Concrete and Asphalt Design Final Flashcards
When using a CBR value for design which value is used, soaked or unsoaked and what penetration is the design value at?
2.5mm, Soaked
For Subgrade investigations, what is the minimum number of boreholes and what is the typical depth?
One every 200m along the profile length with a 3-5m depth
In what situations would you have deeper boreholes (hint theres 2)
- At culvert and bridge locations
- Where thick layers of fill or organic soils are encountered
True or false. Soils with a high silt content are frost susceptible soils, therefore making them problematic
True
True or False. Very fine sands with high silt content are considered deleterious materials for subgrade investigations
True
Contract drawings contain “stick logs” with a summary of samples and soil conditions. What are the 5 soil conditions listed in the stick log?
- Moisture Content
- Soil Classification
- Plasticity Index
- Estimated optimum moisture content
- Estimated Maximum dry content
What are the 6 factors affecting pavement design?
- Traffic Loading (ESALS)
- Subgrade Soil Strength (CBR)
- Materials Used
- Design Life
- Climate Conditions
- Acceptable Serviceability Loss
What Does ACP stand for?
Asphalt Concrete Pavement
What Does GBC stand for?
granular base course
What does ASBC stand for?
Asphalt Stabilized Base Course
What does CSBC stand for?
Cement Stabilized Base course
What is the purpose of using lower-strength material instead of full-depth paving?
Lower strength material transfer loads to the subgrade and save project costs
What are the 3 most common natural deposits of asphalt?
- Pitch Lake
- La Brea Tar Pits
- Fort Mac Oilsands
True or False: Alligator/fatigue cracking is functional and a non-load-associated distress
False. Alligator cracking is structural and load-associated
What causes Alligator cracking?
- Poor Support from base/subbase/subgrade
*May be initiated by weak subgrade during the spring thaw
*Poor Compaction during construction - Failure of pavement structure due to high-traffic loading
What is Alligator cracking measured in?
square meters
What is transverse cracking?
Cracks perpendicular to the centerline of the road, these cracks permit moisture infiltration and result in increased roughness
What are some causes of transverse cracking?
- Temperature Changes
-Hardening of asphalt binder
How is transverse cracking measured?
Linear Meters
What is longitudinal cracking?
Cracking occurring parallel to the centerline of the road, cracks permit moisture infiltration and results in increased roughness of the road surface
What are some possible causes of longitudinal cracking?
- Poor joint construction during pavement laydown
-Reflective cracking from underlying layer
-Low temp shrinkage
How is longitudinal cracking measured?
Linear Meters
What are the sizes of blocks in block cracking?
0.1-9m^2
What is map/block cracking?
Consists of a series of cracks that interconnect to form a block like pattern
What are some causes of block cracking?
- Shrinkage of Hot Mix Asphalt
- Aging Binder
What is block cracking measured in?
Square Meters
What are some causes of edge cracking?
-Weakened base and or subgrade at edge (poor compaction)
-Poor pavement edge support
-Poor shoulder drainage
What is edge cracking measured in?
Linear meters
What is bleeding in asphalt?
Bleeding is the presence of a film of asphalt on the pavement surface
True or false. Bleeding in asphalt pavements cause a shiny surface and can result in loss of skid resistance
True
What causes bleeding in asphalt pavements?
Too much asphalt binder and over-application of spray treatments
True or false. For remediation of asphalt bleeding, excess asphalt is removed using a heater planer or grader
True
True or false for smaller areas with bleeding, you can apply coarse sand to absorb excess binder
True
List 4 types of repairs used for minor maintenance of asphalt pavements
- crack sealing
- pothole repair
- spray patching
- shallow patching
True or false: the primary purpose for performing pavement maintenance activities is to extend the pavement life
False; the purpose of performing pavement maintenance activities is to ensure the design life is met
What is the purpose of pavement rehabilitation?
Activities to extend pavement life
True or false: traffic loading is the primary cause of rutting?
True
How can you repair polished aggregate?
Chip seal, open graded overlay, slurry seal
How can you repair raveling?
Fog seal, sand seal, chip seal
What is slippage and what is the primary cause of it?
Horizontal forces induced by traffic, caused by lack of bond between surface and base coarse
What is raveling, and what is the primary cause?
Progressive loss of surface material by weathering or traffic abrasion caused by a loss of bond between asphalt binder and aggregate
List 5 reasons for using a subbase beneath a rigid pavement
- control pavement pumping
- control frost action
- drainage improvement
- control swelling/shrinkage
- Expedite construction
Fill in the blank: As wheel loads pass over a transverse joint in rigid concrete pavement, a suction force is created beneath the __________ slab. A loss of fines occurs beneath the __________ slab. Eventually ________ of the slab occurs.
- Trailing
- Leading
- Faulting
When frost penetrates the ground, what can form, causing pavement distress?
Ice lenses
True or false frost-susceptible soils have a sufficiently low permeability to allow water migration through soil
False frost susceptible soils have high permeability to water
What types of soils are most frost susceptible?
silts
What types of soils are subject to volume change and result in shrinkage/swelling?
High plastic clays
List three types of pavement distress that can result from pavement pumping?
- Corner Breaks
- Faulting
- Linear Cracks
When there is localized distress from pavement pumping, how can it be remediated?
Full depth patch
What is faulting?
a term used to describe a difference in elevation between adjacent concrete pavement slabs
For faulting 3 to 12mm what two repair methods can be used?
- Diamond Grinding
- Dowel bar retrofit
What are three causes of linear panel cracking?
- Loss of subgrade support
- Thermal Gradient Curling
- Moisture warping and shrinkage due to drying
How is a corner break repaired?
Full depth patch
Breaking and chipping off of concrete along edges of joints of cracks is description of what type of rigid pavement distress?
Spalling
List one way Spalling can occur
- High stress at joints
- construction defects
-Corroded/misaligned dowel bars - freeze thaw damage of PCC slab or durability cracking
In what type of concrete pavement does edge punch out occur and why?
CRCP because CRCP doesn’t have corners so in this case the edge punch out occurs
Name the 2 possibilities for join load transfer system deterioration
- Misalignment of dowel bars
-Corrosion of dowel bars
What type of concrete pavement distress can result from coarse aggregates that are susceptible to freeze-thaw action ?
Durability Cracking
Delayed cutting of sawed construction joints in jointed plain concrete pavement can result in the form of what type of crack?
Shrinkage Cracks
What type of rigid pavement stress occurs from poor Los Angeles abrasion resistance of the aggregate
Polished aggregate
What is another term used for blowup of concrete pavement?
Buckling
True or false buckling occurs during warmer spring/summer weather?
True
