NAME:NAME: ASLAM KHANASLAM KHANSUB TITLE:SUB TITLE: “MANUFACTURE OF PRE “MANUFACTURE OF PRE

STRESSED TUBULAR SPUN STRESSED TUBULAR SPUN CONCRETE POLE OF 11 METRE LONG”.CONCRETE POLE OF 11 METRE LONG”.SUBMITTED UNDER THE GUIDANCE OF SUBMITTED UNDER THE GUIDANCE OF

G.A SATISHG.A SATISHSENIOR LECTURERSENIOR LECTURER

ABSTRACTABSTRACT

The report contains the information about the manufacture The report contains the information about the manufacture of pre stressed Tubular spun concrete poleof pre stressed Tubular spun concrete pole

The industry namely FERRO CEMENT PRE FAB LTD situated The industry namely FERRO CEMENT PRE FAB LTD situated at 14-c Attibele Industrial Area at 14-c Attibele Industrial Area

Bangalore.Bangalore. The products manufactured in Industry involed chian line The products manufactured in Industry involed chian line

production with movements of crane all safety measures production with movements of crane all safety measures were incorporated during the time of manufacture.were incorporated during the time of manufacture. Special emphasis was given to TIME STUDY of manufacture Special emphasis was given to TIME STUDY of manufacture

of pre stressed tubular pole.of pre stressed tubular pole.

1.ABOUT THE INDUSTRY1.ABOUT THE INDUSTRYThe following machinery are available in the Industry.The following machinery are available in the Industry.1.A moving over head crane of 10ton capacity.1.A moving over head crane of 10ton capacity.2.A concrete batch mixing plant.2.A concrete batch mixing plant.3.Small capacity concrete mixers.3.Small capacity concrete mixers.4.molds of different capacities.4.molds of different capacities.5.A boiler for steam producing.5.A boiler for steam producing.6.A wire cutting machine.6.A wire cutting machine.7.A bar bending machine.7.A bar bending machine.8.A compression testing machine of 200ton capacity.8.A compression testing machine of 200ton capacity.9.Sieve shaker,drying ove4n,sieves and other testing 9.Sieve shaker,drying ove4n,sieves and other testing equipments.equipments.10.Motor for spinning. 10.Motor for spinning.

2.MANUFACTURE OF PRE STRESSED TUBULAR SPUN CONCRETE POLE OF 11 METRE LONG.2.MANUFACTURE OF PRE STRESSED TUBULAR SPUN CONCRETE POLE OF 11 METRE LONG.

INTRODUCTIONINTRODUCTION

Wooden,steel and concrete poles were used for power distribution lines since nineteenth century,.Wooden,steel and concrete poles were used for power distribution lines since nineteenth century,.The first pole used was wooden pole and addition to it steel tubular poles and S.M rail pole were in The first pole used was wooden pole and addition to it steel tubular poles and S.M rail pole were in used.used.As wooden poles have small life compare to steel pole but it requires maintenance for protection As wooden poles have small life compare to steel pole but it requires maintenance for protection against corrosion and particularly pre stressed concrete pole can be considered as having un limited against corrosion and particularly pre stressed concrete pole can be considered as having un limited life without maintanence cost for their corrosion protection.life without maintanence cost for their corrosion protection.As these poles are subjected to small vertical forces and large horizontal forces at bottom.As these poles are subjected to small vertical forces and large horizontal forces at bottom.The horizontal forces at their top are smaller along the axis of the power line and much larger on The horizontal forces at their top are smaller along the axis of the power line and much larger on direction perpendicular to it.direction perpendicular to it.As in the perpendicular direction the pole must resist the horizontal forces caused from wind loads As in the perpendicular direction the pole must resist the horizontal forces caused from wind loads against poles and the wires carried by them.against poles and the wires carried by them.As the experience showed that concrete poles with a circular cross section is preferable than As the experience showed that concrete poles with a circular cross section is preferable than rectangular,Tsections as they resist better impact loads and have equal resistance to horizontal rectangular,Tsections as they resist better impact loads and have equal resistance to horizontal forces in all direction. forces in all direction.

