CPII Material Testing 4 — Questions and Answers
Question 1: A steel reinforcing bar is labeled '5 S 60'. What does '60' indicate?
- The bar weighs 60 lb per foot
- The minimum yield strength is 60,000 psi (Correct answer)
- The bar is 60 mm in diameter
- The bar has 60 deformations per foot
Correct answer: The minimum yield strength is 60,000 psi
Grade 60 rebar has a minimum yield strength of 60,000 psi (60 ksi) per ASTM A 615 or A 706.
Question 2: Which test is used to evaluate the bond strength of a tack coat or prime coat in asphalt paving?
- Cantabro loss test
- Lottman moisture susceptibility test
- Pull-off adhesion test (Correct answer)
- Binder extraction test
Correct answer: Pull-off adhesion test
The pull-off adhesion test measures the tensile bond strength between a pavement layer and the underlying surface or tack coat.
Question 3: What is the purpose of the Atterberg Limits test?
- To determine the bearing capacity of in-situ soils
- To define the moisture content boundaries between soil consistency states (Correct answer)
- To measure the permeability of cohesive soils
- To evaluate soil shear strength under dynamic loading
Correct answer: To define the moisture content boundaries between soil consistency states
Atterberg Limits (Liquid Limit, Plastic Limit, Shrinkage Limit) define the moisture contents at which fine-grained soils transition between solid, semi-solid, plastic, and liquid states.
Question 4: Concrete mix design specifies a maximum aggregate size of 1.5 inches. According to ACI 301, this size should not exceed:
- 3/4 of the minimum clear spacing between reinforcing bars
- One-fifth of the narrowest dimension of a form
- Three-fourths of the minimum clear cover
- All of the above apply (Correct answer)
Correct answer: All of the above apply
ACI 301 requires maximum aggregate size to satisfy all three criteria: 1/5 the narrowest form dimension, 3/4 the clear spacing between bars, and 3/4 the minimum clear cover.
Question 5: What does a 'Type III' cement designation indicate in concrete mix specifications?
- Low heat of hydration cement for mass concrete
- High early strength cement (Correct answer)
- Sulfate-resistant cement
- Air-entraining cement
Correct answer: High early strength cement
ASTM C 150 Type III is a high early strength Portland cement that achieves strength faster than Type I, often used in cold weather or early form removal situations.
Question 6: When a nuclear density gauge is used on a project, which safety requirement is mandatory?
- The gauge must be calibrated daily using a sand cone test
- The operator must hold a current radiation safety license or certification (Correct answer)
- The gauge must be stored in a locked container when not in use only on federal projects
- The gauge must be used within 50 feet of a licensed engineer
Correct answer: The operator must hold a current radiation safety license or certification
Nuclear density gauges contain radioactive sources regulated by the NRC; operators must hold a current radiation safety license or certification from their state or the NRC.
Question 7: In a sieve analysis report, the 'fineness modulus' is calculated by:
- Dividing the total percent retained by the number of sieves used
- Summing cumulative percent retained on standard sieves and dividing by 100 (Correct answer)
- Averaging the percent passing on the No. 4 and No. 200 sieves
- Multiplying the D50 particle size by the uniformity coefficient
Correct answer: Summing cumulative percent retained on standard sieves and dividing by 100
Fineness modulus = sum of cumulative percent retained on the No. 100, 50, 30, 16, 8, 4 sieves, and 3/8", 3/4", 1.5" sieves divided by 100.
CPII Material Testing 4
A steel reinforcing bar is labeled '5 S 60'.
What does '60' indicate?