Fero-cement as Bldg. Mat.
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Transcript of Fero-cement as Bldg. Mat.
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FERRO-CEMENT ASBUILDING MATERIAL
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GENERAL
FERROCEMENT IS PRINCIPALLY THE SAME AS REINFORCED
CONCRETE (RCC), BUT HAS THE FOLLOWING DIFFERENCES:
• ITS THICKNESS RARELY EXCEEDS 25 MM, (WHILE RCC COMPONENTS
ARE SELDOM LESS THAN 1 MM)!
• A RICH PORTLAND CEMENT MORTAR IS USED, WITHOUT ANY
COARSE AGGREGATE AS IN RCC!
• COMPARED WITH RCC, FERROCEMENT HAS A GREATER
PERCENTAGE OF REINFORCEMENT, COMPRISING CLOSELY
SPACED SMALL DIAMETER WIRES AND WIRE MESH, DISTRIBUTED
UNIFORMLY THROUGHOUT THE CROSS"SECTION!
FERRO-CEMENT AS BUILDING MATERIAL
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FERRO-CEMENT AS BUILDING MATERIAL
• ITS TENSILE"STRENGTH"TO"WEIGHT RATIO IS HIGHER THAN RCC,
AND ITS CRACKING BEHA#IOUR SUPERIOR !
• FERROCEMENT CAN BE CONSTRUCTED WITHOUT FORMWORK
FOR ALMOST ANY SHAPE!
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FERRO-CEMENT AS BUILDING MATERIAL
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FERRO-CEMENT AS BUILDING MATERIAL
Fabrication of Mould
Skltal Stl
G!I! "ir M#$
Curin% of &anl#
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FERRO-CEMENT AS BUILDING MATERIAL
•FERROCEMENT IS A RELATI#ELY NEW MATERIAL,
•WHICH WAS FIRST USED IN FRANCE, IN THE MIDDLE OF THE 1$TH
CENTURY, FOR THE CONSTRUCTION OF A ROWING BOAT!
• ITS USE IN BUILDING CONSTRUCTION BEGAN IN THE MIDDLE OF
THE 2TH CENTURY IN ITALY!
•ALTHOUGH ITS APPLICATION IN A LARGE NUMBER OF FIELDS HAS
RAPIDLY INCREASED ALL O#ER THE WORLD,
•THE STATE"OF"THE"ART OF FERROCEMENT IS STILL IN ITS
INFANCY, AS ITS LONG"TERM PERFORMANCE IS STILL NOT
KNOWN!
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FERRO-CEMENT AS BUILDING MATERIAL
MORTAR COMPOSITION
• THE ESSENTIAL INGREDIENTS OF THE MORTAR WHICH
REPRESENTS ABOUT $5 % OF FERROCEMENT ARE PORTLAND
CEMENT, SAND, WATER, AND IN SOME CASES AN ADMIXTURE!
• MOST LOCALLY A#AILABLE, STANDARD CEMENT TYPES ARE
SUITABLE, BUT SHOULD BE FRESH, OF UNIFORM CONSISTENCY
AND WITHOUT LUMPS OR FOREIGN MATTER !
• SPECIAL CEMENT TYPES ARE NEEDED FOR SPECIAL USES,
• &!'! SULPHATE"RESISTANT CEMENT IN STRUCTURES EXPOSED TO
SULPHATES (AS IN SEAWATER)!
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FERRO-CEMENT AS BUILDING MATERIAL
FERROCEMENT BOAT CONSTRUCTION IN THE 1$S
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FERRO-CEMENT AS BUILDING MATERIAL
• ONLY CLEAN, INERT SAND SHOULD BE USED,
(FREE FROM ORGANIC MATTER AND DELETERIOUS SUBSTANCES, AND RELATI#ELY
FREE FROM SILT AND CLAY!)
• PARTICLE SIES SHOULD NOT EXCEED 2 MM AND UNIFORM
GRADING IS DESIRABLE TO OBTAIN A HIGH"DENSITY WORKABLE
MIX! LIGHTWEIGHT SANDS (&!'! *+-./0- ., 340-&, 0/&67 .8.0"6&07./7
3.70-) CAN ALSO BE USED, IF HIGH STRENGTHS ARE NOT
RE9UIRED!
• FRESH DRINKING WATER IS THE MOST SUITABLE!• IT SHOULD BE FREE FROM ORGANIC MATTER, OIL, CHLORIDES,
ACIDS AND OTHER IMPURITIES! SEAWATER SHOULD NOT BE USED!
