Canadian User-Producer Group for Asphalt
CUPGA 2007, Sustainability Symposium
November 18, 2007
Reducing the size of the
“asphalt ecological footprint”
with SEAM™
(Sulphur Extended Asphalt Modifier)
Presented by:
Imants Deme
Shell Sulphur Solutions
™Shell Canada Energy
Contents
• Sulphur-Extended Asphalt history
• SEAM™ properties and use
• Health, safety and environment
• SEAM™ technology (40/60 SEAM/bitumen “semi-rigid” pavements)
- Bitumen reduction
- Road performance properties
- Road design
• The green page
• Examples of applications
2
SEAM™ history
3
Historical perspective
Liquid sulphur +
High shear mixer
No H2S scavenger
& no plasticizer
1970s & 80s
NOW
Pelletized sulphur
with dispersing agent,
H2S scavenger &
plasticizer: SulphurExtended Asphalt
Modifier = SEAM
4
SEAM™ properties and use
5
SEAM™ Properties
• Solid pellet at ambient
temperatures (<5 mm)
• Easy to add to asphalt hot-mix
• Melts quickly in hot-mix
• Can be stored on ground or in
silos
• Additive advantages:
- disperses sulphur in bitumen
- reduces odour & gas emissions
- plastification agent
6
Health, safety, environment
7
SEAM Mix Fume Emissions
(Six Hour Average)
2
1
ASPHALT HOT-MIX PLANT:
ASPHALT PAVER:
H2S
S02
H2S & SO2 = 0 AT MIXER AND TRUCK
LOADING AREA (SHOWN BY ARROW)
ABOVE SCREED (1):
0.9 PPM
0 PPM
OPERATOR PANEL (2):
0.1 PPM
0.3 PPM
AVERAGE LIMIT (2002 TLV): 10 PPM
2 PPM
INDUSTRIAL HYGIENIST CONCLUSION:
“…NO BREACH OF COMPLIANCE FOR EMPLOYEE EXPOSURE”
8
Stack emissions not increased
Emissions –
kg/h
Gencor Plant, 300 tph capacity
ASPHALT
MIX
SEAM
MIX
PARTICULATE
MATTER
1.59
(1.25 –
1.97)
1.71
(1.43 –
2.25)
SULFUR
DIOXIDE
0.193
0.017 –
0.534
0.252
0.050 –
0.394
HYDROGEN
SULFIDE
<0.015
0.012 –
0.018
<0.014
0.014 0.015
TOTAL HYDROCARBONS
(expressed CH4)
9.466
8.92210.401
8.240
7.264-9.218
Conclusion: No significant difference in SO2 & H2S emissions and lower
hydrocarbon emissions for SEAM mix
9
VOC reduced by 50%
Date and conditions
Sample
No.
Code
Total
VOC
ppbv
Aug 15: Downwind,
5-m; Asphalt mix
produced @ 152 C
TO21557
DWNo S
214
Aug 15: Upwind, 5m; Asphalt mix
produced @ 152 C
TO21558
UWNo S
257
Aug 16: Breathing
zone; mix with SEAM
Produced @ 140 C
TO21559
BZ-S
98
Aug 16; Downwind,
5m, 450; SEAM mix
produced @ 140 C
TO21560
DWS
99
SUMA vacuum canisters
used in study
10
SEAM™ technology
• Bitumen reduction
• Strength properties
• Road design
11
12
SEAM /
BITUMEN:
25/75 to 30/70
Binder mod.
40/60
Mix Modifier
50/50
Mix Modifier
Bitumen saving,
%
16 - 20
30
40
Mix Type:
FLEXIBLE
SEMI-RIGID
RIGID
Resilient modulus
Similar to asphalt
mix, mix is
“flexible”
High mix
modulus &
strength; low SST
plastic strain
Very high
modulus and very
low SST plastic
strain
Rut resistance
25/75: Same as for
asphalt mix;
30/70: more rut
resistant
50% less rutting
Very rut resistant
Hot mix handling
Similar to normal
asphalt mix
Slightly shorter
time for mix
compaction when
surface cools
rapidly
Significantly less
time available for
compaction
Special
equipment
requirements
(besides SEAM
feeder)
Use in road
structures
None
None
Mass transfer
vehicle for
remixing at paver
(for uniform
temp.)
