Points to Remember While Doing Formwork and Shuttering
Formwork or shuttering in construction is defined as the temporary or permanent structures used to mould and set the poured wet concrete. This article talks about formworks, shuttering and the things to be considered while doing formworks in construction. Read on to know more about the different shuttering material lists, the formwork removal time, and the pointers for successfully carrying on formwork or shuttering in work sites.
List of Contents
1. Difference Between Formwork and Shuttering
Though the Oxford dictionary defines formwork as just another term for shuttering, there is a modest difference between the two. While formwork may either be the horizontal or the vertical arrangement built to retain concrete in the desired position until it stabilizes; shuttering is referred to as the vertical arrangement of the formwork.
2. Types of Formwork
Traditional Timber Formwork
Engineered Formwork Systems
Reusable Plastic Formworks
Permanent Insulated Formwork
Stay-In-Place Structural Formwork Systems
3. Different Materials Used for Shuttering Are
4. 15 Points to Be Remembered During Formwork
The formwork should be erected in such a way that it can be dismantled easily without causing any damage to the concrete.
The shuttering that comes into contact with concrete should not cause leakage of cement grout.
When the centering posts rest on soft ground; the load should get distributed by means of thick planks or other available formwork materials.
The centering posts should be truly vertical and should not be placed at an angle. This should be thoroughly checked.
The levels of the formwork should be checked and corrected as per the drawings.
No gaps should be found in the formwork before concreting starts.
The centering and shuttering should be designed and arranged in such a way that the sides of columns can be removed first, followed by the sides of the beams, and the boarding under the floor slabs, and finally the soffit of the beams.
Precaution must be taken to make sure that the joints of the formworks are made air tight to prevent escape of air and grout during the process of vibration. The seepage of grout and the sucking in of air might cause honey-combing on the surface of the concrete. This will also weaken the structure and impair the finish in appearance.
Normally gaps larger than 1.5 mm should not be permitted between the boards. The sections of the shutter should be made as large as possible to minimize the joints.
Fan clamps, hooks or others should be provided after the shuttering is complete.
Suitable wooden plugs may be placed in the centering for electric fittings.
Similarly, clamps for hanging ceiling fans or other purposes should also be fixed in their correct positions.
The top of the conduit should be at least 18mm below the finished surface to avoid cracking.
To avoid sticking of concrete, mould releasing oil should be applied on the formwork.
5. When Can the Formwork Be Removed?
Once the concrete is cured and is capable of holding its weight along with any other weight it may carry, the formwork can be removed. The process of removing the formwork or shuttering is known as stripping and the stripped formworks can be reused. Once it has set and is capable of holding its weight along with any other weight it may carry.
In places where the temperature is above 20ºC and ordinary cement has been used for concreting; formwork for slabs and others may be removed after the periods given below.
The columns along with vertical sides of beams and slabs = 1-2 days.
Slabs of spans less than 3.6 meters = 8 days
Slabs of spans more than 3.6 meters = 14 days
Beams up to 6 meters span = 14 days
Beams more than 6 meters span = 21 days
6. Why is Formwork and Shuttering Important?
Scaffolding, formwork, and shuttering go hand-in-hand during construction. A small error may cause a lot of havoc during or after concreting. These processes must be carried out with utmost precision to avoid inconveniences during or after concreting.