Civil Engineering Formwork Materials

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Questions and Answers

What is the primary advantage of using timber as a formwork material?

Timber forms are reusable for numerous projects.

Timber is the strongest material for formwork.

Timber has high resistance to moisture damage.

Timber can be cut into any required size easily. (correct)

What is a disadvantage of using wet timber for formwork?

Wet timber increases the overall weight.

It can absorb water from wet concrete, affecting strength. (correct)

It has a tendency to warp when exposed to moisture.

Wet timber is difficult to handle on construction sites.

What makes plywood an attractive choice for formwork compared to timber?

Plywood is significantly cheaper than timber.

Plywood is easier to find on construction sites.

Plywood can withstand higher temperatures than timber.

Plywood provides a smoother finish. (correct)

Which characteristic does not describe timber as a formwork material?

Timber is difficult to dismantle. Signup and view all the answers

What is the primary disadvantage of timber formwork regarding its reuse?

Timber forms have limited usage. Signup and view all the answers

What type of plywood is specifically mentioned for use in formwork?

Exterior plywood Signup and view all the answers

How does the moisture content of wet timber adversely affect concrete?

It compresses wet concrete and forms cracks. Signup and view all the answers

Which property makes aluminum potentially useful for formwork?

Aluminum can be easily recycled. Signup and view all the answers

How many pieces of 2'' x 3'' x 12ft lumber are needed for vertical support in scaffolding for columns?

57 pcs Signup and view all the answers

What is the total number of diagonal braces required for scaffolding?

116 pcs Signup and view all the answers

How many sheets of 3/4'' x 2' x 4' marine plywood are necessary for slab forms?

28 sheets Signup and view all the answers

What is the total quantity of 2'' x 2'' x 12ft lumber required for horizontal support in scaffolding for beams?

70 pcs Signup and view all the answers

What is the calculated weight of 2'' CWN needed for nails?

5.58 kgs Signup and view all the answers

Which type of lumber is utilized for scaffolding diagonal braces?

2'' x 2'' x 12ft Signup and view all the answers

How many kilograms of nails are necessary for 1-1/2'' CWN?

6 kgs Signup and view all the answers

What is the total area calculated for slab support?

72 m² Signup and view all the answers

How many pieces of 2’’ x 2’’ x 10ft lumber are needed for 1 beam?

10.8 pcs Signup and view all the answers

What is the total number of 1-1/2’’ CWN nails needed for 40 pcs of 40cm x 2.4m forms?

2080 pcs Signup and view all the answers

What is the total amount of 2’’ CWN nails required for both 40 pcs and 20 pcs forms combined?

1680 pcs Signup and view all the answers

How many kilograms of 3’’ CWN nails are needed for the given requirements?

6.5 kgs Signup and view all the answers

What type of lumber is used for horizontal support in scaffolding for beams?

2” x 2” lumber Signup and view all the answers

What material is specified for forms and scaffolding for slabs?

3/4" thick Phenolic board Signup and view all the answers

How many pieces of 2’’ x 3’’ lumber are needed for scaffolding under columns?

None specified Signup and view all the answers

What is the function of shoring in scaffolding?

To provide stability and support Signup and view all the answers

How many pieces of 2’’ x 2’’ x 10ft lumber are needed based on the board feet calculation?

80 pcs Signup and view all the answers

What is the total amount of nails needed for the 16 pcs of 30cm x 2.4m forms using 1-1/2’’ CWN?

1,552 pcs Signup and view all the answers

What is the effective total area of the forms for the beams before dividing by the area of one plywood?

48 m² Signup and view all the answers

How many sheets of plywood are required for the formworks of 10 pcs of beams?

19 sheets Signup and view all the answers

If you require 3 kgs of 1-1/2’’ CWN nails, how much would you need for 2’’ CWN nails according to the calculation?

3 kgs Signup and view all the answers

What is the formula for computing the perimeter of the column used in the steps for finding forms?

P = 2d + b + 0.1m Signup and view all the answers

Which calculation is necessary to determine the board foot of lumber needed based on plywood required?

