01-09-2014, 12:42 PM
PROJECT OVERVIEW 1. COMPANY NAME - Mohan International Builders 2. CLIENT NAME - Motia’z Developers Pvt. Ltd. 3. PROJECT NAME - Royal business Park 4. PROJECT COST - 136 Crores 5. PROJECT DURATION - 40 Months 6. NO. OF STOREYS - 16 no’s 7. TOTAL AREA - 65000 sq.ft 8. PROPERTY TYPE - Commercial 9. SUB TYPE - SCO 10. LOCATION - Royal Citi , Zirakpur 11. PROJECT STATUS - Under Construction
STRUCTURAL WORK
MARKING EXCAVATION LINE AND BUILDING LINE :
The very first step of starting a building after reconaissance of the land available is to mark excavation line and building line. Building line is the outer face line of the building to be constructed. Excavation line is the line parallel to building line at a distance of about 10-15 metres outside. This extra area is provided to provide extra land protection for various machineries which are used to construct the footing as well as to avoid land sliding into the constructable area .
EXCAVATION:-
The project was in its initial stage when I joined the training .Excavation was being conducted as construction of basement was going to take place .It was conducted in dry conditions. In this process soil, rock, and other materials are removed from a site, typically with the use of heavy earthmoving equipment such as power shovel(JCB machine) and back hoe loader. The level of excavation was -8200mm down from road level.
DEWATERING:-
Dewatering is the removal of waterfrom solid material or soil by wet classification, centrifugation, filteration or similar solid-liquid separation process. Construction dewatering, unwatering, or water control are common terms used to describe removal or draining groundwater or surface water from a riverbed, construction site. On a construction site, this dewatering may be implemented before subsurface excavation for foundations, shoring, or cellar space to lower the water table. This frequently involves the use of submersible "dewatering" pumps centrifugal ("trash") pumps, eductors, or application of vacuum to well points.
DRESSING OF GROUND:-
After excavation, dressing of ground was done. For dressing the ground we used power shovel (JCB machine). It also helped in roughly levelling the ground. This was done in order to create a smooth site for the construction of the building.
LEVELLING:-
After dressing the ground with the help of a JCB machine, we used Auto level to level the ground more precisely. An auto level or automatic level is an optical instrument used to establish or check points in the same horizontal plane. It is used in surveying and building to transfer, measure, or set horizontal levels. The level instrument is set up on a tripod and, depending on the type, either roughly or accurately set to a levelled condition using levelling screws. The operator looks through the eyepiece of the telescope while an assistant holds a graduated staff vertical at the point under measurement. The instrument and staff are used to gather and/or transfer elevations (levels) during site surveys or building construction. Measurement generally starts from a benchmark which was provided by the supervisor with known height determined by a previous survey, or an arbitrary point with an assumed height.
PCC (Plain Cement Concrete) :
After excavation PCC is laid in the excavated area to provide a solid , clean and levelled bed for the footing. The grade of PCC is M10 (1:3:6) or M15 (1:2:4).The thickness of PCC is generally 75-100mm. We can use water proofing on pcc to prevent the water seepage. For this purpose we use memberane and to protect memberane we use Geotech sheets. To protect all this waterproofing we uses screed of grade same as in pcc.
Things to note:-
1. P.C.C. placed below ground level should be protected from falling earth during and after placing.
2. P.C.C. placed in ground containing deleterious substances should be kept free from contact with such a ground and with water draining there from during placing and for a period of seven days.
3. When joint in layer of concrete are unavoidable, and end is sloped at an angle of 30 and junctions of different layers break joint in layer upper layer of concrete.
4. The lower surface is made rough and clean watered before upper layer is laid.
WATER PROOFING
Bitumen sheet
LAYOUT OF COULMNS AND WALLS :
First of all Transverse and Longitudinal grids are marked. After laying PCC these grids are transferred to it. Then from these grids , the column grids are marked and using these grids as per drawing we can mark the actual layout of columns. While marking these grids on pcc we can do a cross check for correct grids. We calculate the dialgonal distance by using pythagorus theorem and then we measure the actual distance. If both distances are equal then our layout is correct otherwise it is to be done again. The layout of walls (Retaining as well as other) is also done with the help of these grids as per distances mentioned in drawings.
