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 30C 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 25C to 85C. • 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 30C 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