In continuation with the earlier article on ‘the various stages in construction of a house after laying the foundation, the next step is laying of the SLAB.
Slab:
- A slab is a flat, two-dimensional planar structural component of building having a very small thickness compared to its other two dimensions
- Reinforced concrete slabs are used in roofs, floors, ceilings and as the decks of bridges
- The slab may be supported by walls or by reinforced concrete beams usually cast monolithically with the slab or by structural steel beams or by columns, or by the ground
Functions of Slab:
- To provide a flat surface
- To act as sound, heat and fire insulator
- It provides a covering shelter or working flat surface in buildings
- Its primary function is to transfer the load by bending in one or two directions
- The upper slab becomes the ceiling for the storey beneath it
Construction process of a slab:
A structure is composed of several connecting elements of construction like walls, beams, columns, foundation, slabs etc. Out of these, slab is of utmost importance. It helps the other components of the building to withstand different loads.
Concrete floor slab construction process includes the following-
- Assemble and Erect Formwork,
- Prepare and Place Reinforcement,
- Pouring, Compacting and Finishing concrete and
- Removal of Formwork and Curing of Concrete slab
- Assemble and Erect Formwork:
- The formwork shall be designed to withstand construction loads such as fresh concrete pressure and weight of workers and operators and their machines.
- The formwork should be positioned correctly, lined and leveled, joints sealed adequately, and prevent protruding of nails into the concrete etc.,
The site engineer should be aware of the below formwork deficiencies so that the final slab will be laid properly
- Poor or lack of formwork examination during and after concrete placement to identify uncommon deflections or other indications of possible failure that could be corrected
- Inadequate nailing, bolting, welding, or fastening
- Improper lateral bracing
- Construct formwork that does not comply with form drawings
- Lack of proper field inspection to ensure that form design has been properly interpreted by form builders
- Prepare and Place Reinforcement:
- Prior to the placement of reinforcement for concrete floor slab construction, inspect and check forms to confirm that the dimensions and the location of the concrete members conform to the structural plans
- Added to that, the forms shall be properly cleaned and oiled
- Design drawings provides necessary reinforcement details, so it only needs understanding to use designated bar size, cutting required length, and make necessary hooks and bents
- After preparation is completed, steel bars are placed into their positions with the provision of specified spacings and concrete cover
- Wires are used to tie main reinforcement and shrinkage and temperature reinforcement
- It should be known that incorrect reinforcing steel placement can lead to serious concrete structural failures
- Pouring, Compacting and Finishing Concrete:
- Mixing, transporting, and handling of concrete shall be properly coordinated with placing and finishing works
- Concrete should be deposited at or as close as possible to its final position in order to prevent segregation
- Therefore, concrete placement in large and separate piles, then moving them horizontally into final position shall be prevented
- Moreover, site engineer shall monitor concreting properly, and look for signs of problems.
- Furthermore, fresh concrete should be compacted adequately in order to mold it within the forms and around embedded items and reinforcement and to eliminate stone pockets, honeycomb, and entrapped air
- Vibration, either internal or external, is the most widely used method for consolidating concrete
- Removal of Formwork and Curing of Concrete Slab:
- After finishing the slab i.e., pouring-compacting-finishing the concrete suitable technique shall be used to cure the concrete adequately
- Slab curing methods such as water cure, concrete is flooded or ponded or mist sprayed
- In addition to water retaining method in which coverings such as sand, canvas used to kept slab surface wet continuously, chemical membranes, and waterproof paper or plastic film seal
- Regarding curing, it is recommended to remove formworks after 14 days
This is the basic and step wise way in which a RCC slab is laid during the construction of a house.
There are a total of 15 different types of concrete slabs-
- Conventional Slab
- Flat Slab
- Hollow Core Ribbed Slab
- Waffle Slab
- Sunken Slab
- Inclined Slab
- Slab with Arches
- Prestressed Concrete Slab
- Cable Suspended Slab
- Composite Slab
- Precast Slab
- Slab on Grade or Slab on Ground
- Bubble Deck Slab
- Hardy Slab
- Waist Slab
In the next article, we will be discussing on the WALLS & ROOF structure of a house
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PKC Realtors.
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