Sulphur’s Place in CE - Foundationfoundationperformance.org/pastpresentations/FittsPresSlides-18Feb... · aramidfibers, construction materials, sugar manufacture, ... replacement

Technology - Delivery - Partnership Shell Sulphur Solutions

Sulphur’s Place in CEFoundation Performance Association, Houston

Gary L. Fitts, P.E.SE Regional ManagerShell Sulphur SolutionsGarden Ridge, TX

Technology - Delivery - Partnership

DELIVERING INNOVATION TO YOUR ADVANTAGE

Shell Sulphur Solutionshttp://www.shell.com/sulphur


Presentation Topics

• Why sulphur?

• New approaches to using sulphur

– Thiocrete®

– Thiopave®


Sulphur (Sulfur)

• Non-metallic element, S, atomic number 16

• Though naturally occurring, most elemental sulphur produced today is from natural gas and petroleum processing

• USA, Canada, former Soviet Union, West Asia are primary producers

– Canada, Russia, Saudi Arabia chief exporters

• USA, China are largest consumers

• Worldwide sulphur production expected to increase dramatically in the next 10 years


Sulphur uses (from TSI)

The major derivative of sulphur is sulphuric acid (H2SO

4), the highest

production volume chemical, used as an industrial raw material. The

largest single use of sulphuric acid is for the manufacture of phosphoric

acid, a precursor to phosphate fertilizers and non-fertilizer phosphates.

Sulphur and its derivatives are also used in metallurgical ore leaching,

caprolactam, pigments, hydrofluoric acid, pulp and paper chemicals,

sulphur fertilizers, petroleum refining, batteries, detergents, fungicides,

carbon disulphide, pharmaceuticals, personal care products, cosmetics,

leather tanning, rubber vulcanization, plasticizers, dyestuffs, explosives,

aramid fibers, construction materials, sugar manufacture, dehydrating

agent in organic chemical and petrochemical processes, water

treatment, and steel pickling.


Sulphur as a construction

material

• Sulphur concrete (Shell Thiocrete®)

– Patented technology for using sulphur as a

replacement binder for Portland cement for

many pre-cast concrete applications

• Sulphur-enhanced asphalt (Shell

Thiopave®)

– Improved sulphur-extended asphalt

technology


Shell Thiocrete-Benefits

• High strength

• Rapid curing

• Resistance to water and acid

• Tolerant of wide range of aggregate properties

– Can use lesser-quality aggregates than possible with conventional PCC

• Enabling a wide range of colors, textures and finishes

• Easy to recycle

• Requires no water

• Significantly lower carbon footprint than Portland cement


Shell Thiocrete-Potential

Applications

• Sea walls, riprap, jetty blocks

• Pavers, pre-cast curbs

• Road barriers and bollards

• Retaining walls

• Garden products


Shell Thiocrete-How it’s used

• Product to be supplied in liquid or pellet form

• Mixed with aggregate @ 275F (135C)

– HMA plant

• Poured into molds

• When cooled to ambient temperature, it’s ready for use

– No chemical reaction, curing is when the molten sulphur “freezes” into a solid

• To recycle, simply heat to melt sulphur then recast


Shell Thiocrete-What’s next?

• First commercial agreement

established w/Dutch pre-cast

company that makes paving

stones for western European

market

• Will work with suppliers/

fabricators of pre-cast concrete

to identify opportunities


Shell Thiopave

• Solid pellets, ~ 97% sulphur

• Includes plasticizers, compaction agent and fume suppressants

• Can be stored on the ground or in silos

• No concern with moisture during storage

• Blended with the mixture, not directly with asphalt binder

• Melts in hot-mix plant, disperses into mixture

• Keep temperature below 285F


Effects of Thiopave Modification

• Partial replacement of asphalt binder

– 20-25% reduction in bitumen demand

– Increased stiffness at high service temperatures, reduced temperature susceptibility

– Improved resistance to rutting/permanent deformation

• No significant effect on cracking

– Ability to increase total binder content and use softer binders may prove to improve resistance to thermal and fatigue cracking


Thiopave Binder Content Formula

Determination of mass percentage of total binder (Thiopave + Bitumen) to yield the same binder volume as in an existing asphalt mixture design:

Pbt, Total Combined Binder, % mass =

Where:

GTh = Specific gravity of Thiopave

FTh = Percentage of Thiopave in total binder (typically, 30-40%)

R = Thiopave to bitumen substitution ratio

= GTh/Gb for equivalent binder volume*

PTh = Percentage of Thiopave by mass of mixture = Pbt * FTh

Pbm = modified % bitumen by mass of mixture = Pbt - PTh

*A lower ratio as low as 1.7 may be used for “rich” mixes.

