Full Depth Reclamation
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Transcript of Full Depth Reclamation
Full Depth ReclamationFull Depth Reclamation
Current PracticeCurrent PracticeTesting VariabilityTesting Variability
Presented To:Presented To:
Canadian User Group for AsphaltCanadian User Group for AsphaltSunday, November 15, 2009Sunday, November 15, 2009
Delta Beausejour HotelDelta Beausejour Hotel
Moncton, New BrunswickMoncton, New Brunswick
Tom DziedziejkoTom DziedziejkoAME Materials EngineeringAME Materials Engineering
FDRFDR
Rehabilitation Technique that processes the Rehabilitation Technique that processes the full depth of asphalt pavement and a full depth of asphalt pavement and a predetermined portion of the underlying base predetermined portion of the underlying base materialsmaterials
Uniformly pulverizes and blends to provide an Uniformly pulverizes and blends to provide an upgraded and homogeneous materialupgraded and homogeneous material
FDR EquipmentFDR Equipment
Including some underlying Including some underlying granular helps cool cutting granular helps cool cutting tools and enhances tools and enhances pulverization actionpulverization action
Allows simultaneous injection Allows simultaneous injection of stabilizing agents.of stabilizing agents.
Pulverizing drum rotates in Pulverizing drum rotates in an up-cut direction or an up-cut direction or opposite to the forward opposite to the forward direction of travel.direction of travel.
FDR EquipmentFDR EquipmentScreen Deck
CrusherBelt Scale
Pug-Mill and Expansion Manifold
Paver Laid FDR•Recycling Trains•Pulverize, Wind row, Pick up
Distresses That Can Be TreatedDistresses That Can Be Treated
CrackingCracking Age, Fatigue, edge, slippage, block, longitudinal, reflection, Age, Fatigue, edge, slippage, block, longitudinal, reflection,
continuitycontinuity
Ride QualityRide Quality Bumps, Localized Depressions, Cross fall correction, Bumps, Localized Depressions, Cross fall correction,
Permanent DeformationPermanent Deformation Rutting, Shoving, Wash BoardingRutting, Shoving, Wash Boarding
General DeteriorationGeneral Deterioration Raveling, Potholes, Stripping, Delamination, etc.Raveling, Potholes, Stripping, Delamination, etc.
Inadequate Structural CapacityInadequate Structural Capacity
Candidates for FDRCandidates for FDR
Good CandidateGood Candidate Good But Approach with Good But Approach with CautionCaution
Potential serious underlying problemsPotential serious underlying problems Enhancement likely requiredEnhancement likely required
Candidates for FDRCandidates for FDR
If existing pavement structure is adequate for loads If existing pavement structure is adequate for loads then simple pulverization and regrading may be all then simple pulverization and regrading may be all that is required before applying surface.that is required before applying surface.
Corrective aggregate may be required to ensure adequate Corrective aggregate may be required to ensure adequate drainage and mechanical properties of the treated material.drainage and mechanical properties of the treated material.
If structural enhancement is required then If structural enhancement is required then stabilizing agents can be addedstabilizing agents can be added
Type of agent used should be selected based on the Type of agent used should be selected based on the properties of the material present.properties of the material present.
