Materials practice questions

Answer: A) Creep

• ACorrect. It increases long-term deflections.
• BIncorrect. That's load-independent.
• CIncorrect. That's from cyclic loading.
• DIncorrect. That's water rising in fresh concrete.

Answer: A) Ductile-to-brittle transition temperature

Structural steels lose notch toughness below a certain temperature range, called the ductile-to-brittle transition temperature, which is found with Charpy V-notch impact tests at several temperatures.

• ACorrect. Body-centered cubic steels change from ductile, high-energy fracture to brittle, low-energy fracture over a temperature range. Charpy V-notch tests run at several temperatures define it.
• BIncorrect. Recrystallization is a high-temperature annealing process in which new strain-free grains form after cold work. It doesn't describe low-temperature brittleness.
• CIncorrect. The endurance limit is the stress amplitude below which cyclic loading doesn't cause fatigue failure. It comes from S-N testing, not from impact tests at different temperatures.
• DIncorrect. The glass transition describes amorphous polymers and asphalt binders changing from rubbery to glassy. It doesn't describe crystalline structural steel.

Answer: A) Consistency (hardness) at a set temperature

• ACorrect. Lower penetration means harder binder.
• BIncorrect. That's a different test.
• CIncorrect. That's a sieve analysis.
• DIncorrect. That's for concrete.

Answer: C) More anodic (active) metal

• AIncorrect. Weight isn't the factor.
• BIncorrect. The noble metal is protected.
• CCorrect. This is galvanic corrosion.
• DIncorrect. Activity matters most.

Answer: A) 29,000 ksi (200 GPa)

• ACorrect. Nearly constant across steel grades.
• BIncorrect. That's typical of concrete.
• CIncorrect. That's aluminum.
• DIncorrect. That's typical of wood.

Answer: A) Coefficients of thermal expansion

• ACorrect. Both are about 10–12 × 10⁻⁶ per °C.
• BIncorrect. Steel is much stiffer.
• CIncorrect. Steel is far stronger in tension.
• DIncorrect. Steel is about three times denser.

Answer: A) High and low pavement temperatures (°C)

• ACorrect. Performs from 64°C down to −22°C.
• BIncorrect. They're temperature limits.
• CIncorrect. They're temperature limits.
• DIncorrect. They're temperature limits.

Answer: C) High early strength is needed

• AIncorrect. That's Type V.
• BIncorrect. That's Type IV.
• CCorrect. It's ground finer for faster hydration.
• DIncorrect. That's Type I.

Answer: C) Impact toughness

• AIncorrect. That uses a tension test.
• BIncorrect. That uses indentation tests.
• CCorrect. It's often tested at several temperatures.
• DIncorrect. That's a different test.

Answer: A) High tensile strength with low weight and good corrosion resistance, so it confines concrete with little added dead load

FRP wraps are used because they are strong in tension, lightweight and corrosion-resistant, which lets them confine concrete with little added weight. FRP does not yield, is anisotropic and is sensitive to fire.

• ACorrect. FRP has a high strength-to-weight ratio and does not corrode. Wrapping a column confines the concrete and increases its strength and ductility while adding very little weight.
• BIncorrect. FRP behaves linear-elastically until it ruptures. It does not yield, and it fails suddenly once it reaches its ultimate tensile strength.
• CIncorrect. The polymer resin softens at elevated temperatures. Uninsulated FRP-strengthened members lose capacity early in a fire, so fire insulation is often required.
• DIncorrect. FRP is anisotropic and is strongest along the fibers. For confinement, the fibers are placed in the hoop direction.