by

Dr. Mohammad Nahid SiddiquiProf. Mohammad Farhat Ali

&Eng. Mirza Ghouse Baig

Department of Chemistry

King Fahd University of Petroleum & Minerals

Dhahran, 31261

Saudi Arabia

To Study the effects of To Study the effects of antistripping agents on asphalt-antistripping agents on asphalt-aggregate mixtures using aggregate mixtures using Adsorption-desorption and IR test Adsorption-desorption and IR test methodsmethods..

Introduction and BackgroundIntroduction and Background Moisture DamageMoisture Damage Anti-Stripping AdditivesAnti-Stripping Additives

ExperimentalExperimental Asphalt & Aggregate PropertiesAsphalt & Aggregate Properties Adsorption-desorption Testing Adsorption-desorption Testing

Results and DiscussionResults and Discussion ConclusionsConclusions

Moisture DamageMoisture Damage

SignificanceSignificance: :

A A high degree of strippinghigh degree of stripping was was

detected in detected in between 25 to 50%between 25 to 50% on on

various pavement sites inspected various pavement sites inspected

in Saudi Arabia during late 1990.in Saudi Arabia during late 1990.

Moisture DamageMoisture Damage

Main FocusMain Focus: :

To Improve To Improve aggregate aggregate asphalt bonding.asphalt bonding.

Antistripping AdditivesAntistripping Additives

Organic Small MoleculesOrganic Small Molecules Amines, SilanesAmines, Silanes Polyamines, AmidoaminesPolyamines, Amidoamines

Inorganic Aggregate TreatmentsInorganic Aggregate Treatments Hydrated LimeHydrated Lime Portland CementPortland Cement

Polymeric AgentsPolymeric Agents Functionalized ButadieneFunctionalized Butadiene Styrene-ButadieneStyrene-Butadiene

• Asphalt-aggregate interactions in pavements

directly affect the adhesion & bond strength.

• Chemistry of asphalt & surface chemistry of

aggregates particularly affects the interactions.

Asphalt-Aggregate BondingAsphalt-Aggregate Bonding

* *WettabilityWettability

* *Viscosity (temp)Viscosity (temp)

* *Composition Composition (oxygen)(oxygen)

* *DurabilityDurability

**Surface chemistry Surface chemistry (mineral (mineral composition)composition)

* *Surface textureSurface texture

* *PorosityPorosity

* *Surface condition Surface condition (cleanliness, (cleanliness, moisture)moisture)

Asphalt Aggregate

Effect of Surface Film on Aggregate Coverage (after Hubbard)

Effect of Aggregate Surface on Texture Adhesion (after Hubbard)

Contact Angle in an Aggregate, Asphalt and Water System (after pfeiffer).

Effect of Polarity on Adhesion

(after Hubbard)

Molecular Orientation

(after Hubbard)

• Asphalts from Two Refineries• Riyadh Refinery (RY)

• Ras Tanura Refinery (RT)

• Aggregates from Three different regions• Taif

• Eastern Province (EP)• Riyadh

• Three Anti-Stripping Agents• Iterlene IN/400-S• Cecabase 260• Polyram L200

Elemental Analysis (wt %) of RT and RY Asphalts

ElementsSample IDRT RY

C

H

S

N

O

H/C

O/C (x10-3)

S/C (x10-2)

N/C (x10-3)

Asphaltenes %

Ni

V

V/Ni

84.66

10.41

4.58

0.39

Nil

1.46

Nil

2.03

3.96

33

114

3.45

84.25

10.14

4.99

0.41

0.21

1.43

1.87

2.22

4.19

27

97

3.59

Physical Characteristics of RT and RY Asphalts

TEST RT RY

Specific Gravity 1.020 1.028

Penetration @ 25°C 57.2 53.2

Penetration @ 4°C 31 22

Softening Point, °C 50.50 50.00

Flash Point, °C 308 325

Ductility, cm 120.83 150+

Sliding Plate Viscosity @ 25°C, Pa.s 88091.9 93744.5

Absolute Viscosity @ 60°C, Poise 3252.51 2695.82

Rotational Viscosity @ 135°C, cP.s 463 494

Kinematic Viscosity @ 135°C, cst 464.39 479.56

Asphalt Grade (WASHO Classification) AR-8000 AR-8000

Aggregates

1. Limestone (Eastern Province)

2. Basalt (granite) (Western Province, TAIF)

3. Limestone (Riyadh Area)

Properties Riyadh (RN) Taif (WP) Dammam (EP)

Aggregate Type Lime stone Basalt (granite) Lime stone

ASTMC-131L.A.Abrasion,%loss 26.4 22.5 32.2

ASTMC-88 Soundness, %loss 6.3 5.24 7.83

C-127 Bulk Specific Gravity of Coarse Aggregate

2.598 2.841 2.587

C-128 Bulk Specific Gravity of Fine Aggregate

2.427 2.709 2.436

Specific Gravity of Mineral Filler 2.672 2.783 2.621 D-2419 Sand Equivalent 53 68 48

Plasticity Index NP NP NP

% Absorption of FA C-128 or

CA C-127

1.1 0.7 2.1

Properties of Aggregates

Anti-Stripping Agents

S.NoS.NoProduct NameProduct Name Physical Physical

StateState

Recommended Recommended Dosage (wt %)Dosage (wt %)

