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
Per ASTM C90, what is the minimum net area compressive strength required for load-bearing concrete masonry units (CMU)?
Answer: 1,900 psi
ASTM C90 specifies a minimum average net area compressive strength of 1,900 psi for load-bearing CMU used in structural masonry walls.
Carbonation of concrete is a durability concern primarily because it:
Answer: Reacts CO₂ with calcium hydroxide, reducing internal pH and depassivating reinforcement
Carbonation lowers the concrete's pH from ~12.5 to below 9, destroying the alkaline passive film that protects embedded rebar from corrosion.
Fiber-reinforced polymer (FRP) composites are increasingly used in building construction primarily because they offer:
Answer: High strength-to-weight ratio and inherent corrosion resistance
FRP composites combine high tensile strength with very low weight and do not corrode, making them valuable in corrosive environments and for strengthening existing structures.
Alkali-silica reaction (ASR) in concrete is caused by:
Answer: Alkalis in the cement pore solution reacting with reactive silica in certain aggregates
ASR is a chemical reaction between alkali hydroxides (from cement) and amorphous or cryptocrystalline silica in reactive aggregates, producing an expansive gel.
Among common building insulation materials, which product provides the highest R-value per inch of thickness?
Answer: Closed-cell spray polyurethane foam (~R-6.5/in)
Closed-cell SPF achieves approximately R-6 to R-7 per inch because its closed cells trap a low-conductivity blowing agent and the rigid foam resists convective heat transfer.
According to ASTM C270, what is the minimum compressive strength at 28 days for Type S mortar used in masonry construction?
Answer: 1,800 psi
Type S mortar has a minimum 28-day compressive strength of 1,800 psi per ASTM C270, making it suitable for below-grade and high-lateral-load masonry applications.
In masonry construction, 'efflorescence' refers to:
Answer: White crystalline salt deposits left on the surface as water migrates outward and evaporates
Efflorescence occurs when water-soluble salts within the masonry or mortar dissolve, migrate to the surface, and crystallize as the water evaporates, leaving white deposits.