This document discusses deep foundations and pile foundations. Deep foundations are needed when adequate soil capacity is not available near the surface and loads must be transferred to deeper, firmer layers of soil. Common deep foundation systems include caissons and piles. Piles transmit structural loads deep into the ground. They can be classified as end-bearing or friction piles depending on how the loads are supported. Various types of piles include precast concrete, steel, composite, and bored piles which are formed by excavating soil and filling with concrete. Pile foundations are tested to confirm their design and load capacity before full construction.
Cast in situ piles are concrete piles that are constructed by excavating soil and pouring concrete directly into the hole. There are several types of cast in situ piles including simplex, franki, and vibro piles. The simplex pile is most common in Bangladesh. To construct a simplex pile, a casing is installed and reinforced with rebar before concrete is poured into the casing while it is vibrated out of the ground. Cast in situ piles are preferable to driven piles in areas with noise limitations, existing structures nearby, or weak and loose soils. The construction process involves soil testing, boring, installing rebar cages, and pouring concrete through a tremie pipe.
This document discusses different types of piles classified based on their material composition. It describes pre-cast concrete piles, cast-in-situ concrete piles including driven piles and bored piles, timber piles, steel piles, and composite piles. Specific pile types are explained in detail such as Raymond piles and McArthur cased piles. Piles transfer structural loads to deeper, stronger soil and are used when shallow foundations are inadequate.
This document provides information on formwork used for constructing concrete structures. It discusses the different types of formwork including wooden, plywood, steel and combined forms. It also describes requirements for proper formwork like being waterproof and strong enough to support loads. Common formwork systems are described for columns, beams, slabs, stairs and walls. Standards for stripping formwork from concrete structures are also outlined according to the Indian Standard code.
The discussion on rehabilitation of foundations were discussed. The types used for rehabilitation were explained with the procedure. in addition, the case study under each type were also discussed for better understanding of the subject.
The document discusses different types of foundations and piles used in construction projects. It describes shallow foundations that are at ground level and deep foundations like piles and piers that extend below the surface into stronger soil layers. It outlines various pile types including timber, concrete, steel, and composite piles. For each pile type, it provides details on materials, advantages, disadvantages, installation methods, and factors to consider in selection. The document is an informative overview of foundation and pile foundation options for structural support.
The document describes the cut and cover construction method used to build sections of a tunnel. It discusses (1) the reception area and sections built using diaphragm walls, soil nailing, and shotcrete; (2) the challenges of relocating utilities for the cut and cover sections; and (3) the process of excavating trenches, installing diaphragm walls, pouring concrete tunnel segments, and waterproofing. Cut and cover allows shallow tunnel sections to be constructed by excavating an open trench, installing structural supports, and then casting the tunnel structure.
This document discusses deep foundations and pile foundations. Deep foundations are needed when adequate soil capacity is not available near the surface and loads must be transferred to deeper, firmer layers of soil. Common deep foundation systems include caissons and piles. Piles transmit structural loads deep into the ground. They can be classified as end-bearing or friction piles depending on how the loads are supported. Various types of piles include precast concrete, steel, composite, and bored piles which are formed by excavating soil and filling with concrete. Pile foundations are tested to confirm their design and load capacity before full construction.
Cast in situ piles are concrete piles that are constructed by excavating soil and pouring concrete directly into the hole. There are several types of cast in situ piles including simplex, franki, and vibro piles. The simplex pile is most common in Bangladesh. To construct a simplex pile, a casing is installed and reinforced with rebar before concrete is poured into the casing while it is vibrated out of the ground. Cast in situ piles are preferable to driven piles in areas with noise limitations, existing structures nearby, or weak and loose soils. The construction process involves soil testing, boring, installing rebar cages, and pouring concrete through a tremie pipe.
This document discusses different types of piles classified based on their material composition. It describes pre-cast concrete piles, cast-in-situ concrete piles including driven piles and bored piles, timber piles, steel piles, and composite piles. Specific pile types are explained in detail such as Raymond piles and McArthur cased piles. Piles transfer structural loads to deeper, stronger soil and are used when shallow foundations are inadequate.
This document provides information on formwork used for constructing concrete structures. It discusses the different types of formwork including wooden, plywood, steel and combined forms. It also describes requirements for proper formwork like being waterproof and strong enough to support loads. Common formwork systems are described for columns, beams, slabs, stairs and walls. Standards for stripping formwork from concrete structures are also outlined according to the Indian Standard code.
