CCIL - Canadian Council of Independent Laboratories Concrete Field Testing Procedures Questions and Answers

Question 1

According to CSA A23.2-5C, when performing a slump test, how should the slump cone be lifted from the concrete sample?

Accepted Answer

Vertically, in a smooth and continuous motion taking approximately 5 seconds

Answer

CSA A23.2-5C specifies that the slump cone must be lifted vertically without any lateral or torsional motion. The entire lifting process should take approximately 5 seconds to ensure the concrete subsides due to its own weight and not due to the motion of the cone removal.

Question 2

A field technician is preparing to measure the air content of a fresh concrete sample using the pressure method (CSA A23.2-4C). The concrete has a specified slump of 30 mm. How should the concrete be consolidated in the measuring bowl?

Accepted Answer

By using an internal vibrator

Answer

CSA A23.2-4C and A23.2-3C note that for low slump concrete (≤ 40 mm), consolidation should be achieved through vibration rather than rodding to ensure proper compaction and removal of large entrapped air voids.

Question 3

As per CSA A23.2-1C, a representative sample of concrete for testing must be obtained from which portion of the ready-mix truck's discharge?

Accepted Answer

Between the 10% and 90% points of discharge

Answer

CSA A23.2-1C requires that a grab sample for testing be taken after the first 10% of the load has been discharged and before the last 10% is discharged. This ensures the sample is representative of the entire batch and avoids the less uniform concrete often found at the very beginning or end of the discharge.

Question 4

A technician is casting 100 mm x 200 mm cylinders for compressive strength testing from a concrete mix with a slump of 80 mm. Which of the following correctly describes the rodding procedure according to CSA A23.2-3C?

Accepted Answer

Fill the mold in 3 equal layers, rodding each layer 20 times with a 10 mm rod.

Answer

For 100 mm diameter cylinders, CSA A23.2-3C specifies filling the molds in 3 equal layers. Since the slump is greater than 40 mm, rodding is the correct consolidation method. For this cylinder size, a 10 mm diameter rod is used, and each layer is rodded 20 times.

Question 5

When measuring the temperature of freshly mixed concrete according to CSA A23.2-17C, what is the minimum time the temperature measuring device must be left in the concrete?

Accepted Answer

A minimum of 2 minutes or until the reading stabilizes

Answer

CSA A23.2-17C requires the temperature measuring device to be immersed in the fresh concrete for at least 2 minutes or until the temperature reading stabilizes to ensure an accurate measurement is taken. The entire test must be completed within 5 minutes of obtaining the sample.

CCIL - Canadian Council of Independent Laboratories Practice Test

CCIL - Canadian Council of Independent Laboratories Practice Test

CCIL - Canadian Council of Independent Laboratories Concrete Field Testing Procedures Questions and Answers