upgrading the value of bitumen by using performance...
TRANSCRIPT
Upgrading the Value of Bitumen by Using
Performance Grading
Hussain U. Bahia Director of MARC, University of Wisconsin- Madison, USA May 2nd , 2016, Dubai, UAE
Bitumen and Pavement Life Cycle Cost (LCC)
• Pavement LCC depends on bitumen quality Better quality = reduce life cycle cost, and = less
environmental impact.. Sustainable roads
• Bitumen plays a big role in pavement life Bitumen value should be proportional to its role; Better
bitumen should be worth more
• Performance Grading system can define value The Pen 60/70 and VG grading systems could give inaccurate
definition of factual quality
• Modification allow upgrading bitumen value
Deterioration of Asphalt Pavements Life Cycle Cost concepts
Ro
ad
Co
nd
itio
n
Pavement Age or Traffic
Min. Acceptable Rating
Resurfacing
Corrective Maint.
Reconstruction
Restoration
Preventive Maint.
New
Road
Bitumen also affect Environmental Impact Embodied Carbon in Asphalt Most critical: Drying and Bitumen
Component CO2 eq/ Ton of Asphalt
Aggregate 4
Heating & Drying 21 (42%)
Bitumen 18 (36%)
Mixing 4
Delivery 3
Total 50
Source: Loveday 2009
82%
Modified Bitumen = More durability = (Less cost , less CO2+Less Energy ) per year
Less Durable: Initial cost/
emissions spread on shorter life
More Durable: initial cost/CO2
emissions spread on longer life.
Time
Condition
life Cycle More important than Initial
http://www.eurobitume.eu/bitumen/production-process
Bitumen cost is always a function of crude oil; but there is
no clear system/scale to upgrade value & increase profit
The Performance Grading System allows defining Quality in terms of Pavement Condition Indictors (PCIs)
Thermal
Cracking
Fatigue
Cracking
Permanent
Deformation
(mixing &
compaction)
Performance Grade : PG 76-10
- 10 37 76 135
1. Workability:
Production/cons
truction
4. Thermal Cracking 3. Fatigue
Cracking
2. Rutting
The New Grading System- AASHTO M332 1. Climate: xx-yy 2. Traffic conditions- Trucks (S,H,V,E) 3. Reliability , and 4. Modification
PG 76(V)-10 Performance
Grade Summer
Average 7-day
max pavement
design temp
Winter
Min pavement
design temp
Traffic
Volume &
Speed
Better Value/Price
Scale
Example of PG Grading- Qatar-QCS
Item Property Test
Method
Criteria
PG76S-10
PG76H-10
PG76V -10
PG76E -10
1 Traffic Volume: 20–Year Design ESALs, millions
< 10 10 – 30 30-50 ≥ 50
2 If Traffic Speed is less than 20 km/hr (Standing/Intersections)
Use grade PG76H-10
Use grade PG76V-10
Use grade PG76E-10
Use grade PG76E-10
3 Flash Point, min, C ASTM D92
230 230 230 230
4 Viscosity @ 135C, max, Pa.s ASTM D4402
3.00 3.00 3.00 3.00
5 Dynamic Shear, G*/sinδ @
76C and 10 rad/s, min, kPa ASTM D7175
1.00 1.00 1.00 1.00
6
Separation Test: Absolute
Difference between G* @ 76C and 10 rad/s of Top and Bottom Specimens, max, %
ASTM D7173
20 20 20 20
7
Time Stability: Average of G*
values measured in Separation test (item 6) divided by the initial G* value measured in (item 5), range
0.8 - 1.2 0.8 - 1.2 0.8 - 1.2 0.8 - 1.2
8 Particulate Retained on Sieve Test, %
PWA 100 0 0 0 0
9 Solubility, min, % ASTM D5546
99 99 99 99
10 Polymer Content, min, % by mass
Supplier Certificat
e Required
2.0 2.0 3.0 3.0
Rolling Thin Film Oven (RTFO) Residue
11 Mass Change, max, % ASTM D2872
1.00 1.00 1.00 1.00
12 Dynamic Shear, G*/sinδ, @
76C and 10 rad/s, min, kPa ASTM D7175
2.20 2.20 2.20 2.20
13 MSCR, Jnr3.2 @ 76C, max, kPa-1
ASTM D7405
4.50 2.00 1.00 0.50
14 MSCR, Recovery R3.2 @ 76C and 3.2 kPa, %
Not applicable
Not applicable
Not applicable
Not applicable
MSCR, Jnr-diff @ 76C, % Not
applicable Not
applicable Not
applicable Not
applicable
Better Quality , Better Return
on Investment = Higher Price
Technical
Quality
Criteria
Can better bitumens fetch higher price? Yes… example from the region
Product
Quality
Price per M. Ton
(QAR)
Percent Price
Increase
Pen 60/70 1,470 0.0
PMB (PG 76-22) 1,992 36%
PMB (PG82-22) 2,105 43%
PMB – Special Grade 2,223 51%
Cost – Benefit Analysis of PMBs
Users:
Very high return on
Investment
Producer:
Specialty product=
Better profit margin
Economics of Modified asphalts
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NPV = Net Present Value
The Production of Pen 60/70 Bitumen products not well defined
The final bitumen product can be produced to technical
specification either:
1. Directly in the refining process or by blending
bitumens with different physical properties.
