Shell Sulphur Solutions Thiopave ® - Sulphur Enhancement for Asphalt Mixtures W. Allen Palmer, P.E. NC Region Marketing Manager Shell Sulphur Solutions Tulsa, OK DELIVERING INNOVATION TO YOUR ADVANTAGE Shell Sulphur Solutions http://www.shell.com/sulphur
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Shell Sulphur Solutions
Thiopave® - Sulphur Enhancement for Asphalt Mixtures
W. Allen Palmer, P.E.NC Region Marketing ManagerShell Sulphur SolutionsTulsa, OK
DELIVERING INNOVATION TO YOUR ADVANTAGEShell Sulphur Solutionshttp://www.shell.com/sulphur
Shell Sulphur Solutions
Overview
• Background on Sulphur
• Thiopave Product
• Production
• Mix Designs with Thiopave• Scott Quire – Frankfort Testing Laboratory
Shell Sulphur Solutions
Thiopave
“Thio” is the Greek word for Sulphur
Shell Sulphur Solutions
Uses For Sulphur
Source: Utilization of Sulfur Wastes from Sour Gas and Crude Oil Production, Krishnan and Freeman, Integrated Environmental Solutions
Shell Sulphur Solutions
Sulphur Extended Asphalt (SEA)
• Great deal of interest in 1970’s and 1980’s– Driven by oil embargo and supply shortage
– Sulphur offered means to extend bitumen supply
• Molten sulphur was used– Incorporated directly into hot bitumen
– High mixing temperatures
• Economics eventually flipped
Shell Sulphur Solutions
What Role Does Sulphur Play?
• Partially replaces (extends) bitumen– 20% - 25% of bitumen replaced with similar volume of
sulphur
– Actual amount varies based on particular mix/project
• Mixture modifier - not Bitumen modifier
Shell Sulphur Solutions
What Role Does Sulphur Play?
• Crystallizes in mixture when cooled
– Acts as solid mineral filler in mixture
– Increased pavement stiffness (modulus) at high temperatures• AMPT studies
– No adverse effect on low temp properties• TSRST studies
Shell Sulphur Solutions
Sulphur in Bitumen
Source: Performance Properties of Sulphur Extended Asphalt Mixtures with SEAM (Shell internal)
Shell Sulphur Solutions
Marshall Stability Comparison
Qatar Test Road Results
0
2000
4000
6000
8000
10000
12000
14000
16000
Conventional Mix SEAM Mix
Mar
shal
l Sta
bili
ty, N
1 Day 14 Days
Thiopave
1800 lbs
>10% higher initially, over 80% higher after 14 days
Shell Sulphur Solutions
What Is Thiopave
• Currently, a system of two components
• Solid pellets introduced into mixing drum
– Melts quickly to form part of the total binder
• Includes organic compaction agent (wax)
– Improves workability at lower mix temps
Shell Sulphur Solutions
Production-Feed System
Wax Feeder
Pneumatic Feed System
Shell Sulphur Solutions
Pneumatic System Basics
MaterialHopper
Air Flow To Plant
Pellets Loaded Here
Vane Feeder
Rotation speed varieswith plant
production rate
Shell Sulphur Solutions
Production
DOUBLE BARREL DRUM MIXER
COUNTERFLOW DRUM MIXER
DRUM MIXER WITH SEPARATE COATING MIXER
BATCH MIXING PLANT WITH RAP FEEDER
RAP BIN
BELT FEEDER
RAP BIN
*
**
*
*Thiopave add point
Shell Sulphur Solutions
Plant Introduction Point
ThiopavePellets
Wax
Shell Sulphur Solutions
Plant Introduction Point
Shell Sulphur Solutions
Plant Introduction Point
Shell Sulphur Solutions
Plant Introduction Point
Shell Sulphur Solutions
Order of Addition
• “Ideally”, materials should be mixed in this order– Hot Aggregate
– RAP
– Virgin Bitumen
– Wax
– Baghouse Dust
– Thiopave pellets
Shell Sulphur Solutions
Temperature Control
• Critical Temperatures– 240°F: Pellets melt
– 300°F: H2S generation likely
– 265°F: Ideal plant discharge
٭ By necessity, a warm mix application
• Compaction Agent– Allows for improved workability at reduced temperatures