Construction Materials and Properties Flashcards
7 cards from real Building Engineering practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Construction Materials and Properties flashcards as text
The slump test performed on fresh concrete primarily measures which property?
Answer: Workability and consistency
The slump test measures the consistency or workability of fresh concrete by recording how much a standard cone of concrete settles.
Per ASTM C39, what is the standard age at which concrete cylinder specimens are tested for compressive strength?
Answer: 28 days
ASTM C39 specifies 28 days as the standard testing age because concrete reaches approximately 99% of its design strength by then under normal curing conditions.
The modulus of elasticity (Young's modulus) of structural steel is approximately:
Answer: 29,000 ksi
The modulus of elasticity of steel is approximately 29,000 ksi (200 GPa), a constant value used in all structural steel deflection and stiffness calculations.
Which ASTM standard governs the compressive strength testing of cylindrical concrete specimens?
Answer: ASTM C39
ASTM C39 covers the standard test method for compressive strength of cylindrical concrete specimens; C31 covers making and curing specimens.
Reinforcing bar (rebar) in the US is designated by bar number. What does the bar number represent?
Answer: Approximate diameter in eighths of an inch
A rebar bar number equals the approximate diameter in eighths of an inch; for example, a #4 bar has a nominal diameter of 4/8 = 0.5 inches.
What role does fly ash play when used in a concrete mix design?
Answer: It acts as a supplementary cementitious material (SCM)
Fly ash is a pozzolan that reacts with calcium hydroxide in concrete to form additional cementitious compounds, improving long-term strength and durability.
The flexural strength (modulus of rupture) of concrete is approximately what percentage of its compressive strength?
Answer: 10–15%
Concrete's modulus of rupture (fr ≈ 7.5√f'c in psi) is roughly 10–15% of its compressive strength, reflecting concrete's inherent weakness in tension.