FOUNDATION:-
A foundation is the part of the structure which transfers the load of the building to the soil on which it rests.
Types of foundation:-
1. Shallow foundation
2. Deep foundation
Shallow foundation:-
Shallow foundations are those founded near to the finished ground surface; generally where the founding depth is less than the width of the footing and less than 3m. These are not strict rules, but merely guidelines: basically, if surface loading or other surface conditions will affect the bearing capacity of a foundation it is 'shallow'. Shallow foundations (sometimes called 'spread footings') include pads ('isolated footings'), strip footings and rafts. Shallows foundations are used when surface soils are sufficiently strong and stiff to support the imposed loads; they are generally unsuitable in weak or highly compressible soils, such as poorly-compacted fill, peat, recent lacustrine and alluvial deposits, etc.
Deep foundation:-
Deep foundation is that whose depth is more than its width.
Type of foundation used at site:
Raft /mat foundation is used as a part of shallow foundation at our site.
RAFT or MAT FOUNDATION:
In made up grounds , soft clayey or marshy sites having low value of bearing capacities , having concenterated structural loads are generally supported by providing RAFT FOUNDATION. Also if the structure is liable to subsidence on account of its being located in minimum area or due to uncertain behaviours of its subsoil water conditions, RAFT FOUNDATIONS consists of thick reinforced concrete slab covering the entire of the bottom of the structure like a floor. The slab is reinforced with bars running at right angle to each other both near bottom and top face of the slab. The grade used in RAFT FOUNDATION is M25 (1:1:2). Thickness of Raft slab is generally about 600 mm.
Raft foundation is used because load was to be distributed and it is not possible to provide individual footings due to space constraints that is they would overlap on each other. Raft foundations have the advantage of reducing differential settlements as the concrete slab resists differential movements between loading positions. They are often needed on soft or loose soils with low bearing capacity as they can spread the loads over a larger area.
Cover to raft reinforcement:- A 50mm cover was provided to the raft reinforcement as shown.
Description of raft reinforcement:-
20mm dia. Bars were used to form 200mm x 200mm square mesh.
1. Total thickness of raft is 600mm.
2. Designed for 30 t/m2
3. M25 mix used.
Bottom, top, side covers :- 50mm
Then chairs were fixed on lower mesh. Chairs are used to keep spacing in between the lower and upper mesh of raft reinforcement. Chair provide base to upper reinforcement to be laid.
Lower mesh:-
20 mm dia. bars
Upper mesh reinforcement for raft:-
16mm dia. Bars were used to form mesh of 100mm x 100mm
16mm dia. Bars in upper mesh :-
100mm
100mm
Concreting of raft:-
Concrete is a mixture of cement, sand, stone aggregates and water. A cage of steel rods used together with the concrete mix leads to the formation of Reinforced Cement Concrete popularly known as RCC. Concrete has two main stages:
Fresh Concrete
Hardened concrete
Fresh Concrete should be stable and should not segregate or bleed during transportation and placing when it is subjected to forces during handling operations of limited nature. The mix should be cohesive and mobile enough to be placed in the form around the reinforcement and should be able to cast into the required shape without losing continuity or homogeneity under the available techniques of placing the concrete at a particular job. The mix should be amenable to proper and through compaction into a dense, compact concrete with minimum voids under the existing facilities of compaction at the site. A best mix from the point of view of compatibility should achieve a 99 percent elimination of the original voids present.
Segregation:-
The stability of a concrete mix requires that it should not segregate and bleed during the transportation and placing, Segregation can be defined as separating out of the ingredients of a concrete mix, so that the mix is no longer in homogeneous condition. Only the stable homogeneous mix can be fully compacted.
The segregation depends upon the handling and placing operations. The tendency to segregate, amount of coarse aggregate, and with the increased slump. The tendency to segregate can be minimized by:
1. Reducing the height of drop by concrete.
2. Not using the vibration as a means of spreading a heap of a concrete into a level mass over a large –area.
3. Reducing the continued vibration over a longer time, as the coarse aggregate tends to settle to the bottom and the seum would rise to the surface.