The discussion on rehabilitation of foundations were discussed. The types used for rehabilitation were explained with the procedure. in addition, the case study under each type were also discussed for better understanding of the subject.
The document discusses different types of foundations and piles used in construction projects. It describes shallow foundations that are at ground level and deep foundations like piles and piers that extend below the surface into stronger soil layers. It outlines various pile types including timber, concrete, steel, and composite piles. For each pile type, it provides details on materials, advantages, disadvantages, installation methods, and factors to consider in selection. The document is an informative overview of foundation and pile foundation options for structural support.
The document describes the cut and cover construction method used to build sections of a tunnel. It discusses (1) the reception area and sections built using diaphragm walls, soil nailing, and shotcrete; (2) the challenges of relocating utilities for the cut and cover sections; and (3) the process of excavating trenches, installing diaphragm walls, pouring concrete tunnel segments, and waterproofing. Cut and cover allows shallow tunnel sections to be constructed by excavating an open trench, installing structural supports, and then casting the tunnel structure.
This document provides information on formwork used in concrete construction. It defines formwork and lists its common materials as steel and wood. It describes the major objectives in formwork as quality, safety, and economy. It discusses the various types of formwork including temporary and permanent structures. It also provides details on formwork for different structural elements like walls, columns, slabs, beams, stairs, and chimneys. Finally, it covers topics like requirements, loads, design, and maintenance of formwork.
This document provides information on pile foundations, including when they are used, their functions, types, and construction methods. Pile foundations are used when the soil at shallow depths does not have adequate bearing capacity. The key points are:
- Pile foundations transmit loads from structures to deeper, stronger soil layers through end bearing, friction, or both.
- They are used when shallow soils cannot support heavy loads, have low bearing capacity, or experience issues like high water levels.
- Piles can be made of concrete, timber, steel, or composites, and are either pre-cast or poured in place. Common types include end bearing, friction, compaction, and anchor piles.
This document discusses pile walls as a type of side support system for excavations. It provides information on different pile wall systems including contiguous pile walls, secant pile walls, and tangent pile walls. Continuous flight auger piling and rotary piling installation methods are described. The document also covers site investigation, soil parameters, structural design, load considerations, failure modes, and construction stages for pile walls.
This document discusses the components and process of estimating the costs for a post-tension slab-on-grade foundation. It covers calculating quantities and costs for excavation, forming, post-tension tendons, concrete, and other materials. Key steps include calculating cubic yards for excavation and concrete, converting square footage of forms to board feet, and taking off post-tension tendons by the linear foot and converting to pounds. Proper concrete mix design, placement, finishing, and curing are also important to consider in the estimate.
This document discusses deep foundation piles. It defines deep foundations as those where the depth is much larger than the width and are not constructed through ordinary open pit excavation. It then discusses different types of piles based on function and material, including bearing piles, friction piles, sheet piles, and timber, concrete, composite and steel piles. It provides details on pile construction procedures, including borehole drilling, reinforcement installation, concrete pouring using a tremie pipe, and casting the pile cap. It concludes by discussing potential causes of pile failure.
This document compares end bearing piles and friction piles. End bearing piles transfer loads through their base onto a firm soil layer, acting like a column. Friction piles transfer loads through skin friction along their length as they have no firm layer. Precast piles are constructed by driving piles into the ground using pile drivers. Continuous flight auger piles have advantages like low vibrations, quick installation, and not requiring casing. Reinforced concrete piles are manufactured through a process including forming steel cages, placing concrete in molds, curing, and demolding. When placing concrete in piles through a tremie pipe, the pipe must be kept full of concrete and the top raised above cutoff level to prevent soil or water from entering the pile.
The document discusses different types and uses of concrete. It describes three ways concrete can be classified: by binding material (cement or lime concrete), design (plain, reinforced, or pre-stressed concrete), and purpose (vacuum, air entrained, or light weight concrete). For each type, the key ingredients and common uses are provided. The document also covers mix design ratios, water-cement ratios, slump and workability tests, and the compaction factor test for evaluating concrete workability.