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FERRO-CEMENT AS BUILDING MATERIAL
• ADMIXTURES CAN BE USED FOR WATER REDUCTION,
• THUS INCREASING STRENGTH AND REDUCING PERMEABILITY (BY ADDING
SO"CALLED SUPERPLASTICIERS); FOR WATERPROOFING;
• FOR INCREASED DURABILITY (&!'! BY ADDING UP TO
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FERRO-CEMENT AS BUILDING MATERIAL
• THE RECOMMENDED MIX PROPORTIONS ARE: SAND=CEMENT
RATIO OF 1!5 TO 2!5, AND WATER=CEMENT RATIO OF !!
• GREAT CARE SHOULD BE EXERCISED IN CHOOSING AND
PROPORTIONING THE CONSTITUENT MATERIALS,
• ESPECIALLY WITH A #IEW TO REDUCING THE WATER
RE9UIREMENT,
• AS EXCESSI#E WATER WEAKENS THE FERROCEMENT!
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FERRO-CEMENT AS BUILDING MATERIAL
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FERRO-CEMENT AS BUILDING MATERIAL
REINFORCEMENT
• THE REINFORCING MESH (WITH MESH OPENINGS OF ? TO 25 MM)
MAY BE OF DIFFERENT KINDS, THE MAIN RE9UIREMENT BEING
FLEXIBILITY!
• IT SHOULD BE CLEAN AND FREE FROM DUST, GREASE, PAINT,
LOOSE RUST AND OTHER SUBSTANCES!
• GAL#ANIING, LIKE WELDING, REDUCES THE TENSILE
STRENGTH, AND THE INC COATING MAY REACT WITH THE
ALKALINE EN#IRONMENT TO PRODUCE HYDROGEN BUBBLES ON
THE MESH! THIS CAN BE PRE#ENTED BY ADDING CHROMIUM
TRIOXIDE TO THE MORTAR!
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FERRO-CEMENT AS BUILDING MATERIAL
• THE #OLUME OF REINFORCEMENT IS BETWEEN > AND @ % IN BOTH
DIRECTIONS, IE BETWEEN
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FERRO-CEMENT AS BUILDING MATERIAL
• S9UARE WELDED WIRE MESH IS MUCH STIFFER THAN
CHICKEN WIRE MESH AND PRO#IDES INCREASED RESISTANCE
TO CRACKING! HOWE#ER, INADE9UATE WELDING PRODUCES
WEAK SPOTS!
• S9UARE WO#EN WIRE MESH HAS SIMILAR CHARACTERISTICS
AS WELDED MESH, BUT IS A LITTLE MORE FLEXIBLE AND EASY
TO WORK WITH THAN WELDED MESH! MOST DESIGNERS
RECOMMEND S9UARE WO#EN MESH OF 1 MM (1$ GAUGE) OR
1!? MM (1? GAUGE) DIAMETER WIRES SPACED 1< MM (!5 IN)
APART!
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FERRO-CEMENT AS BUILDING MATERIAL
• EXPANDED METAL LATH, WHICH IS FORMED BY SLITTING
THIN GAUGE SHEETS AND EXPANDING THEM IN THE
DIRECTION PERPENDICULAR TO THE SLITS, HAS ABOUT THE
SAME STRENGTH AS WELDED MESH, BUT IS STIFFER AND
HENCE PRO#IDES BETTER IMPACT RESISTANCE AND BETTER
CRACK CONTROL! IT CANNOT BE USED TO MAKE
COMPONENTS WITH SHARP CUR#ES!
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FERRO-CEMENT AS BUILDING MATERIAL
• SKELETAL STEEL, WHICH GENERALLY SUPPORTS THE WIRE
MESH AND DETERMINES THE SHAPE OF THE FERROCEMENT
STRUCTURE, CAN BE SMOOTH OR DEFORMED WIRES OF
DIAMETERS AS SMALL AS POSSIBLE (GENERALLY NOT MORE
THAN 5 MM) IN ORDER TO MAINTAIN A HOMOGENOUS
REINFORCEMENT STRUCTURE (WITHOUT DIFFERENTIAL
STRESSES)! ALTERNATI#ELY, SKELETAL FRAMEWORKS WITH
TIMBER OR BAMBOO HA#E BEEN USED, BUT WITH LIMITED
SUCCESS!
• FIBRES, IN THE FORM OF SHORT STEEL WIRES OR OTHER
FIBROUS MATERIALS, CAN BE ADDED TO THE MORTAR MIX TO
CONTROL CRACKING AND INCREASE THE IMPACT RESISTANCE!
