About Post tension, pre tension, Cable Suspension,Low roof ,projected,Grads ,Sunken,Miscellaneous slab
POST TENSION SLAB:
The slab which is tensioned after constructing slab is called Post tension slab. Reinforcement is provided to resist the compression. In Post tension slab the reinforcement is replaced with cables/ steel tendons.
Post-tensioning provides a means to overcome the natural weakness of concrete in tension and to make better use of its strength in compression. The principle is easily observed when holding together several books by pressing them laterally. Linder such pressure the whole row gains enough stiffness and strength to ensure its integrity. In concrete structures, this is achieved by placing high-tensile steel tendons/cables in the element before casting When the concrete reaches the desired strength the tendons are pulled by special hydraulic jacks and held in tension using specially designed anchorages fixed at each end of the tendon This provides compression at the edge of the structural member that increases the strength of the concrete for resisting tension stresses. If tendons are appropriately curved to a certain profile, they will exert, in addition to compression at the perimeter, a beneficial upward set of forces (load balancing forces) that will counteract applied loads, relieving the structure from a portion of gravity effects. This is a one of the types of concrete slabs.
In this type of slab cables are tied instead of reinforcement. In Steel reinforcement the spacing between bars is 4inch to 6inch where as in Post tension slab the spacing is more than 2m. This is a one of the types of concrete slabs.
Advantages:
Disadvantages:
PRE TENSION SLAB :
The slab which is tensioned before placing the slab is called Pre tension slab. The slab has same features of Post tensio.
CABLE SUSPENSION SLAB:
If the span of the slab is very long, then we go for cable suspension slab which is supported on cable such as London bridge, Howrah bridge etc. Generally in construction of houses for every 4m we provide a column wheras in cable suspension slab for every 500m we provide a column. This kind of slab is provided where length of span is more and difficulty in building columns. The slabs are tied with cables and these cables are joined to columns.
LOW ROOF SLAB:
The slab which provided above the door for storage purpose is called. Low roof slab. Slab is closed at all ends and open at one end. This slab lies below the actual slab and above the door sill level. These types of concrete slabs are used in houses.
PROJECTED SLAB:
The slab which has one side fixed and the other side is free is called as Projected Slab. These type of slabs are generally constructed in hotels, Universities, function halls, etc. to use that area for dropping or picking up zone and for loading and unloading area. This is a one of the types of concrete slabs.
Grads Slab/ Slab on grade:
The slab which is casted on surface of the wearth is called a Ground slab. This type opf slab is used in Basement floor.
There are two types of Grade slabs:
Usually after casting Plinth beams. Sand is filled at an height of 0.15m and then Sand level is rammed. Then PCC is poured on sand upto a height of Plinth beams. Its an economic way of constructing ground slab which use majorly in India.
In high rise buildings after constructing Plinth beam the termite control is done in between the beams and then polythene sheet is laid to avoid termites inside the slab and then steel mesh is provided and concrete is filled. This costs more when compared with the previous one and requires more concrete than first one.
SUNKEN SLAB :
Slab which is provided below the washrooms to hide the sewage pipes or sewerage pipes is called Sunken slab. Since the pipes that carry water are concealed below the floor, care has to be taken to avoid leakage problems. After casting sewage pipes in the slab the slab is filled with coal or broken pieces of bricks. There are two types of sunken slab.
1. The slab which is provided below the normal floor level at a depth of 200mm to 300 mm and filled with broken pieces of bricks is called Sunken slab
2. The Slab which is provided above the normal floor level at a height of 200mm to 300mm and filled with coal or broken pieces of bricks called sunken slab.
MISCELLANEOUS SLAB:
ROOM CHAJJA OR LOFT :
This kind of chajja (Slab) is provided in drawing rooms and kitchen for storing House material. The usual difference between low roof slab and Room chajja is Low roof slab hides house material and whereas Room Chajja or Loft doesnt hides house material they are open and provided above the door side. This is a one of the types of concrete slabs.
KITCHEN SLAB :
The slab is provided in kitchen for its platform. For placing stove and other kitchen material is called Kitchen Slab. It has a breadth of 0.5m and length of wall and thickness is 2″.
LINTELS:
Lintels are provided Inside building above the doors and windows to re direct the top load. There are two types of lintels
Pre cast Lintels: Lintels which are manufactured in factories is called Pre cast Lintels
Cast in situ: Lintels are casted at site itself is called Cast in situ lintels.
The length of lintel is more than door length and has a width of wall, thickness of lintel is 0.1m
SUN SHADE SLAB:
Sun Shade is provided outside building above the Doors and windows are called Sun shade slab. The slab stops rain to come inside the building and direct sunglight. This is a one of the types of concrete slabs.
The slab which is tensioned after constructing slab is called Post tension slab. Reinforcement is provided to resist the compression. In Post tension slab the reinforcement is replaced with cables/ steel tendons.