Well foundations, also known as caissons, are deep foundations used to transfer structural loads through unstable soil layers to more competent soil or bedrock. They are constructed by sinking a watertight retaining structure (caisson) into the ground and then filling it with concrete. Key components include the cutting edge, well curb, bottom plug, steining, top plug, and well cap. Construction involves excavating inside the caisson while applying an air pressure differential to counter soil and groundwater pressures (pneumatic caisson). Workers are at risk of decompression sickness if pressure changes are not controlled slowly.
This document discusses different types of floor construction. It describes timber suspended upper floors consisting of beams or joists supported by load bearing walls. As span increases above 3m, joists can twist causing damage, so strutting is included if span exceeds 2.5m. Reinforced concrete flat slabs are not usually economical over 5m spans, so beams can be added. Ribbed floors provide an alternative, reducing depth through narrow spaced shallow beams rather than wide spaced deep beams. Floor screeds are usually applied to provide a smooth, level surface to receive floor finishes.
Chapter 4.2 coffer dam, well foundation-final1DYPCET
The document discusses cofferdams, which are temporary structures used to keep water and soil out of excavation sites. It describes the types of cofferdams, factors affecting their design, and advantages. It also covers well foundations, including definitions, components, construction sequences, design considerations, causes of tilts/shifts, and precautions to prevent them. Risks to workers from decompression sickness when working under pressure (caisson disease) are also outlined.
Rigid pavements are constructed using reinforced concrete slabs that provide a strong wearing surface and base course. They are used in areas with adverse conditions like heavy rainfall, poor soil/drainage, or extreme climate. Materials for rigid pavements include Portland cement, coarse and fine aggregates, and water. Reinforcement includes dowel bars at joints. Rigid pavements have longitudinal and transverse joints, including contraction joints to relieve stresses, expansion joints to allow for expansion, and construction joints. They can be constructed using slipform pavers, fixed form pavers, or manual methods. Quality control ensures the concrete meets specifications. Traffic is only allowed after a minimum 28-day curing period.
Rigid pavements are constructed using reinforced concrete slabs that provide a strong wearing surface and base course. They are used in areas with adverse conditions like heavy rainfall, poor soil/drainage, or extreme climate. Materials for rigid pavements include Portland cement, coarse and fine aggregates, and water. Reinforcement includes dowel bars at joints. Rigid pavements have longitudinal and transverse joints, including contraction joints to relieve stresses, expansion joints to allow for expansion, and construction joints. They can be constructed using slipform pavers, fixed form pavers, or manual methods. Quality control checks materials and finished surface properties. Traffic is allowed after a minimum 28-day curing period.
This document summarizes the construction of rigid pavements. Rigid pavements use plain cement concrete slabs with dowel bars at joints for load transfer. They are used in areas with adverse conditions like heavy rainfall, poor soil/drainage, or extreme climate. Materials include cement, coarse and fine aggregates, and water. Construction involves subgrade preparation, forming slabs with joints, curing, and allowing time before opening to traffic. Joints include longitudinal, contraction, and expansion joints with filler and dowel bars to allow for expansion/contraction. Reinforcement improves strength and load distribution. Advantages include durability and low maintenance, while disadvantages include higher initial costs and traffic disruption during repairs.
This document provides information about pile foundations, including:
- Piles transfer structural loads through weak soil layers into stronger soils and rocks below.
- Common types of piles include pre-cast concrete, cast-in-situ concrete (e.g. Raymond, MacArthur), steel, timber, and composite piles.
- Piles are selected based on factors like soil properties, loading conditions, costs, and availability of materials. Proper pile type and design are necessary to safely support structures.
This document outlines the steps involved in drilling an oil or gas well. It begins by discussing preliminary data collection and land leasing. Key steps include obtaining permits, developing a drilling program, soliciting bids from contractors, and constructing access infrastructure. Safety systems like blowout preventers are also highlighted. The document then covers well drilling and completion activities such as installing casing, treating the formation, and installing lifting equipment. It provides an overview of the equipment used in rotary drilling like the derrick, kelly, drill pipe, drill bit, and mud circulation system.
This document provides information about constructing a diaphragm wall for basement excavation using the diaphragm wall method. It discusses what a diaphragm wall is, its applications, and the steps involved in constructing one including excavating a pre-trench, installing guide walls and reinforcement cages, concreting using tremie tubes, and joining wall panels with water stops. It also addresses selecting suitable temporary excavation support systems, advantages of diaphragm walls, excavator machines used, and providing additional wall support with ground anchors.
