FCC Concrete & Masonry Construction 1 — Questions and Answers
Question 1: What is the minimum compressive strength (f'c) typically specified for residential concrete footings in Florida per the Florida Building Code?
- 2,000 psi
- 2,500 psi (Correct answer)
- 3,000 psi
- 4,000 psi
Correct answer: 2,500 psi
The Florida Building Code requires a minimum compressive strength of 2,500 psi for residential concrete footings to ensure adequate structural support.
Question 2: When testing concrete for slump, what does a higher slump value indicate about the concrete mix?
- Greater compressive strength
- Lower water-cement ratio
- Higher workability and water content (Correct answer)
- Better air entrainment
Correct answer: Higher workability and water content
A higher slump value indicates more workability due to a higher water content, which generally reduces the final compressive strength of the concrete.
Question 3: In Florida's coastal environment, which type of cement is most commonly specified to resist sulfate attack in soils and groundwater?
- Type I Portland cement
- Type II Portland cement
- Type III Portland cement
- Type V Portland cement (Correct answer)
Correct answer: Type V Portland cement
Type V Portland cement provides high sulfate resistance and is specified in aggressive sulfate exposure conditions common in Florida's coastal soils and groundwater.
Question 4: What is the minimum concrete cover required for reinforcing steel in a concrete slab exposed to earth or weather per ACI 318?
- 3/4 inch
- 1 inch
- 1.5 inches (Correct answer)
- 2 inches
Correct answer: 1.5 inches
ACI 318 requires a minimum of 1.5 inches of concrete cover for #5 bars and smaller in slabs exposed to weather to protect the reinforcement from corrosion.
Question 5: Which masonry unit type has the highest compressive strength rating and is commonly used for load-bearing walls in Florida construction?
- Grade N concrete masonry units (Correct answer)
- Grade S concrete masonry units
- Hollow clay brick
- Autoclaved aerated concrete (AAC) block
Correct answer: Grade N concrete masonry units
Grade N concrete masonry units have the highest compressive strength and are suitable for use above and below grade in exterior and interior walls.
Question 6: According to ASTM standards, what is the maximum allowable absorption rate for a Grade SW (severe weathering) brick?
- 8%
- 12%
- 17%
- 22% (Correct answer)
Correct answer: 22%
ASTM C216 allows a maximum water absorption of 22% by weight for Grade SW brick, which is designed for exterior use in severe weather conditions.
Question 7: When placing concrete in hot weather conditions (above 90°F), which of the following is the most effective method to reduce mix temperature?
- Adding extra cement to the mix
- Using chilled water or ice to replace part of the mix water (Correct answer)
- Increasing the water-cement ratio
- Using Type III cement for faster set
Correct answer: Using chilled water or ice to replace part of the mix water
Substituting chilled water or ice for a portion of the mix water directly lowers the concrete temperature, preventing rapid setting and strength reduction in hot weather.
FCC Concrete & Masonry Construction 1
What is the minimum compressive strength (f'c) typically specified for residential concrete footings in Florida per the Florida Building Code?