TECHNICAL SPECIFICATION FOR SPUN TECHNICAL SPECIFICATION FOR SPUN CONCRETE POLESCONCRETE POLES

SCOPE: This specification covers design,manufacture,testing SCOPE: This specification covers design,manufacture,testing and supply of pre stressed coincrete tubular spun poles and supply of pre stressed coincrete tubular spun poles designed for a working load of 500kg.designed for a working load of 500kg.APPLICABLE STANDARDS: The codes shall comply the APPLICABLE STANDARDS: The codes shall comply the provisions made in IS specification except with the conflict provisions made in IS specification except with the conflict with specific requirements in this specification.with specific requirements in this specification.a) IS 1678-1978 specification for stressed concrete poles a) IS 1678-1978 specification for stressed concrete poles overhead power, traction and telecommunication lines.overhead power, traction and telecommunication lines.b) IS 2905-1966 methods of tests for concrete poles for b) IS 2905-1966 methods of tests for concrete poles for overhead power and telecommunication lines.overhead power and telecommunication lines.c) IS 7321-1974 code of practice for selection handling and c) IS 7321-1974 code of practice for selection handling and errection of concrete poles for overhead power and errection of concrete poles for overhead power and telecommunication lines.telecommunication lines.d) IS 13158-1991 pre stressed concrete circular spun poles for d) IS 13158-1991 pre stressed concrete circular spun poles for overhead power lines.overhead power lines.

TERMINOLOGY:TERMINOLOGY:For the purpose of this specificationFor the purpose of this specification the the definitions of average, permanent load,load definitions of average, permanent load,load factor, tranverse load at first crack, ultimate factor, tranverse load at first crack, ultimate tranverse load and working load shall be as per IS tranverse load and working load shall be as per IS 1678 or other equivalent International standards.1678 or other equivalent International standards.

DIMENSIONS AND SHAPES:DIMENSIONS AND SHAPES:The pole shall be of hollow and circular in shape with an The pole shall be of hollow and circular in shape with an outside taper of 1:75.The diameter and thickness shall be outside taper of 1:75.The diameter and thickness shall be as per design requirements.as per design requirements.

CEMENT:CEMENT: High strength ordinary portland cement conforming to IS High strength ordinary portland cement conforming to IS 269-1976 or Rapid hardening cement conforming to IS 804-269-1976 or Rapid hardening cement conforming to IS 804-1978 shall be used which shall have additional 1978 shall be used which shall have additional requirements.requirements.Initial setting time:Not less than 30 minutes.Initial setting time:Not less than 30 minutes.Final setting time:Not more than 600 minutes.Final setting time:Not more than 600 minutes.The minimum compressive strength at 7 days shall be 375 The minimum compressive strength at 7 days shall be 375 kgs/cmsquare. kgs/cmsquare.

AGGREGATES:AGGREGATES:Coarse aggregates and fine aggregates for casting pole shall Coarse aggregates and fine aggregates for casting pole shall confirm to IS 383.The normal maximum size of aggregates shall in confirm to IS 383.The normal maximum size of aggregates shall in no case more than 20mm or .25 the minimum thickness of pole no case more than 20mm or .25 the minimum thickness of pole which ever is less than the spacing between the pre stressing which ever is less than the spacing between the pre stressing wires.wires.

WATER:WATER:Water should be free from chlorides, sulphates other salts and Water should be free from chlorides, sulphates other salts and organic matter.organic matter.

ADMIXTURES:ADMIXTURES:Admixtures should not contain calcium chloride or other Admixtures should not contain calcium chloride or other chlorides and salts which are likely to promote corrosion in chlorides and salts which are likely to promote corrosion in steel.steel.