Pile foundations extend deep below buildings to support heavy loads on poor soil conditions. There are different types of piles including wood, steel, and concrete piles that are installed using various methods such as driving, drilling, or jacking. Piles can be classified based on their material, load transfer method, degree of soil displacement during installation, and installation method. Common types include end bearing piles that transfer load to firm soil at depth and friction piles that transfer load along their shaft through skin friction with surrounding soil.
1. Concrete is a composite material made by mixing cement, fine and coarse aggregates, and water.
2. The document discusses the history and development of concrete, including the first American concrete street and the Hoover Dam project.
3. It provides details on the composition, types, properties, and uses of concrete in construction.
Diaphragm walls, cut-off walls, and slurry walls are types of concrete or reinforced concrete walls constructed below ground using trench excavation methods. Diaphragm walls provide structural support and can retain excavations, while cut-off walls are primarily used to minimize groundwater flow with low permeability. Slurry walls are constructed using excavation techniques that use a bentonite slurry to support the trench walls and can be built with a single-phase or two-phase process depending on the depth.
World trade center in kerala proposal- AR. DEEKSHITH MAROLI 724519251008 REPORTdeekshithmaroli666
World trade center live proposal in kerala.
Future of our nation is looking towards kerala..?
Yes, because the biggest sludge less port is going to open in kerala soon and also about the hidden massing growth of tourism, it , business sector
TRENDS IN SOLID WASTE MANAGEMENT Digital Technologies can play a crucial role in making Metro Rizal's waste management systems more circular and sustainable
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Similar to LEC 15hsjsjjsjdjjdjdnnhdhdhdbdhdndd F C.ptx
This document provides information on formwork used in concrete construction. It defines formwork and lists its common materials as steel and wood. It describes the major objectives in formwork as quality, safety, and economy. It discusses the various types of formwork including temporary and permanent structures. It also provides details on formwork for different structural elements like walls, columns, slabs, beams, stairs, and chimneys. Finally, it covers topics like requirements, loads, design, and maintenance of formwork.
This document provides information on pile foundations, including when they are used, their functions, types, and construction methods. Pile foundations are used when the soil at shallow depths does not have adequate bearing capacity. The key points are:
- Pile foundations transmit loads from structures to deeper, stronger soil layers through end bearing, friction, or both.
- They are used when shallow soils cannot support heavy loads, have low bearing capacity, or experience issues like high water levels.
- Piles can be made of concrete, timber, steel, or composites, and are either pre-cast or poured in place. Common types include end bearing, friction, compaction, and anchor piles.
This document discusses pile walls as a type of side support system for excavations. It provides information on different pile wall systems including contiguous pile walls, secant pile walls, and tangent pile walls. Continuous flight auger piling and rotary piling installation methods are described. The document also covers site investigation, soil parameters, structural design, load considerations, failure modes, and construction stages for pile walls.
This document discusses the components and process of estimating the costs for a post-tension slab-on-grade foundation. It covers calculating quantities and costs for excavation, forming, post-tension tendons, concrete, and other materials. Key steps include calculating cubic yards for excavation and concrete, converting square footage of forms to board feet, and taking off post-tension tendons by the linear foot and converting to pounds. Proper concrete mix design, placement, finishing, and curing are also important to consider in the estimate.
This document discusses deep foundation piles. It defines deep foundations as those where the depth is much larger than the width and are not constructed through ordinary open pit excavation. It then discusses different types of piles based on function and material, including bearing piles, friction piles, sheet piles, and timber, concrete, composite and steel piles. It provides details on pile construction procedures, including borehole drilling, reinforcement installation, concrete pouring using a tremie pipe, and casting the pile cap. It concludes by discussing potential causes of pile failure.
This document compares end bearing piles and friction piles. End bearing piles transfer loads through their base onto a firm soil layer, acting like a column. Friction piles transfer loads through skin friction along their length as they have no firm layer. Precast piles are constructed by driving piles into the ground using pile drivers. Continuous flight auger piles have advantages like low vibrations, quick installation, and not requiring casing. Reinforced concrete piles are manufactured through a process including forming steel cages, placing concrete in molds, curing, and demolding. When placing concrete in piles through a tremie pipe, the pipe must be kept full of concrete and the top raised above cutoff level to prevent soil or water from entering the pile.
