FREE General Contractor License Site Work and Concrete Questions and Answers

Question 1

A competent person inspects an excavation and classifies the soil as Type C. According to OSHA standards for excavations 20 feet or less in depth, what is the maximum allowable simple slope?

Accepted Answer

1 ½ horizontal to 1 vertical (1½:1)

Answer

OSHA's Subpart P specifies the maximum allowable slopes for excavations less than 20 feet deep. For Type C soil, which is the least stable classification (includes granular soils, submerged soil, or soil with freely seeping water), the required slope is 1½ horizontal to 1 vertical (1½:1), which corresponds to a 34-degree angle.

Question 2

During a concrete slump test (ASTM C143), the fresh concrete is placed into the cone in three equal layers by volume. How many times should each layer be rodded?

Accepted Answer

25 times

Answer

The standard procedure for the ASTM C143 slump test requires that each of the three layers of concrete placed in the slump cone be rodded exactly 25 times. This ensures uniform compaction of the sample to get an accurate measure of the concrete's consistency and workability.

Question 3

A contractor is preparing to place a 6-inch thick concrete slab on grade. To ensure the rebar provides the intended tensile strength and is protected from corrosion, it must be positioned correctly within the slab. What is the primary purpose of using rebar chairs or bolsters during this process?

Accepted Answer

To maintain the proper concrete cover over the reinforcement.

Answer

Rebar chairs, bolsters, or other supports are used to hold the reinforcing steel at the correct height within the formwork before and during the concrete pour. This ensures that the specified amount of concrete cover (the distance from the steel to the surface) is maintained, which is critical for protecting the rebar from corrosion and for the structural integrity of the slab.

Question 4

Which of the following best describes the primary goal of concrete curing?

Accepted Answer

To maintain satisfactory moisture and temperature conditions.

Answer

Curing is the process of maintaining adequate moisture and temperature in freshly placed concrete for a period of time to allow for proper cement hydration. This process is critical for the concrete to achieve its designed strength, durability, and other potential properties. It is not about drying the concrete, but rather controlling the rate of moisture loss.

Question 5

A laboratory soil analysis, known as a Proctor test (ASTM D698), is performed on a soil sample from a job site. What is the primary purpose of this test?

Accepted Answer

To establish the optimal moisture content for maximum compaction.

Answer

The Proctor compaction test is a laboratory method used to determine the optimal moisture content at which a specific soil type will achieve its maximum dry density (compaction). This information is crucial for site work to ensure that fills and subgrades are properly compacted for stability.

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FREE General Contractor License Site Work and Concrete Questions and Answers