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tellenbosch Cold Recycling & Bitumen Stabilised Materials BSMs Research and Implementation? tellenbosch Kim Jenkins 57 th Annual Illinois Bituminous Paving Conference 12 th December 2016 Outline 1. What is BSM? 2. Mix Design 3. Structural Design 4. Application 5. Where to now?

Cold Recycling & Bitumen Stabilised Materials BSMs ...bituminousconference.ict.illinois.edu/files/2016/12/1.-Kim-Jenkins.pdf · Cold Recycling & Bitumen Stabilised Materials BSMs

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tellenbosch

Cold Recycling & Bitumen

Stabilised Materials BSMs

Research and

Implementation?

tellenbosch

Kim Jenkins

57th Annual Illinois Bituminous

Paving Conference12th December 2016

Outline

1. What is BSM?

2. Mix Design

3. Structural Design

4. Application

5. Where to now?

BSM Binder Options

FOAMED BITUMEN

Mill

Acid or

Caustic Soda

Surfactants

Wat BitumenWater

5 microns

Water

Hot

bitumen

Air

Expansion chamber

BITUMEN EMULSION

Colloidal Mill

Flexibility

Rig

idit

y

320 1

3

4 5

4

2

1

0

Cem

en

t %

Bitumen %6

Cement stabilised

Bound

Granular

Unbound

Non-

continuously

Bound

BSM

Asphalt

Bound

Orientation on BSM

Influence of Active Filler

Strength versus 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-

bre

ak

0

500

1000

1500

2000

2500

3000

3500

4000

Un

co

nfi

ned

Co

mp

ressiv

e

Str

en

gth

(kP

a)

Foamed bitumen, Strain

Cement, Strain*

Foamed bitumen, UCS

Cement, UCS*

* Cement treated with 2 percent cement and no foamed bitumen. Values plotted

at an arbitrary ratio of 1.25 for 2 percent cement and 1.2 for 1 percent cement.

CSIR

BSM

eb

BSM foam

Cement < 1%

BSM Triaxial Tests Shear properties (monotonic tests at 25°C)

Cohesion C

0

100

200

300

400

500

A-7

5C

-0

B-7

5C

-0

C-7

5C

-0

A-7

5C

-1

B-7

5C

-1

C-7

5C

-1

A-7

5M

-0

B-7

5M

-0

C-7

5M

-0

Co

hesio

n [

kP

a]

E E E E E E FFF20

25

30

35

40

45

50

A-7

5C

-0

B-7

5C

-0

C-7

5C

-0

A-7

5C

-1

B-7

5C

-1

C-7

5C

-1

A-7

5M

-0

B-7

5M

-0

C-7

5M

-0

Fri

cti

on

an

gle

[d

eg

rees]

Friction Angle f

E E E E E E FFF

Jenkins, 1999 & Ebels, 2006

25% RAP 25% RAP75% RAP 75% RAP

Resilient Modulus of BSM

Stress dependency: Foamed 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)

Re

silie

nt

Mo

du

lus M

r (M

Pa

)

12kPa

24kPa

48kPa

72kPa

s3

HMA > 2500 MPa

GCS

BSM

Research: Visco-elasto-plastic &flexural properties on BSM-foam

Tref = 20C

HMA/WMA

HWFatigue cracks

Rutting

HOT T or

Slow TrafficEquiv

COLD T or

Fast TrafficEquiv

BSM

BSM

BSM test methods

Years

20101990 2000

RealityIndex

Compaction

TestingZ

e

r

o

L

i

n

e

S

l

e

e

v

e

B

a

s

e

P

l

a

t

e

S

t

e

e

l

R

o

d

S

id

e

o

f

M

o

ul

d

V

i

b

r

a

t

o

r

y

H

a

m

m

e

r

W

o

o

d

e

n

b

a

s

e

C,f Mix design to PerformanceDesign BSM layers

h1

h2

h3

>200 project mix designs!

Mix Design Flowchart

Sampling

Sample preparation

Preliminary tests

SUITABLE?

Blend

Effect of active filler

Optimum bitumen addition

Determine shear

properties

Yes

No

ITS

TRIAXIAL

Specification

C (kPa) f (0)

>250 >40

PUGMILL MIXER

FOAMED BITUMEN UNIT

Standardised Mixing Method

Lab Compaction: Vibratory Hammer

Vibratory hammer

Power rating (W)

Frequency (Hz)

Mass (Kg)

PointEnergy (J)

Kango 637® 750 45.83 7.5 27

Bosch GSH 11E® 1500 15 - 31.5 10.1 16.8

Bosch GSH 11VC® 1700 15 - 30 11.4 23

For PI >8%, cannot achieve 100% Mod. AASHTO density

Influence of Frame

2050

2100

2150

2200

2250

2300

2350

2400

G2 G4

Den

sit

y (

kg

/m3)