The document discusses different types and uses of concrete. It describes three ways concrete can be classified: by binding material (cement or lime concrete), design (plain, reinforced, or pre-stressed concrete), and purpose (vacuum, air entrained, or light weight concrete). For each type, the key ingredients and common uses are provided. The document also covers mix design ratios, water-cement ratios, slump and workability tests, and the compaction factor test for evaluating concrete workability.
Well foundations, also known as caissons, are deep foundations used to transfer structural loads through unstable soil layers to more competent soil or bedrock. They are constructed by sinking a watertight retaining structure (caisson) into the ground and then filling it with concrete. Key components include the cutting edge, well curb, bottom plug, steining, top plug, and well cap. Construction involves excavating inside the caisson while applying an air pressure differential to counter soil and groundwater pressures (pneumatic caisson). Workers are at risk of decompression sickness if pressure changes are not controlled slowly.
This document discusses different types of floor construction. It describes timber suspended upper floors consisting of beams or joists supported by load bearing walls. As span increases above 3m, joists can twist causing damage, so strutting is included if span exceeds 2.5m. Reinforced concrete flat slabs are not usually economical over 5m spans, so beams can be added. Ribbed floors provide an alternative, reducing depth through narrow spaced shallow beams rather than wide spaced deep beams. Floor screeds are usually applied to provide a smooth, level surface to receive floor finishes.
Chapter 4.2 coffer dam, well foundation-final1DYPCET
The document discusses cofferdams, which are temporary structures used to keep water and soil out of excavation sites. It describes the types of cofferdams, factors affecting their design, and advantages. It also covers well foundations, including definitions, components, construction sequences, design considerations, causes of tilts/shifts, and precautions to prevent them. Risks to workers from decompression sickness when working under pressure (caisson disease) are also outlined.
Rigid pavements are constructed using reinforced concrete slabs that provide a strong wearing surface and base course. They are used in areas with adverse conditions like heavy rainfall, poor soil/drainage, or extreme climate. Materials for rigid pavements include Portland cement, coarse and fine aggregates, and water. Reinforcement includes dowel bars at joints. Rigid pavements have longitudinal and transverse joints, including contraction joints to relieve stresses, expansion joints to allow for expansion, and construction joints. They can be constructed using slipform pavers, fixed form pavers, or manual methods. Quality control ensures the concrete meets specifications. Traffic is only allowed after a minimum 28-day curing period.
Rigid pavements are constructed using reinforced concrete slabs that provide a strong wearing surface and base course. They are used in areas with adverse conditions like heavy rainfall, poor soil/drainage, or extreme climate. Materials for rigid pavements include Portland cement, coarse and fine aggregates, and water. Reinforcement includes dowel bars at joints. Rigid pavements have longitudinal and transverse joints, including contraction joints to relieve stresses, expansion joints to allow for expansion, and construction joints. They can be constructed using slipform pavers, fixed form pavers, or manual methods. Quality control checks materials and finished surface properties. Traffic is allowed after a minimum 28-day curing period.
This document summarizes the construction of rigid pavements. Rigid pavements use plain cement concrete slabs with dowel bars at joints for load transfer. They are used in areas with adverse conditions like heavy rainfall, poor soil/drainage, or extreme climate. Materials include cement, coarse and fine aggregates, and water. Construction involves subgrade preparation, forming slabs with joints, curing, and allowing time before opening to traffic. Joints include longitudinal, contraction, and expansion joints with filler and dowel bars to allow for expansion/contraction. Reinforcement improves strength and load distribution. Advantages include durability and low maintenance, while disadvantages include higher initial costs and traffic disruption during repairs.
This document provides information about pile foundations, including:
- Piles transfer structural loads through weak soil layers into stronger soils and rocks below.
- Common types of piles include pre-cast concrete, cast-in-situ concrete (e.g. Raymond, MacArthur), steel, timber, and composite piles.
- Piles are selected based on factors like soil properties, loading conditions, costs, and availability of materials. Proper pile type and design are necessary to safely support structures.
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This document provides information about constructing a diaphragm wall for basement excavation using the diaphragm wall method. It discusses what a diaphragm wall is, its applications, and the steps involved in constructing one including excavating a pre-trench, installing guide walls and reinforcement cages, concreting using tremie tubes, and joining wall panels with water stops. It also addresses selecting suitable temporary excavation support systems, advantages of diaphragm walls, excavator machines used, and providing additional wall support with ground anchors.