4. Adding small quantity of water which improves cohesion of the mix.
Bleeding:-
Bleeding is due to the rise of water in the mix to the surface because of the inability of the solid particles in the mix to the hold all the mixing water during settling of practical’s under the effect of compaction. The bleeding causes formation of a porous, weak and non-durable concrete layer at the top of placed concrete.in case of lean mixes bleeding may create capillary channels increasing the permeability of the concrete. When the concrete is placed in different layers and each layer is compacted after allowing certain time to lapse before the next layer is laid, the bleeding may cause a plane of weakness between two layers .any laitance formed should be removed by brushing and washing before a new layer is added over compacted the surface should be avoided.
Hardened concrete:-
One of the most important properties of the hardened concrete is its strength which represents the ability if concrete to resist forces. If the nature of the force is to produce compression, the strength is termed compressive strength. The compressive strength of hardened concrete is generally considered 10 be the most important property and is often taken as the index of the overall quality of concrete. The strength can indirectly give an idea of the most of the other properties of concrete which are related directly to the structure of hardened cement paste. A stronger concrete is dense, compact, impermeable and resistant to weathering and to some chemicals. However, a stronger concrete may exhibit higher drying shrinkage with consequent cracking, due to the presence of higher cement content.
Some of the other desirable properties like shear and tensile strengths, modulus of elasticity, bond, impact and durability etc. are generally related to compressive strength. As the compressive strength can be measured easily on standard sized cube or cylindrical specimens, it can be specified as a criterion for studying the effect of any variable on the quality of concrete. However, the concrete gives different values of any property under different testing conditions. Hence method of testing, size of specimen and the rate of loading etc. are stipulated while testing the concrete to minimize the variations in test results. The statistical methods are commonly used for specifying the quantitative value of any particular property of hardened concrete.
Compressive strength:-
The compressive strength of concrete is defined as the load which causes the failure of specimen, per unit area of cross-section in uniaxial compression under given rate of loading. The strength of concrete is expressed as N/mm2. The compressive strength at 28 days after casting is taken as a criterion for specifying the quality of concrete. This is termed as grade of concrete. IS 456:2000 stipulates the use of 150 mm cubes.
Tensile strength:-
The concrete has low tensile strength: it ranges from 8-12 per cent of its compressive strength. An average value of 10 per cent is generally adopted.
Shear strength:-
The concrete subjected to bending and shear stress is accompanied by tensile and compressive stresses. The shear failures are due to resulting diagonal tension. The shear strength is generally 12-13 per cent of its compressive strength.
Bond strength:-
The resistance of concrete to the slipping of reinforcing bars embedded in concrete is called bond strength. The bond strength is provided by adhesion of hardened cement paste, and by the friction of concrete and steel. It is also affected by shrinkage of concrete relative to steel. On an average bond strength is taken as 10 per cent of its compressive strength.
Concreting of raft is done with the help of concrete pump.
This is the main type of concrete pump either known as a truck-mounted concrete pump or placed on a trailer, and it is commonly referred to as a line pump or trailer-mounted concrete pump. This pump requires steel or rubber concrete placing hoses to be manually attached to the outlet of the machine.
Those hoses are linked together and lead to wherever the concrete needs to be placed.
Line pumps normally pump concrete at lower volumes than boom pumps and are used for smaller volume concrete placing applications such as swimming pools, sidewalks, and single family home concrete slabs and most ground slabs.
The concrete is carried away with the help of concrete pump pipes. Series of these pipes were joined with the help of a clamp to obtain desired length. Length of a single pipe was 3m. Diameter of the pipe was 150 mm.
Placing of concrete :-
Vibrators consolidate freshly poured concrete so that trapped air and the concrete settles firmly. Improper consolidation of concrete can cause product defects, compromise the concrete strength, and produce surface blemishes such as bug holes and honeycombing. An internal concrete vibrator is a steel cylinder about the size of the handle of a baseball bat, with a hose or electrical cord attached to one end. The vibrator head is immersed in the wet concrete.
FOOTING :
During the binding of steel for raft the steel of footing is also bind as the height of footing given by the designer in drawings. All footings may or may not be of equal sizes. Its size depends upon the load transfered from the structure . It forms base for the column. For footings the grade used is same as used in raft. Footing plays a very vital role in life of structure.
Dressing of concrete:-
After concreting, dressing was done.
Scaffolding:-
Temporary structures are needed to support the platform over which the workmen can sit and carry on the constructions. These temporary structures constructed very close to wall, is in the form of timber or steel formwork, commonly called as scaffolding.
