tellenbosch
Cold Recycling & Bitumen
Stabilised Materials BSMs
Research and
Implementation?
tellenbosch
Kim Jenkins
57th Annual Illinois Bituminous
Paving Conference
12th December 2016
Outline
1. What is BSM?
2. Mix Design
3. Structural Design
4. Application
5. Where to now?
BSM Binder Options
FOAMED BITUMEN
Mill
Acid or
Caustic Soda
Surfactants
Wat BitumenWater
5 microns
Water
Hot
bitumen
Air
Expansion chamber
BITUMEN EMULSION
Colloidal Mill
Flexibility
R
ig
id
it
y
320 1
3
4 5
4
2
1
0
C
e
m
e
n
t
%
Bitumen %
6
Cement
stabilised
Bound
Granular
Unbound
Non-
continuously
Bound
BSM
Asphalt
Bound
Orientation on BSM
Influence of Active Filler
Strength versus Flexibility
0
100
200
300
400
500
600
700
800
0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2 1.3
Cement : Foamed Bitumen Ratio
S
tr
a
in
-a
t-
b
re
a
k
0
500
1000
1500
2000
2500
3000
3500
4000
U
n
c
o
n
fi
n
e
d
C
o
m
p
re
s
s
iv
e
S
tr
e
n
g
th
(
k
P
a
)
Foamed bitumen, Strain
Cement, Strain*
Foamed bitumen, UCS
Cement, UCS*
* Cement treated with 2 percent cement and no foamed bitumen. Values plotted
at an arbitrary ratio of 1.25 for 2 percent cement and 1.2 for 1 percent cement.
CSIR
BSM
eb
BSM foam
Cement < 1%
BSM Triaxial Tests Shear properties
(monotonic tests at 25°C)
Cohesion C
0
100
200
300
400
500
A
-7
5
C
-0
B
-7
5
C
-0
C
-7
5
C
-0
A
-7
5
C
-1
B
-7
5
C
-1
C
-7
5
C
-1
A
-7
5
M
-0
B
-7
5
M
-0
C
-7
5
M
-0
C
o
h
e
s
io
n
[
k
P
a
]
E E E E E E FFF
20
25
30
35
40
45
50
A
-7
5
C
-0
B
-7
5
C
-0
C
-7
5
C
-0
A
-7
5
C
-1
B
-7
5
C
-1
C
-7
5
C
-1
A
-7
5
M
-0
B
-7
5
M
-0
C
-7
5
M
-0
F
ri
c
ti
o
n
a
n
g
le
[
d
e
g
re
e
s
]
Friction Angle f
E E E E E E FFF
Jenkins, 1999 & Ebels, 2006
25% RAP 25% RAP75% RAP 75% RAP
Resilient Modulus of BSM
Stress dependency: Foamed BC = 2%
150
350
550
750
950
1150
1350
0.0 200.0 400.0 600.0 800.0 1000.0
Sum of Principal Stresses q (kPa)
R
e
s
il
ie
n
t
M
o
d
u
lu
s
M
r
(M
P
a
)
12kPa
24kPa
48kPa
72kPa
s3
HMA > 2500 MPa
GCS
BSM
Research: Visco-elasto-plastic &
flexural properties on BSM-foam
Tref = 20C
HMA/WMA
HW
Fatigue cracks
Rutting
HOT T or
Slow Traffic
Equiv
COLD T or
Fast Traffic
Equiv
BSM
BSM
BSM test methods
Years
20101990 2000
Reality
Index
Compaction
Testing
Z
e
r
o
L
i
n
e
S
l
e
e
v
e
B
a
s
e
P
l
a
t
e
S
t
e
e
l
R
o
d
S
id
e
o
f
M
o
ul
d
V
i
b
r
a
t
o
r
y
H
a
m
m
e
r
W
o
o
d
e
n
b
a
s
e
C,f Mix design to
Performance
Design BSM layers
h1
h2
h3
>200
project mix
designs!
Mix Design Flowchart
Sampling
Sample
preparation
Preliminary
tests
SUITABLE?
