and ferrocement buoys for a floatation system in the

culture of green mussels. This is the first large-scale use of ferrocement for these

purposes.

In Africa, ferrocement boatyards have been successfully established in

Kenya, Sudan and Malawi. The boatyards are now self-supporting under the

management of local staff trained by the consultants. The objective of these

boatyards is to provide rural fisherman opportunities to explore the fishable grounds

to increase their income. Figure 2.3 shows a ferrocement boat under constructions;

meanwhile Figure 2.4 shows a typical ferrocement boat.

Figure 2.3: A ferrocement boat under constructions

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Figure 2.4: A typical ferrocement boat

2.7.3 Agriculture Applications

Agriculture provides the necessary resource for economic growth in

developing countries. The use of ferrocement technology can contribute towards

solving some of the production and storage problems of agricultural produce.

Ferrocement has been used for grain storage bins in Thailand, India and Bangladesh

to reduce losses from attack by birds, insects, rodents and moulds.

Thailo, a conical ferrocement bin; was designed and first constructed at the

Asian Institute of Technology (AIT), Bangkok, Thailand. Storage capacities range

from 1 to 10 tons. This bin has proved to be structurally sound and construction has

provided adequate protection to the produce against rodent, insect and bird attacks.

The bin costs well within the means of the farmers. Besides, this type of silo also

can hold up to 5000 gallons (22.7m3) of drinking water.

In Ethiopia, underground pits are the traditional method of grain storage. It

has been found that when the traditional pit is lined with ferrocement and provided

with an improved airtight lid, a hermetic and waterproof storage chamber can be

achieved.

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2.7.4 Water and Sanitation Applications

Ferrocement can be effectively used for various water supply structures like

well casings for shallow wells, water tanks, sedimentation tanks, slow sand filters

and for sanitation facilities like septic tanks, service modules and sanitary bowls.

Some findings indicated that ferrocement tanks are less expensive than steel or

fibreglass tanks. The reasons why ferrocement is cheaper are:

Ferrocement is an feasible material for the construction of water storage

Flexibility of shape, freedom from corrosion, possibility of hot storage,

relative lack of maintenance, and ductile mode of failure are important

advantages of ferrocement over other materials

Ferrocement tanks require less energy to produce than steel tanks.

Ferrocement water tanks of 20 to 2000 gallons (0.09 to 9m3) capacity are

mass-produced in India. Bamboo-cement well casings have been built in Indonesia

to prevent contamination of the water.

2.7.5 Miscellaneous Applications

Ferrocement is proving to be a technology that can respond to the diverse

economic, social and cultural needs of man. Ferrocement has been used to

strengthen older structures, a medium for sculpture and for many other types of

structures. Ferrocement as a medium for sculpture proves its versatility and the

unlimited dimension to which it can be used. Ferrocement in art is an exciting

development and it open new horizons. Figure 2.5 shows a typical sculpture made

from ferrocement.

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Figure 2.5: A typical ferrocement sculpture

Universiti Teknologi Malaysia (UTM), Skudai, Malaysia also gained some

experiences in constructing the prefabricated and landscaping objects. The objects

done by Mohd. Warid Hussin, Abdul Rahman Mohd. Sam, and the staff from

Structural and Material Laboratory, Faculty of Civil Engineering are:

Garden and outdoor furniture

Decorative mushroom

Fascia

Sidewalk slab

Sun Screen/shade

Ferrocement canoe

Some of these objects are still well in condition and can be found within the

area of the laboratory. Figure 2.6 shows the ferrocement objects in UTM.

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a: Sunshade and irrigation canal

lining

b: Canoe

c: Chairs and table d: Mushroom

Figure 2.6: Some of ferrocement objects that can be found in UTM

2.8 Conclusion

Ferrocement has gained widespread use and acceptance, particularly in

developing countries and has already attained worldwide popularity in almost all

kinds of applications: marine, housing, water resources and sanitation, grain and

water storage, biogas structures, and for repair and strengthening of structures.

Widespread use of ferrocement is evident in countries like China, Russia, India,

Cuba, South East Asia and others.

There are several reasons for its widespread use. On the construction side, it

can be fabricated into almost any shape, skill needed for the construction can be

easily acquired, heavy plant and machinery is not required and easy to repair.

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Meanwhile, on the material side, ferrocement possesses a degree of toughness,

ductility, durability, strength and crack resistance that is considerably greater than

that found in other forms of concrete construction.

However, there are still areas of applications where ferrocement is not widely

used, such as structural components, like main beam, column, etc. This may be due

to insufficient understanding on the behaviour of ferrocement. Hence, more

researches still have to be done. This present research will contribute to the

enrichment of information and understanding on this subject.

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