E i ith SBR d SBS difi dExperiences with SBR and SBS modified binders in the construction of seals in RSA

JG L /TR Di tiJG Louw/TR Distin

Cost effective high performance surfacingsperformance surfacings

Overview

f f• Use of modified binders in RSA• Properties of SBR and SBS modified binders• Storage stability during handling• Storage stability during handling• Application techniques for spray seals • Design of modified binder spray sealsDesign of modified binder spray seals• Summary

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Modified bitumen usage in Sealsg

• < 1982 - mainly SBR and natural latex in anionic emulsions• 1982 Bitumen rubber• 1982 - Bitumen-rubber • 1984 - SBR latex in hot bitumen• 1989 - SBR latex in cationic emulsions• 1990 - SBS polymer in hot bitumen

44%8%16% penetration

cutbackemulsion

2%10%20%

SBSSBRRubber

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SBS block co-polymer

Ordered molecular structure

SBR (latex)

Random molecular structureRandom molecular structure

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= styrene = butadiene

P l t d i

Polystyrenedomain

Polystyrene domain

Butadiene chain

Butadienechains

B h d SBSLinear SBS Branched SBS

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Softening Point of SBR vs SBSg(80/100 pen base bitumen)

110

90

100

(deg

C)

60

70

80

ning

Poi

nt

SBS

SBR

40

50

60

0 1 2 3 4 5

Softe

0 1 2 3 4 5

Polymer content (%m/m)

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Viscosities – SBR vs SBS(80/100 pen base bitumen)

900

600

700

800

mPa

.s)

3% SBR

200

300

400

500

Vis

cosi

ty (m

3% SBS80/100

0

100

200

130 140 150 160 170 180 190 200 210

V

130 140 150 160 170 180 190 200 210

Temperature (deg C)

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Elastic Recovery – SBR vs SBS y(80/100 pen base bitumen)

90

75808590

deg

C (%

)

60657075

over

y @

15

3% SBR

3% SBS

40455055

last

ic R

eco

405 10 15 20

Temperature (deg C)

El

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1 40

1.60

0.80

1.00

1.20

1.40

sion

J/c

m2

3% SBR

80/100 Cohesion

0.00

0.20

0.40

0.60

Coh

es 3% SBS properties

@ 5°C

Tensile Properties – NF EN 13587

10 20 30 35 40 45 50 60

Temperature (deg C)

Tensile Properties NF EN 13587Initial length = 50 mm

Unit 80/100 3% SBR in 80/100

3% SBS in 80/100

At break:At break:ElongationStress

%MPa

3390,06

>9000,59

>9000,68

Deformation Energy Properties – NF EN 13703

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o o gy op s 3 03At break:

Mean energy J/cm2 9,6 24,1 29,1

Storage Stability at application g y pptemperature

70

Ring and Ball Softening Point

1200

Dynamic Viscosity

10203040506070

& B

Sof

t Poi

nt

(deg

C)

SBR (200 deg C)SBS (180 deg C)

0200400600800

10001200

Visc

osity

@ 1

35

deg

C (m

Pa.s

)

SBR (200 deg C)SBS (180 deg C)

010

R &

0 5 11 13 16 18

Time after manufacture (hrs)

0V

0 5 11 13 16 18

Time after manufacture (hrs)

4050607080

ecov

ery

g C

(%)

Elastic Recovery

010203040

Elas

tic R

e@

15

deg

0 5 11 13 16 18

Time after manufacture (hrs)

SBR (200 deg C)SBS (180 deg C)

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( )

Typical modified binder seals yp

Single Seal Double Seal

EXISTING SUBSTRATE EXISTING SUBSTRATE

Split Seal Cape Seal

EXISTING SUBSTRATE EXISTING SUBSTRATE

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Typical application rates

Aggregate

Single seal 13,2 mm aggregate (ALD = 8,2)

Traffic (ELV)5000 1000 > 20000 Spread

rate (m3/m2)

Bi d li ti t (l/ 2) h tBinder application rate (l/m2) hot

3% SBR + 80/100 1,65 1,24 1,15 90 – 100

3% SBS + 80/100 1,78 1,34 1,20 90 – 100

Cationic Spray Grade 70% + 5% latex 1,68 1,27 1,13 90 – 100

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5% latex

Spray rate ajustment factors – TRH 3p y j

SBR modified bitumen

T ffi ( l ’ ) Si l S l D bl S l S li S lTraffic (elv’s) Single Seal Double Seal Split Seal

< 5000 1,3 1,1 1,2

5000 – 20000 1,2 1,0 1,15000 0000 , ,0 ,

> 20000 1,1 1,0 1,0

SBS modified bitumen

< 5000 1,4 1,2 1,3

5000 – 20000 1,3 1,1 1,2

> 20000 1,2 1,0 1,1> 20000 1,2 1,0 1,1

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Construction of seals

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Use of cutters

• General resistance amongst practitioners• No cutters allowed on National Route contracts

When used with discretion excellent results• When used with discretion – excellent results• Generally not more than 4% cutter used• Cutback SBR marginally less temperature sensitive• Cutback SBR marginally less temperature sensitive

than SBS PMB’s

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Semi-priming polymer modified binderp g p y

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Summaryy

• With the increase in traffic and rapid ageing of the South African national & provincial road networkSouth African national & provincial road network have lead to 70% of all reseals being constructed using modified binders

• Practitioners recognise the improved life cycle costs associated with the use of these binders Th i d f ti f SBS• The improved performance properties of SBS vs SBR modified binders have resulted in an increase demand for SBS modified binders

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