At our site the material used for scaffolding are standards, ledgers. These are the mild steel pipes of different lengths according to the requirements of site.
Component parts of scaffolding:-
1. STANDARDS:- These are the vertical members of formwork, supported on the ground or drums, or embedded into the ground.
2. LEDGERS:- These are horizontal members, running parallel to the wall. As shown in above picture.
3. BRACES:- These are diagonal members fixed on standards, which use to tie up the standards in correct manner and also it helps to keep the standards in its proper position.
4. COUPLERS:- Couplers are very important component used in scaffolding which is used to tie up standards and horizontal main cross pipes. These contain a pair of nut and bolts by which we tighten the standards and cross pipes as shown in picture.
5. BASE PLATES:- Base plates are used below standards which avoid sharpen edge of standards to sink or penetrate in the ground. It also increases the bearing area below standards. These plates are normally of mild steel.
6. BOARDING:-These are horizontal members which support workmen and material. These are supported on the horizontal cross pipes or ledgers. At our site these are of rectangular steel pipes which are welded with the help of a perpendicular rectangular pipe of same size.
COLUMNS CASTING :
For casting of a column , first column steel is bind. then check the numbers of outer bars in column transverse as well longitudnal direction.Master ring is provided to bind the whole outer bars of the column then make the pairs of columns in both directions then provide the internal ring to each pair.If there is any odd number of bar is left then provide link.Then starter is made according to the grids in drawing. Height of starter is 3'.Then shuttering plates are fixed according to the startes.When shuttering of columns is done with the frame,the height of the frame is maximum three meters(3m).Cover blocks are provided to provide clear cover of about 40-50mm in columns.Vibrator is used while casting of column to provide flow of concrete.The nozzle used in vibrator is 40mm or 60mm.The grade of concrete used in column casting of M40(i.e design mix).
While casting columns first of all the slump test of the concrete is done. Also cubes 15*15*15 cm are filled. 7 days and 28 days testing is done in labortary. For 7 days test 67% and for 28 days 100% strength should be attained by the concrete.Shuttering is removed after 24 hours in case of vertical members.
Couplers:- These are used to overlap steel bars of larger dia (more than 16 mm). These are made up of mild steel. They are easily workable. They should be properly checked for tightness before concreting. By using couplers the laping length of the steel bar is eliminated. Thus saving the wastage of steel.
STRUCTURAL WORK
MARKING EXCAVATION LINE AND BUILDING LINE :
The very first step of starting a building after reconaissance of the land available is to mark excavation line and building line. Building line is the outer face line of the building to be constructed. Excavation line is the line parallel to building line at a distance of about 10-15 metres outside. This extra area is provided to provide extra land protection for various machineries which are used to construct the footing as well as to avoid land sliding into the constructable area .
EXCAVATION:-
The project was in its initial stage when I joined the training .Excavation was being conducted as construction of basement was going to take place .It was conducted in dry conditions. In this process soil, rock, and other materials are removed from a site, typically with the use of heavy earthmoving equipment such as power shovel(JCB machine) and back hoe loader. The level of excavation was -8200mm down from road level.
DEWATERING:-
Dewatering is the removal of waterfrom solid material or soil by wet classification, centrifugation, filteration or similar solid-liquid separation process. Construction dewatering, unwatering, or water control are common terms used to describe removal or draining groundwater or surface water from a riverbed, construction site. On a construction site, this dewatering may be implemented before subsurface excavation for foundations, shoring, or cellar space to lower the water table. This frequently involves the use of submersible "dewatering" pumps centrifugal ("trash") pumps, eductors, or application of vacuum to well points.
DRESSING OF GROUND:-
After excavation, dressing of ground was done. For dressing the ground we used power shovel (JCB machine). It also helped in roughly levelling the ground. This was done in order to create a smooth site for the construction of the building.