REINFORCEMENT:REINFORCEMENT:Reinforcement steel bars and wires used for the Reinforcement steel bars and wires used for the manufacture of pre stressed pole shall confirm manufacture of pre stressed pole shall confirm following Standards.following Standards.IS 2090-1983 Specification for high tensile steel IS 2090-1983 Specification for high tensile steel bars used in PSC.bars used in PSC.IS 6003-1983Specification for indented wire for IS 6003-1983Specification for indented wire for PSC(first revision).PSC(first revision).The surface of all reinforcement shall be free from The surface of all reinforcement shall be free from ioose scale, oil grese,clayor any other material ioose scale, oil grese,clayor any other material that may have deterioting effect on the bond that may have deterioting effect on the bond between the reinforcement and concrete. between the reinforcement and concrete.

CONCRETE:CONCRETE:The concrete mix shall be designed to the The concrete mix shall be designed to the requirements as per standards.requirements as per standards.

a) Minimum cube strength at 28 days should be a) Minimum cube strength at 28 days should be at least 50 N/mmsquare.at least 50 N/mmsquare.

b) The concrete strength at least half the 28 day b) The concrete strength at least half the 28 day strength in the designed strength.strength in the designed strength.

MOULDS:MOULDS:Moulds shall be of steel or rigid construction to Moulds shall be of steel or rigid construction to prevent distortion and so arranged as to provide prevent distortion and so arranged as to provide smooth surface. The moulds shall not allow any smooth surface. The moulds shall not allow any leakage of cement grout during casting. The leakage of cement grout during casting. The holes in the plates for HT wire shall be accurately holes in the plates for HT wire shall be accurately drilled by jugs to ensure inter changeability.drilled by jugs to ensure inter changeability.

The end plate is designed to withstand forces The end plate is designed to withstand forces arising out of the change in direction of pre arising out of the change in direction of pre stressing wires during tensioning.stressing wires during tensioning.

TENSIONING OF WIRES:TENSIONING OF WIRES:The HT wires shall be placed axially at regular spacing The HT wires shall be placed axially at regular spacing along the circumference. As per standards.along the circumference. As per standards.Helical steel shall be of 2.7 mm dia MS wires pitch shall be Helical steel shall be of 2.7 mm dia MS wires pitch shall be of 150mm.of 150mm.The clear cover shall be of 20mm.The clear cover shall be of 20mm.Pre tensioning shall be by automatic machines. Force shall Pre tensioning shall be by automatic machines. Force shall be applied for the entire group of HT wires to ensure be applied for the entire group of HT wires to ensure equally stressed.equally stressed.The pre stressing wires shall be stretched by an approved The pre stressing wires shall be stretched by an approved method so as tom prevent slippage.method so as tom prevent slippage.The force induced in the pre stressing wires can be The force induced in the pre stressing wires can be determined by guages attached to the pre tensioning determined by guages attached to the pre tensioning apparatus.apparatus.

DE-TENSIONING OF WIRES:DE-TENSIONING OF WIRES:ANCHORING SYSTEM SHALL PROVIDE A DEVICEANCHORING SYSTEM SHALL PROVIDE A DEVICE

FOR GRADUAL DETENSIONING OF THE WIRES. FOR GRADUAL DETENSIONING OF THE WIRES. NO BACK PULLING OF THE WIRES SHALL BE NO BACK PULLING OF THE WIRES SHALL BE PERMITTING IN GRADUAL DE TENSIONING DEVICE. PERMITTING IN GRADUAL DE TENSIONING DEVICE. FLAME CUTTING OF WIRES BEFORE RELEASE OFFLAME CUTTING OF WIRES BEFORE RELEASE OF FULL TENSION SHALL BE STRICTLY PROHIBITEB.FULL TENSION SHALL BE STRICTLY PROHIBITEB.

THE TRANSFER OF PRESTRESS SHALL NOT BE THE TRANSFER OF PRESTRESS SHALL NOT BE EFFECTED UNTIL THE POLES HAS ATTAINED SPECIFIED EFFECTED UNTIL THE POLES HAS ATTAINED SPECIFIED

AS AS ESTABLISHED OF THE CUBE TESTS. ESTABLISHED OF THE CUBE TESTS.

