Concrete
When should curing concrete for the slab-on-grade and/or panels begin?
Immediately after the slab is poured and finished
What is the required percent of floor space range for all the panels to be poured on the slab to prevent the need for stacking?
<80%, but <70% is better
Hard-troweled finish
What is the maximum compaction of the slab subgrade?
90% of theoretical max
What is the common 28-day compressive strength for tilt-up panels and what is the typical lift compressive strength?
3000 psi, 2500 psi
Define "panelizing" the building
Laying out how tilt-up walls are split into panels, such as what sizes, shapes, and where the joints are
How should chalk lines used for layout of the formwork be sealed to prevent erasure?
Spray with bond breaker
When are stepped footings used?
When the sub-grade elevation changes
List three advantages of reducing the water content in concrete.
Higher strength, less shrinkage and cracking from drying, increased resistance to weathering, increased bond between concrete and reinforcement
Define/explain a tilt-up sandwich panel.
When should you check if the bond breaker and curing compound are compatible?
Before beginning to pour the slab
What is the primary advantage of using plastic tipped chairs?
Plastic tips won't rust when exposed on outside face of panel.
What defines cold weather concrete practices?
Average daily temperature for 3 consecutive days is below 40 degrees F.
How should panels be stacked for casting when stacking panels of different heights?
Biggest panel should be on the bottom, and panels should get smaller as you stack upwards.
List four materials that can be used to fill floor joints. What material should never be used?
Use: silicone, latex, cementitious filler, gypsum, pre-molded or extruded joint filler, wax, foam, tape, drywall mud, grout
Never use: asphalt
Does higher slump concrete reduce shrinkage of the concrete? Why or why not?
No, higher slump means a higher water to cement ratio. The higher the water to cement ratio, the more water in the mix. The more water in the mix, the more shrinkage will occur.
What defines hot weather concrete practices?
High ambient temperature, high concrete temperature, low relative humidity, high wind speed, solar radiation
When lifting panels from the inside of the building, the head or top of the panel should be nearest to what?
The outside edge of the building footprint.
How can you minimize floor cracking when erecting panels from the interior of the building?
Use timber cribbing to distribute crane wheel and outrigger loads more evenly among the slab.
What is the principle reason for air-entrainment?
To help the concrete resist against freeze-thaw cycles when below grade.