StabilityStability Chemical NameChemical Name Flash Flash PointPoint

11 ITERLENE ITERLENE IN/400-SIN/400-S

LiquidLiquid 0.2 - 0.40.2 - 0.4 Heat Heat Stable Stable (170(170oo C)C)

Alkylamido-Alkylamido-imidazoimidazo

PolyaminePolyamine

>180>180oo

CC

22 CECABASE CECABASE 260260

LiquidLiquid 0.2 - 0.40.2 - 0.4 Heat Heat StableStable

Alkylamido-Alkylamido-imidazoimidazo

PolyaminePolyamine

>100>100oo

CC

33 POLYRAM POLYRAM L200L200

LiquidLiquid 0.2 - 0.40.2 - 0.4 Heat Heat StableStable

N-Alkyl ‘tallow’ N-Alkyl ‘tallow’ dipropylene dipropylene triaminetriamine

>100>100oo

CC

Chromatography Column

Adsorption Equation

Ai = [VC (A1 – A2)]/50 A1

where,

Ai = initial adsorption, mg/gm

V = volume of solution in the column at the

time A2 is measured, ml = 00.0 ml

C = initial concentration of asphalt in solution,

gm/l = 1.2 g/l

A1 = first absorbance reading

A2 = second absorbance reading after 6.5 hours

Results & Discussion:

Initial and Net Adsorption Values for Riyadh

Asphalt with Cesabase-260Mass of Asphalt

(gm)Asphalt

Solution g/L

Initial Adsorption Ai (mg/g)

Net Adsorption An (mg/g)

%Differenc

e between Ai

and An

A1 A2 A3

Taif 0.12 0.63 0.606 0.62 1.2 0.036 0.015 58.75E.P. 0.124 0.71 0.68 0.695 1.24 0.052 0.026 50.51

Riyadh 0.123 0.72 0.69 0.71 1.23 0.052 0.017 67

AggregateAbsorbance

Results:

Mass of Asphalt

(gm)Asphalt

Solution g/L

Initial Adsorption Ai

(mg/g)

Net Adsorption An (mg/g)

%Difference between Ai and

An

A1 A2 A3

Taif 0.124 0.7 0.69 0.695 1.24 0.017 0.008 50.51E.P. 0.129 0.792 0.765 0.78 1.29 0.054 0.024 56

Riyadh 0.121 0.675 0.656 0.665 1.21 0.03 0.016 47.9

AggregateAbsorbance

(Cont’d)

Initial and Net Adsorption Values for Ras-Tanura Asphalt with

Cesabase-260

Results:

Mass of Asphalt

(gm)Asphalt

Solution g/L

Initial Adsorption Ai

(mg/g)

Net Adsorption An (mg/g)

%Difference between Ai and

An

A1 A2 A3

Taif 0.114 0.85 0.81 0.845 1.14 0.076 0.009 87.63E.P. 0.11 0.785 0.765 0.774 1.1 0.034 0.018 45.56

Riyadh 0.114 0.74 0.715 0.732 1.14 0.041 0.013 68.32

AggregateAbsorbance

(Cont’d)

Initial and Net Adsorption Values for Ras-Tanura Asphalt with

Iterlene 400-S

Results:

Typical Comparison on Riyadh asphalt-aggregate mix

(Cont’d)

0.0

10.0

20.0

30.0

40.0

50.0

60.0

70.0

% a

sph

alt

rem

ain

ed

adso

bed

Taif E.P. Riyadh

Aggregates

Figure 1: Effect of Antistipping agent in adsorption behavior of Riyadh asphalt-aggregate mixtures

Asphalt Riyadh

Cesabase-260

Iterlene IN/400-S

Polyram L200

Results:

Typical Comparison on Ras Tanura asphalt-aggregate mix

(Cont’d)

0.010.020.0

30.040.050.060.070.0

80.090.0

% a

sph

alt

rem

ain

ed

adso

rbed

Taif E.P. Riyadh

Aggregates

Figure 2: Effects of Antistripping agent on Ras Tanura asphalt-aggregate mixtures

Asphalt Ras Tanura

Cesabase-260

Iterlene IN/400-S

Polyram L200

Based on the results of this study Based on the results of this study following conclusions were drawn.following conclusions were drawn.

Type of Aggregates has significant Type of Aggregates has significant effect on absorption behavior.effect on absorption behavior.

Different aggregate showed different Different aggregate showed different adsorption for same asphalt.adsorption for same asphalt.

Moisture sensitivity for each asphalt-Moisture sensitivity for each asphalt-aggregate combinations depend on the aggregate combinations depend on the type of antistripping agent used. type of antistripping agent used.

No single antistripping agent could work No single antistripping agent could work with all three aggregate types studied. with all three aggregate types studied. Therefore, selection of proper Therefore, selection of proper antistripping agent will be unique for antistripping agent will be unique for each project.each project.

Among the three antistripping agents Among the three antistripping agents studiedstudied Cecabase was found to be more effective Cecabase was found to be more effective

with Riyadh asphalt mixtures. with Riyadh asphalt mixtures. Iterlene was found to be more effective with Iterlene was found to be more effective with

Ras Tanura asphalt mixtures Ras Tanura asphalt mixtures

(Cont’d)

More fundamental work is needed on More fundamental work is needed on the chemistry of asphalt-aggregate the chemistry of asphalt-aggregate interaction for a better understanding interaction for a better understanding of the chemical compositional factors of the chemical compositional factors that control asphalt properties..that control asphalt properties..