CURING:CURING:THE CURING SHALL BE DONE ON A SATURATED THE CURING SHALL BE DONE ON A SATURATED

STEAM AT 65 DEGREES CENTIGRADE. ENSURESTEAM AT 65 DEGREES CENTIGRADE. ENSURE THAT 80%OF STRENGTH IS REACHED IN 6 HOURS. THAT 80%OF STRENGTH IS REACHED IN 6 HOURS. THERE AFTER WIRES WILL BE CUT DEMOULDED THERE AFTER WIRES WILL BE CUT DEMOULDED AND TRANSFERRED TO WATER FOR 14 DAYS AND TRANSFERRED TO WATER FOR 14 DAYS CURING.CURING.

DURING MANUFACTURING PERIODICAL TESTS ON DURING MANUFACTURING PERIODICAL TESTS ON CONCRETE CUBES OF HALLOW CYLINDRUCAL SPECIMEN CONCRETE CUBES OF HALLOW CYLINDRUCAL SPECIMEN MEASURING 200M DIA AND 300 MM HEIGHT SHALL CARRIED MEASURING 200M DIA AND 300 MM HEIGHT SHALL CARRIED OUTB TILL THE CONCRETE ACHIEVES THE REQUIRES OUTB TILL THE CONCRETE ACHIEVES THE REQUIRES STRENGTH AT TRANSFER. THERE AFTER TEST ON STRENGTH AT TRANSFER. THERE AFTER TEST ON CONCRETE SHALL BE CARRIED OUT AS PER IS 1343CONCRETE SHALL BE CARRIED OUT AS PER IS 1343

EARTHING:EARTHING:EARTHING SHALL BE PROVIDED BY HAVING A EARTHING SHALL BE PROVIDED BY HAVING A LENGTH OF 8SWG GI WIRE EMBEDDED IN LENGTH OF 8SWG GI WIRE EMBEDDED IN CONCRETE DURING MANUFACTURING AND ENDS CONCRETE DURING MANUFACTURING AND ENDS OF THE WIRES LEFT PROJECTING FROM THE POLE OF THE WIRES LEFT PROJECTING FROM THE POLE TO A LENGTH OF 100MM AT 250MM FROM TOP TO A LENGTH OF 100MM AT 250MM FROM TOP AND 150MM BELOW GROUND LEVEL.AND 150MM BELOW GROUND LEVEL.

EARTH WIRE SHALL NOT BE ALLOWED TO COME EARTH WIRE SHALL NOT BE ALLOWED TO COME IN CONTACT WITH THE PRE STRESSING WIRE.IN CONTACT WITH THE PRE STRESSING WIRE.

FINISH: FINISH: Poles shall be free from surface defects including hair cracks. The Poles shall be free from surface defects including hair cracks. The surface of the poles in contact with the steel mould shall be surface of the poles in contact with the steel mould shall be smooth and regular in shape and shall as for as possible be free smooth and regular in shape and shall as for as possible be free from pores. Water retaining pockets and honeycombing formation from pores. Water retaining pockets and honeycombing formation shall not be admissible . 25mm thick 1:2 cement mortar cover shall not be admissible . 25mm thick 1:2 cement mortar cover shall be provided on the full area of the top of pole.shall be provided on the full area of the top of pole.The end of the pre stressing wires shall be cut as close to surface The end of the pre stressing wires shall be cut as close to surface of the pole as possible and in any case shall not project more than of the pole as possible and in any case shall not project more than 3mm. 3mm. The end of pre stressing wires shall be given two coats of suitable The end of pre stressing wires shall be given two coats of suitable anti corrosive paints approved by BESCOM.anti corrosive paints approved by BESCOM.No touching up or finishing by cement grout shall be done on the No touching up or finishing by cement grout shall be done on the poles after it is removed from the mould.poles after it is removed from the mould.Metallic base plate is to be provided at the bottom of the poleMetallic base plate is to be provided at the bottom of the pole

WELDING AND LAPPING OF STEEL:WELDING AND LAPPING OF STEEL:The high tensile steel wire shall be continous over The high tensile steel wire shall be continous over the entire length of the tendon.Welding shall not the entire length of the tendon.Welding shall not be allowed in any case.be allowed in any case.

