KDOT Construction Materials Testing & Quality Control 5

Question 1

What is the purpose of the 'ignition oven' method (AASHTO T 308) in HMA quality control?

Accepted Answer

Measure the asphalt binder content of a mix by burning off the binder

Answer

The ignition oven method burns the organic asphalt binder from the aggregate at high temperature, allowing calculation of binder content by weight difference.

Question 2

During concrete paving operations, a KDOT inspector notices bleed water sheen on the surface during finishing operations. The correct action is to:

Accepted Answer

Delay finishing operations until the bleed water evaporates

Answer

Finishing concrete before bleed water evaporates traps water in the surface layer, creating a weak, porous layer prone to scaling and dusting.

Question 3

A geosynthetic fabric is being placed as a separator layer between subgrade and aggregate base. What test property is most critical for this application?

Accepted Answer

Apparent opening size (AOS) and permittivity

Answer

For a separator application, the fabric must allow water drainage (permittivity) while retaining fine soil particles, making apparent opening size and permittivity the critical design properties.

Question 4

When sampling freshly mixed concrete from a transit mixer per AASHTO T 141, composite samples must be collected over what minimum time span?

Accepted Answer

Between 10% and 90% of the load discharge

Answer

AASHTO T 141 requires composite samples to be collected from the middle portion of the load, between 10% and 90% of the total discharge, to avoid non-representative material.

Question 5

A field moisture test on a soil sample using the speedy moisture tester (calcium carbide method) reads 8.2%. The true oven-dry moisture content is 7.9%. What does this indicate about the speedy tester result?

Accepted Answer

Both methods agree within acceptable tolerance for field use

Answer

A 0.3% difference between the speedy moisture tester and oven-dry method is within the acceptable tolerance for field quality control decisions.

(KDOT) Certified Kansas Department of Transportation Inspector Practice Test

(KDOT) Certified Kansas Department of Transportation Inspector Practice Test

KDOT Construction Materials Testing & Quality Control 5