Pile foundations extend deep below buildings to support heavy loads on poor soil conditions. There are different types of piles including wood, steel, and concrete piles that are installed using various methods such as driving, drilling, or jacking. Piles can be classified based on their material, load transfer method, degree of soil displacement during installation, and installation method. Common types include end bearing piles that transfer load to firm soil at depth and friction piles that transfer load along their shaft through skin friction with surrounding soil.
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Diaphragm walls, cut-off walls, and slurry walls are types of concrete or reinforced concrete walls constructed below ground using trench excavation methods. Diaphragm walls provide structural support and can retain excavations, while cut-off walls are primarily used to minimize groundwater flow with low permeability. Slurry walls are constructed using excavation techniques that use a bentonite slurry to support the trench walls and can be built with a single-phase or two-phase process depending on the depth.
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World trade center in kerala proposal- AR. DEEKSHITH MAROLI 724519251008 REPORTdeekshithmaroli666
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1. Concrete Technology
4th Sem BE
Civil Engineering
Lec 15: Fresh concrete
Placing, compacting, Finishing, curing
2. Covered so far
Materials for Concrete Making
Fresh Concrete: Types of concretes
Property of Fresh Concrete:
– Workability, Tests for Workability,
segregation, Bleeding, Setting Time,
Batching, Mixing, Blending and
transportation
4. Placing Concrete
(a) Placing concrete within earth mould.
Foundation concrete for a wall or column).
(b)Placing concrete within large earth mould or timber
plank formwork.
Road slab and Airfield slab
(c)Placing concrete in layers within timber or steel
shutters.
Mass concrete in dam construction or construction of concrete
abutment or pier
(d ) Placing concrete within usual form work.
Columns, beams and floors
(e) Placing concrete under water.
Placing
4
5. Concrete in foundation
Precautions:
Remove all the loose earth from the bed.
Any root of trees passing through the
foundation must be cut, charred or tarred
effectively to prevent its further growth and
piercing the concrete at a later date.
The surface of the earth, if dry, must be
just made damp so that the earth does not
absorb water from concrete.
Placing
4
6. Form work: Form work shall be designed and
constructed so as to remain sufficiently rigid
during placing and compaction of concrete. The
joints are plugged to prevent the loss of slurry
from concrete.
Stripping Time: Formwork should not be
removed until the concrete has developed a
strength of at least twice the stress to which
concrete may be subjected at the time of
removal of formwork.
Placing
4
7. In special circumstances the strength
development of concrete can be assessed by
placing companion cubes near the structure and
curing the same in the manner simulating curing
conditions of structures. In normal
circumstances, where ambient temperature
does not fall below 15°C and where ordinary
Portland cement is used and adequate curing is
done, following striking period can be
considered sufficient as per IS 456 of 2000.
Placing
4
8. Vertical formwork to columns walls and beams 16 - 24
hours
Soffit formwork to slabs (props to be refixed immediately
after removal of formwork) 3 days
Soffit formwork to beams (Props to be refixed
immediately after removal of formwork) 7 days
Props to slab
– spanning up to 4.5 m 7 days
– spanning over 4.5 m 14 days
Props to beam and arches
– Spanning up to 6 m 14 days
– Spanning over 6 m 21 days
Placing
4
9. Underwater Concreting
Placing
4
The word "tremie" is derived from the French word hopper
In 1960, the Norwegian engineer, August Gunderson, introduced new method
for submarine placing of concrete for Construction of the Detroit River tunnel.
The method was named the "tremie method".
The principle of the method is to bring the concrete through a pipe to the interior
of the concrete being poured, thus preventing contact with the surrounding
water. Before concrete is poured into the tremie pipe, a plug that keeps the
concrete separated from the water, is placed in the pipe. When the go-devil
reaches the bottom, the pipe is .lifted, so that the concrete flows out. Concrete is
continuously fed to the tremie pipe-through a hopper and the pipe is lifted as the
concrete level rises. Concrete 1s added continuously until the pour is
completed.
This method is best applied to concreting in regularly shaped forms. Flat
horizontally extensive structures should normally not be concreted by this
method, since the number of .starts will be great relative to the amount of
concrete poured. The method is particularly fit for concreting of tall narrow
volumes, such as big diameter piles reinforced as well as unreinforced.
10. basic tremie process
Drive a form pipe or hollow tube to the desired depth below grade.
