Construction and Building Materials Multiple Choice Questions on “Materials Used for Formwork”.
1. The _______ is used for formwork when it is desired to reuse the formwork several times.
Clarification: The erection and removal of steel formwork is simple and it presents a smooth surface on removal. The initial cost of steel formwork is very high. But it proved to be economically for large ones requiring many repetitions of the formwork.
2. ___________ gives excellent exposed concrete surface requiring no further finishing treatment.
b) Teak wood
d) Fibre glass
Clarification: The exposed surface obtained by use of timber formwork invariably requires plastering for getting the desired finish of the concrete surface. Steel possesses more strength and is more durable than timber formwork.
3. When form work is required for small ones requiring less repetitions, the ________ is preferred to Steel.
c) Fibre glass
d) Metal sheets
Clarification: The Timber formwork is cheap in initial cost and it can be easily adopted or altered for new use. The timber to be used as formwork should be well Seasoned, free from loose knots, light in weight and easy workable without splitting.
4. The __________ formwork should be neither too dry nor too wet.
a) Fibre glass
Clarification: If it is too dry, the timber will swell and get distorted when wet concrete is placed on it. This will affect the workability of concrete and honeycomb surface will appear on removal of the formwork.
5. It is found that moisture content of about __________ is appropriate for the timber formwork.
Clarification: If the timber is too wet, it will shrink in hot weather resulting in gaps in the form work through which concrete will flow out. Hence, the ridges will be formed on the concrete surface.
6. The _________ formwork can be reused several time as compared to ordinary Timber formwork.
c) Fibre ply
Clarification: Under normal conditions, the plywood formwork can be used for 20 times to 25 times and the timber formwork can be used for 10 times to 12 times. The plywood formwork give surface which are plain and smooth and they may not required any further finishing treatment.
7. The column formwork consists of a box prepared from _______ separate sides.
Clarification: The four sides of boxer held in position by wooden blocks, bolts and yokes. The details of formwork for an RCC column of section is 300 mm x 300 mm. Here, the spacing of yokes is about 1 metre in length.
8. The formwork for an ___________ consists of rows of the vertical post which carry small wooden beams at their tops.
a) RCC floors
b) RCC slab
c) RCC column
d) RCC beam
Clarification: The formwork for an RCC floor consists of a skeleton to receive the concrete. The planks for slab are placed on these beams. The boxes for beams are prepared from two sides and one bottom.
9. In case of formwork for the floor, the ________ supports should be firmly supported at the bottom.
Clarification: For this purpose, the base plates of Steel may be used. The wooden wedges are provided at the bottom so as to facilitate the tightening or loosening of the post.
10. The formwork for ________ consists of stringers, sheets, joist, bearers and vertical post.
Clarification: The Riser forms are supported on the plates which are fixed on the stringers for walls as the case may be. The bottom edge of the Riser forms is Chamfered so that concrete can be placed right up to the level of the next riser.
11. The formwork for ___________ consists of sheets, studs, Wales, ties and braces.
Clarification: The Sheets are supported by vertical studs and horizontal wales. The ties are provided to maintain the distance between the sheets to resist the bursting action of the concrete.
12. The forms are raised by the concrete is in a plastic state and such forms are therefore sometimes referred to as the ___________
a) Climbing forms
b) Jumping forms
c) Riser forms
d) Running forms
Clarification: After a set of slip forms is completely assembled on a concrete base, the forms are filled slowly with concrete. When the concrete in the bottom portion of the forms has gained sufficiently rigidity, the upward movement of the form is started and it is continued at a speed that is controlled by the rate at which the concrete sets.