Layout and construct formwork for slabs on grade Flashcards
What are deformed bars?
Bars with lugs for extra bond to the concrete
List for grades of rebar steel
300 350 400 550
What is the difference between yield strength and ultimate strength and rebar?
Yield is max load a bar should receive so the bar won’t be damaged
Ultimate is the load limit which steel bar breaks
What diameter is a 10 MA 15 M and a 20 M bar
11.3 and 16.0 and 19.5
Why does reinforcing need a minimum concrete coverage?
To minimize damage from corrosion on fire
What are the minimum concrete cover requirements around Rebar concrete against earth, such as in footings
75 mm or 3 inches
What are the minimum concrete cover requirements around rebar for concrete exposed to weather above ground such as a driveway
38 mm
Where should re-Barbie placed in concrete members such as beans
On the tension face of the concrete where the cracking will start
Why are trust bars sometimes used in continuous beams
To follow
The tension stresses
Vertical bars in a basement wall should be placed near the___face of the wall
Inside
Why should Slabs on ground have reinforcing placed no more than 50 mm down from the top, regardless of slab thickness
To keep any cracks that may develop tightly together at the surface
Give an example of where reinforcement would be in compression
Column
In welded fabric what does 152×152 times MW 9.1/MW9.1 stand for
The spacing and the wire size and the type of fabric
List five advantages to using fibres for reinforcement in concrete
Corrosion resistance where resistance, improved, tensile strength, less drying, shrinkage, concretes more flexible without cracking
List, two materials, fibre reinforcement is made from
Steel and poly propylene
How much should Rebar be laughed at splices
300 mm
When is regular Welding of rebar permitted
On large rebar
What is the difference between a slab bolster and an individual highchair?
Slabs come in long lengths and cut to length as needed. Chairs are smaller.
What are chairs made from?
Steel wire, plastic concrete blocks
Welded wire fabric is spliced by lapping 200 mm
Tru
Where are stirrups used?
Beams and grade beams
What are column ties
Same as stirrups, but used in columns
Name five items that cause stress in slabs on grade that may cause cracking of the slab
Drying shrinkage temperature changes nonuniform soil support under the slab moisture in the soil. Traffic loads.
Describe columns, bile reinforcement
A continuous piece of rebar wound like a spring and is used to hold the vertical bars in place in Collom