LEVELLING:-
After dressing the ground with the help of a JCB machine, we used Auto level to level the ground more precisely. An auto level or automatic level is an optical instrument used to establish or check points in the same horizontal plane. It is used in surveying and building to transfer, measure, or set horizontal levels. The level instrument is set up on a tripod and, depending on the type, either roughly or accurately set to a levelled condition using levelling screws. The operator looks through the eyepiece of the telescope while an assistant holds a graduated staff vertical at the point under measurement. The instrument and staff are used to gather and/or transfer elevations (levels) during site surveys or building construction. Measurement generally starts from a benchmark which was provided by the supervisor with known height determined by a previous survey, or an arbitrary point with an assumed height.
PCC (Plain Cement Concrete) :
After excavation PCC is laid in the excavated area to provide a solid , clean and levelled bed for the footing. The grade of PCC is M10 (1:3:6) or M15 (1:2:4).The thickness of PCC is generally 75-100mm. We can use water proofing on pcc to prevent the water seepage. For this purpose we use memberane and to protect memberane we use Geotech sheets. To protect all this waterproofing we uses screed of grade same as in pcc.
Things to note:-
1. P.C.C. placed below ground level should be protected from falling earth during and after placing.
2. P.C.C. placed in ground containing deleterious substances should be kept free from contact with such a ground and with water draining there from during placing and for a period of seven days.
3. When joint in layer of concrete are unavoidable, and end is sloped at an angle of 30 and junctions of different layers break joint in layer upper layer of concrete.
4. The lower surface is made rough and clean watered before upper layer is laid.
WATER PROOFING
Bitumen sheet
LAYOUT OF COULMNS AND WALLS :
First of all Transverse and Longitudinal grids are marked. After laying PCC these grids are transferred to it. Then from these grids , the column grids are marked and using these grids as per drawing we can mark the actual layout of columns. While marking these grids on pcc we can do a cross check for correct grids. We calculate the dialgonal distance by using pythagorus theorem and then we measure the actual distance. If both distances are equal then our layout is correct otherwise it is to be done again. The layout of walls (Retaining as well as other) is also done with the help of these grids as per distances mentioned in drawings.
FOUNDATION:-
A foundation is the part of the structure which transfers the load of the building to the soil on which it rests.
Types of foundation:-
1. Shallow foundation
2. Deep foundation
Shallow foundation:-
Shallow foundations are those founded near to the finished ground surface; generally where the founding depth is less than the width of the footing and less than 3m. These are not strict rules, but merely guidelines: basically, if surface loading or other surface conditions will affect the bearing capacity of a foundation it is 'shallow'. Shallow foundations (sometimes called 'spread footings') include pads ('isolated footings'), strip footings and rafts. Shallows foundations are used when surface soils are sufficiently strong and stiff to support the imposed loads; they are generally unsuitable in weak or highly compressible soils, such as poorly-compacted fill, peat, recent lacustrine and alluvial deposits, etc.
Deep foundation:-
Deep foundation is that whose depth is more than its width.
Type of foundation used at site:
Raft /mat foundation is used as a part of shallow foundation at our site.
RAFT or MAT FOUNDATION:
In made up grounds , soft clayey or marshy sites having low value of bearing capacities , having concenterated structural loads are generally supported by providing RAFT FOUNDATION. Also if the structure is liable to subsidence on account of its being located in minimum area or due to uncertain behaviours of its subsoil water conditions, RAFT FOUNDATIONS consists of thick reinforced concrete slab covering the entire of the bottom of the structure like a floor. The slab is reinforced with bars running at right angle to each other both near bottom and top face of the slab. The grade used in RAFT FOUNDATION is M25 (1:1:2). Thickness of Raft slab is generally about 600 mm.
Raft foundation is used because load was to be distributed and it is not possible to provide individual footings due to space constraints that is they would overlap on each other. Raft foundations have the advantage of reducing differential settlements as the concrete slab resists differential movements between loading positions. They are often needed on soft or loose soils with low bearing capacity as they can spread the loads over a larger area.
Cover to raft reinforcement:- A 50mm cover was provided to the raft reinforcement as shown.
Description of raft reinforcement:-
20mm dia. Bars were used to form 200mm x 200mm square mesh.
1. Total thickness of raft is 600mm.
2. Designed for 30 t/m2
3. M25 mix used.
Bottom, top, side covers :- 50mm
Then chairs were fixed on lower mesh. Chairs are used to keep spacing in between the lower and upper mesh of raft reinforcement. Chair provide base to upper reinforcement to be laid.
