Concrete
Concrete (6 of 115 items) covers volume takeoff, testing, and quality control under ACI 318. This chapter reviews cubic-yard calculations and the slump and cylinder tests.
Estimating concrete volume
Concrete is ordered by the cubic yard. Compute volume as length x width x thickness (all in feet) divided by 27, since there are 27 cubic feet in a cubic yard. For a slab, convert the thickness from inches to feet first (for example, 6 inches = 0.5 foot). Estimators then add a waste factor for spillage and subgrade irregularity.
Fresh and hardened concrete testing
The slump test measures the consistency and workability of fresh concrete, not its strength; a slump outside the specified range signals a mix or water-content problem before placement. Compressive strength is verified by breaking cured cylinders, typically at 28 days, under ACI 318. Proper curing (keeping the concrete moist and at a suitable temperature) is essential to reach design strength.