A staging pad is 160 ft by 90 ft and needs 8 in. of compacted aggregate base. Using 1.6 tons per cubic yard, what aggregate tonnage is closest?
Correct Answer
B) 569 tons
Area is 160 x 90 = 14,400 sf. Thickness is 8/12 = 0.667 ft, so volume is 9,600 cf or 355.6 cy. At 1.6 tons/cy, tonnage is 355.6 x 1.6 = 568.9 tons, or about 569 tons. Other choices use 6 in. thickness, a higher density, or a waste factor not stated.
Why This Is the Correct Answer
Area is 160 x 90 = 14,400 sf. Thickness is 8/12 = 0.667 ft, so volume is 9,600 cf or 355.6 cy. At 1.6 tons/cy, tonnage is 355.6 x 1.6 = 568.9 tons, or about 569 tons. Other choices use 6 in. thickness, a higher density, or a waste factor not stated.
Why the Other Options Are Wrong
Option A: 474 tons
aggregate base tonnage, choice b: 474 tons applies the perimeter, door deduction, or waste step incorrectly.
Option C: 640 tons
aggregate base tonnage, choice c: 640 tons is wrong because 640 tons applies the perimeter, door deduction, or waste step incorrectly.
Option D: 711 tons
aggregate base tonnage, choice d: 711 tons applies the perimeter, door deduction, or waste step incorrectly.
Memory Technique
Remember aggregate base tonnage as "base, adjustment, final unit"; the last unit should read 569 tons.
Reference Hint
Open Pipe and Excavation Contracting, 2011; use the index entry or section for "Aggregate base quantity takeoff" to confirm that Area is 160 x 90 = 14,400 sf.
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