Types of Stabilizing AdditivesTypes of Stabilizing Additives
BituminousBituminous Foamed AsphaltFoamed Asphalt Asphalt EmulsionsAsphalt Emulsions
ChemicalChemical Portland CementPortland Cement LimeLime Fly Ash Types C and FFly Ash Types C and F Kiln Dust (Lime/LKD or Cement/CKD), Cement, Lime BlendsKiln Dust (Lime/LKD or Cement/CKD), Cement, Lime Blends
Combinations of the aboveCombinations of the above Bituminous additives blended with Chemical additivesBituminous additives blended with Chemical additives
Types of Stabilizing AdditivesTypes of Stabilizing Additives
Popularity of Recycling is spawning interest in Popularity of Recycling is spawning interest in new stabilizers and additivesnew stabilizers and additives
Foam Enhancing additivesFoam Enhancing additives Pine Tar EmulsionsPine Tar Emulsions
Bituminous AdditivesBituminous Additives
Asphalt EmulsionsAsphalt Emulsions Coats all aggregates with emulsionCoats all aggregates with emulsion Emulsion breaks leaving particles cemented together with Emulsion breaks leaving particles cemented together with
bitumenbitumen Paving can not proceed until emulsion break is completePaving can not proceed until emulsion break is complete Days? Weeks? Cement sometimes added to accelerate Days? Weeks? Cement sometimes added to accelerate
break of emulsionbreak of emulsion
Bituminous AdditivesBituminous Additives
Foamed AsphaltFoamed Asphalt Fast becoming the most popular choice for FDRFast becoming the most popular choice for FDR Small amount of water added to hot asphalt results in foamSmall amount of water added to hot asphalt results in foam Pulverized material needs fines present up to 20%Pulverized material needs fines present up to 20% Foam mixes with fines present in material to form a mastic binderFoam mixes with fines present in material to form a mastic binder Mastic spot welds to larger aggregate in material to form bonds Mastic spot welds to larger aggregate in material to form bonds
that hold mix togetherthat hold mix together Aggregates with PI as high as 15 treated successfully with no Aggregates with PI as high as 15 treated successfully with no
special processesspecial processes Typical delay before paving - two daysTypical delay before paving - two days
Additive Selection for FDRAdditive Selection for FDR
FDR is a Soil Stabilization TechniqueFDR is a Soil Stabilization Technique When Bituminous Additives are used the process becomes a When Bituminous Additives are used the process becomes a
Hybrid Asphalt and Soil productHybrid Asphalt and Soil product Asphalt products provide a binder systemAsphalt products provide a binder system Produces a flexible material with properties that resist fatigue and Produces a flexible material with properties that resist fatigue and
adds flexibility to the processed mat.adds flexibility to the processed mat.
Additives used provide some enhancement to asphalt Additives used provide some enhancement to asphalt interaction with soils but also impacts soil properties interaction with soils but also impacts soil properties similar to soil stabilization techniques.similar to soil stabilization techniques.
Chemical AdditivesChemical Additives
Lime Lime Most often used where soil has Most often used where soil has
high PI (>10)high PI (>10) Benefits Benefits
Mitigates effect of reactive claysMitigates effect of reactive clays Reduces PI of soil after application Reduces PI of soil after application
and reduces swelling potentialand reduces swelling potential Decreases susceptibility to Decreases susceptibility to
moisture damage (stripping)moisture damage (stripping) Increases tensile and compressive Increases tensile and compressive
strength of mixstrength of mix Typical addition 1% to 3%Typical addition 1% to 3%
No Lime 2%Hydrated Lime
Dry Strength 445 kPa 372 kPa
Wet Strength 128 kPa 223 kPa
TSR 29% 60%
Chemical AdditivesChemical Additives Portland Cement Portland Cement
Most often used where soil has low Most often used where soil has low PI (<10)PI (<10)
Primarily adds strength to weak Primarily adds strength to weak materialsmaterials
Benefits Benefits Increases compressive strength of Increases compressive strength of
mix.mix. Strength increase over timeStrength increase over time Impact on moisture susceptibility Impact on moisture susceptibility
variable (stripping)variable (stripping) Typical addition 1% to 2%Typical addition 1% to 2% Excessive addition results in Excessive addition results in
potential cracking of the stabilized potential cracking of the stabilized soilsoil
No Portland Cement
With 2% Portland Cement
Dry Strength 276 kPa 341 kPa
Wet Strength 163 kPa 216 kPa
TSR 59% 63%
Chemical AdditivesChemical Additives Fly ashFly ash
Fly ash is a pozzolan Fly ash is a pozzolan typically requiring presence typically requiring presence of lime or hydrating cement of lime or hydrating cement to gain strengthto gain strength
Some clays can react with Some clays can react with calcium oxide in Type C Fly calcium oxide in Type C Fly ash alone resulting in ash alone resulting in strength gain.strength gain.
Some fly ash has percentage Some fly ash has percentage of lime present that allows of lime present that allows some hydration some hydration
Potential to Mitigate effect Potential to Mitigate effect of reactive clays - Limeof reactive clays - Lime
Slower strength gain than Slower strength gain than cement but carries on longercement but carries on longer
Excessive addition results in Excessive addition results in potential cracking of potential cracking of stabilized soilstabilized soil
No Fly Ash With 1% Fly Ash
Dry Strength 260 kPa 271 kPa
Wet Strength 168 kPa 292 kPa
TSR 65% 108%
Data Source: Job Report Cold RecyclingWR 2500: Foam recycling in EstesNational Park, Colorado /USA
Pre Engineering Pre Engineering Rule of Thumb Engineering is the Most Costly Form of Rule of Thumb Engineering is the Most Costly Form of
DesignDesign Proper Engineering Assessment should be carried out to Proper Engineering Assessment should be carried out to
identify the best choice of additive.identify the best choice of additive. Must consider :Must consider :
Amount of strength enhancement required.Amount of strength enhancement required. Pavement Structural Design – Traffic?Pavement Structural Design – Traffic?