Ensure that there is no dirt in the pipe. Typically an auger is used to remove
earth/soil. The pipe will in most cases fill with ground water.
Install appropriate reinforcing.
Place the tremie pipe inside the other pipe and lower the tremie pipe. There
will be, in most cases, water in the temie pipe.
Place a ball in the top of the tremie pipe and start pumping concrete into the
tremie pipe, on top of the ball. As the ball descends due to the weight of the
concrete, it will prevent water from mixing with the concrete.
The ball will exit the bottom of tremie pipe and float to the surface, and the
concrete will exit the tremie pipe and start filling the form pipe from the
bottom, forcing the water out the top as the level of the concrete rises.
As the level of concrete is increasing, the tremie pipe will be raised,
ensuring that the lower end always stays in the concrete.
Placing
4
15. Compaction of concrete
Compaction is the process which expels
entrapped air from freshly placed concrete
and packs the aggregate particles together
so as to increase the density of concrete.
4
Compacting
16. Entrapped Air
Air gets entrapped within concrete during
– mixing,
– transporting and
– placing of concrete
The lower the workability, higher is the
amount of air entrapped.
Stiff concrete mix has high percentage of
entrapped air and need higher compacting
efforts
4
Compacting
17. Need for compaction
It increases significantly the ultimate
strength of concrete and enhances the
bond with reinforcement.
It also increases the abrasion resistance
and general durability of the concrete,
decreases the permeability and helps to
minimize its shrinkage-and-creep
characteristics.
4
Compacting
19. Methods for compaction
(a) Hand Compaction
Rodding
Ramming
Tamping
(b) Compaction by Vibration
Internal vibrator (Needle vibrator)
Formwork vibrator (External vibrator)
Table vibrator
Platform vibrator
Surface vibrator (Screed vibrator)
Vibratory Roller.
(c ) Compaction by Pressure and Jolting
(d) Compaction by Spinning
4
Compacting
20. Hand Compaction
Rodding: poking the concrete with about 2
metre long, 16 mm diameter rod to pack
the concrete between the reinforcement
and sharp corners and edges.
Rodding is done continuously over the
complete area to effectively pack the
concrete and drive away entrapped air.
Iron rod, bamboos or cane is used for
rodding
4
Compacting
21. 4
Compacting
Ramming should be done with care. Light
ramming can be permitted in unreinforced
foundation concrete or in ground floor
construction. Ramming should not be
permitted in case of reinforced concrete or in
the upper floor construction, where concrete
is placed in the formwork supported on struts.
If ramming is adopted in the above case the
position of the reinforcement may be
disturbed or the formwork may fail,
particularly, if steel rammer is used.
22. Tamping: usual methods for compacting
roof or floor slab or road pavements
Thickness less and surface to be finished
smooth and level.
It consists of beating the top surface by
wooden cross beam of section about 10 x
10 cm. Since the tamping bar is sufficiently
long it not only compacts, but also levels
the top surface across the entire width.
4
Compacting
23. For high strength concrete, w/c ration is
lesser and the mix is stiff.
mechanically operated vibratory
equipment is used
Compaction by Vibration Compacting
4
24. Internal Vibrator
most commonly used.
also called,
Needle Vibrator,
Immersion Vibrator, or
Poker Vibrator.
The vibrations are caused by eccentric weights
attached to the shaft or the motor or to the rotor of
a vibrating element
It consists of
a power unit,
a flexible shaft and
a needle
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Compacting
25. The power unit
electrically driven or
petrol engine or
air compressor.
They are portable
can be shifted from place to place
Can be used in difficult positions and
situations
IS 2505-1963 (i.e., Specification for concrete
vibrators, immersion type)
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Compacting
28. External Vibrator
Formwork Vibrator
used for concreting columns, thin walls or
in the casting of precast units. The
machine is clamped on to the external wall
surface of the formwork. The vibration is
given to the formwork so that the concrete
in the vicinity of the shutter gets vibrated.
Produce good finish
Consumes more power
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Compacting
31. Table Vibrator
This is the special case of formwork
vibrator, where the vibrator is clamped to
the table. or table is mounted on springs
which are vibrated transferring the
vibration to the table.
Used for vibrating concrete cubes.
Adopted mostly in the laboratories and in
making small but precise prefabricated
R.C.C. members.
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Compacting
33. Platform Vibrator
Platform vibrator is a table vibrator, but it is
larger in size.
