NASCLA Commercial General Building Contractor Exam — All Questions
2 questions
How many cubic yards of concrete are needed for a slab 20 ft by 30 ft placed 6 inches thick (before any waste factor)?
- a.3.7 cy
- b.11.1 cy✓
- c.22.2 cy
- d.100 cy
Convert thickness to feet (6 / 12 = 0.5 ft), then volume = (20 x 30 x 0.5) / 27 = 300 / 27 = 11.1 cubic yards. There are 27 cubic feet in a cubic yard, so dividing by 27 converts cubic feet to cubic yards.Concrete volume: (L x W x thickness) / 27
On a commercial pour, the crew measures the concrete's slump before placement. What does the slump test primarily indicate?
- a.The compressive strength at 28 days
- b.The air-entrainment percentage
- c.The chloride-ion content
- d.The consistency and workability (relative fluidity) of the fresh concrete✓
The slump test measures the consistency and workability of fresh concrete. It does not measure strength, which is verified by breaking cured cylinders (typically at 28 days per ACI 318). A slump outside the specified range signals a mix or water problem before the concrete is placed.ACI 318 / concrete slump test