PROVISION OF HOOKS AND HOLES.PROVISION OF HOOKS AND HOLES.

TESTS:TESTS:Tranverse strength test:Poles made of ordinary portland Tranverse strength test:Poles made of ordinary portland cement shall be tested on co0mpletion of 28 days and cement shall be tested on co0mpletion of 28 days and poles made of rapid hardening cement shall be tested on poles made of rapid hardening cement shall be tested on completion of 14 days.completion of 14 days.The pole may be tested for horizontal or vertical position.The pole may be tested for horizontal or vertical position.the pole is rigidly supported at the buttoned for a distance the pole is rigidly supported at the buttoned for a distance to the agreed depth of planting.to the agreed depth of planting.Load shall be applied at a point 600mm from the top of the Load shall be applied at a point 600mm from the top of the pole and be steadily and gradually increased to the pole and be steadily and gradually increased to the designed value of tranverse load at first crack.the designed value of tranverse load at first crack.the deflection at this point is measured.deflection at this point is measured.

A pre stressed concrete pole shall be deemed not to have A pre stressed concrete pole shall be deemed not to have passed the test if visible cracks appear at a srage prior to the passed the test if visible cracks appear at a srage prior to the application of designed tranverse load for the first crack.application of designed tranverse load for the first crack.The load shall then be reduced to zero and increased gradually The load shall then be reduced to zero and increased gradually to a load equall to the first crack load plus 10% of the minimum to a load equall to the first crack load plus 10% of the minimum ultimate tranverse load and held up for two minutes .ultimate tranverse load and held up for two minutes .This procedure shall be repeated untill load reaches the value This procedure shall be repeated untill load reaches the value of 80% of the minimum ultimate tranverse load and thereafter of 80% of the minimum ultimate tranverse load and thereafter increased by 5% of the ultimate tranverse load untill failures increased by 5% of the ultimate tranverse load untill failures occur.occur.Each time load is applied it is held for two minutes.The load Each time load is applied it is held for two minutes.The load applied to PSC poles at the point of failures and shall be applied to PSC poles at the point of failures and shall be measured to the naerest 5kg.measured to the naerest 5kg.The pole shall be deemed not to have passed the test if the The pole shall be deemed not to have passed the test if the observed ultimate tranverse load is less than the designed observed ultimate tranverse load is less than the designed ultimate tranverse load.ultimate tranverse load.

MANUFACTURING PROCESS OF TUBULAR PRE STRESSED MANUFACTURING PROCESS OF TUBULAR PRE STRESSED CONCRETE POLE OF 11 METER LONGCONCRETE POLE OF 11 METER LONG

The manufacture of Tubular PSC poles consists of the following operations.The manufacture of Tubular PSC poles consists of the following operations.a) Cleaning the moulds and oilinga) Cleaning the moulds and oilingb) Preparing the reinforcement cageb) Preparing the reinforcement cagec) Placing of PVC inserts and through holes in the mouldc) Placing of PVC inserts and through holes in the mouldd) Placing of the reinforcement cage in the mouldd) Placing of the reinforcement cage in the moulde) Mixing of concretee) Mixing of concretef) Placing the concrete in the mouldf) Placing the concrete in the mould

g) Placing other half of the mould and fixingg) Placing other half of the mould and fixingh) Pre tensioning of the wiresh) Pre tensioning of the wiresi) Spinning of the mouldi) Spinning of the mouldJ) curing with steamJ) curing with steamK) Demoulding the mouldK) Demoulding the mouldL) finished dimension of the poleL) finished dimension of the pole

