Materials — Quiz 4

Questions in this quiz (10)

1. A steel specimen with a modulus of elasticity of $$200000\ \text{MPa}$$ reaches its proportional limit at a strain of $$0.0018$$. Calculate the stress at the proportional limit.

   • 240 MPa
   • 300 MPa
   • 360 MPa
   • 400 MPa

2. An aggregate sample has a density of $$2700\ \text{kg/m}^3$$. Calculate the specific gravity of the aggregate. Use the density of water as $$1000\ \text{kg/m}^3$$.

   • 2.30
   • 2.50
   • 2.70
   • 2.90

3. A soil sample has a wet unit weight of $$20.2\ \text{kN/m}^3$$ and a moisture content of $$10\%$$. Calculate the dry unit weight of the soil.

   • 16.91 kN/m³
   • 18.36 kN/m³
   • 19.20 kN/m³
   • 20.00 kN/m³

4. A compacted fill has a field dry unit weight of $$18.5\ \text{kN/m}^3$$. If the maximum dry unit weight from a Proctor test is $$19.6\ \text{kN/m}^3$$, calculate the relative compaction of the fill.

   • 88.5%
   • 91.2%
   • 94.4%
   • 98.2%

5. A hot-mix asphalt specimen compacted in a Superpave gyratory compactor has a bulk specific gravity $$G_{mb}$$ of $$2.405$$ at $$N_{design}$$. If the maximum theoretical specific gravity $$G_{mm}$$ is $$2.495$$, calculate the percent of $$G_{mm}$$ achieved at $$N_{design}$$.

   • 94.2%
   • 96.4%
   • 98.1%
   • 102.0%

6. A steel component is subjected to cyclic loading with a stress amplitude of $$280\ \text{MPa}$$. Using the Basquin equation $$\sigma_a=\sigma'_f(2N_f)^b$$ with $$\sigma'_f=850\ \text{MPa}$$ and $$b=-0.12$$, calculate the fatigue life $$N_f$$.

   • 18,420 cycles
   • 31,250 cycles
   • 46,800 cycles
   • 62,500 cycles

7. Concrete is cured at temperatures of $$18^\circ C$$, $$22^\circ C$$, $$24^\circ C$$, $$21^\circ C$$, and $$19^\circ C$$ over five consecutive $$6$$-hour periods. Using the Nurse-Saul maturity method with a datum temperature of $$-10^\circ C$$, calculate the maturity index.

   • 720 °C·hours
   • 810 °C·hours
   • 900 °C·hours
   • 990 °C·hours

8. Calculate the cross-sectional area of a No. 7 reinforcing bar with a diameter of $$22.2\ \text{mm}$$.

   • 304 mm²
   • 387 mm²
   • 456 mm²
   • 608 mm²

9. In an aggregate impact value test, a sample with an original weight of $$400\ \text{g}$$ produces $$52\ \text{g}$$ of material passing the $$2.36\ \text{mm}$$ sieve after testing. Calculate the aggregate impact value (AIV).

   • 9%
   • 11%
   • 13%
   • 18%

10. A steel bar with a cross-sectional area of $$450\ \text{mm}^2$$ and length of $$2.5\ \text{m}$$ is subjected to an axial tensile load of $$120\ \text{kN}$$. If the modulus of elasticity is $$200000\ \text{MPa}$$, calculate the elastic strain energy stored in the bar using $$U=\frac{P^2L}{2AE}$$.

    • 90 J
    • 120 J
    • 150 J
    • 180 J