( )[ ]bTh

b

GRFR

RP

−−

×

100

100

Technology - Delivery - Partnership Shell Sulphur Solutions13

Example Calculation

Assume: Pb = 5.3%

FTh = 40% (ie. 40% Thiopave/60%Bitumen blend by mass)

GTh = 2.00

Gb = 1.03 ⇒ R = 2.00/1.03 = 1.94

Pbt % = 5.3{ 100 (1.94) } = 5.3 {1.23}*

100(1.94) - (40)(1.94-1.03)

= 6.6%

∴ PTh = 2.6%, Pbm = 4.0%

Technology - Delivery - Partnership Shell Sulphur Solutions14

Effect on Marshall Stability PG 58-28, Fine-Graded Aggregate

0

2000

4000

6000

8000

10000

12000

14000

16000

18000

20000

0/100 30/70 40/60 50/50

Thiopave / Bitumen Weight Ratio

Mars

hall S

tab

ility, N

ew

ton

s

Minimum MS-2, 75 Blows = 1800 lbs

Marshall Stability increases with Thiopave content


Marshall Stability Comparison

0

2000

4000

6000

8000

10000

12000

14000

16000

Conventional Mix SEAM Mix

Ma

rsh

all S

tab

ilit

y,

N

1 Day 14 Days

Thiopave

1800 lbs

>10% higher initially, over 80% higher after 14 days

Qatar Test Road Results


-10

-9

-8

-7

-6

-5

-4

-3

-2

-1

0

0 5000 10000 15000 20000 25000

Cycle

Ru

t D

ep

th (

mm

)

R4/R5 Stripping Inflection Pt.

= 8500 cycles

16

Comparison of HWT (50C) Results for Port of

Oakland, Thiopave and Heavy-Duty HMA

Heavy Duty Asphalt HMA

Thiopave- Modified HMA

Example HWT Specification Criteria, PG 76-22:

(1) Colorado DOT: rut depth less than 10 mm

(2) Texas DOT: rut depth less than 12.5 mm


Thiopave-

modified HMA

Conventional

HMA

Thiopave-

modified HMA

Conventional

HMA

Crushed aggregate“Sandy” aggregate

gradation

Asphalt Pavement Analyzer (APA)

Specimens after 8000 passes

Asphalt Binder: PG 58-28

Technology - Delivery - Partnership Shell Sulphur SolutionsTemperature, C

Temperature Sensitivity

• Thiopave-modified

mixtures are much stiffer

at high temperatures

than conventional HMA

• Minimal difference in

stiffness at low

temperatures

• Conclusion: The stiffness

of Thiopave mixtures is

less sensitive to

temperature changes

than conventional HMA

Thiopave-modified

Control

Frequency = 1 Hz


Sensitivity to Loading Time

0

1000

2000

3000

4000

5000

6000

1 3 10 15 20

Frequency, Hz

Mo

du

lus,

MP

a

Conv (AC-20)

Thiopave

• Greater stiffness at lower

speed

– More rut-resistant

– Structural improvement

• Less flexural strain

• Less vertical compressive

strain @ top of subgrade

• Thiopave is less affected

by changes in the loading

rate than conventional

T = 30C


10

100

1000

10000

100000

-6.00 -4.00 -2.00 0.00 2.00 4.00 6.00

Log Reduced Frequency, Hz

|E*|

, ksi

0% Thiopave, 4% Design Va

30% Thiopave, 3.5% Design Va


40% Thiopave, 3.5% Design Va


Master Curves (NCAT)


0

2000

4000

6000

8000

10000

12000

14000

16000

18000

25 Hz 10 Hz 5 Hz 1 Hz 0.5 Hz 0.1 Hz 0.01 HzTest Frequency

Dyn

am

ic M

od

ulu

s (

E*)

(M

Pa

)

0% SEAM 4% Design Va

30% SEAM 3.5% Design Va

40% SEAM 3.5% Design Va

E* vs Frequency, after 1 day


0

2000

4000

6000

8000

10000

12000

14000

16000

18000

25 Hz 10 Hz 5 Hz 1 Hz 0.5 Hz 0.1 Hz 0.01 Hz

Test Frequency

Dyn

am

ic M

od

ulu

s (

E*)

(M

Pa

)

