ATT ATT Flat, Elongated Particles & Sand Equivalent

Question 1

Which ASTM standard covers the test method for flat particles, elongated particles, or flat and elongated particles in coarse aggregate?

Accepted Answer

ASTM D4791

Answer

ASTM D4791 is the standard test method for flat particles, elongated particles, or flat and elongated particles in coarse aggregate.

Question 2

In ASTM D4791, a particle is classified as 'flat' when the ratio of its width to thickness exceeds:

Accepted Answer

3:1

Answer

Per ASTM D4791, a particle is classified as flat when the ratio of width to thickness is greater than a specified value, commonly 3:1 for standard testing.

Question 3

Why are flat and elongated particles undesirable in concrete aggregate?

Accepted Answer

They tend to orient horizontally and create planes of weakness, increasing water demand

Answer

Flat and elongated particles orient themselves horizontally under compaction, creating planes of weakness and requiring more water for adequate workability.

Question 4

The proportional caliper device used in ASTM D4791 testing measures:

Accepted Answer

The ratio between two dimensions of a particle

Answer

The proportional caliper used in ASTM D4791 is set to a specific ratio (e.g., 1:3 or 1:5) and directly indicates whether a particle's dimensional ratio exceeds the threshold.

Question 5

In ASTM D4791, what is the minimum number of particles required for a valid flat and elongated test?

Accepted Answer

100 particles

Answer

ASTM D4791 requires a minimum of 100 particles per size fraction to achieve statistically reliable results.

(ATT) ACI Aggregate Testing Technician Practice Test

(ATT) ACI Aggregate Testing Technician Practice Test

ATT ATT Flat, Elongated Particles & Sand Equivalent