Post-tensioning provides a means to overcome the natural weakness of concrete in tension and to make better use of its strength in compression. The principle is easily observed when holding together several books by pressing them laterally. Linder such pressure the whole row gains enough stiffness and strength to ensure its integrity. In concrete structures, this is achieved by placing high-tensile steel tendons/cables in the element before casting When the concrete reaches the desired strength the tendons are pulled by special hydraulic jacks and held in tension using specially designed anchorages fixed at each end of the tendon This provides compression at the edge of the structural member that increases the strength of the concrete for resisting tension stresses. If tendons are appropriately curved to a certain profile, they will exert, in addition to compression at the perimeter, a beneficial upward set of forces (load balancing forces) that will counteract applied loads, relieving the structure from a portion of gravity effects. This is a one of the types of concrete slabs.
In this type of slab cables are tied instead of reinforcement. In Steel reinforcement the spacing between bars is 4inch to 6inch where as in Post tension slab the spacing is more than 2m. This is a one of the types of concrete slabs.
Advantages:
- It allows slabs and other structural members to be thinner
- It allows us to build slabs on expansive or soft soils
- Cracks that do form are held tightly together
- Post tension slabs are excellent ways to construct stronger structures at an affordable price.
- It reduces or eliminates shrinkage cracking-therefore no joints, or fewer joints, are needed
- It lets us design longer spans in elevated members, like floors or beams
Disadvantages:
- The post tension slab can be made only by skillful professionals.
- The main problem with using post tension slab is that if care is not taken while making it, it can lead to future mishaps. Many a times, ignorant workers do not fill the gaps of the tendons and wiring completely. These gaps cause corrosion of the wires which may break untimely, leading to some failures unexpectedly.
PRE TENSION SLAB :
The slab which is tensioned before placing the slab is called Pre tension slab. The slab has same features of Post tensio.
CABLE SUSPENSION SLAB:
If the span of the slab is very long, then we go for cable suspension slab which is supported on cable such as London bridge, Howrah bridge etc. Generally in construction of houses for every 4m we provide a column wheras in cable suspension slab for every 500m we provide a column. This kind of slab is provided where length of span is more and difficulty in building columns. The slabs are tied with cables and these cables are joined to columns.
LOW ROOF SLAB:
The slab which provided above the door for storage purpose is called. Low roof slab. Slab is closed at all ends and open at one end. This slab lies below the actual slab and above the door sill level. These types of concrete slabs are used in houses.
PROJECTED SLAB:
The slab which has one side fixed and the other side is free is called as Projected Slab. These type of slabs are generally constructed in hotels, Universities, function halls, etc. to use that area for dropping or picking up zone and for loading and unloading area. This is a one of the types of concrete slabs.
Grads Slab/ Slab on grade:
The slab which is casted on surface of the wearth is called a Ground slab. This type opf slab is used in Basement floor.
There are two types of Grade slabs:
Usually after casting Plinth beams. Sand is filled at an height of 0.15m and then Sand level is rammed. Then PCC is poured on sand upto a height of Plinth beams. Its an economic way of constructing ground slab which use majorly in India.
In high rise buildings after constructing Plinth beam the termite control is done in between the beams and then polythene sheet is laid to avoid termites inside the slab and then steel mesh is provided and concrete is filled. This costs more when compared with the previous one and requires more concrete than first one.
SUNKEN SLAB :
Slab which is provided below the washrooms to hide the sewage pipes or sewerage pipes is called Sunken slab. Since the pipes that carry water are concealed below the floor, care has to be taken to avoid leakage problems. After casting sewage pipes in the slab the slab is filled with coal or broken pieces of bricks. There are two types of sunken slab.
1. The slab which is provided below the normal floor level at a depth of 200mm to 300 mm and filled with broken pieces of bricks is called Sunken slab
2. The Slab which is provided above the normal floor level at a height of 200mm to 300mm and filled with coal or broken pieces of bricks called sunken slab.
MISCELLANEOUS SLAB:
ROOM CHAJJA OR LOFT :
This kind of chajja (Slab) is provided in drawing rooms and kitchen for storing House material. The usual difference between low roof slab and Room chajja is Low roof slab hides house material and whereas Room Chajja or Loft doesnt hides house material they are open and provided above the door side. This is a one of the types of concrete slabs.
KITCHEN SLAB :
The slab is provided in kitchen for its platform. For placing stove and other kitchen material is called Kitchen Slab. It has a breadth of 0.5m and length of wall and thickness is 2″.
LINTELS:
Lintels are provided Inside building above the doors and windows to re direct the top load. There are two types of lintels
Pre cast Lintels: Lintels which are manufactured in factories is called Pre cast Lintels
Cast in situ: Lintels are casted at site itself is called Cast in situ lintels.
The length of lintel is more than door length and has a width of wall, thickness of lintel is 0.1m
SUN SHADE SLAB:
Sun Shade is provided outside building above the Doors and windows are called Sun shade slab. The slab stops rain to come inside the building and direct sunglight. This is a one of the types of concrete slabs.
Comments
Post a Comment