G5 Flashcards
What is the minimum strength required by building code for concrete?
15 MPa (Mllion pascals) or 2000psi (pounds per square inch). By keeping the water-cement ratio low, strengths of as high as 35MPa or 5000 psi can be obtained.
What can concrete resist much more easier, Tensile strength or compressive strength?
Compressive strength.
What kind of strength does rebar give to concrete in Beams, girders and slabs?
Tensile strength
What kind of strength does rebar give to columns?
Compressive strength
Since steel is so much stronger than concrete, columns supporting heavy construction loads are reinforced with what?
Huge rebars, often 50 mm in diameter.
In rebar within columns, what keeps the re-bar from bowing inwards?
Cement in-between
In rebar within the column, what keeps the rebar from bowing outwards?
Smaller bars(ties) wrapped around them.
They are called Ties, they may be Rectangular, circular or in a spiral shape.
What does rebar have to help it bond bond with concrete?
Lug-like ridges along them.
A 20 M bar has a diameter of what?
20 mm
How is the strength of a rebar referred to as?
Referred to as Yield. Grade 40 equates to 40,000 PSI, which starts to stretch at 40,000 LB.
The strengths of a Grade 60 rebar is how many psi?
60,000 PSI, very hard to bend.
How are different sizes of lengths of pre-cut rebar identified on a job site?
With paint marks.
How much should a dowel penetrate into each concrete section?
If the distance is not specified,
24 X DIAMETER OF DOWEL. EX 12 mm X 24 = 288 MM
What type of bar is used in keyway forms to secure stair, porch or cantilever supports to a foundation?
DEFORMED, rather than smooth.
What kind of forming construction uses steel dowels?
An expansion joint uses smooth dowels to keep two slabs in alignment.