CLEANING THE MOULD:CLEANING THE MOULD:Mould is made of MS sheet it is 11M in length with two halves.Mould is made of MS sheet it is 11M in length with two halves.Each halves is made of four pieces and joined to gather.Each halves is made of four pieces and joined to gather.One half of the mould is placed on roller and other on ground.One half of the mould is placed on roller and other on ground.The mould is cleaned with wire brush and oiled using paint The mould is cleaned with wire brush and oiled using paint brush.brush.Dimensions:Dimensions:length=11000mmlength=11000mmOD (big end)=390mmOD (big end)=390mmOD (small end)=225mmOD (small end)=225mmThe mould when placed on the rollers rthe bigger rest on The mould when placed on the rollers rthe bigger rest on rollers powered by motor and the remaining mould rests on rollers powered by motor and the remaining mould rests on support rollers. Spacing between drive and the support support rollers. Spacing between drive and the support rolleris 3000mm .number of rolling point is 5. rolleris 3000mm .number of rolling point is 5.

PREPARING THE REINFORCEMENT CAGE:PREPARING THE REINFORCEMENT CAGE:The reinforcement cage consists of the following:The reinforcement cage consists of the following:a) 7mm dia HT indented wire of 13.5 meter length-11 nos.a) 7mm dia HT indented wire of 13.5 meter length-11 nos.b) 3 ply 3mm strands 5 mater length -5nos.b) 3 ply 3mm strands 5 mater length -5nos.c) 2.7 dia coil 54 meter long.c) 2.7 dia coil 54 meter long.The coil is fabricated to helical shape in a machine.The coil is fabricated to helical shape in a machine.The bigger end dia of 342.5mm and smaller end dia of 177.7mm.The bigger end dia of 342.5mm and smaller end dia of 177.7mm.The helical coil is placed on the concrete mould having the shape of The helical coil is placed on the concrete mould having the shape of the pole placed on ground.the pole placed on ground.3 ply of 3mm rods of 5m are inserted in to the helical coil and 3 ply of 3mm rods of 5m are inserted in to the helical coil and binded by binding wire.binded by binding wire.11nos of 7mm dia are placed at equal spacing at the circumference 11nos of 7mm dia are placed at equal spacing at the circumference of coil.of coil.These 7mm dia rods of 13.5 meter long are tiedto the coil by binding These 7mm dia rods of 13.5 meter long are tiedto the coil by binding wire.wire.End plates are inserted to the cage.End plates are inserted to the cage.

PLACING PVC INSERTS,NUTS AND PLACING PVC INSERTS,NUTS AND THROUGH HOLES IN THE MOULD:THROUGH HOLES IN THE MOULD:

The above depends on designed aspect which are The above depends on designed aspect which are inserted in to the mould.inserted in to the mould.

The PVC inserts,nuts bolts dependas upon the The PVC inserts,nuts bolts dependas upon the design.design.

PLACING OF THE REINFORCEMENT PLACING OF THE REINFORCEMENT CAGE IN THE MOULD:\CAGE IN THE MOULD:\The cage is lifted from the concrete mould by The cage is lifted from the concrete mould by tower crane and placed on the MS mould for tower crane and placed on the MS mould for casting of the pole.casting of the pole.

The end plates are fixed to the mould by bolts.The end plates are fixed to the mould by bolts.

Suitable arrangments for earthing is done.Suitable arrangments for earthing is done.

MIXING OF CONCRETE:MIXING OF CONCRETE: CementCement : Cement of Birla 53 grade is used the : Cement of Birla 53 grade is used the tests are conducted for every batch of 200 bags tests are conducted for every batch of 200 bags and results are approved for use of cement.and results are approved for use of cement.Sand: Sand: Locally available sand is used and it is Locally available sand is used and it is stored under shade.stored under shade.The tests carried on sand are:The tests carried on sand are:a) Bulking of sanda) Bulking of sandb) Specific gravityb) Specific gravityc) Sieve analysisc) Sieve analysisd) Water contentd) Water content

