Construction Materials (CON1165)
Comprehensive Final Exam
Instructions:
-
Allowable time - 1:50 hours
Closed Book
1.
Cements may be classified according to their bonding mechanism. Which type of cement
cures or sets by the interaction with water?
a.
Reaction bonding
b.
Hydration bonding
c.
Precipitation bonding
2.
What water/cement ratio is recommended for a balance between strength, workability,
and shrinkage?
a.
0.35 to 0.40
b.
0.45 to 0.50
c.
0.55 to 0.60
d.
1:1 by weight.
3.
What is the normal curing time for concrete in air?
a.
24 hours
b.
7 days
c.
14 days
d.
28 days
4. What type of concrete matches up with Type 10 concrete (from the old system)?
a.
GU
b.
MS
c.
HS
d.
HE
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5.
What is the expected strength of GU Portland Cement?
a.
10 million psi
b.
2 million psi
c.
6000 psi
d.
15 tons
6.
What admixture may be added to concrete to increase workability, enabling easier placing
and compaction?
a.
Plasticizers
b.
Accelerators
c.
Retarders
d.
Air-entrainment
7.
What admixture may be added to concrete to extend the time between initial mixing and
final compaction?
a.
Plasticizers
b.
Accelerators
c.
Retarders
d.
Air-entrainment
8. Pig iron is made by which process?
a.
Blast Furnace
b.
Electric Arc Furnace
c.
Open Hearth Furnace
d.
Basic Oxygen Furnace
9. A steel with 0.2% carbon in it is considered:
a.
An alloy.
b.
A mild steel.
c.
Tool steel.
d.
Pig Iron.
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10. Martensite is characterized by which unit cell?
a.
Body-centered cubic
b.
Face-centered cubic
c.
Body-centered tetragonal
d.
It is amorphous.
11. A face-centered cubic has how many atoms?
a.
6
b.
9
c.
14
d.
17
12. What is a steel that is heated above its upper critical temperature called?
a.
Allotropic
b.
A liquid
c.
Martensite
d.
Austenite
13. Alloy steel is typically melted in what type of furnace?
a.
Blast Furnace
b.
Electric Arc Furnace
c.
Open Hearth Furnace
d.
Basic Oxygen Furnace
14. The heat-treating process that involves the cooling of steel in still air is called:
a.
Quenching
b.
Hardening
c.
Normalizing
d.
Tempering
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15. The annealing process that involves heating the steel to its lower critical temperature and
allowed to cool:
a.
Full anneal
b.
Tempering
c.
Spheroidizing
d.
Process anneal
16. The straight, sloped line on the stress-strain curve represents the:
a.
Elastic range
b.
Plastic range
c.
Yield point
d.
Ultimate tensile strength
17. The surface hardening technique that involves heating the steel above the upper critical
temperature in the presence of natural gas:
a.
Carburizing
b.
Nitriding
c.
Flame hardening
d.
Induction hardening.
18. Steel is hardest when it is in the form of:
a.
Austenite.
b.
Martensite
c.
Pearlite
d.
Ferrite
19. Steel is toughest when it is in the form of:
a.
Austenite.
b.
Martensite
c.
Pearlite
d.
Ferrite
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20. Cast iron typically has how much carbon content?
a.
Almost none
b.
0.2% to 1.0%
c.
2% to 6%
d.
Greater than 6%
21. A substance in which impurity atoms replace the original atoms of the crystal structure is
known as:
a.
Amorphous solid
b.
Interstitial solid
c.
Crystalline solid
d.
Substitutional solid
22. For fine aggregate, what does a higher fineness modulus indicate?
a.
The fine aggregate is coarser
b.
The fine aggregate is finer
c.
A water-cement ratio
d.
A lower bulk density
23. What is the bulk density?
a.
The density of the coarse aggregate particles
b.
The density of the coarse aggregate in a known volume
c.
The density of the water between the particles of an aggregate
d.
The density of the freshly mixed concrete
24. What does ‘Saturated Surface Dry’ mean?
a.
Aggregate that is completely dry
b.
Aggregate immersed in water
c.
Aggregate that cannot absorb more water
d.
The difference between the potential absorption and bone dry aggregate
25. What is the typical yield strength of reinforcing bar?
a.
6000 psi
b.
60,000 psi
c.