Multiply pieces of plywood by the factor from table 5.1 Signup and view all the answers

In the calculation for nails needed for 16 pcs of 40cm x 2.4m forms, how many nails are required for 3” CWN?

224 pcs Signup and view all the answers

What are the primary components of cement paste?

Cement and water Signup and view all the answers

Which type of Portland cement is known for providing high strength?

Type III Signup and view all the answers

What is the maximum size of coarse aggregate typically used in concrete?

38mm Signup and view all the answers

Which of the following characteristics primarily depends on the water to cement ratio?

Strength Signup and view all the answers

What does the term 'designed mixture' refer to in concrete classification?

Mixture proportions established by the contractor Signup and view all the answers

What is a key requirement for fresh concrete according to ACI requirements?

Must be workable Signup and view all the answers

Which type of pozzolan cement is suitable for critical concrete works that require early strength?

Type 1P Signup and view all the answers

What is one characteristic of durable concrete?

Must resist environmental conditions Signup and view all the answers

Study Notes

Different Formwork Materials

Various formwork materials include timber, plywood, steel, aluminum, plastics, magnesium, and fabric.

Timber as Formwork Material

Timber is the most traditional and widely used formwork material, known for its cost-effectiveness.
Advantages of timber:
- Easily cut into required sizes.
- Lightweight and easy to handle.
- Good thermal resistance prevents concrete damage in cold conditions.
- Construction methods are straightforward, requiring no highly skilled workers.
- Damaged parts can be replaced easily.
- Dismantling is uncomplicated.
Disadvantages of timber:
- Dry timber can absorb water from wet concrete, reducing concrete strength.
- Wet timber can compress wet concrete, leading to cracks and grout leakage.
- Limited reuse potential.

Plywood as Formwork Material

Plywood, a manufactured timber product, is increasingly used for formwork, especially for facing panels, providing smoother finishes.
Exterior plywood is used for its watertight properties, with thicknesses ranging from 7mm to 32mm.

Material Requirements for Formworks

Specific lumber and nails needed based on dimensions and quantities of formwork.
Example formula for calculating lumber:
- For a column: Requires 2 pieces of 2" x 2" x 10 ft lumber.
- Nails needed vary by piece size and form type, with calculations provided for 1-1/2", 2", and 3" CWN nails.

Steps for Finding Forms for Rectangular Beams

Compute the perimeter and total area for forms.
Material calculations involve dividing total area by the area of one plywood sheet.
For beams, forms must be monolithically poured, requiring all forms per level to be utilized.

Steel Pipe Scaffolding

Steel pipe scaffolding is versatile, allowing for prefabrication according to site specifications.
Galvanized steel provides durability, economical delivery, and storage.
Standard scaffolding frames feature heights from 0.90 to 1.70m, useful for access and concrete support work.

Concrete Composition

Concrete is a mixture of cement paste (cement and water), fine aggregates (natural sand), and coarse aggregates (crushed rock or gravel).
Coarse aggregate size ranges from 20mm to 38mm.
Clean water is essential for mixing, free from harmful substances.

Types of Cements

Portland Cement:
- Type I: Common and least expensive.
- Type II: Moderate heat for large pours.
- Type III: High strength.
- Type IV: Low heat.
- Type V: Sulfate-resistant.
Pozzolan Cement: Mixture of Portland cement and pozzolanic materials for varied strength requirements.

Characteristics and Classification of Concrete

Characteristics:
- Workability: Should flow around reinforcements filling voids.
- Strength: Must support design loads.
- Durability: Able to withstand expected conditions.
- Economy: Cost-effective production.
Classification:
- Designed Mixture: Contractor establishes proportions for strength.
- Prescribed Mixture: Engineer specifies proportions; contractor mixes as prescribed.

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Description

This quiz explores various materials used in formwork for construction, focusing on their advantages and disadvantages. It includes a discussion on timber, plywood, steel, aluminum, and more, highlighting how these materials contribute to successful construction projects.