0% SEAM 4% Design Va30% SEAM 3.5% Design Va40% SEAM 3.5% Design Va

E* vs Frequency, after 14 days


Fatigue Testing, Port of Oakland

1000

10000

100000

1000000

600 650 700 750 800 850 900 950 1000

Tensile Stress, kPa

Nu

mb

er

of

Cy

cle

s t

o F

ailu

re

Thiopave

“Heavy-duty” HMA


Effect of Thiopave on Thermal Stress Restrained Specimen Tests (TSRST) Results

Bitumen grade

70/100 100/150 160/220 250/330

Fra

ctu

re t

em

pe

ratu

re,

oC

-40

-30

-20

-10

0

Conventional asphalt mix

Sulphur modified asphalt mix

“A Study of the Low-Temperature Properties of Sulphur Extended

Asphalt Mixtures” , Strickland, Bouldin and Colange, CTAA 2008

Amount of modifed sulphur added, % mass

-10 0 10 20 30 40 50

Fra

ctu

re tem

pera

ture

, oC

-35

-30

-25

-20

-15

-10

-5

0

contr

ol

70/100 Pen


TSRST Comparison

-45

-40

-35

-30

-25

-20

-15

-10

-5

0

Cra

ckin

g T

em

pera

ture

, C

Conventional Thiopave Binder LT Grade

PG46-34 PG52-34 PG58-28 PG64-22 PG58-28

300/400 200/300 150/200 80/100 80/100

Note: Thiopave Mixtures: 40% Thiopave/60% Bitumen


Production-Feed System

SILO FEEDERBIN & BELT FEEDER

• Developing a pneumatic feed system for Thiopave pastilles

• Best to feed them at/near baghouse fines return


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

Requires strict temperature

control

~ 135C (275F) is ideal


HS&E - Sulphur

• Non-toxic

• Does not leach

• Does not react at ambient temperatures


HS&E – Emissions at HMA Plant

ASPHALT HOT-MIX PLANT:

H2S & SO2 = 0 AT MIXER AND

TRUCK LOADING AREA

Six Hour Average, Oct. 2002


HS&E – Emissions at the Paver

ASPHALT PAVER: H2S SO2

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

2

1

2

1

Six Hour Average, Oct. 2002


HS&E - EmissionsReduced Hydrocarbon Content and Temperature Results

in Greatly Reduced VOCs

Date and conditions Total VOC

ppbv

Aug 15: Downwind, 5m; Control

HMA produced @ 152C 214

Aug 15: Upwind, 5-m; Control HMA

@ 152C 257

Aug 16: Breathing zone; Thiopave

mix produced @ 140C 98

Aug 16; Downwind, 5m, Thiopave

mix produced @ 140C 99


Greenhouse Gases

• Reduced hydrocarbon concentration and

temperature reduces CO2 footprint

• Blue Source Study (Alberta)

– Developing methodology to properly

document carbon footprint of paving materials

– Sea-to-Sky (British Columbia) field validation


Potential Applications &

Limitations

• Applications:

– Stiff, rut resistant layers

• High modulus asphalt base

course

• Perpetual Pavement

structural layers

– “Black” Bases

– Ports, intermodal terminals,

container loading facilities

• Any paving application where

RCC would be considered

– Intersections

• Limitations:

– MUST be able to control

temperatures during

production!

• Don’t expose sulphur to

temperatures exceeding 285F!

– Do NOT use with:

• Polymer-modified bitumens

• Mixtures using hydrated lime

or Portland cement fillers

– Don’t use in thin-surfaced

flexible pavements


Ongoing Research

• Projects in British Col.,

California

• Full-scale test tracks

– NCAT (2 sections)

– Louisiana ALF (2 sections)

• Laboratory

– NCAT, LTRC

– Commercial laboratories

• HS&E

– Blue Source (Canada)

StructuralPerformance

Material Properties,Local Materials

Q’s & A’s

Stay tuned,

much more to come!


Conclusions

• Thiopave provides a safe, practical and economic way to enhance asphalt mixture qualities with sulphur

• Thiopave is a viable alternative for producing heavy-duty mixtures

• Shell is firmly committed to developing civil engineering applications for elemental sulphur


Thiopave®-Sulphur Enhancement for Asphalt Mixtures

Gary L. Fitts, P.E.SE Regional ManagerShell Sulphur SolutionsGarden Ridge, TX

DELIVERING INNOVATION TO YOUR ADVANTAGE

Shell Sulphur Solutionshttp://www.shell.com/sulphur

Thank you!

Documents

Sulphur’s Place in CE - Foundationfoundationperformance.org/pastpresentations/FittsPresSlides-18Feb... · aramidfibers, construction materials, sugar manufacture, ... replacement