PIC Mix Design & Specification Compliance Flashcards

On a paving project, the inspector receives a load of HMA with a delivery ticket showing binder content of 5.8% and the JMF target is 5.4% with a ±0.3% tolerance. The load should be:

Answer: Rejected because 5.8% exceeds the allowable range of 5.1%–5.7%

The allowable range is 5.4% ± 0.3%, which equals 5.1% to 5.7%; a binder content of 5.8% is outside this range and the load should be rejected.

The Hamburg Wheel Tracking Test is used to evaluate an HMA mix for resistance to:

Answer: Rutting and moisture damage under repeated wheel loads in a heated water bath

The Hamburg Wheel Tracking Test measures rut depth under repeated wheel passes in a water bath at elevated temperature, evaluating both rutting resistance and moisture susceptibility.

The term 'extracted gradation' during quality control refers to:

Answer: The gradation of the aggregate obtained from a recovered HMA plant sample after binder extraction

Extracted gradation is performed on the aggregate remaining after chemically removing the asphalt binder from a plant-produced HMA sample, verifying the blend matches the JMF.

If a project specification requires a minimum film thickness for tack coat application of 0.04–0.08 gallons per square yard (residual), a paving inspector should verify the rate using:

Answer: Catch pan measurements calibrated to the distributor's spray bar output

Calibrated catch pan tests placed beneath the distributor's spray bar measure the actual application rate across the width to verify compliance with specification residual rate requirements.

Dust-to-binder ratio (P0.075 / Pbe) is a Superpave mix design parameter that controls:

Answer: The percentage of fines passing the No. 200 sieve relative to effective binder content

The dust-to-binder ratio compares the percentage of material passing the No. 200 sieve (P0.075) to the effective binder content (Pbe), and Superpave limits this ratio to control mix workability and durability.

A paving inspector checking plant records notices the mixing temperature of the HMA consistently exceeds the maximum temperature specified. The primary concern is:

Answer: Overheating can oxidize and age the asphalt binder, reducing mix durability

Excessive mixing temperatures accelerate oxidative aging of the asphalt binder, reducing its flexibility and durability and increasing susceptibility to cracking.