Coarse aggregates:Coarse aggregates:Coarse aggregates of 12.5mm are used .Coarse aggregates of 12.5mm are used .The test conducted are a) Sieve analysis b) Surface dry.The test conducted are a) Sieve analysis b) Surface dry.By trial methods a mix of 1:1:2.5 with water cement ratio of By trial methods a mix of 1:1:2.5 with water cement ratio of .35 and a plasticizer conplast SP 430 300 ml per bag of .35 and a plasticizer conplast SP 430 300 ml per bag of cement is used gives concrete strength of M52.5.cement is used gives concrete strength of M52.5.Concrete is mixed in a batch mixer .3 loads of concrete is Concrete is mixed in a batch mixer .3 loads of concrete is required for casting the pole.required for casting the pole.Each load consists of 85kgs of cement,85 kgs of sand,212.5 Each load consists of 85kgs of cement,85 kgs of sand,212.5 kgs of coarse aggregates,28 litres of water and 416 ml of kgs of coarse aggregates,28 litres of water and 416 ml of SP430 are mixed for 10 minutes in the mixer.SP430 are mixed for 10 minutes in the mixer.The concrete is transported in trolley over the railling. The concrete is transported in trolley over the railling.

PLACING OF CONCRETE IN THE PLACING OF CONCRETE IN THE MOULD:MOULD:Concrete is placed manually by masons and Concrete is placed manually by masons and compacted lightly by tamping rod.compacted lightly by tamping rod.The quantity of concrete is uniformly placed The quantity of concrete is uniformly placed through out the mould starting from the bigger through out the mould starting from the bigger end.end.HT wires are button headed at the at the bigger HT wires are button headed at the at the bigger end securely.end securely.9 cubes of 15 cms cubes are prepared for 9 cubes of 15 cms cubes are prepared for compression test.compression test.

PLACING OF OTHER HALF OF THE PLACING OF OTHER HALF OF THE MOULD:MOULD:The other half of the mould is lifted by truss with The other half of the mould is lifted by truss with chains using overhead crane.chains using overhead crane.

This half mould is placed on the already This half mould is placed on the already concreted mould properly.concreted mould properly.

After placing the two halves are thoroughly After placing the two halves are thoroughly tightened using bolts and nuts.tightened using bolts and nuts.

PRE TENSIONING THE WIRES:PRE TENSIONING THE WIRES:The HT indented 11 nos of wires are pre tensioned at the smaller end of The HT indented 11 nos of wires are pre tensioned at the smaller end of the already casted having fresh concrete.the already casted having fresh concrete.Diametrically opposite pairs of HT wire are pre tensioned at a time using Diametrically opposite pairs of HT wire are pre tensioned at a time using two hydraulic jacks.two hydraulic jacks.The wires to be tensioned are buttoned securely to the anchoring plate.The wires to be tensioned are buttoned securely to the anchoring plate.The hydraulic jacks are inserted to the wires and buttoned headed and load The hydraulic jacks are inserted to the wires and buttoned headed and load is applied to the wire manually.is applied to the wire manually.An extension of 115mm is obtd by applying pressure through the jack.An extension of 115mm is obtd by applying pressure through the jack.Normally 330 to 340kg per sqcm pressure is recorded in the pressure Normally 330 to 340kg per sqcm pressure is recorded in the pressure guage attached to the jack.guage attached to the jack.After tensioning of the wire excess wire is cut.After tensioning of the wire excess wire is cut.Care should be taken that no movement of persons is allowed in front of Care should be taken that no movement of persons is allowed in front of the mould in the direction of the tension.the mould in the direction of the tension.Sometimes if wires are not properly buttoned the wires may come shoot Sometimes if wires are not properly buttoned the wires may come shoot out of the mould with great force.out of the mould with great force.

SPINNING OF THE MOULD:SPINNING OF THE MOULD:After tensioning the wires all bolts are checked to its After tensioning the wires all bolts are checked to its tightness.tightness.Both the ends are covered with covering plates and Both the ends are covered with covering plates and tightened with bolts.tightened with bolts. Time Motor speed(rpm) mouldspeed(rpm)Time Motor speed(rpm) mouldspeed(rpm) 2 minutes 550 722 minutes 550 72 3 minutes 750 108 3 minutes 750 108 4 minutes 950 1364 minutes 950 136 5 minutes 1100 1565 minutes 1100 156The above speeds and time is arrived by trials.The above speeds and time is arrived by trials.