Material Type

80% OMC, RFR,10kg Surcharge

80% OMC, LFR,10kg Surcharge

80% OMC, RFR,20kg Surcharge

80% OMC,LFR,20kg Surcharge

Refusal Density

Comparison of refusal density for G2 and G4 material

FRAMETYPE

Rigid

Loose

Rigid

Loose

(Stell Univ)

Inter-Layer Roughening (ILR) Device

6 layersX 50mm

2 layersITS

Triaxial

Inventor: Wynand van Niekerk

CT ScansBSM-emulsion

S1A

-5

5

15

25

35

45

55

65

75

85

0 20 40 60 80 100

Volume in %

Sca

n s

lice

nu

mm

er

(bo

ork

ern

le

ng

te i

n m

m).

voids

Mortar

stone

Poor attention to

interlayer preps

tellenbosch

N7 PSPA Mr Analysis over 7 Months

0

500

1000

1500

2000

2500

3000

3500

4000

0 50 100 150 200 250

Time (days)

Mr

(MP

a)

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

PSPA

Moisture

Mr

Why is curing important?

Mr (field) versus cure

% OMC

100

40

60

80

MC

New Triaxial

Confining Pressure s3

(inflate tube)

Apply Load (stress s1)

Test at

25ºC

tellenbosch

Validation Research Triaxial Test RTT versus

Simple Triaxial Test STT

0

200

400

600

800

1000

1200

1400

0.0 1.0 2.0 3.0 4.0 5.0

Strain [%]A

pp

lied

Str

ess [

kP

a]

RTT

STT

0

200

400

600

800

1000

1200

0.0 1.0 2.0 3.0 4.0

Strain [%]

Ap

pli

ed

Str

ess [

kP

a]

RTT

STT

BSM Crushed Hornfels with 3.3% Emulsion

s3 =50 kPa and 1% Cement s3 = 200 kPa and 0% Cem

APPLY CONFINING PRESSURE (AIR)

APPLY LOAD (3mm/min)

σ1

σ3

t

s

Shear stress

Normal stress

(kPa)

Cohesion

f Friction angle

UNBOUND

BSM

σ1

σ3

σ1

σ3

0 50 100 200

Determine shear properties (C and φ)

Durability of BSMt

s

Shear

stress

Normal

stress

CBSM

Cohesion

f Friction

angle

Retained Cohesion CR = CR*100/CBSM

Effect of

Moisture

Cohesion Loss = 25% max

Structural DesignConsiderations

250mm CIPR:

2.5% Foam 1% Cem

90mm Asphalt

Lab Triaxial Analysis

Permanent deformation (rutting) design for granular material

BSM Design for Max Rut Depth(same principle as Granular Design)

Design Life for 10mm rut

Design Function for BSM

𝑁 = 𝑓 (𝑅𝐷, 𝑅𝑒𝑡𝐶, 𝑃𝑆, 𝑆𝑅)

Relative Density Plastic Strain (a/b)

Retained Cohesion Stress Ratio

ab

Mr change with trafficking (triaxial)

0.0

200.0

400.0

600.0

800.0

1000.0

1200.0

1400.0

1600.0

1800.0

2000.0

100 1,000 10,000 100,000 1,000,000

Resil

ien

t M

od

uli

(M

Pa)

.

Load repetitions

SR=49%SR=57%SR=65%SR=67%

Jenkins et al, IJPE

BSM1-foam (2%)

Jenkins, TU Delft, 1999

In service behaviour of MrInfluence of support & traffic

0

500

1000

1500

2000

0 1 2 3 4 5 6 7 8 9 10

Effe

ctiv

e St

iffn

ess

(Mp

a)

Years or Traffic

1% cem CTSB

1% cem G5SB

1% cem G7SB

Cem % BSM1

TrafficPoor SupportHigh sd/sd,f

Conceptual

N7

Supporttype

Effective Long Term Mr for BSM base Mr from FWD back-calcs

SAPDM - R35 : Theyse, 2015 & Lynch, 2014

1%cem1%cem

2%cem

2%cem

Effective Long Term Mr Stiffness (MPa)for BSM base

BSM Class Cemented Subbase

Granular Subbase

BSM (RAP + GCS)

900 – 1750 700 – 1200

BSM (GCS Grade Crushed Stone)

800 – 1200 600 – 900

ELT Mr = f (aggregate type and quality, RAP %, bitumen %, support, traffic, climate)

Supporting Layer

30

Case Study – Ayrton Senna Highway

Brazil’s most heavily-trafficked highway

8-lanes / divided

AADT > 200,000vpd (15% heavy)(> 15,000 heavies / day in each direction)

Milling & Replacing 100mm HMA lasts < 3 months

Lane closure only between 21:00 – 05:00

Key Data

8 HOURS

Results from Pavement Investigation

HMA ± 100mm

SELECTED COARSE GRAVEL (CBR >25) ± 200mm

EMBANKMENT (RIVER LEEVEE) (CBR > 15)Semi-infinite

GRADED CRUSHED STONE ± 200mm

CEMENTED CRUSHED STONE ± 250mm

6% CEMENT

Rehabilitation Options?? (8-hour working window)

HMA ?350mm

BSM-a 200mm

BSM-b 130mm

20mmHMA

50mm

?

