Chapter 5 - Compacting grading, finishing & ripping Flashcards
What is the difference between compaction and consolidation
Compaction - increasing soil density by the use of machines
Consolidation - Natural compaction - takes years.
What are the 4 basic compaction forces:
1) Static weight - All compactors utilize static weight but most combine with other methods
2) Manipulation - The most effective compaction in plastic soils
3) Impact or tamping - It involves blows delivered at low frequencies (10 cycles per second) most effective for plastic soils
4) Vibration - Effective in compaction of cohesionless soils sicj as sand and gravel
In-place density test types
1) Traditional method
2) Nuclear density gauges
3) Nonnuclear density gauges
4) Equipment-mounted compaction measurements systems
How one can verify the adequacy of compaction?
By comparing with the specified density
Explain what is Pneumatic rollers
1) Pneumatic rollers - most effective on almost all types of soils but least effective on clean sands and gravel
Explain what is Vibratory compactors
2) Vibratory compactors- most effective in compacting noncohesive soils, but at low frequency and high amplitude they are effective in cohesive soil
Explain what is Tamping for rollers
3) Tamping for rollersMost effective on cohesive soils
What are the 6 main variables for a compaction plan?
1) Soil moisture content
2) Lift thickness
3) No of passes used
4) Ground contract pressure
5) Compactor weight
6) Compactor speed
What graders can be used for?
light stripping, grading, finishing, trimming, bank sloping, ditching, backfilling and scarifying
What are the 3 modes of grader operation?
1) Straight: for the conventional manner
2) Articulated: To turn in a short radius
3) Crab: While the rear driving wheels stay on firm ground, the machine cuts banks, side slopes, or ditching.
What are the grader’s main components?
1) Moldboard/blade: Equipped with flat, curved (for cutting hard materials), or serrated (for breaking up packed gravel, frozen soil, and ice).
* One of the most expensive grader components
2) Scarifier: Used when the material is too hard to cut with the blade. The removable teeth can be adjusted to cut to a depth of 12 inches.
3) The range of depth for ripping 12-18 in
True or false: Turning the grader to starting point is normally more efficient than backing
False: For short distances (less than 1000 ft) backing the grader to starting point is normally more efficient than turning and continuing the work from the far end.
True or false: Minimize the number of passes to accomplish work and preferably plan an even number of passes for the grader.
False, odd number
What are the 4 tips for grader job management:
1) Use backing for short distances (less than 1000ft), and turning to continue the work from the far end
2) Plan an odd number of passes for efficiency
3) Operate at full throttle in each gear
4) Do not use overinflated tires, it results in loss of friction between the tires and road surface.