Blend
Effect of active
filler
Optimum
bitumen
addition
Determine
shear
properties
Yes
No
ITS
TRIAXIAL
Specification
C (kPa) f (0)
>250 >40
PUGMILL
MIXER
FOAMED BITUMEN UNIT
Standardised Mixing Method
Lab Compaction: Vibratory Hammer
Vibratory
hammer
Power
rating (W)
Frequency
(Hz)
Mass
(Kg)
Point
Energy (J)
Kango 637® 750 45.83 7.5 27
Bosch GSH 11E® 1500 15 - 31.5 10.1 16.8
Bosch GSH 11VC® 1700 15 - 30 11.4 23
For PI >8%, cannot achieve 100% Mod. AASHTO density
Influence of Frame
2050
2100
2150
2200
2250
2300
2350
2400
G2 G4
D
e
n
s
it
y
(
k
g
/m
3
)
Material Type
80% OMC, RFR,
10kg Surcharge
80% OMC, LFR,
10kg Surcharge
80% OMC, RFR,
20kg Surcharge
80% OMC,LFR,
20kg Surcharge
Refusal Density
Comparison of refusal density for G2 and G4 material
FRAME
TYPE
Rigid
Loose
Rigid
Loose
(Stell Univ)
Inter-Layer Roughening (ILR) Device
6 layers
X 50mm
2 layersITS
Triaxial
Inventor: Wynand van Niekerk
CT Scans
BSM-emulsion
S1A
-5
5
15
25
35
45
55
65
75
85
0 20 40 60 80 100
Volume in %
S
c
a
n
s
li
c
e
n
u
m
m
e
r
(b
o
o
rk
e
rn
l
e
n
g
te
i
n
m
m
).
voids
Mortar
stone
Poor
attention to
interlayer
preps
tellenbosch
N7 PSPA Mr Analysis over 7 Months
0
500
1000
1500
2000
2500
3000
3500
4000
0 50 100 150 200 250
Time (days)
M
r
(M
P
a
)
B1-B3 B4-B6 Poly. (B4-B6)
PSPA
Moisture
Mr
Why is curing important?
Mr (field) versus cure
% OMC
100
40
60
80
MC
New Triaxial
Confining Pressure s3
(inflate tube)
Apply Load (stress s1)
Test at
25ºC
tellenbosch
Validation
Research Triaxial Test RTT versus
Simple Triaxial Test STT
0
200
400
600
800
1000
1200
1400
0.0 1.0 2.0 3.0 4.0 5.0
Strain [%]
A
p
p
li
e
d
S
tr
e
s
s
[
k
P
a
]
RTT
STT
0
200
400
600
800
1000
1200
0.0 1.0 2.0 3.0 4.0
Strain [%]
A
p
p
li
e
d
S
tr
e
s
s
[
k
P
a
]
RTT
STT
BSM Crushed Hornfels with 3.3% Emulsion
s3 =50 kPa and 1% Cement s3 = 200 kPa and 0% Cem
APPLY CONFINING PRESSURE (AIR)
APPLY LOAD (3mm/min)
σ1
σ3
t
s
Shear
stress
Normal
stress
(kPa)
Cohesion
f Friction
angle
UNBOUND
BSM
σ1
σ3
σ1
σ3
0 50 100 200
Determine shear properties (C and φ)
Durability of BSM
t
s
Shear
stress
Normal
stress
CBSM
Cohesion
f Friction
angle
Retained Cohesion CR = CR*100/CBSM
Effect of
Moisture
Cohesion Loss = 25% max
Structural Design
Considerations
250mm CIPR:
2.5% Foam 1% Cem
90mm Asphalt
Lab Triaxial
Analysis
Permanent deformation
(rutting) design for granular
material
BSM Design for Max Rut Depth
(same principle as Granular Design)
Design Life for 10mm rut
Design Function for BSM
𝑁 = 𝑓 (𝑅𝐷, 𝑅𝑒𝑡𝐶, 𝑃𝑆, 𝑆𝑅)
Relative Density Plastic Strain (a/b)
Retained Cohesion Stress Ratio
a
b
Mr change with trafficking (triaxial)
0.0
200.0
400.0
600.0
800.0
1000.0
1200.0
1400.0
1600.0
1800.0
2000.0
100 1,000 10,000 100,000 1,000,000
R
e
s
il
ie
n
t
M
o
d
u
li
(
M
P
a
)
.
Load repetitions
SR