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FERRO-CEMENT AS BUILDING MATERIAL
H&.'+/. 06&& S4.6& +*&/ 06&& E3./& &7..7
S4.6& &&
06& &
W+*&/ &
(4/4.7& 06&)P.07& &
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FERRO-CEMENT AS BUILDING MATERIAL
• THE FIRST STEP IS TO PREPARE THE SKELETAL FRAMEWORK
ONTO WHICH THE WIRE MESH IS FIXED WITH A THIN TIE WIRE (OR
IN SOME CASES, BY WELDING)! A MINIMUM OF TWO LAYERS OF
WIRE MESH IS RE9UIRED, AND DEPENDING ON THE DESIGN, UP TO
12 LAYERS HA#E BEEN USED (WITH A MAXIMUM OF 5 LAYERS PER
CM OF THICKNESS)!
• THE SAND, CEMENT AND ADDITI#ES ARE CAREFULLY
PROPORTIONED BY WEIGHING, MIXED DRY AND THEN WITH
WATER! HAND MIXING IS USUALLY SATISFACTORY, BUT
MECHANICAL MIXING PRODUCES MORE UNIFORM MIXES,
REDUCES MANUAL EFFORT AND SA#ES TIME! THE MIX MUST BE
WORKABLE, BUT AS DRY AS POSSIBLE, FOR GREATER FINAL
STRENGTH AND TO ENSURE THAT IT RETAINS ITS FORM AND
POSITION BETWEEN APPLICATION AND HARDENING!
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FERRO-CEMENT AS BUILDING MATERIAL
• AFTER CHECKING THE STABILITY OF THE FRAMEWORK AND
WIRE MESH REINFORCEMENT, THE MORTAR IS APPLIED EITHER
BY HAND OR WITH A TROWEL, AND THOROUGHLY WORKED
INTO THE MESH TO CLOSE ALL #OIDS! THIS CAN BE DONE IN A
SINGLE APPLICATION, THAT IS, FINISHING BOTH SIDES BEFORE
INITIAL SET TAKES PLACE! FOR THIS TWO PEOPLE ARE NEEDED
TO WORK SIMULTANEOUSLY ON BOTH SIDES!
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FERRO-CEMENT AS BUILDING MATERIAL
• THICKER STRUCTURES CAN BE DONE IN TWO STAGES,
THAT IS, PLASTERING TO HALF THICKNESS FROM ONE SIDE,ALLOWING IT TO CURE FOR TWO WEEKS, AFTER WHICH THE
OTHER SURFACE IS COMPLETED!
COMPACTION IS ACHIE#ED BY BEATING THE MORTAR WITH
A TROWEL OR FLAT PIECE OF WOOD!
• CARE MUST BE TAKEN NOT TO LEA#E ANYREINFORCEMENT EXPOSED ON THE SURFACE, THE MINIMUM
MORTAR CO#ER IS 1!5 MM!
• EACH STAGE OF PLASTERING SHOULD BE DONE WITHOUT
INTERRUPTION, PREFERABLY IN DRY WEATHER OR UNDER
CO#ER, AND PROTECTED FROM THE SUN AND WIND! AS INCONCRETE CONSTRUCTION, FERROCEMENT SHOULD BE
MOIST CURED FOR AT LEAST 1> DAYS!
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FERRO-CEMENT AS BUILDING MATERIAL
APPLICATIONS
• BOAT CONSTRUCTION (ONE OF THE MOST SUCCESSFUL USES!
ESPECIALLY IN CHINA)!
• EMBANKMENT PROTECTION, IRRIGATION CANALS, DRAINAGE
SYSTEMS!
• SILOS (ABO#E GROUND OR UNDERGROUND) FOR STORAGE OF
GRAIN AND OTHER FOODSTUFFS!
• WATER STORAGE TANKS, WITH CAPACITIES UP TO 15 M
• SEPTIC TANKS AND A9UA PRI#IES, AND E#EN COMPLETE
SER#ICE MODULES WITH WASHING AND TOILET FACILITIES!
• PIPES, GUTTERS, TOILET BOWLS, WASHBASINS, AND THE LIKE!
• WALLS, ROOFS AND OTHER BUILDING COMPONENTS, OR
COMPLETE BUILDING, EITHER IN SITU OR IN THE FORM OF
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FERRO-CEMENT AS BUILDING MATERIAL
• FURNITURE, SUCH AS CUPBOARDS, TABLES AND BEDS, ETC! AND
#ARIOUS ITEMS FOR CHILDRENS PLAYGROUNDS!
