Construction Concrete and Masonry

Question 1

What is the standard water-to-cement ratio range for most structural concrete mixes?

Accepted Answer

0.45–0.60

Answer

Most structural concrete uses a water-to-cement (w/c) ratio of 0.45–0.60; lower ratios increase strength while higher ratios improve workability but reduce strength.

Question 2

What is the purpose of rebar (reinforcing steel) in concrete?

Accepted Answer

To resist tensile stresses that concrete cannot handle

Answer

Concrete is strong in compression but weak in tension; rebar is embedded to carry tensile forces and prevent cracking under loads.

Question 3

What is the minimum curing time for standard Portland cement concrete to achieve adequate strength?

Accepted Answer

7 days

Answer

Concrete should be cured for a minimum of 7 days for adequate strength development; however, the standard 28-day strength is used for design purposes.

Question 4

What does the designation 'f'c = 4000 psi' mean for concrete?

Accepted Answer

The specified compressive strength at 28 days is 4000 psi

Answer

f'c denotes the specified compressive strength of concrete measured in pounds per square inch (psi) at 28 days after placement.

Question 5

What is the purpose of a slump test for concrete?

Accepted Answer

To measure the workability and consistency of fresh concrete

Answer

The slump test measures the workability (flowability) of fresh concrete by measuring how much a cone of concrete settles after the cone mold is removed.

Construction Practice Test

Construction Practice Test

Construction Concrete and Masonry