Installation Techniques & Methods Flashcards

What property of fresh concrete does the slump test (ASTM C143) primarily measure?

Answer: Consistency and workability

The slump test gauges fresh concrete consistency, which indicates workability.

Per ACI 318, what is the minimum concrete cover for reinforcement in concrete cast against and permanently exposed to earth?

Answer: 3 in.

ACI 318 requires 3 in. of cover for concrete cast directly against and permanently exposed to earth.

ACI 306 defines cold weather concreting as a period when the air temperature has fallen to, or is expected to fall below, what value during the protection period?

Answer: 40°F

ACI 306 uses 40°F as the threshold that triggers cold weather concreting measures.

In tilt-up construction, how are the wall panels typically produced?

Answer: Cast horizontally on the floor slab or a casting bed, then lifted into place by crane

Tilt-up panels are cast flat on site, usually on the building slab, then tilted up with a crane.

Saw-cut contraction joints in a slab-on-grade are generally cut to what depth?

Answer: About 1/4 of the slab thickness

Cutting about one-quarter of the slab depth creates a weakened plane so cracking happens at the joint.

Slipforming is best suited for which type of structure?

Answer: Tall continuous vertical elements such as cores, silos, and towers

Slipforms rise continuously while concrete is placed, which suits tall elements with a uniform cross-section.

When consolidating concrete placed in layers with an internal vibrator, what is the recommended practice?

Answer: Insert vertically and penetrate several inches into the previous layer

Inserting vertically and penetrating about 6 in. into the lower layer knits the lifts together and avoids cold joints.