SOME APPLICATIONS OF FERROCEMENT
FURNITURE, SANITARY UNITS, ROOFING ELEMENTS AT THE
STRUCTURAL ENGINEERING RESEARCH CENTRE, MADRAS, INDIA!
LATRINE S9UATTING SLAB, WASHING BASIN, TOILET FLUSH
CISTERN AND WATER TANK (MADE OF 5 S9UARE ELEMENTS,
ASSEMBLED ON SITE) AT THE HOUSING BUILDING RESEARCH
INSTITUTE, DHAKA, BANGLADESH!
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FERRO-CEMENT AS BUILDING MATERIAL
ADANTAGES
• THE MATERIALS RE9UIRED TO PRODUCE FERROCEMENT AREREADILY A#AILABLE IN MOST COUNTRIES!
• IT CAN TAKE ALMOST ANY SHAPE AND IS ADAPTABLE TO
ALMOST ANY TRADITIONAL DESIGN!
• WHERE TIMBER IS SCARCE AND EXPENSI#E, FERROCEMENT IS A
USEFUL SUBSTITUTE!• AS A ROOFING MATERIAL, FERROCEMENT IS A CLIMATICALLY
AND EN#IRONMENTALLY MORE APPROPRIATE AND CHEAPER
ALTERNATI#E, TO GAL#ANIED IRON AND ASBESTOS CEMENT
SHEETING!
• THE MANUFACTURE OF FERROCEMENT COMPONENTS RE9UIRES
NO SPECIAL E9UIPMENT, IS LABOUR INTENSI#E AND EASILY
LEARNT BY UNSKILLED WORKERS!
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FERRO-CEMENT AS BUILDING MATERIAL
• COMPARED WITH REINFORCED CONCRETE, FERROCEMENT IS
CHEAPER, RE9UIRES NO FORMWORK, IS LIGHTER, AND HAS A
TEN TIMES GREATER SPECIFIC SURFACE OF REINFORCEMENT,
ACHIE#ING MUCH HIGHER CRACK RESISTANCE!
• FERROCEMENT IS NOT ATTACKED BY BIOLOGICAL AGENTS,
SUCH AS INSECTS, #ERMIN AND FUNGUS!
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FERRO-CEMENT AS BUILDING MATERIAL
PROBLEMS
• FERROCEMENT IS STILL A RELATI#ELY NEW MATERIAL,
THEREFORE ITS LONG"TERM PERFORMANCE IS NOT
SUFFICIENTLY KNOWN!
• ALTHOUGH THE MANUAL WORK IN PRODUCING FERROCEMENT
COMPONENTS RE9UIRES NO SPECIAL SKILLS, THE STRUCTURAL
DESIGN, CALCULATION OF RE9UIRED REINFORCEMENTS AND
DETERMINATION OF THE TYPE AND CORRECT PROPORTIONS OF
CONSTITUENT MATERIALS RE9UIRES CONSIDERABLE KNOW"
HOW AND EXPERIENCE!
• GAL#ANIED MESHES CAN CAUSE GAS FORMATION ON THE
WIRES AND THUS REDUCE BOND STRENGTH!
• THE EXCESSI#E USE OF FERROCEMENT FOR BUILDINGS CAN
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FERRO-CEMENT AS BUILDING MATERIAL
REMEDIES !
• RESEARCH ON THE CONDITION OF OLDER FERROCEMENT
STRUCTURES!
• DE#ELOPMENT OF SIMPLE CONSTRUCTION GUIDELINES
AND RULES OF THUMB WHICH CAN BE APPLIED WITHOUTSPECIAL TECHNICAL KNOWLEDGE!
• GAL#ANIED MESH CAN BE IMMERSED IN WATER FOR 2>
HOURS AND THEN DRIED FOR 12 HOURS, IN ORDER TO
ALLOW THE SALTS USED DURING GAL#ANIING TO COME TO
THE SURFACE! THE RESIDUE CAN THEN BE BRUSHED OFF!
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FERRO-CEMENT AS BUILDING MATERIAL
• PROBLEMS WITH GAL#ANIED MESH CAN BE REDUCED BY
ADDING CHROMIUM TRIOXIDE TO THE MIXING WATER!
• COMPLETE ENCLOSURE OF DWELLING UNITS WITH
FERROCEMENT COMPONENTS (IE FOR FLOOR, WALLS AND
ROOF) SHOULD BE A#OIDED!
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FERRO-CEMENT AS BUILDING MATERIAL
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