2 to 4 million psi
d.
30 million psi
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Short Answer:
26. What field test is used to measure water/cement ratio of freshly mixed concrete?
27. What are the two components used in concrete to bind the aggregate into a solid mass?
28. List the three main components of cement (0.5 marks each)
a.
b.
c.
29. What effect would improperly placing steel reinforcing bars have on a structural concrete
member?
30. What does the addition of flyash do to the slump of freshly mixed concrete?
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31. Describe the post-tensioning technique of pre-stressing concrete.
32. Choose the best type of cement for the following applications (1 mark each)
a.
The concrete that would be most suitable for a sewage pipe.
b.
The concrete that would be most suitable for a large structure.
c.
The concrete that would be most suitable for winter construction.
d.
The concrete that would be most suitable for a large, indoor floor slab.
33. List three raw materials used to make Pig Iron. (0.5 marks each)
a.
b.
c.
34. How much carbon does 1090 steel have?
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35.
Describe how a basic oxygen furnace works.
36. What does tempering do to the mechanical properties of steel?
37. What two grains would you expect to find in hypoeutectic steel?
38. List two precautions when pouring concrete in hot weather (0.5 marks each).
a.
b.
39. How much does steel strain under a 60,000 psi stress within the elastic range? (Assume a
Modulus of Elasticity of 30 million psi)
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Matching:
40. Identify the following points on the Stress-Stain Curve below. (7 marks)
Match the correct term from the following list to letter shown on the Stress-Strain Curve:
A. __________
D. __________
B. __________
E. __________
C. __________
F. __________
1. Ductility
2. Breaking Strength
3. Maximum Load
4. Stress [psi]
5. Plastic Range
6. Modulus of Elasticity
G. __________
7. Toughness
8. Proportional Limit
9. Ultimate Tensile Strength
10. % Reduction of Area
11. Yield Strength
12. Strain [%]
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41. Identify the components of a iron-carbon diagram. (5 marks)
Phase Diagram for Steel from 0% to 1% Carbon
A. __________
B. __________
D. __________
E. __________
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
Hypoeutectic steel
Hypereutectic steel
Eutectic point
Martensite
Pearlite
Ferrite
Austenite
Upper Critical Temperature
Lower Critical Temperature
Transition Temperature
10
C. __________
Mix Design:
42. For the following design conditions, determine the required mass of components. (20
marks for correct answer; 15 marks for substantially correct; 10 marks for some aspects
correct; 0 for no apparent clue)
Concrete is required for a 250 mm thick reinforced indoor slab. There is no statistical data for
this mix.
Minimum design compressive strength = 25 MPa @ 28 days
Design slump 75 - 100 mm
Cement:
Type 10 Portland cement
Coarse Aggregate:
Density = 3000 kg/m³
37.5 mm Nominal Maximum size (angular)
Density
= 2500 kg/m³
Bulk Density
= 1650 kg/m³
Moisture Content
= 1.76%
Absorption Capacity = 1.27%
Fine Aggregate:
Fineness Modulus
= 2.40
Density
= 2750 kg/m³
Moisture Content
= 0.97%
Absorption Capacity = 2.4%
Minimum Comp. Strength
Design + correction =
_________________ MPa
Water/Cement Ratio
_________________
Maximum Slump (per spec)
_________________ mm
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Water Required
__________________ kg/m³
Amount of Cement Required
_________________ kg/m³
Bulk volume of Coarse Aggregate
__________________
Mass of Coarse Aggregate
__________________ kg/m³
Calculate Absolute Volume of Components (1 m³ of concrete):
Absolute Volume of Water
__________________ m³
Absolute Volume of Cement:
__________________ m³
Absolute Volume of Air:
__________________ m³
Absolute Volume of Coarse Aggregate:
__________________ m³
Subtotal
__________________ m³
Absolute Volume of Fine Aggregate
__________________ m³
Mass of Fine Aggregate
__________________ kg
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Water Correction:
Water (Corrected)
_________________ kg
Final Mix (1 m³ of concrete):
Water
__________________ kg
Cement
__________________ kg
Coarse Aggregates (corrected for MC)
__________________ kg
Fine Aggregates (corrected for MC)
__________________ kg
Estimated Concrete Density
__________________ kg/m³
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Mix Design Tables:
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