Roller Pattern & Compaction Equipment Flashcards
7 cards from real PIC practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Roller Pattern & Compaction Equipment flashcards as text
When using a vibratory steel drum roller, at what speed should the roller typically operate to achieve effective compaction without causing mix displacement?
Answer: 1–3 mph
Vibratory rollers should operate at 1–3 mph to allow sufficient dwell time for the vibration to densify the mix without shoving or tearing.
Which roller configuration is BEST suited for breakdown rolling immediately behind the paver?
Answer: Steel tandem vibratory roller
A steel tandem vibratory roller is typically used for breakdown rolling because it provides high compactive effort closest to the paver while the mix is hottest.
What is the primary purpose of the finish (third) pass in a three-stage compaction operation?
Answer: To remove roller marks and surface blemishes
The finish pass uses a static roller or smooth-drum pass to remove any marks, tears, or surface irregularities left by previous rolling stages.
A roller operator notices the asphalt mat is cracking transversely ahead of the drum. What is the MOST likely cause?
Answer: Mix temperature is too low
Transverse cracking ahead of the drum indicates the mix has cooled below the minimum compaction temperature and has become too stiff to compact without fracturing.
For a 4-inch compacted lift of dense-graded HMA, how many passes with a vibratory roller are typically required to achieve 92–96% density?
Answer: 3–5 passes
Typically 3–5 passes of a vibratory roller are needed for standard HMA lifts; exact count depends on mix type, roller weight, and amplitude settings.
What effect does increasing the amplitude on a vibratory roller have on compaction of a thin HMA lift?
Answer: May cause mix displacement and segregation
High amplitude generates large force that can over-compact or displace a thin lift, causing shoving and segregation rather than uniform densification.
During compaction, an inspector observes that the pneumatic tire roller is leaving depressions in the mat. What corrective action should be taken FIRST?
Answer: Increase tire inflation pressure
Increasing tire inflation pressure distributes the roller's load over a smaller contact area, reducing the indentation caused by under-inflated tires on a soft mat.