Methods and Materials of Wall Forming Systems
Topic 2 – Methods and Materials of Wall Forming Systems
Wall forms usually are made of manufactured panel products and come with additional hardware to connect the forms and secure them during placement. Consideration in selecting a form system include cost, weight, assembly time, durability and application. Plates or kickers may be used to help align the forms to the building lines. Window and door openings are created by installing door and window bucks. Blockouts are installed in the formwork to allow for electrical, plumbing, and mechanical penetrations. Bulkheads are used for changes in elevation, or for a temporary opening. A bulkhead may also be used when the concrete cannot be placed all at once. Waterstops are used to prevent the passage of water between joints and are formed into a bulkhead or keyway. Once the form is set the walls are braced as necessary to keep them straight. Wall straightness can be checked using a line and gauge blocks.
Proper care of concrete forms will increase the lifespan of materials and reduce construction costs. Ensure proper attention is given to:
- Cleaning
- Repairing and oiling
- Handling and storage
- Hardware maintenance
The most common time for damage to the forms to happen is during dismantling.
Form failure usually occurs during placement due to too much pressure being placed on the formwork. The form will fail at its weakest location or component. Failure is caused by one or a combination of poor design, poor planning, inadequate inspection, weather or human error.
Four factors that determine how much pressure the formwork will hold are:
- Tie spacing
- Pour rate
- Temperature
- Vibration and impact
Four types of concrete joints in concrete walls and foundations used are:
- Construction joints
- Control joints
- Isolation joints
- Expansion joints
For further reading and images refer to LO3 LS1 Reading Exercise 1.1
- Carpentry, study the section titled “Wall and Column Forms” (Chapter 31) to get acquainted with wall formwork and the terminology used
- Principles and Practices of Commercial Construction, study pages on “Formwork and
- Materials”
- Canadian Wood-Frame House Construction, study section on “Foundations”
Review Instruction Sheets from FNDT 100 (p. 74 – 102):
- IS 1.1 Wall Forms
- IS 1.3 Forming Processes
- IS 1.4 Concrete Joints
- IS 1.5 Care of Concrete Forms
- IS 1.6 Dismantling Concrete Forms
- IS 1.7 Causes of Failure in Wall Forming Systems
Review Questions
- Braces for formwork are most effective if they are placed at an angle of _____° to _____° to the horizontal.
- List six items that may be used to give more rigidity and help align panels for wall forming systems.
- Rough bucks should be made at least _____ mm narrower than the concrete wall thickness.
- Describe how to form a control joint in a foundation wall.
- Crack control joint are required in concrete foundation walls if they exceed _____ m in length.
- Explain the purpose of the following concrete joints:
- Construction joint
- Control Joint
- Isolation Joint
- Expansion Joint
- What are some things a person watches for while inspecting forms during a pour?
- Explain what is meant by the term “rate of pour”.
- While placing concrete in wall forms on a warm day, the pressure on the forms would _____ compared to placing concrete on a cooler day.
- Increase faster
- Decrease faster
- Have no difference
- List two problems that may be caused by over vibration.