Rheological and Rotational Viscosity Behavior of ...

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Huachun Zhai, Joe Corona, Eric Milliron. Integrated Asphalt Solutions, LLC ... Controlled stress Bohlin CVO Dynamic Shear Rheometer (DSR) with cup-and-bob ...
Rheological and Rotational Viscosity Behavior of Road Asphalt Emulsions

Delmar Salomon Pavement Preservation Systems, LLC Boise, Idaho, USA Huachun Zhai, Joe Corona, Eric Milliron Integrated Asphalt Solutions, LLC Nampa, Idaho, USA

4th Pacific Rim Conference on Rheology August 77--11, 2005

Shanghai, China

Goals for asphalt emulsion work • New instrumentation tests for asphalt emulsions • Develop new viscosity standard for asphalt emulsions • Develop suitable rheological tests that simulate asphalt emulsion applications in the field

Can we simulate this?>>>>> Chip seal spraying application

Rheological Properties of Emulsified Asphalt • Emulsion properties, such as stability, workability, breaking and curing, are associated with the rheological properties of the emulsified asphalt. • Current specifications do not give a clear relationship between the emulsion rheological properties and their field applications. • Tests developed for asphalt testing, such as stress sweep, frequency sweep and creep and recovery have been used to obtain rheological properties of emulsified asphalt.

Asphalt emulsion = asphalt + water+ chemical + other additive • Asphalt emulsion types (eight types) Cationic slow setting: CSS-1 Cationic medium setting: CMS-2, CMS-2s Cationic rapid setting: CRS-2 Cationic rapid setting polymer modified: CRS-2P, CHRS-2P Anionic rapid setting emulsions: HFRS-2, HFRS-2P All emulsions typically had an average asphalt residue of 65%. • Equipment – Controlled stress Bohlin CVO Dynamic Shear Rheometer (DSR) with cup-and-bob geometry C25 (coaxial cup-and-bob with a 25mm diameter bob).

Viscometers for asphalt emulsions • Viscosity measurements: – ASTM Standard Method: Saybolt Furol Viscometer – Alternative Methods: – Rotational coaxial viscometer – Rotational Paddle Viscometer (Proposed at ASTM: Committee D04.42)

Rotational Paddle Viscometer

Thixotropic behavior of asphalt emulsions @ 50 C, 50 RPM

Apparent viscosity (mPa s)

700 600 500 Equilibrium viscosity

400 300 200 100 0 0

5

10

15 20 Time (minutes)

25

30

35

Saybolt Furol vs. Brookfield Rotational Viscometer @ 50 C, 50 RPM 700

Equilibrium Viscosity (mPa s)

600

R 2 = 0.80

500

400

300

200

100

0 50

100

150

200

250

Saybolt Viscosity (Saybolt Furol second)

300

350

Correlation between Saybolt Furol and Bohlin rotational viscometer @ 50 C and 50 RPM Equilibrium Viscosity (mPa s)

600

500

400

300

200

100

0 100

150

200

250

Saybolt Viscosity (Saybolt Furol second)

300

350

Equilibrium viscosity (m P a s)

Correlation between Saybolt and Paddle Viscometer @ 50 C, 100 RPM 1200 1000 800

2

R = 0.903 600 400 200 0 0

50

100

150

200

250

Saybolt Viscosity (Saybolt Furol second)

300

350

Rheological Test Protocols • • • •

Stress/Strain Sweep Test Temperature Sweep Test Time Sweep Test (3-step test) Simulate asphalt emulsion spray application)

Gel Point • The gel point is a “cross over” from liquid-like to solid-like behavior (G’=G’’) • The difference in gel points may be related to the relative rate of emulsion breaking. • A lower gel point means a shorter breaking time for the emulsion under same conditions.

Stress Sweep Test • Test the flow behavior for different emulsions. • At 30C with a shear stress range from 0.01 to 10 Pa and a frequency of 1 Hz. • The complex shear modulus G* versus stress/strain plot was used to determine the linear viscoelastic region.

