Development of Emergency Pothole Repair Material Using Polyurethane for Asphalt Pavement

Presenter : Yeongmin Kim, Senior Researcher

Research Background

Traffic Increase Heavy Rain Material Change

Development of Pothole Resistance

Material and Repair Technology

MaintenanceMaterials Construction

Long-life PavementReduction in Traffic Accident, Maintenance Cost, Premature Failure

Pothole IncreaseTraffic

AccidentPavement

Failure

Causes of Pothole Occurrence

1. Existence of cavity in pavement

2. Poor drainage (pore water pressure)

3. Aggregate coated by excessive dust

4. Fragile aggregate

5. Overlay on weaken concrete pavement

Occurrence Causes

1. Drainage problem

2. Cracking

3. Poor construction of longitudinal joint

4. Bonding deficiency

5. Bad tack coat

1. Water, temperature(freeze and thaw), bad tack coat

2. Water, saturation degree, traffic

3. Dust and clay content

4. Aggregate durability

5. Water, water pressure

Influencing Factors

1. Water, saturation degree, water pressure,

air voids

2. Water, saturation degree, air voids

3. Air voids, density

4. Water, density

Literature

Review

Field

Survey

Pothole Cause #1

Cavity in Pavement

Stage 1 Stage 2

Stage 3 Stage 4

Video of Pothole Occurrence

Pothole Cause #2

Poor Drainage

• Pothole occurs with the excessive water in pavement due to poor drainage

Pothole Cause #3

Fatigue Cracking

• Fatigue cracking due to the repetition of overloaded trucks

Pothole Cause #4

Poor Construction of Longitudinal Joint

• Insufficient compaction on the longitudinal joint between existing and new lanes

Pothole Cause #5

Bonding Deficiency

• A loss of bonding between repair material and existing pavement

- 25

- 20

- 15

- 10

- 5

0

0 5000 10000 15000 20000

Number of Wheel Passes

Imp

ressio

n,

mm

권

Post Compaction

Consolidation

Inverse Stripping

Slope

Inverse Creep

Slope

Stripping Point

Test Method for Pothole Evaluation 1

Hamburg Wheel-Tracking Test Result MVT (Material Verification Tester)

Test Method for Pothole Evaluation 2

Analysis Method of MVT Result

0

0.5

1

1.5

2

2.5

3

0 1000 2000 3000 4000 5000 6000 7000 8000

Inflection Point

Rutting

Slope

Stripping

Slope

Test Condition

• Water Bath Temp : 50℃• Hose Pressure : 100psi

• Axial Force : 100lb

Analysis Method

• Fixed Cycle(8000 cycles)

• Total Deformation(TD)

• Stripping Deformation(SD)

• SD/TD ratio

Test Results for Pothole Evaluation 1

Air Voids 2%

0

1

2

3

4

5

6

7

0 2000 4000 6000 8000

왕복 횟수( No )

De

form

ati

on

(mm

)

1cycle

2cycle

3cycle

0

1

2

3

4

5

6

7

0 2000 4000 6000 8000

왕복 횟수( No )

De

form

ati

on

(mm

)

1cycle

2cycle

3cycle

Air Voids 8%

0

1

2

3

4

5

6

7

0 2000 4000 6000 8000

왕복 횟수( No )

De

form

ati

on

(mm

)

1cycle

2cycle

3cycle

Air Voids 4%

Test Results for Pothole Evaluation 2

Air Void Frozen-Thaw TD(mm) SD(mm) SD/TD(%)

2%

1 cycle 0.273 - -

2 cycle 2.008 0.580 28.9

3 cycle 2.622 0.877 33.4

4%

1 cycle 1.953 0.682 34.9

2 cycle 3.013 1.027 34.1

3 cycle 5.400 1.898 35.1

8%

1 cycle 4.508 2.501 55.4

2 cycle 5.590 3.046 54.5

3 cycle 6.658 3.981 59.8

• TD : Total Deformation(Rutting + Stripping)

• SD : Stripping Deformation

Summary of Laboratory Test Results

• TD, SD, and SD/TD increase when the air voids are higher resulting in

more water absorption.

• Water in air voids causes large deformation by reducing binder adhesion

and bonding between binder and aggregate.

• As a number of cycle of frozen-thaw increases, TD value increases but

SD and SD/TD values are not changed significantly.

• Stripping Deformation value is not affected by a number of cycle of

frozen-thaw.

• The primary factor of pothole occurrence is the air voids.

Higher air voids increases the possibility of pothole occurrence.

A number of cycle of frozen-thaw is not main factor for stripping deformation.

Development of Waterscape Emergency Repair Material

Problems of existing repair materials

1. Poor workability

2. Poor adhesion with existing pavement

3. Long curing time

4. Bad compaction due to strong elastic restoring force

Need to improve the water resistance

Need to consider workability and short curing time

Polyurethane binder is selected, instead of cutback asphalt

binder which is normally used for emergency repair material.

Component of Waterscape Emergency Repair Material

Polyurethane (PU)

A polymer containing a large quantity of urethane links

Urea Reaction 2 R-N=C=O + H-O-H R-NHCONH-R + CO2

MDI Water Urea Gas

1. Waterscape material (excellent water resistance)

2. Shorter curing time and adjustable curing time by

catalyst (possible in production stage)

3. Outstanding adhesion and chemical resistance

4. Oil is added to improve the workability

Flowchart of Development

Flowchart 1 Flowchart 2

Determined

gradation

0

10

20

30

40

50

60

70

80

90

100

0 0.075 0.15 0.33 1.18 2.36 4.75 9.5

Pe

rcen

t p

as

sin

g in

we

igh

t(%

)

s ieve size(mm)

CASE1 CASE2

0

100

200

300

400

500

600

700

800

부착

강도

(kg

f)

A B C CASE1 CASE2

보수재 종류

Evaluation of Material Properties

0.000

0.500

1.000

1.500

2.000

2.500

3.000

3.500

1일 2일 4일 8일 16일 32일

양생 시간(day)

인장

강도

(㎏/㎠

)

A

BC

CASE1CASE2

CASE1m(수침 후)CASE2m(수침 후)

CAS

E 1

CAS

E 2

1. Securing the stability to water, strong adhesion force, and increased strength

2. Development of cold-mix repairing asphalt for color asphalt pavement

3. Applicability to the area with residual water, and reduction of premature failure after repairing

Tensile StrengthMaterial Properties

Bond Strength

Bo

nd

ing s

tren

gth

(kgf)

Ten

sile

str

ength

(kgf/

cm2)

Curing time(day)

1day 2day 4day 8day 16day 32day

Type of repairing material

Comparison against the Existing Material (Video)

Application to Field (Video)

News Reports( MBC News on Mar. 26. 2010)

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