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 ?