CURRENT PRACTICES

Gerrie van Zyl

MYCUBE ASSET MANAGEMENTSYSTEMS (PTY) LTDMYCUBE ASSET MANAGEMENTSYSTEMS (PTY) LTD

Acknowledgements

International overview

Local experiences

Winter seal experiments

General embargo during winter USA, Australia, New Zeeland

Central Africa still high use of cutbacks (TRL influence)

However cutters and adhesion agents used by

several contractors (Australia and NZ) Australia prefer primer seals on new roads and single

seals as reseals

NZ prefer racked-in seals due to stone loss

General drive towards emulsions Varying specs on temperatures and humidity

USA limitations - varying

Australia General winter embargos in SRAs

Primer seals with cutters

Cutters with 60/70 grade std

Precoating variations

New Zeeland NZTA – Winter embargo

Using cutters during summer season 1-5% on 130/150 Pen

Temporary holding seals if necessary

Rapid setting low temperature emulsions

High float emulsions

Promote adhesion No/low dust

Precoating/ Wetting agents

Soft binders/ cut-back/ emulsions

Heated aggregate

Tandem sprayer/chipper

Increased binder (50 – 70% of stone height)

Racked-in seals

Additional rolling/ compaction

High road surface temperatures

Observations Low volume roads

Wetting agents and cutters added

Open seal structure

Binder rise

Warmer areas – just adhere to temp specs Emulsion sealing – always 2 coats Cutback of conventional 80/100 pen bitumen Cape seals Grit/ sand/ graded aggregate seals Cut-back binder or emulsion

Proprietary products e.g. Wintergrade BR Microsurfacing

Emulsion seals (Cationic) Suppliers added 2-4% Cutter

Larger window due to road surface temperature

Typical Cape seals and single seals + grit

Conventional cut-back binders MC 3000

Sand/Grit seals, 13+Grit/sand

Worked well on Low volume roads

Cut-back on site for single seals (refer TRH3)

Winter grade modified binders WG Bitumen rubber

WG Polymer Modified (SBR or SBS)

Temperature and Wind chill

Humidity

Rainfall soon after construction

Adhesion development

Precoating Wet vs Dry precoating

Tar based vs Bitumen

Wet aggregate

Traffic

History of up to 12% cutters in 80/100 Pen

3-5% suggested by practitioners

Only in latter half of winter

Not in Cape Seals, Geotexstiles

TG 1- < 5000 elv/day, heavies < 15%, not in high stress areas

Opinions on negative effect on properties of bitumen rubber

Hazard of heating cut-back binders

No heating during transportation

Guidelines for safehandling

19 Sites evaluated Cut-back Bitumen rubber (13.2 Single)

Cut-back Polymer modified (SBS & SBR - 9.5 Single)

19 Cape seals (70/100 or S-E1 precoated)(SC-E1

precoated or Cat 65 fogspray)

Effect of cutters – more rapid ageing ?

19 Sites evaluated continue… 19/6/6 SC-E1/ S-E1(4%LFS) plus anionic or cationic emulsion

fogspray Effect of anionic stable versus cationic spray grade

ANIONIC CATIONIC

19 Sites evaluated continue… Microsurfacing (Rapid setting slurry)

Concerns

9.5 mm Cape Seal (Temp)

SC-E1(t) @ 1.0 l/m2 + M-F slurry @ 200 l/m3

Emulsion seals Emulsion seals (Cat 65 or SC-E1 plus Cat 65)

With and without fogspray

Grit seals Precoated and unprecoated

MC 3000 and Cat 65

Sensitivity to rain

Stone & 1/3 13.2 plus Grit or 13.2 plus 4.75

19 plus 6.7

Risks

Experimental Matrix Seal types

Binder types & combinations

Application rates

Traffic Low

Med

High

Climatic conditions Dry winter

Wet winter

Seal types Binders Application Cover spraySolvents

13 Single

19/9 Double

19/6/6 Split

BR Summer

BR Winter

NCRT

S-E1(SBS)

S-E1(SBS)

SC-E1

S-E1(SBR)

4% HFS

0-4% LFS

None

0.8-1.0 l/m2

50/50 - Undiluted

0-3% LFS

0.8-1.0 l/m2

50/50 - Undiluted

0-3% LFS

0.8-1.0 l/m2

50/50 - Undiluted

0-3% LFS

Low –High

Low –High

Low –High

0-4% LFS

0-3% LFS

13/6, 19/9, 19/6/6,Cape Seals

Stone packing on Cape Seals

Binder distribution e.g. 40/60 with SC-E1and S-E1

Seal at 10(SC-E1),15 and 20oC dependant on LFS

Heavy traffic

Precoating with emulsion