100mm

100mm

Step 1. Mill off asphalt layers

Impact crusher (20mm setting)

Grading Correction using Single Stage Crushing

Normal CONTINUOUSAFTER CRUSHINGRAP

Wirtgen KMA 220 plant mixer

2.0% / 2.1% Foamed Bitumen1.0% OPC

Mixed material placed in stockpile

250mm

Step 2. Mill and remove CTB layer

130mm BSM (RAP / crushed stone blend)

Step 5. Import / pave / compact 130mm BSM layer

20mm HMA (gap-graded / fine mix)Temporary surfacing

Step 6. Import / pave / compact 20mm HMA

18th November 2011

31ST January 2012

Currently (3.75 years later)

> 100 lane-km rehabilitated using this method

PROBLEM SOLVED !

Way Forward: ResearchMonotonic Load Cycle (triaxial)

(Bredenhann & Jenkins, 2016)

GCS BSM

Way Forward: ResearchDynamic Conditioning (triaxial)

(Bredenhann & Jenkins, 2016)

GCS BSM

Way Forward: Research(2)

Dynamic Triaxial – Permanent Deformation

(Bredenhann & Jenkins, 2016)

GCS

BSM

0.000

0.005

0.010

0.015

0.020

0.025

0.030

0.035

0.5 0.6 0.7 0.8 0.9 1

Def

orm

atio

n r

ate

Stress ratio

(ep/N

x 1

0-6

)

All beams compacted in a mould

Testing temperature: 25°C

LVDT on top of the beam to accurately measure displacement in the middle of

the beam.

LVDT

Flexural Strain-at-break

(Campher, 2014)

Specimen

specification

Material parameter

Average

Maximum Stress

(kPa)

Average Strain-

at-break

(µԐ)

Average

Dissipated

energy (Pa)

Average

stiffness

(MPa)

0.9% Emulsion; 1%

Cement 174.4 376.5 39.1 524.2

2.4% Emulsion; 1%

Cement 254.9 537.2 89.8 473.1

2.4% Emulsion; 2%

Cement 320.4 391.1 78.8 821.6

2.4% Foamed; 1%

Cement 211.6 480.8 68.7 447.4

2.4% Foamed; 2%

Cement 383.8 508.7 151.3 761.9

-40.00 -20.00 0.00 20.00 40.00 60.00 80.00 100.00 120.00 140.00

Average Strain-at-break (µԐ)

Average Dissipated energy (Pa)

Average stiffness (MPa)

% Change in parameter value

Fle

xib

ilit

y r

ela

ted

p

ara

me

ters

Increase in bitumen emulsion (specimenscontaining 1% cement)Increase in cement (stabilised with bitumenemulsion)Increase in cement (stabilised with foamedemulsion)bitumen

Flexural Strain-at-break & DE

(Campher, 2014)

Flexibility (triaxial)

(Llewellyn, 2016)

Flexibility (triaxial)

(Llewellyn, 2016)

Factors Influencing BSM FlexibilityAnalysis of Variance

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

0.45

0.5

0.55

0.6

0.65

0.7

0.75

0.8

0.85

P-value

Summary of P values for variables in ANOVA analysis

Strain at Break

DissipatedEnergy

Fenton, 2013

SignificantVariables <0.05

tellenbosch

Conclusions

• Mix design system in place

– Aim for flexibility not high strength

– Update of equipment (vib hammer & triax)

• Pavement design

– New ME design function

– Link of mix- and pavement-design (C & f)

• Application (field performance data)

• Way forward: flexibility focus

tellenbosch

tellenbosch

Pavement Balance

Mr (MPa)

Granular Base

Asp

G1

G5

SG

Asp

BSM1

G5

SG

3000

BSM Base

Mr (MPa)

500

350

150

200

800

3000

350

150

200

Base

Subbase

Subgrade

CTB 2800 >1000

---- >1500 CTSB

Research on BSM FlexibilityHow can we benefit from?

(Llewellyn, 2016)

Strain-at-break vs Fatigue25%RA & 0%Cem

1E+00

1E+01

1E+02

1E+03

1E+04

1E+05

1E+06

1E+07

100 1,000 10,000

Nu

mb

er o

f re

peti

tio

ns

Strain [x 10-6]

emulsion A

emulsion B

foamed bitumen C

Strain at break

AB

C

4PB Fatigue

Stellenbosch University