General Contractor License Site Work and Concrete 4

Question 1

What is the purpose of vapor retarder under a concrete slab-on-grade?

Accepted Answer

To prevent soil moisture from migrating up through the slab

Answer

A vapor retarder (typically polyethylene sheeting) prevents ground moisture from wicking up through the concrete slab.

Question 2

Reinforcing steel cover in concrete refers to:

Accepted Answer

The minimum distance from the rebar surface to the concrete surface

Answer

Cover is the minimum thickness of concrete between the surface and the nearest reinforcing bar, protecting steel from corrosion and fire.

Question 3

What is 'blowout' in the context of concrete formwork?

Accepted Answer

Sudden failure of formwork under hydrostatic concrete pressure

Answer

Formwork blowout is a sudden structural failure caused by the lateral hydrostatic pressure of fresh concrete exceeding the formwork's capacity.

Question 4

In soil classification, 'cohesive' soils primarily include:

Accepted Answer

Clay and silt

Answer

Cohesive soils such as clay and silt have particles that stick together due to electrochemical forces rather than friction.

Question 5

What does 'compaction factor' refer to in earthwork calculations?

Accepted Answer

The ratio of compacted fill volume to the bank (in-place) volume from which it came

Answer

The compaction factor (or swell/shrinkage factor) accounts for volume changes when soil is excavated and recompacted in a new location.

General Contractor License Practice Test