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Concrete floor slab construction process includes erection of formwork, placement of reinforcement, pouring, compacting and finishing concrete and lastly removal of formwork and curing of concrete slab.Contents:
Concrete Floor Slab Construction Process
- Assemble and Erect Formwork
- Prepare and Place Reinforcement
- Pour, Compact and Finish Concrete
- Curing Concrete and Remove Formwork
1. Assemble and Erect Formwork for Slab
The formwork shall be designed to withstand construction loads such as fresh concrete pressure and weight of workers and operators and their machines. Guide to Formwork for Concrete ACI 347-04 shall be followed for the design of formworks. Moreover, there are various construction aspects that need to be considered during the erection of formworks. For example, it should be positioned correctly, lined and levelled, joints sealed adequately, and prevent protruding of nails into the concrete etc... Furthermore, different materials such as wood, steel, and aluminum can be used for the formworks of concrete floor slab.
Fig. 1: Concrete Floor Slab Formwork
- 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
- Use of damaged or inferior lumber having lower strength than needed.
2. Prepare and Place Reinforcement for Slab
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 but not in such amount as to run onto bars or concrete construction joints. 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. The concrete cover and spacing for floor slabs can be maintained by introducing spacers and bars supporters. Wires are used to tie main reinforcement and shrinkage and temperature reinforcement (distribution reinforcement).
Fig. 2: wires used to tie reinforcement and supporters used to maintain concrete cover
Fig. 3: Provision of concrete cover for reinforcement bars in slab
3. Pour, Compact and Finishing Concrete Floor Slab
Mixing, transporting, and handling of concrete shall be properly coordinated with placing and finishing works. In floor slab, begin concrete placing along the perimeter at one end of the work with each batch placed against previously dispatched concrete.
Fig. 4: Concrete placement started from one end of the slab
Fig. 5: Concrete placement using pumps
Fig. 6: Placing and vibrating fresh concrete
4. Curing Concrete and Remove Formwork
After finishing ended, suitable technique shall be used to cure the concrete adequately. Slab curing methods such as water cure;Â concrete is flooded; ponded; or mist sprayed. In addition to water retaining method in which coverings such as sand; canvas; burlap; or straw 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. For detailed formwork removal time, Please click here.
Fig. 7: Curing concrete slab by ponding
Fig. 8: Illustration of reinforced concrete slab construction
Fig. 9: Wire used to bind main and shrinkage and temperature reinforcement (Detail 'A')
