ferro cement
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FERRO CEMENT
BUILDING TECHNOLOGY AND MANAGEMENT
Definition
“Ferro cement is a type of thin wall
reinforced concrete, 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
materials”
-ACI Committee 549, 1980
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• Cement mortar is reinforced with layers of
continuous and small diameter wire meshes
• Mortar provides the mass and wire mesh
imparts tensile strength and ductility
• Italian engineer Pier Liugie Nervi is credited
with inventing ferro cement in the 1940’s
Ferro cement
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Materials used in Ferro cement
• Cement mortar mix
• Skeleton steel
• Steel mesh reinforcement or Fibre-
reinforced polymeric meshes
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Typical section of Ferro cement
Cement mortar mix
• OPC and fine aggregate matrix is used
• The matrix constitutes 95% of the
composite and governs its behavior
• FA (sand), occupies 60 to 75% of the volume
of the mortar
• Plasticizers and other admixtures are used
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Mix Proportions
• Sand: cement ratio (by mass) 1.5 to 2.5
• Water: cement ratio (by mass) 0.35 to 0.60
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Skeleton steel
• Forms the skeleton of the structure
• 3 to 8 mm steel rods are used
• Used in the form of tied reinforcement or
welded wire fabric
• Used to impart structural strength in case
of boats, barges etc
• Reinforcement should be free from dust,
rust and other impurities
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Steel mesh reinforcement
• Consists of galvanized steel wires of
diameter 0.5 to 1.5 mm, spaced at 6 to
20mm centre to centre
• Available as woven/interlocking mesh and
welded mesh
• Welded wire mesh has hexagonal or
rectangular openings
• Expanded-metal lath is also used
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Types of Wire Meshes
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Chicken wire mesh
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Expanded Metal Lath
Fibre-reinforced Polymeric meshes
Made from carbon, glass etc.
Advantages:
I. High corrosion resistance
II. High strength
III. Lower unit weight
IV. Easy to handle
V. Good fatigue behavior
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Disadvantages:
I. High cost
II. Low shear strength
III. Low ductility
IV. Susceptibility to stress rupture failure
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Fibre-reinforced Polymeric meshes
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Typical cross-sections of Ferro cement(Source: Naaman 1999)
Ferro cement Construction
• Container for water treatment
Container for water treatment.flv
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Behavior of Ferro cement in Tension
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RC in tension Ferro cement in tension
(Source: Naaman 1999)
Advantages of Ferro cement
• High ductility
• High resistance to cracking width
• Ability to undergo large deflection
• Improved impact resistance and toughness
• Good fire resistance
• Good impermeability
• Low strength to weight ratio
• Low maintenance costs
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Construction Methods for Ferro cement
• Skeletal Armature Method
• Closed Mould Method
• Integral Mould Method
• Open Mould Method
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Skeletal Armature Method
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(Source: Naaman 1999)
Closed Mould Method
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(Source: Naaman 1999)
Integral Mould Method
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(Source: Naaman 1999)
Integral mould
• C:\Users\CIVIL\Downloads\video (1).flv
• C:\Users\CIVIL\Downloads\video (2).flv
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Open Mould Method
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(Source: Naaman 1999)
Applications of Ferro cement
• Marine applications
• Water supply and sanitation
• Agricultural
• Residential buildings
• Rural energy
• Other structures
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1. Marine Applications
• Boats, fishing vessels, barges, cargo tugs,
catamarans, yachts and flotation buoys
• Key criteria for marine applications: light
weight, impact resistance, thickness and
water tightness
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27Boat with Ferro-cement hull
2. Water supply and sanitation
Water tanks, sedimentation tanks, swimming
pool linings, well casings, septic tanks etc.
3. Agricultural
Grain storage bins, silos, canal linings, pipes,
shells for fish and poultry farms
4. Residential Buildings
Houses, community centers, precast housing
elements, corrugated roofing sheets, wall
panels etc.28
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Ferro cement structure for roofing
5. Rural Energy
Biogas digesters, biogas holders,
incinerators, panels for solar energy
collectors etc.
6. Other structures
Bus shelters, industrial shelters, pedestrian
bridges, skateboard rings, sculptures etc.
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Reference
o Naaman, AE, Ferrocement & Laminated
Cementitious Composites, Techno Press
3000
o Santhakumar, AR, Concrete Technology,
Oxford University Press
o Gambhir, ML, Concrete Technology: Theory
and Practice, McGraw Hill
o Shetty, MS, Concrete Technology, S Chand
Publishers
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