CURING WITH STEAM:CURING WITH STEAM:After spinning cover at the bigger end is removed After spinning cover at the bigger end is removed and the cube already casted in mould are placed and the cube already casted in mould are placed in the casted mould.in the casted mould.Another cover plate having a hole for passing of Another cover plate having a hole for passing of steam is fixed.steam is fixed.Steam is passed through a boiler of temperature Steam is passed through a boiler of temperature 100 deg centg for 8-10 hrs till the required 100 deg centg for 8-10 hrs till the required strength is obtd.strength is obtd.Which can be obtd by cube test.Which can be obtd by cube test.The pole after de moulding is lifted and placed in The pole after de moulding is lifted and placed in curing tank for 14 days.curing tank for 14 days.

DEMOULDING:DEMOULDING:After cooling of the steam cover plates are After cooling of the steam cover plates are removed.removed.

The cubes are sent for testing compressive The cubes are sent for testing compressive strength.strength.

The top mould is removed using truss.The top mould is removed using truss.

Tension is released by cutting HT wires.Tension is released by cutting HT wires.

The casted pole is lifted with the help of crane.The casted pole is lifted with the help of crane.

THE DIMENSIONS OF FINISHED POLE:THE DIMENSIONS OF FINISHED POLE:Bigger end outer diameter: 390mm-inner Bigger end outer diameter: 390mm-inner diameter:290mmdiameter:290mm

Smaller end:outer diameter:220mm-inner Smaller end:outer diameter:220mm-inner diameter:120mmdiameter:120mm

Thickness of the pole wall:100mmThickness of the pole wall:100mm

Length of the pole: 11000mm.Length of the pole: 11000mm.

TESTING OF POLE:TESTING OF POLE:Test bench is established in the factory on ground Test bench is established in the factory on ground with rigid support at the bigger end 1.5meter with rigid support at the bigger end 1.5meter from the bigger end.from the bigger end.Intermediate rollers are provided at 4 meter from Intermediate rollers are provided at 4 meter from as required by BESCOM.as required by BESCOM.Load is applied as pull from a dynamometer at Load is applied as pull from a dynamometer at the smaller end first crack is noted.the smaller end first crack is noted.This load should not be less than 500kg.This load should not be less than 500kg.Test is also carried out to destruction of pole and Test is also carried out to destruction of pole and the load at the destruction is noted.the load at the destruction is noted.

CONCLUSION:CONCLUSION:Ferro cement elements are 10 to40% more Ferro cement elements are 10 to40% more economical when compared with RC economical when compared with RC structures.structures.

The use of industrialised ferro cement The use of industrialised ferro cement products needs to be popularised in low products needs to be popularised in low cost housing because of inherent cost housing because of inherent advantages such as low weigth,reduction in advantages such as low weigth,reduction in labour and easy transportation and better labour and easy transportation and better control over quality and reduced cost. control over quality and reduced cost.

Description Time in minutesDescription Time in minutesInserts releasing Inserts releasing 20 20HT wire cuttingHT wire cutting 30 30Bolts and nuts removingBolts and nuts removing 30 30De mouldingDe moulding 20 20Pole releasingPole releasing 15 15Pole shiftingPole shifting 15 15Cleaning of mould 40 Cleaning of mould 40 Cage fixing and end plates 15Cage fixing and end plates 15Inserts fixing for first half 15Inserts fixing for first half 15Mixing first load of concrete 15Mixing first load of concrete 15Pouring of first load 15Pouring of first load 15Mixing and pouring of second load 15Mixing and pouring of second load 15Mixing and pouring of third load 15Mixing and pouring of third load 15Mould assembling Mould assembling 30 30Pre tension Pre tension 30 30SpinningSpinning 20 20

Total Total 245 245