ACI ASTM C 138-unit weight of concrete questions with answers graded A+

ACI ASTM C 138-unit weight of concretewhen 3 1/2 in. slump concrete is consolidated in a 0.5 cubic foot measure, consolidation is accomplished by? a. either rodding or vibration b. rodding c. vibration - correct answer b. rodding what is the air content (in percent) of the following concrete batching? Theoretical density computed on an air-free basis: 145lb/cubic ft. Actual density (unit weight): 137lb/cubic ft. a. 5.5 = [(145 - 137) / 145] × 100 b. 5.8 = [(145 - 137) / 145] × 100 c. Insufficient information provided - correct answer a. 5.5 = [(145 - 137) / 145] × 100 the minimum capacity of a measure used for C 138 tests is based on the ? a. air content of the concrete b. slump of the concrete c. nominal maximum size of course aggregate in the concrete d. volume of the composite sample of the concrete - correct answer c. nominal maximum size of course aggregate in the concrete calculate the density (unit weight) of concrete in pound's per cubic foot (lb/cubic ft.), given the following information volume of the measure ( cubic ft.): 0.4 mass of empty measure (lb): 17 mass of measure plus concrete (lb): 76 a. 30.4 = 76 × 0.4 b. 37.2 = (76 + 17) × 0.4