Linear Viscoelastic Region for cationic emulsion (Stress Sweep) 100

Linear region: below 0.1 Pa

G* (Pa)

CRS-2P 10

CRS-2

1

CSS-1

0 0.01

0.10

1.00

Stress (Pa)

10.00

100.00

Linear Viscoelastic Region for cationic emulsion (strain sweep) 100.0

The lowest linear region: 1%

CRS-2P G * (Pa )

10.0

CSS-1

CRS-2

1.0

0.1 0.00

0.01

0.10

Strain

1.00

10.00

Temperature Sweep Test • Temperature Range from 25C to 85C. • Oscillation tests were performed at 1 Hz and 1% shear strain. • Determine the gel point: the temperature at which the storage modulus G’ equals to the loss modulus G” (G’= G” or tan δ = 1)

Temperature Sweep for CRS-2P 9.0

G'

8.0

G"

tan d

2.5

G’

2.0

6.0 1.5

5.0

G’’

4.0

1.0

3.0 2.0

0.5

1.0 Gel Point

0.0 15

35

55 Te mperature (C)

67 C 75

0.0 95

tan d

G', G" (Pa)

7.0

Temperature Sweep for CRS-2 5.0

4.5

G"

4

4.0

3.5

3.5

3

3.0 2.5 2.5 2

tand

2.0

1.5

1.5

G'

1.0

1 0.5

0.5 0.0

0 15

25

35

45

55

Temperature (C)

65

75

85

tan d

G*, G' and G" (Pa)

4.5

Temperature Sweep Test (G*) 1.00E+02 HFRS-2P CHFRS-2P

G * (P a )

1.00E+01 CRS-2P

1.00E+00 CSS-1

1.00E-01 20

30

40

50

60

Temperature (C)

70

80

90

Temperature Sweep Test (G*) 1.00E+02 HFRS-2 CMS-2

G * (P a )

1.00E+01 CRS-2

1.00E+00 CSS-1

1.00E-01 20

30

40

50

60

Temperature (C)

70

80

90

Temperature Sweep vs. phase angle, d 90 80

CSS-1

More viscous

CHFRS-2P CRS-2

70

CHFRS-2P CRS-2P HFRS-2 HFRS-2P CSS-1 CRS-2

60

d

50 40 CRS-2P

30 HFRS-2P

20 HFRS-2

10

More elastic

0 20

30

40

50

60

Temperature (C)

70

80

90

Gel point for different asphalt emulsion residues, CRS-2P 2 CRS-2P(2)

Lower asphalt content

1.5

tand

CRS-2P(1)

1

0.5

0 40

50

60

70

Temperature (C)

80

90

Time Sweep Test: 3-step protocol • Temperature at 30C with continuous shear • 3 steps – Step 1 (Storage in the tank): The sample was submitted to a shear rate of 0.1 s-1 for 180 seconds. – Step 2 (Spraying and pumping): The shear rate was then increased to 100 s-1 for 180 seconds. – Step 3 (Setting): The shear rate was decreased to 0.1 s-1. • The viscosity versus time plot

Flow Behavior: storage,spraying,setting storage Viscosity Ratio (% of initial viscosity)

140%

spraying

Step 1

setting

Step 2

Step 3

120%

CRS-2P

100% CRS-2

80% 60%

CMS-2

40%

CRS-2 CMS-2 CRS-2P

20% 0% 0

100

200

300

400

Time (s)

500

600

700

Conclusions 1. A new rotational viscosity method for asphalt emulsions (ASTM proposed: Committee D04.42) 2. Rheological measurements can be used to predict the field applications of emulsified asphalts. 3. Gel point determined by temperature sweep test can be used to study storage stability and breaking time of different emulsions. • Asphalt emulsion field application can be simulated using rheological tests.

Thank

you

for your

attention