Introduction to Bitumen Stabilised Materials BSMs · Mill Acid or Caustic Soda Surfactants ... 5 microns Water Hot bitumen Air Expansion chamber BITUMEN EMULSION Colloidal Mill. 2.

Introduction to Bitumen Stabilised Materials BSMs

Kim Jenkins

SARF Course on BSMsAssagai, Shongweni

14 and 15 July 2015

tellenbosch

Hot

ColdIn Place In Plant

What defines a BSM?

Bitumen

Cem

ent

Rut resistant

Strongly cemented

Lightly cemented

UnboundCrushed stone / gravel / soil

Stress dependent

Less economical

Fatigueresistant

1%

3%

2%

1% 2% 3% 4%

FBS(NZ)

FBS(Aus)

QuickLime

0%

HMA

BSM(RSA)

?

?

5%

1. BSM Binder Type

FOAMED BITUMEN

Mill

Acid orCaustic Soda

Surfactants

Wat BitumenWater

5 microns

Water

Hot bitumen

Air

Expansion chamber

BITUMEN EMULSION

Colloidal Mill

2. Bitumen Dispersion

BSM-emulsion BSM-foam

Microscopic Analysis

Type of Dispersion

BSM-emulsion BSM-foam

Painting Spot-welding

Nature of BSMs (cold)

0.5mm

Bitumen dispersion:Non-continuously bound

BSM-foam (sand)

BITUMEN DISPERSION

Particles < 0.075 mm (# 200 sieve)

± 100°C

Thin bitumen film around steam

± 20°C

Tiny bitumen “pieces”

Natural Gravel

CBR>25%

Crushed Gravel

CBR>45%

GradedCrushed

Stone

50% RAP+ GCS

100% RAP

3. Aggregate TypesRecycled Materials

4. Grading requirements

0

20

40

60

80

100

0.08 0.15 0.3 0.6 1.18 2.36 4.75 6.7 9.5 13.2

Sieve size (mm)

Cum

ulative

% p

ass

ing

Foam

Emulsion

Optimisation of grading curve

0

100

200

300

400

500

600

700

Emulsion

3.3% bitumen

Foam

3.5% bitumen

Indi

rect

Ten

sile

Str

engt

h (k

Pa)

Without blending

With 10% fines blend

Moisture: DurabilityEMULSION FOAMED BITUMEN

Poorly graded Well graded Well graded

5. Bitumen content

BSM Class Aggregate Bitumen (%)

BSM 1 >75% RAP + Crush agg 1.6 – 2.1

BSM 1 >25% RAP + Crush agg 1.8 – 2.5

BSM 1 <25% RAP + Crush agg 2.0 – 3.0

BSM2 Natural Gravel (CBR>45%) 2.2 – 3.5

BSM 3 Natural Gravel (CBR>25%) 2.5 – 4.0

(Wirtgen Recycling Manual, 2012)

Foam > 25ºC

Foam 15ºCEmulsion 10ºC

Foam <15ºCEmulsion<10ºC

Aggregate Mixing Temperature

√

OK

X

Aggregate Temperature vs Particle coating (BSM -foam)

05

101520

25303540

35 45 65 85

Aggregate Mixing Temperature (degC)

Max

imum

Par

ticle

Siz

e (

mm

)

Practically no coating

Partial coating

Completecoating

Jenkins , 2000

7. Moisture Regime (mix & compact)EMULSION

Bitumen coating (thin films)

Some partial coating

FOAMED BITUMEN

Bitumen dispersion selective

Partial coating

Optimum Fluids Content 70% to 90% of OMC

MOISTURE DURABILITY

HVS Cape Town on BSM

Water introduction into 2.3% foamed bitumen stabilised base

PERMEABILITY

Resilient Modulus of BSM -foam (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)

Res

ilien

t Mod

ulus

Mr

(MP

a)

12kPa24kPa48kPa72kPa

s3

8. Behaviour = Granular type

Stress dependency (triaxial)

Resilient moduli 75C -0 blend

100

1000

10000

100 1000 10000

Bulk stress [kPa]

Res

ilien

t mod

ulus

[MP

a]

A-75C-0

B-75C-0

C-75C-0

Mix:1% cem0% cem

Not main purpose

BSM-emulsionBSM-foam

Visco -elastic properties of BSM-foam

Tref = 20C

HMAHW

Fatigue cracks

Rutting

HOT T or Slow Traffic

Equiv COLD T or Fast Traffic

Equiv

BSM

Validation (100% RAP Foamed Mix)

0.00

1.00

2.00

3.00

4.00

5.00

6.00

7.00

8.00

9.00

10.00

0 200000 400000 600000 800000 1000000

Number of load repetitions [-]

Per

man

ent a

xial

strai

n [%

]

60C

40C

50C

σ1

σ2

Repeated Load

Triaxial

40ºC

50ºC60ºC

10. Active Filler: Purpose?• Improve adhesion• Improve dispersion• Modify plasticity• Increase stiffness & strength• Accelerate curing

Emulsion Foam• Breaking time Dispersion! • Improve workability

• Improve adhesion PRIMARY• Improve dispersion REASONS• Modify plasticity• Increase stiffness & strength• Accelerate curing

Emulsion Foam• Breaking time Dispersion ! • Improve workability

Influence of Active Filler

Strength and 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

Str

ain-

at-b

reak

0

500

1000

1500

2000

2500

3000

3500

4000

Unc

onfin

ed C

ompr

essi

ve

Str

engt

h (k

Pa)

Foamed bitumen, StrainCement, Strain*Foamed bitumen, UCS Cement, UCS*

* CSIR

εb

BSM

Cement < 1 %?

Can 1.5% cement work?

BSM-foam + 1.5% cemusing cracked CTB

2 years of traffic

0

200

400

600

800

1000

1200

1400

1600

1800

0 0.1 0.2 0.3 0.4 0.5 0.6

Strain

Str

ess

(kP

a)Mix Design Testing

A1

Cemented

Bituminous

It’s undeniable: More cement = more strength!

CompressiveTensileShear

strength

0

200

400

600

800

1000

1200

1400

1600

1800

0 0.1 0.2 0.3 0.4 0.5 0.6

Strain

Str

ess

(kP

a)Dissipated Energy

W = 0.5 σεA1A2

Cemented

Bituminous

It’s undeniable: More cement = more strength!

CompressiveTensileShear

strength

11. Time DependencyMr (field) versus cure

N7 PSPA Mr Analys is ove r 7 Months

0500

1000150020002500300035004000

0 50 100 150 200 250

Tim e (days)

Mr (

MP

a)

B1-B3 B4-B6 Poly. (B4-B6)

PSPA

Moisture

Mr

TG2 : 2nd EDITION

Published inSouth Africa

byAsphalt Academy

(CSIR / SABITA)

May 2009

BITUMEN STABILISED MATERIALS

Conclusions

• Many combinations of aggregates can be used (continuous grading)

• BSMs = asphalt• BSM is granular with higher

cohesion and shear strength• Flexibility is NB! Active filler content

needs to be restricted

/

Thank you

Roads & Enviro !