Used in the manufacture of large
prefabricated concrete elements such as
electric poles, railway sleepers, prefabricated
roofing elements etc.
Sometimes, the platform vibrator is also
coupled with jerking or shock giving
arrangements such that a thorugh
compaction is given to the concrete.
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Compacting
34. Surface Vibrator
Surface vibrators "Screed Board Vibrators".
A small vibrator placed on the screed board gives an effective
method of compacting and levelling of thin concrete members,
such as floor slabs, roof slabs and road surface.
Mostly, floor slabs and roof slabs are so thin that internal
vibrator or any other type of vibrator cannot be easily
employed. In such cases, the surface vibrator can be
effectively used.
In general, surface vibrators are not effective beyond about 15
cm. In the modern construction practices like vaccum
dewatering technique, or slip-form paving technique, the use
of screed board vibrator are common feature.
In the above situations double beam screed board vibrators
are often used.
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Compacting
38. Compaction by
Pressure and Jolting
Effective for compacting very dry concrete.
Used for compacting hollow blocks, cavity blocks
and solid concrete blocks.
The stiff concrete is vibrated, pressed and also
given jolts.
Combined action of the jolts vibrations and
pressure, the stiff concrete gets compacted to a
dense form to give good strength and volume
stability.
By using high pressure, a concrete of very low
water cement ratio can be compacted to yield very
high strength.
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Compacting
39. Spinning: recent methods of compaction of
concrete.
Adopted for the fabrication of concrete pipes.
The plastic concrete when spun at a very high
speed, gets well compacted by centrifugal force.
Patented products such a "Hume Pipes", "spun
pipes" are compacted by spinning process.
Compaction by Spinning Compacting
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40. Vibratory Roller
very dry and lean concrete is compacted using
Vibratory Roller.
Such concrete is known as “Roller Compacted
Concrete”.
Was used in Japan and later spread to USA and other
countries mainly for the construction of dams and
pavements.
Heavy roller which vibrates while rolling is used for the
compaction of dry lean concrete. Such roller
compacted concrete of grade M 10 has been
successfully used as base course, 15 cm thick, for the
Delhi-Mathura highway and Mumbai-Pune express
highways
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Compacting
41. Points of Caution
Pour concrete in small layers
Active part of needle should be immersed in concrete
Concrete should be poked at 40 to 60 cm intervals in large
surface members
The needle should be withdrawn gradually
New filing should be vibrated as early as possible
Vibrate till circular shaped cement grout is seen at the top of
concrete
Vibrating near the surface of hardened concrete should be
done carefully.
In RCC work, the needle shall not touch the reinforcement
Don’t vibrate very close to formwork.
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Compacting
42. Over-vibration
Normal-weight concretes that are well proportioned are
not readily susceptible to defects caused by over-
vibration.
These result from segregation and are characterised by
an excessive thickness of mortar at the surface of the
concrete. The surface may also have a frothy
appearance.
Over-vibration may cause problems when grossly
oversized equipment is operated for an excessive length
of time, but is more likely to cause problems with poorly-
proportioned mixes or those to which excessive amounts
of water have been added.
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Compacting
43. 4
Compacting
Under-vibration is far more common than
over-vibration and, when it occurs, can
cause serious defects. Invariably, the
concrete is incompletely compacted which
reduces its strength, its durability and will
possibly affect its surface finish.
46. Curing
controlling the rate and extent of moisture
loss from concrete during cement
hydration
Control of temperature since this affects
the rate at which cement hydrates.
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Curing
48. Why moisture loss?
Moisture loss could occur during
– manufacture,
– transportation,
– placement or
– afterwards
Moisture is required for hydration of
cement which continues for days, and
even weeks rather than hours
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Curing
51. Curing is the process of controlling the rate and extent of
moisture loss from concrete during cement hydration. It
may be either after it has been placed in position (or
during the manufacture of concrete products), thereby
providing time for the hydration of the cement to occur.
Since the hydration of cement does take time – days,
and even weeks rather than hours – curing must be
undertaken for a reasonable period of time if the
concrete is to achieve its potential strength and
durability. Curing may also encompass the control of
temperature since this affects the rate at which cement
hydrates.
Curing
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52. How long?
The curing period may depend on the
properties required of the concrete, the
purpose for which it is to be used, and the
ambient conditions, ie the temperature and
relative humidity of the surrounding
atmosphere.
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Curing