244G Concrete Finisher Practice Quiz
Free · 200 Questions.

• Washing facilities with clean water, soap and individual towels
• A drinking-water cooler and disposable cups at the gate
• A first-aid kit and a tube of barrier cream on the truck
• A portable shower trailer with hot water on site on every pour day

Why: Section 30 requires that workers who handle or use corrosive, poisonous or other substances likely to endanger their health be provided with washing facilities with clean water, soap and individual towels. Wet cement is corrosive to skin.

• About 50 mm of graded fine compactable fill, so sharp stone cannot puncture the retarder
• About 50 mm of concrete sand, so the coarse stone drains faster than before
• A second layer of polyethylene that can be peeled away after the pour
• A 25 mm layer of lean mortar screeded smooth, so the retarder lies flat on a hard, even surface

Why: CIP 29 says to choke the top of a coarse capillary break with 2 in. (about 50 mm) of graded, fine-grained compactable fill and to lay the retarder on that smooth, compacted surface. A coarse stone layer does not stop vapor from the sub-grade, so the retarder is still needed above it.

• At the discharge end of the pump
• At the batch plant, before loading
• At the pump hopper, before pumping starts
• At the truck drum after one revolution

Why: The manual says concrete tends to lose slump and entrained air when pumped, so both slump and air tests should be measured at the discharge end of the pump. If that is not practical, a correlation between truck discharge and pump outlet is established.

• The top has stiffened ahead of the concrete below, so troweling now seals in bleed water and air and risks blisters
• Cracking, because the subgrade has drawn out all the bleed water and left the whole slab too dry
• Frost damage, because the cold has stopped hydration in the top layer until the afternoon
• Over-troweling, because the subgrade has sped up setting through the full depth of the slab

Why: NRMCA explains that a cold subgrade makes the slab stiffen from the top down. The surface appears ready while the concrete beneath is still bleeding and releasing air, and finishing then traps them under a sealed skin.

• Plastic sheeting or waterproof paper for 3 to 7 days, not a standard curing compound
• A heavy wax-based membrane compound applied in two coats at right angles
• Continuous ponding with water for the whole 28 days before the flooring goes on
• No curing at all, since the flooring will cover the slab surface in any case

Why: NRMCA's slab moisture sheet advises curing to retain moisture with plastic sheeting or waterproof paper for 3 to 7 days, and to avoid curing compounds on floors to receive coverings or coatings unless the manufacturer states otherwise. Moist curing lengthens drying time.