2. Blending of higher and lower viscosity residues in
the required proportions.
3. The blending may take place at the refinery, at
terminals or at a third party facility.
Finished products can have very variable quality !!
Risks to Quality .. and Real value Uncertainty drives price & profit down
• Blending from different sources could be a problem.
Not all chemistries are similar.
• Oxidation changes chemistry, molecular weight, and
could upset balance of bitumen.
• De-asphalted bitumen is not really a paving grade
material.
• It is very hard to tell when Pitch is used in bitumen
production
• Soft bitumen-Vacuum Tower Bottoms (VBTs) are
abundant.
Examples of low cost VTB based feed stock in the GCC region
Property Source 1 Source 2 Source 3
Pen at 25 C, dmm 119 169 60
R&B Softening Pt, °C 43 34 51
Ductility, cm 84 >125 >125
Flash point , C 321 328 346
R. Vis at 135C 212 100 388
The fair solution: Better Bitumen Grading System- PG 1. Climate 2. Traffic conditions- Trucks 3. Reliability , and 4. Cost/Modification
PG 76 (X)-10 Performance
Grade Summer
Average 7-day
max pavement
design temp
Winter
Min pavement
design temp
Traffic
Volume &
Speed
The fair solution: Benefits of Bitumen Modifiers- Asphalt Institute
1) Build more roads Pave more miles by reducing road
thickness, while maintaining road performance
OR
2) Build better roads Extend the maintenance cycle by 5 yrs
thereby reducing maintenance costs
Infrastructure dollars are extremely limited,
while demands to build & improve roads continues to grow
Stretch paving dollars with Modified Binders
Type of
Highway
Approximate
Speed MPH
Not
Modified
7.5%
SBS
2.5 %
HON
% Increase in Service Pavement Life
Expressway 60- 80 0% 64% 107%
Intersections ~ 5 0% 173% 218%
% Reduction in Asphalt Layer Thickness
Expressway 60- 80 0% 9% 14%
Intersections ~ 5 0% 20% 22%
Benefits Quantified Using the Current AASHTO 1993 Design
4 in.
6 in.
6 in.
Top Layer
Middle Layer
2.2 in.
6 in.
6 in. Base Layer
Savings 1.8 in.
Significant savings in cost & natural resources
by reducing pavement top layer Thickness
Polymer Additive
Aggregate Base
Subsoil
Average Road
Top Layer
Middle Layer
Base Layer
Aggregate Base
Subsoil
45%
Reduction
With
Specific
PMBs
Build better roads and improve bitumen profit margin
• Reduce total road life costs by 35%
Extend the maintenance cycle by 5 yrs using specialty additives…
Today (4 in)
With Titan
Additive (4 in)
Desired Road Life 50 years 50 years
Initial road cost/mile $117K $126K
Maintenance cycle* (maintain <0.25 in rutting)
Every 7 yrs Every 12 yrs
Maintenance cycle cost/mile** $70K $75K
Total # of maintenance cycles 6 cycles 3 cycles
Total Road Life Cost $537K $351K
Environmental Impact – Effect of Polymers on compaction effort of mixtures at 145 oC
Sample N92- 8 % air-voids
N96 – 4% air-voids
% Change in compaction effort
Control 36 111 0 Polymer 1: SBS* 32 100 -10 Polymer 2: Titan 26 86 -23
Hybrid 24 76 -41
• Titan and Hybrid can reduce compaction effort ( up to 40%)
• Or allow wider temperature range for compaction
Concluding Remarks- Upgrading Bitumen Value and Profit Margin
• It could be a Win-Win for User and Producer
• Pen grading is a threat not only to pavement life, but also fair
value and profit margin
– Oxidation, rectification, de-asphalting and cracking are common
refinery practices that present risk to quality
• Measures to check and prevent poor quality bitumen should
be used. Performance grading (PG) is a ready solution
• Modification can reduce life cycle cost and Environmental
impact is a significant cost
Thank You
•Organizers of the conference
•Sponsors /partners of MARC
Hussain U. Bahia, Ph.D. [email protected]
UWMARC.org
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