ACI Certification Field Testing Technician 4

Question 1

Per ASTM C31, standard 4x8 inch (100x200 mm) concrete test cylinders are filled in:

Accepted Answer

2 approximately equal layers

Answer

ASTM C31 requires filling 4x8 inch cylinders in 2 approximately equal layers.

Question 2

When rodding a 4x8 inch cylinder per ASTM C31, how many strokes are applied per layer?

Accepted Answer

25 strokes

Answer

ASTM C31 specifies 25 uniformly distributed rodding strokes per layer for 4x8 inch cylinders.

Question 3

Per ASTM C31, concrete with a slump of 1 inch (25 mm) or less must be consolidated in cylinder molds by:

Accepted Answer

Internal vibration

Answer

ASTM C31 requires internal vibration for concrete with slump at or below 1 inch because hand rodding cannot adequately consolidate stiff mixes.

Question 4

Per ASTM C31, the required initial curing temperature range for standard-cured specimens is:

Accepted Answer

60F to 80F (16C to 27C)

Answer

ASTM C31 requires standard-cured specimens to be maintained between 60F and 80F (16C to 27C) during the initial curing period.

Question 5

Immediately after finishing the top surface of concrete cylinders in the field per ASTM C31, the molds should be covered with:

Accepted Answer

A non-absorbent, non-reactive plate or plastic lid

Answer

A non-absorbent, non-reactive cover must be placed over freshly filled cylinders immediately to prevent surface moisture loss.

ACI (American Concrete Institute Certification) Practice Test