FREE ACI Field Testing Technician Questions and Answers

Question 1

The concrete sample that will be used for the slump test needs to be obtained in compliance with ASTM Standard _____.

Accepted Answer

C172, Standard Practice for Sampling Freshly Mixed Concrete

Answer

The concrete sample for a slump test must be obtained in compliance with ASTM Standard C172, Standard Practice for Sampling Freshly Mixed Concrete. Adhering to this standard ensures that the sample is representative of the concrete batch, which is critical for accurate and reliable test results. Proper sampling prevents misleading data that could lead to incorrect assessments of concrete quality.

Question 2

Before starting any tests on a composite sample, certain portions of the sample must be fully blended. Is it True or False?

Accepted Answer

TRUE

Answer

TRUE. Before starting any tests on a composite concrete sample, certain portions of the sample must be fully blended. This ensures that the sample is homogeneous and representative of the entire batch of concrete, providing accurate and consistent test results. Proper blending prevents segregation of aggregates and ensures uniformity.

Question 3

Use one stroke for every _____ of top surface area when rodding a flexural strength test specimen.

Accepted Answer

2 in.^2 [14 cm^2]

Answer

When rodding a flexural strength test specimen, you should use one stroke for every 2 in.^2 [14 cm^2] of top surface area. This specific rodding frequency, as outlined in ASTM standards, ensures uniform compaction of the concrete within the mold. Proper compaction is essential for producing a consistent and representative specimen, which is critical for accurate flexural strength testing.

Question 4

Every layer ought to occupy around _____ of the mold's volume.

Accepted Answer

One-third

Answer

Every layer of concrete ought to occupy approximately one-third of the mold's volume when preparing test specimens. This standardized layering technique, combined with proper rodding or vibration, ensures uniform compaction throughout the specimen. Filling the mold in equal layers helps eliminate voids and segregation, leading to consistent and reliable test results for concrete properties.

Question 5

Which consolidation technique needs to be applied when the slump is less than one inch? (25 mm)?

Accepted Answer

Vibration

Answer

When the concrete slump is less than one inch (25 mm), indicating a very stiff mix, vibration is the necessary consolidation technique. Rodding alone is insufficient to remove entrapped air and achieve proper density in such low-slump concrete. Vibration effectively mobilizes the stiff concrete, allowing it to settle and fill the mold completely, ensuring a dense and void-free specimen.

ACI (American Concrete Institute Certification) Practice Test

ACI (American Concrete Institute Certification) Practice Test

FREE ACI Field Testing Technician Questions and Answers