Type and quality of base materials presentType and quality of base materials present Drainage CharacteristicsDrainage Characteristics Presence of Clays and SiltsPresence of Clays and Silts Plasticity IndexPlasticity Index
Pavement DrainagePavement Drainage Ditching Ditching Sub drainsSub drains
Pre EngineeringPre Engineering Thickness of existing pavementThickness of existing pavement
Optimize percent of pulverized pavement in process depthOptimize percent of pulverized pavement in process depth + 60% RAP + 60% RAP
Identify excessively thick areasIdentify excessively thick areas Over 200mm pavement depth could be a problem to Over 200mm pavement depth could be a problem to
process due to equipment capacityprocess due to equipment capacity
Consider Pre-milling Options to reuse excess in other Consider Pre-milling Options to reuse excess in other parts of project. – Shoulder stabilizationparts of project. – Shoulder stabilization
Pre EngineeringPre Engineering
Proper Mixture DesignProper Mixture Design Pre tender laboratory design trials to confirm additive Pre tender laboratory design trials to confirm additive
selected will work is advisable.selected will work is advisable.
Mix design before construction is compulsoryMix design before construction is compulsory
Testing VariabilityTesting Variability
20
25
30
35
40
45
50
55
60
0 50 100 150 200 250 300Time (Minutes)
Tem
pera
ture
('C
)
Time (Minutes)
Room Temperature
Specimen Surface Temperature
Specimen Internal (core)TemperatureLinear (Room Temperature)
Poly. (Specimen Internal (core)Temperature)Poly. (Specimen SurfaceTemperature)
Internal = 26oC
Surface = 24oC
Internal = 34oC
Surface = 28oC
Dry Tensile Strength
0
100
200
300
400
500
600
152025303540
Temperature (oC)
Ten
sile
Str
eng
th (
kPa)
Accurate Test Results Dictate Acceptance
•Stabilized Sample Temperature is Critical
Temp = 25 C: Strength = 360Temp = 26 C: Strength = 340
Test VariabilityTest Variability Strength Change with Varying Conditioning TemperatureStrength Change with Varying Conditioning Temperature
Dry Tensile Strength
0
100
200
300
400
500
600
15 20 25 30 35 40
Temperature (oC)
Ten
sile
Str
eng
th (
kPa)
Wet Tensile Strength
0
100
200
300
400
500
600
15 20 25 30 35 40
Temperature (oC)
Ten
sile
Str
eng
th (
kPa)
Tensile Strength Ratio
0
20
40
60
80
100
120
140
160
15 20 25 30 35 40
Temperature (oC)
Ten
sile
Str
eng
ht
Rat
io (
%)
Testing VariabilityTesting VariabilityTensile Strength Increase with Time
(Cooling Time from 60oC)
250
300
350
400
450
500
2 4 24
Hours
Te
ns
ile
Str
en
gth
(k
PA
)
Strength Increase
2 Hrs Room Curing
4 Hrs Room Curing
24 Hrs Room Curing
Testing VariabilityTesting Variability
Dry Bulk Relative Denstiy
19001920194019601980200020202040206020802100
0.0 2.0 4.0 6.0 8.0 10.0
Moisture (%)
Bu
lk R
elat
ive
Den
sity
Dry Tensile Strength
0.0
100.0
200.0
300.0
400.0
500.0
600.0
0.0 2.0 4.0 6.0 8.0 10.0
Moisture (%)
Ten
sile
Str
eng
th (
kPa)
Wet Tensile Strength
0.0
50.0
100.0
150.0
200.0
250.0
300.0
350.0
400.0
0.0 2.0 4.0 6.0 8.0 10.0
Moisture (%)
Ten
sile
Str
eng
th (
kPa)
Optimum Moisture – Field Sample – AC 2.8%
•Strength Varies with moisture content at time of compaction
ConclusionsConclusions
Select FDR based on engineering designSelect FDR based on engineering design Selected process and enhancement should be based Selected process and enhancement should be based
on existing conditions.on existing conditions. Chemical treatments should be established using Chemical treatments should be established using
Material requirementsMaterial requirements Ensure Quality Verification Testing is Ensure Quality Verification Testing is
completed accuratelycompleted accurately Sample Temperature significantly influences Sample Temperature significantly influences
results results
Thank YouThank You
Questions ?Questions ?