G8 - Install Specialized Formwork Flashcards
What is used to temporarily secure tilt-up panels?
adjustable braces
How are tilt-up panels permanently secured to one another after they are set in place?
bolted or welded
What is done to ensure uniform panel surfaces when casting tilt-up panels?
The slab is steel trowelled very flat, smooth and level.
How are fragile tilt-up panels with openings protected when they are being lifted?
They have strong backs attached to them.
How is a slab design changed if a crane is to work on it?
It is designed to withstand heavy loads.
What is used at the bottom of tilt-up panels to temporarily hold them in position?
dowels or guide pins
What type of surface does seeding produce on a tilt-up panel?
exposed aggregate
What kind of forming material is most commonly used in tilt-up construction?
wood
Why is additional reinforcing steel commonly added to tilt-up panels?
To resist loads imposed by lifting
Why is it important to locate lifting inserts in tilt-up panels as specified by the engineer?
to evenly distribute the loads resulting from the lift
What type of form is sometimes built vertically between tilt-up panels?
pilaster form
What occurs after the tilt-up panels are plumb with wall braces installed?
The crane is released.
What is the usual minimum number of braces per tilt-up panel?
2
What must be done if any changes occur to a tilt-up panel design?
Changes are authorized by a registered engineer.
How are joints between tilt-up panels weatherproofed?
Backer rod and caulking are applied between panels.
What is usually used to hold pre-cast units permanently in place?
welded plates
After erecting pre-cast panels, what is done with their surface lifting-loops?
They are cut off.
Once pre-cast units are ready for assembly, which piece of equipment must be available at all times?
crane
Which component is usually installed right after footings and foundations are in place?
columns
If the following components are all to be used in a structure, which of them should be set in place last?
T-joists
If the following components are all to be used in a structure, which of them should be set in place second?
girders
Which of the following would be best suited to moving and erecting heavy, delicate architectural panels without lifting rings?
flat nylon slings
What is often placed on top of T-joists or rough floor slabs?
topping concrete
Which of the following is often designed to carry only its own weight?
curtain wall
What type of concrete construction incorporates “pre-tensioned” or “post-tensioned” cables?
pre-stressed
In pre-stressed concrete, what are the tendons used for?
to counteract external tension on the concrete
Why are some concrete members pre-stressed?
to strengthen them
What is the term used to describe the system when cables are placed in a member and tightened after the concrete is cast?
post-tensioned
In post-tensioned beam construction, what are tendons attached to and tightened against?
ends of the beam
When are pre-stressed members pre-tensioned?
before concrete is placed
In pre-tensioned applications, how are cables held in a draped position?
cable tie-downs are attached to the casting bed
Why are pre-tensioned components usually made in permanent plants?
Special casting beds are required.
What usually happens to concrete beams as tendons are stressed?
the middle lifts
What is the term used for members with cables placed into a concrete form and tightened before the concrete is cast?
pre-tensioned
In post-tensioned concrete beams, what keeps the cables from slipping through the concrete?
anchorage using wedge-like clamps
When is pre-tensioning carried out?
before the concrete has been placed
What is the slight inward leaning of vertical slip-forms called?
form batter
What is the integral member that hold a slip form assembly together?
yoke
What limits the size of the lifting loads of slip-form jacks?
strength of the rods
When slip-forms are used, what components must withstand the entire pressure of concrete forms?
yokes
What is the maximum rate of upward movement for slip-forms?
18” per hour
On slip-forms, to what is the working deck attached?
yoke
What has traditionally been used to make the curved walers for slip-forms?
laminated lumber
What is the height of the sheathing for a typical vertical slip-form?
36” – 42”
For maximum strength, at what angle to the forms should anchors and ties be?
90°
Why can cantilevered forms on mass concrete projects be as high as 10’?
The forms are so long and wide that the rate of placement is very low.
In mass concrete applications, what is the purpose of panel-aligning bolts?
to adjust the form for alignment
When mass concrete is placed, which component must withstand the entire pressure of the concrete forms?
anchors
What is the size of a typical concrete lift in mass forming?
7’
What type of concrete structures are gravity dams, ship locks and gravity retaining walls?
mass concrete
What is the maximum allowable sheathing deflection for architectural concrete required by the CSA standards?
1/400
When casting architectural concrete, what may be required when using form liners?
A bond breaker
Which of the following best describes the use of rustication strips?
Strips used to conceal construction joints
What are weld plates used for in precast concrete construction?
To connect the precast sections
Why must forms for architectural concrete be built stronger or have lower rates of placement than other forms?
The forms have lower specified deflection ratios, as the surface will be the wall finish., The extensive use of plasticisers in architectural concrete produce higher form pressures.
What are the factors that affect the maximum rate of placement into a form?
ambient temperature, slump, concrete density, tie pattern and strength
Why does standard form-ply have painted edges?
to prevent moisture absorption
What type of ties are required when using form liners?
ties that are longer and incorporate rubber washers at each end.
Which of the following statements best describe form liners?
reduce the effective wall thickness which must be accounted for
What is done to achieve an exposed aggregate finish on a vertical wall?
Apply a surface retarder to the inside of the form
Which drawings would include the location and details of metal embeds?
Architectural and Structural
What is the term used to describe disposable forms used to create complicated details?
Waste mould
What is the purpose of a “reveal” on an exterior concrete soffit?
To create a drip line
Who or what determines when re-shores can be removed?
The engineers approval
How is an exposed aggregate finish on a slab achieved?
By using a gap graded mix
What is typically done on an architectural, rectangular column to prevent spalling at the corners?
Install chamfer strip
When stripping forms, what should be done to reduce marring of the fresh concrete surface?
Use wooden wedges or levers
What is the main advantage of two part caulking compounds?
They cure by chemical reaction and can be used underwater.
What is the cross section shape of the caulk when a combination of backer rod and tooling is used?
an hourglass
Caulking should be removed and replaced on a regular basis. What is the recommended maximum interval for this maintenance procedure?
5 years
How do acrylic based caulking compounds cure?
through solvent loss
Which of the following statements best describe polysulfide based caulking compounds?
They release harmful vapours as they cure.
Which of the following statements best describe butyl base caulking?
It is available in different colours.
What is required for silicone caulking to cure properly?
atmospheric moisture
What is required for the placement of backer rod?
It must be compatible with the caulking material being used.
Which of the following statements best describe bond breaker tape?
It ensures that the caulking bonds only to two surfaces on either side of the joint.