Lower mesh:-
20 mm dia. bars
Upper mesh reinforcement for raft:-
16mm dia. Bars were used to form mesh of 100mm x 100mm
16mm dia. Bars in upper mesh :-
100mm
100mm
Concreting of raft:-
Concrete is a mixture of cement, sand, stone aggregates and water. A cage of steel rods used together with the concrete mix leads to the formation of Reinforced Cement Concrete popularly known as RCC. Concrete has two main stages:
Fresh Concrete
Hardened concrete
Fresh Concrete should be stable and should not segregate or bleed during transportation and placing when it is subjected to forces during handling operations of limited nature. The mix should be cohesive and mobile enough to be placed in the form around the reinforcement and should be able to cast into the required shape without losing continuity or homogeneity under the available techniques of placing the concrete at a particular job. The mix should be amenable to proper and through compaction into a dense, compact concrete with minimum voids under the existing facilities of compaction at the site. A best mix from the point of view of compatibility should achieve a 99 percent elimination of the original voids present.
Segregation:-
The stability of a concrete mix requires that it should not segregate and bleed during the transportation and placing, Segregation can be defined as separating out of the ingredients of a concrete mix, so that the mix is no longer in homogeneous condition. Only the stable homogeneous mix can be fully compacted.
The segregation depends upon the handling and placing operations. The tendency to segregate, amount of coarse aggregate, and with the increased slump. The tendency to segregate can be minimized by:
1. Reducing the height of drop by concrete.
2. Not using the vibration as a means of spreading a heap of a concrete into a level mass over a large –area.
3. Reducing the continued vibration over a longer time, as the coarse aggregate tends to settle to the bottom and the seum would rise to the surface.
4. Adding small quantity of water which improves cohesion of the mix.
Bleeding:-
Bleeding is due to the rise of water in the mix to the surface because of the inability of the solid particles in the mix to the hold all the mixing water during settling of practical’s under the effect of compaction. The bleeding causes formation of a porous, weak and non-durable concrete layer at the top of placed concrete.in case of lean mixes bleeding may create capillary channels increasing the permeability of the concrete. When the concrete is placed in different layers and each layer is compacted after allowing certain time to lapse before the next layer is laid, the bleeding may cause a plane of weakness between two layers .any laitance formed should be removed by brushing and washing before a new layer is added over compacted the surface should be avoided.
Hardened concrete:-
One of the most important properties of the hardened concrete is its strength which represents the ability if concrete to resist forces. If the nature of the force is to produce compression, the strength is termed compressive strength. The compressive strength of hardened concrete is generally considered 10 be the most important property and is often taken as the index of the overall quality of concrete. The strength can indirectly give an idea of the most of the other properties of concrete which are related directly to the structure of hardened cement paste. A stronger concrete is dense, compact, impermeable and resistant to weathering and to some chemicals. However, a stronger concrete may exhibit higher drying shrinkage with consequent cracking, due to the presence of higher cement content.
Some of the other desirable properties like shear and tensile strengths, modulus of elasticity, bond, impact and durability etc. are generally related to compressive strength. As the compressive strength can be measured easily on standard sized cube or cylindrical specimens, it can be specified as a criterion for studying the effect of any variable on the quality of concrete. However, the concrete gives different values of any property under different testing conditions. Hence method of testing, size of specimen and the rate of loading etc. are stipulated while testing the concrete to minimize the variations in test results. The statistical methods are commonly used for specifying the quantitative value of any particular property of hardened concrete.
Compressive strength:-
The compressive strength of concrete is defined as the load which causes the failure of specimen, per unit area of cross-section in uniaxial compression under given rate of loading. The strength of concrete is expressed as N/mm2. The compressive strength at 28 days after casting is taken as a criterion for specifying the quality of concrete. This is termed as grade of concrete. IS 456:2000 stipulates the use of 150 mm cubes.
Tensile strength:-
The concrete has low tensile strength: it ranges from 8-12 per cent of its compressive strength. An average value of 10 per cent is generally adopted.
Shear strength:-
The concrete subjected to bending and shear stress is accompanied by tensile and compressive stresses. The shear failures are due to resulting diagonal tension. The shear strength is generally 12-13 per cent of its compressive strength.
