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GROWTH OF ORGANISM IN ASPHALT CONCRETE
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Project CycleProject Cycle
Project
(1) SubstrateCharacteristics Consultants
Architect
Specification
Project
(1) SubstrateCharacteristics
(2) PerformanceRequirements
ConsultantsArchitect
Specification
DesignInnovation
Specification
Project
(1) SubstrateCharacteristics
(2) PerformanceRequirements
ConsultantsArchitect
MaterialSupplier
Specification
DesignInnovation
Specification
Material Innovation
Material Supply
Project
(1) SubstrateCharacteristics
(2) PerformanceRequirements
(3) Application
ConsultantsArchitect
MaterialSupplier
Contractor
Specification
DesignInnovation
Specification
Material Innovation
Material Supply
Installation
Project
(1) SubstrateCharacteristics
(2) PerformanceRequirements
(3) Application
(4) Verification
ConsultantsArchitect
MaterialSupplier
TestLaboratory
Contractor
Specification
DesignInnovation
Specification
Material Innovation
Material Supply
Installation
Project
(1) SubstrateCharacteristics
(2) PerformanceRequirements
(3) Application
(4) Verification
ConsultantsArchitect
MaterialSupplier
TestLaboratory
Contractor
ContractorManagement
Maintenance Specification
DesignInnovation
Specification
Material Innovation
Material Supply
Installation
Substrate CharacteristicsSubstrate Characteristics
1. Chemistry of Asphalt2. Physical Properties of Asphalt3. Asphalt Substrates4. Principles of Coating Technology
Terminology: Bitumen
Bitumen = amorphous substance:
• asphaltenes = dispersed phase
Chemical Structure of Ashaltenes
CH2
CH3
CH2
CH2CH2
CH2CH
CH2CH2
CH2CH2
CH2CH3
CH3
Terminology: Bitumen
Bitumen = amorphous substance:
• asphaltenes = dispersed phase• polar resin (protective layer)
“Asphaltic cement” = binder
• mixture of aromatic oils
Terminology: Asphalt
Asphalt partially crystalline mixture • Bitumen (polymer-modified)• Aggregate (rock)• Sand“Asphaltic Concrete”
Polymer Modifications• Epoxy Asphalt• Polyurethane Asphalt• Polysulfide Asphalt• Polyester Asphalt• Phenolic Asphalt• Rubber Asphalt• Thermoplastic Asphalt
Terminology: Asphalt Emulsions
Mixture produced in colloid mill:• Asphalt in water emulsion• Stabilized by anionic or cationic surfactantsUsed in subbase stabilization, cold patch compound, road oils
Substrate Characteristics (2)Substrate Characteristics (2)1.Chemistry of Asphalt2. Physical Properties of Asphalt3. Asphalt Substrates4. Principles of Coating Technology
Glass Transition Temperature Tg
Transition of amorphous Materialsfrom glass-like, hard-elasticto liquid, rubber-elastic
Based on freeze-thaw-cycle of Brown’s molecular movements
Rheological Behavior of Bitumen
Temperature
Visc
osity
Newtonian Liquid
Ideal Behavior
Modified Bitumen
-25°C to -15°CTg
50°C to 70°CViscoelastic to Newtonian
ServiceRange
ProcessRange
Rheological Nature of Asphalt
Newtonian fluidT > 70 °C
viscoelastic, thixotropic fluid- 10 °C < T < 50 °C
amorphous, glass-like materialT < - 20 °C
RheologyTemperatureT (in °C)
Dilutent Evaporation
0
10
20
30
40
50
60
70
80
90
100
1 day 1 week 1 month 4 month
% o
f Dilu
tent
Eva
pora
ted
Rapid CureMedium CureSlow Cure
Substrate Characteristics (3)Substrate Characteristics (3)1. Chemistry of Asphalt2. Physical Properties of Asphalt3. Asphalt Substrates4. Principles of Coating Technology
Asphalt Concrete Paving
Asphaltic Concrete (“Blacktop”):Mixture of polymer-modified asphalt(asphaltic cement), aggregate and sand• Penetration Grade (ASTM D 946)• Viscosity Grade (ASTM D 3381)
Installation
• Surface Preparation(compaction of subbase, prime coat)
• Placement of asphalt concrete mixture (spreading at a minimumtemperature of 105 °C/225 °F)
• Rolling (Compaction)
Field Quality ControlASTM F2157-02 - Standard Specificationfor Synthetic Surfaced Running Tracks
Section 5 -Test Methods and Requirementsfor Asphalt Base
5.1 Type and Compactiontwo layers: base and wearing course95% density (machine finished areas)90% density (hand packed areas)
5.2 Test Method ASTM D2950
Field Quality Control (2)ASTM F2157-02 - Standard Specificationfor Synthetic Surfaced Running Tracks
Section 5 -Test Methods and Requirementsfor Asphalt Base
5.3 Evenness3-m straight edge depression not to exceed
6 mm (Class A & B)8 mm (Class C)
Substrate Characteristics (4)Substrate Characteristics (4)1.Chemistry of Asphalt2. Physical Properties of Asphalt3. Asphalt Substrates4. Principles of Coating Technology
Polyurethane (PUR) Coating
• 1-component (1K) moisture curedPUR Prepolymer + water
• 2-component (2K) chemical curedDiisocyanate (NCO) or PUR-Prepolymerreacting with Polyol-component
1K PUR: Advantages and Application Limitations
– curing profile greatly dependent onclimate conditions
moisture leveltemperature
– no thick film applications
+ no second component required
1K PUR Prepolymer (Binder)
3939Moisture-cured prepolymerBinding of rubber granulesPaved to 10 mm thicknessCure time of 24 hours
Spurtan: Sandwich SystemTop layer poured-in place
EmbeddedEPDM granules
UV protection& durability
Paved in placePUR-bound rubber-base-mat
2K PUR: Advantages and Application Limitations
+ thin and thick-film applications+ curing profile independent of
moisture levels in environment
– mixing of A&B component at correct mixing ratio required
APT PU Mixing machine
APT 2K PUR MachineSpeed ControlVFD Pump A
Speed ControlVFD Pump B
Progressive Cavity Pump A Progressive Cavity Pump B
Mixing Tube
PUR A/B Output
from B-reservoirfrom A-reservoir
EMO-500Ratio Monitor
Flowmeter A Flowmeter B
2K PUR Coating
5050Chemical-cured coatingEmbedding of EPDMPot life 35 minutesCure time of 24 hours
Rekortan: Full-pour SystemTop layer poured-in place Embedded
EPDM granules
Automated Installation of2K PUR Coating
Multi-LayerMiddle:Shock Absorbingmicro-foam PURQualipur 5050SABottom:Leveling layer
ReferencesReferences[1] Usmani, A.M.; Asphalt Science and Technology. 1st
ed.;New York, NY: Marcel Dekker, Inc., 1997[2] HEWLETT, P. (Editor): Lea’s Chemistry of Cement and
Concrete, 4th ed., Burlington, MA: Elsevier, 2004[3] ASTM F2157-02: Standard Specification for Synthetic
Surfaced Running Tracks, West Conshohocken, PA: ASTM International 2002
[4] ASTM D946-99: Standard Specification for Penetration-Graded Asphalt Cement for Use in Pavement Construction, West Conshohocken, PA: ASTM International, 1999
[5] ASTM D3381-99: Standard Specification for Viscosity-Graded Asphalt Cement for Use in Pavement Construction, West Conshohocken, PA: ASTM International, 1999