The approximate concrete depth (in vert distance) after placing the first layer is __.

• A. 2-1/4"
• B. 2-5/8"
• C. 3-1/4"
• D. 3-1/2"

Answer: (B)

In two-lift concrete placement, the first layer is meant to be thick enough to be properly placed, consolidated, and finished, while still leaving room for the second layer to reach the final slab thickness. About two and five-eighths inches is a common first-lift depth because it provides enough material for solid consolidation and finishing, and it leaves a workable amount of thickness for the second lift to bring the total to the required final thickness (often around four inches in many standard slabs). If the first lift is much shallower, joints can be weak and finishing harder; if it’s much thicker, the second lift becomes thin and difficult to consolidate and finish cleanly. That’s why the approximate depth after the first layer is around 2-5/8 inches.