Suitable for all
road designs
Thick & strong road
structures, deflection
< 1.2mm*
Very thick road base
structures, deflection
< 0.5mm*
SEAM* “PG Performance” based on Marshall
SEAM addition to asphalt mix increases Marshall Stability and has
the same effect as using modified bitumens which are from 1.8 to
3.6 PG grades higher
16000
P G 5 8 -2 8 + S E A M
15000
P G 5 2 -2 8 + S E A M
P G 6 4 -2 2 + S E A M
M a rs h a ll S ta b ility , N
14000
PG70-22 +
SEAM
P G 4 6 -3 4 + S E A M
13000
12000
PMA

PMA
11000
10000
9000
8000
7000
6000
5000
46
52
58
64
70
76
P G H ig h T e m p e ra tu re V a lu e o f A s p h a lt C e m e n t a n d P M A , C
* In “semi-rigid” mix (40SEAM/60Bitumen)
82
Marshall Stability: 2-3 PG grade increase
Marshall Stability, N
HL4 Asphalt Mix
HL4 SEAM Mix
HL4 PMB Mix
18000
16000
14000
12000
10000
8000
6000
4000
2000
0
PG46-34 PG52-34 PG58-28 PG64-22 PG70-22 PG64-34 PG70-34
300/400
200/30
150/200
80/100
59 Pen
PMB
PMB
A P A R u t D ep th C o m p aris o n –
APA Wheel
Rutting (After 8000 wheel passes)
H L 4 & H L 1 A s p h alt & S E A M M ix es
ASPHALT
S E AM
19 m m F in e-G rad ed A g g reg ate M ix es (HL 4, P G 58-28)
ASPHALT
S E AM
16 m m C o ars e-G rad ed (S u p erp av e) A g g reg ate M ix es (HL 1, P G 58-28)
20
SEAM modulus is less
temperature sensitive
7000
Asphalt 1Hz
Resilient Modulus, MPa
6000
SEAM 1Hz
5000
4000
3000
2000
1000
0
-10
0
10
15
Temperature, C
20
30
Thick SEAM pavements may prolong road life
Road Life, msa
msa = millions
standard axles
70
60
50
40
30
20
10
0
Asphalt
SEAM
57.9
0.8 1.3
100mm
+300mm gran. base
sub-base
1.2
4.9
200mm
sub-base
11.5
300mm
Asphalt or SEAM
Pavement thickness
sub-base
Predicted road life increases with pavement thickness & SEAM may provide
exceptionally longer road lives when used in thick pavements
17
Restrained Specimen (TSRST) Cooling Test
MIX: PG52-34 + SEAM
COOLING RATE: -10 C/h
18
Addition of SEAM to asphalt mix
does not change pavement
resistance to cracking at low temperatures
A s phalt M ix
-45
S E A M M ix
B itum en
C rackin g T em p eratu re, C
-40
-35
-30
-25
-20
-15
-10
-5
0
PG46-34
PG52-34
PG58-28
PG64-22
PG58-28
300/400
200/300
150/200
80/100
80/100
NB: Mix cracking temperature within 2.4 °C of bitumen PG low temperature value
19
Uses for which SEAM is
particularly suited
• Heavy duty use: heavy duty pavements, high traffic intersections, bus
lanes, truck climbing lanes, truck terminals, airfields, container
terminals
• Upgrades quality of mixes made with poor aggregates:
- Rut resistant mixes from fine-graded (sandy, marginal) aggregates
- Aggregate conservation: reduces amount of stone required to be
crushed to make angular fines (important in aggregate-scarce areas)
- Safeguard against premature rutting for pavement sections which
were under-compacted during construction
• The combination of high rut resistance, constant stress fatigue
resistance (road life) & higher modulus (load spreading), makes SEAM
mixes particularly suitable for thick long life “perpetual” pavement
designs
• Prevents pavement cracking in cold climate areas without
compromising resistance to rutting of pavements
• Improves performance of mixes made with poor quality (e.g. waxy)
bitumens (i.e.resistance to rutting and cracking)
20
The Green Page –
Advantages from SEAM use
• Energy Cost Saving (approx. 5 % direct; 11% indirect)
- Less bitumen to heat
- Lower mix temperature (ie. 1/3 way to “warm” mix)
- Lower plant fuel consumption
- Significantly lower fuel consumption relative to PMA
• Conservation of Hydrocarbon Resources
- Conserves fuel & bitumen
• Conservation of Aggregate Resources
- Permits use of fine-graded (marginal, sandy) aggregates
- Stability of sand-asphalt mixes increased significantly
• Environment
- Reduces VOCs (volatile organic constituents)
- Use in roads provides sulphur producers with a sustainable
application for unmarketable sulphur
- Provides a carbon credit (bitumen reduction/lower energy, etc.)
21
Summary of SEAM-specific issues
• Feeder required for adding SEAM pellets
accurately
• Strict temperature control is required during
SEAM mix processing
• SEAM mixes emit more odor, fumes, and eye
irritant than conventional asphalt mix during mix
placement
(NB: SEAM use complies with regulatory
exposure requirements)
• More difficult to recycle hot
22
High stress intersection
Storage terminal parking lot
Vancouver, Canada
Las Vegas, USA
SEAM w earing & base
course
Port of Oakland, California
300mm SEAM pavement
Yunnan, China Tollway SEAM
base course with SMA top
course
Nantong Port, China storage
terminal
Kazakhstan SEAM
pavement
Saudi Arabia SEAM
test road
Reducing the size of the
asphalt ecological footprint
29
Calgary, Canada –
SEAM wearing course