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.
What kind of construction is steel wire mesh used in?
As reinforcement for slab-on-grade construction.
If a plan calls for 150 by 150 by P9/P9, what does that mean?
This indicates that the wires are spaced 150 mm apart in both directions and that the cross-sectional area of the end of the wires will be 9 MM
What are 2 common strengths of Steel Wire Mesh?
300 MPa and 400 MPa
If wire mesh in concrete slabs is placed at the bottom what happens?
IT IS USELESS!!!
If a plan doesn’t indicate the lap for rebar, what is the typical placement?
Horizontal lapped 24 bar diameter and vertical lapped 20 bars diameter
What is bar splicing?
Bar splicing can be done instead of lapping through ties or by using mechanical connectors or by welding. It is the P.ng that specifies the type and location for splicing and lapping.
What type of wire is used for tying rebar?
Anneal wire - typically 19 to 13 gauge
What are the two purposes of Anchor bolts on concrete foundation walls?
They hold the building down to the foundation and provide lateral support to the foundation wall. Lateral support is needed to resist the sideways force of the backfill.
What does the building code specify anchor bolts to be spaced at?
2.4 m o.c. More commonly is 1.2 m oc or less on field
The length and diameter of anchor bolts for residential construction is usually.
6 inch and 1/2 diameter. This is the minimum, most often longer and heavier bolts are used.
What is a common practice to help anchor bolts stay put?
Bends at the end to prevent them from turning or pulling out when their nuts are tightened.
The compressive strength of concrete is about how many times its tensile strength?
10
What is the size of a 10 m bar?
10 MM
What type of construction uses welded wire mesh for reinforcing cocnrete?
Slab - on - grade
Welded wire mesh is available in sheets 6100 mm long or rolls 61,000 mm long. How wide is it?
2.288 M 2.288 M
In the description of 254 by 254 x P13/P13, what does P13 mean?
Cross section of Wire is 13 mm
What does yield mean, as applied to reinforcing steel?
Fails at that strength
How are L-Shaped anchor bolts placed when great accuracy is not required?
Placed by hand as soon as the concrete has been leveled and floated