Bond strength:-
The resistance of concrete to the slipping of reinforcing bars embedded in concrete is called bond strength. The bond strength is provided by adhesion of hardened cement paste, and by the friction of concrete and steel. It is also affected by shrinkage of concrete relative to steel. On an average bond strength is taken as 10 per cent of its compressive strength.
Concreting of raft is done with the help of concrete pump.
This is the main type of concrete pump either known as a truck-mounted concrete pump or placed on a trailer, and it is commonly referred to as a line pump or trailer-mounted concrete pump. This pump requires steel or rubber concrete placing hoses to be manually attached to the outlet of the machine.
Those hoses are linked together and lead to wherever the concrete needs to be placed.
Line pumps normally pump concrete at lower volumes than boom pumps and are used for smaller volume concrete placing applications such as swimming pools, sidewalks, and single family home concrete slabs and most ground slabs.
The concrete is carried away with the help of concrete pump pipes. Series of these pipes were joined with the help of a clamp to obtain desired length. Length of a single pipe was 3m. Diameter of the pipe was 150 mm.
Placing of concrete :-
Vibrators consolidate freshly poured concrete so that trapped air and the concrete settles firmly. Improper consolidation of concrete can cause product defects, compromise the concrete strength, and produce surface blemishes such as bug holes and honeycombing. An internal concrete vibrator is a steel cylinder about the size of the handle of a baseball bat, with a hose or electrical cord attached to one end. The vibrator head is immersed in the wet concrete.
FOOTING :
During the binding of steel for raft the steel of footing is also bind as the height of footing given by the designer in drawings. All footings may or may not be of equal sizes. Its size depends upon the load transfered from the structure . It forms base for the column. For footings the grade used is same as used in raft. Footing plays a very vital role in life of structure.
Dressing of concrete:-
After concreting, dressing was done.
Scaffolding:-
Temporary structures are needed to support the platform over which the workmen can sit and carry on the constructions. These temporary structures constructed very close to wall, is in the form of timber or steel formwork, commonly called as scaffolding.
At our site the material used for scaffolding are standards, ledgers. These are the mild steel pipes of different lengths according to the requirements of site.
Component parts of scaffolding:-
1. STANDARDS:- These are the vertical members of formwork, supported on the ground or drums, or embedded into the ground.
2. LEDGERS:- These are horizontal members, running parallel to the wall. As shown in above picture.
3. BRACES:- These are diagonal members fixed on standards, which use to tie up the standards in correct manner and also it helps to keep the standards in its proper position.
4. COUPLERS:- Couplers are very important component used in scaffolding which is used to tie up standards and horizontal main cross pipes. These contain a pair of nut and bolts by which we tighten the standards and cross pipes as shown in picture.
5. BASE PLATES:- Base plates are used below standards which avoid sharpen edge of standards to sink or penetrate in the ground. It also increases the bearing area below standards. These plates are normally of mild steel.
6. BOARDING:-These are horizontal members which support workmen and material. These are supported on the horizontal cross pipes or ledgers. At our site these are of rectangular steel pipes which are welded with the help of a perpendicular rectangular pipe of same size.
COLUMNS CASTING :
For casting of a column , first column steel is bind. then check the numbers of outer bars in column transverse as well longitudnal direction.Master ring is provided to bind the whole outer bars of the column then make the pairs of columns in both directions then provide the internal ring to each pair.If there is any odd number of bar is left then provide link.Then starter is made according to the grids in drawing. Height of starter is 3'.Then shuttering plates are fixed according to the startes.When shuttering of columns is done with the frame,the height of the frame is maximum three meters(3m).Cover blocks are provided to provide clear cover of about 40-50mm in columns.Vibrator is used while casting of column to provide flow of concrete.The nozzle used in vibrator is 40mm or 60mm.The grade of concrete used in column casting of M40(i.e design mix).
While casting columns first of all the slump test of the concrete is done. Also cubes 15*15*15 cm are filled. 7 days and 28 days testing is done in labortary. For 7 days test 67% and for 28 days 100% strength should be attained by the concrete.Shuttering is removed after 24 hours in case of vertical members.
Couplers:- These are used to overlap steel bars of larger dia (more than 16 mm). These are made up of mild steel. They are easily workable. They should be properly checked for tightness before concreting. By using couplers the laping length of the steel bar is eliminated. Thus saving the wastage of steel.