uk experience of in situ recycling with cement for the

Seminar onRoad PavementRecycling,WarsawOctober, 2002

UK experience of in situ recycling with cement for the structural maintenance

of pavements

Sally EllisSally Ellis

Head of Centre for SustainabilityHead of Centre for SustainabilityTRL LimitedTRL Limited

sjellissjellis@@trltrl.co..co.ukuk


UK EXPERIENCE OF IN SITU UK EXPERIENCE OF IN SITU RECYCLING WITH CEMENTRECYCLING WITH CEMENT

Introduction

Background to current guidance

Current guidance

SMART


UK EXPERIENCE OF IN SITU RECYCLING WITH CEMENT

INTRODUCTION

COLD IN SITU RECYCLINGCOLD IN SITU RECYCLING‘… the procedures using specialistplant to pulverise and stabilise existing road materials, in-place, at ambient temperature with the addition of hydraulic and/or bitumen binder…’

LINEAR QUARRY PROJECTLINEAR QUARRY PROJECT‘Every deteriorated road is a ‘Every deteriorated road is a source of aggregate for its ownsource of aggregate for its ownstructural maintenance by coldstructural maintenance by coldin situ recycling.’in situ recycling.’

TRL 386 (1999)TRL 386 (1999)


UK EXPERIENCE OF IN SITU RECYCLING WITH CEMENT

INTRODUCTIONPavement thickness designPavement thickness design

Original pavement Recycled pavement

Original surfacing

Original roadbase

New surfacing

Recycled structural course

Original subbase

Sub-grade Sub-grade

Remaining subbase as foundation platform


UK EXPERIENCE OF IN SITU RECYCLING WITH CEMENTBACKGROUND TO CURRENT GUIDANCE

THE LINEAR QUARRY PROJECTTHE LINEAR QUARRY PROJECTRESEARCH METHODOLOGYRESEARCH METHODOLOGY

Examination of nine in-service roadsmaintained by cold in situ recycling

• 7 foamed bitumen• 2 cement

Construction and monitoring of two full-scale road trials on A3008Cartgate Road in Somerset



CARTGATE ROAD TRIAL PHASE 1CARTGATE ROAD TRIAL PHASE 1• 2.5 lane kilometres• 8 trial sections

• 4 cement• 4 foamed bitumen

• 2 control sections

• 2.4 lane kilometres• 2 trial sections

• 1 cement• 1 foamed bitumen

CARTGATE ROAD TRIAL PHASE 2



DATA COLLECTION FROM ROAD TRIALSDATA COLLECTION FROM ROAD TRIALS

• Extraction of cores• Falling Weight Deflectometer• Visual inspection• Particle size distribution• Moisture content• Cube refusal density• As placed density by NDM• Thickness of recycled layer• Cube compressive strength


UK EXPERIENCE OF IN SITU RECYCLING WITH CEMENTCURRENT GUIDANCE

TRL 386TRL 386(1999)(1999)



PART ONEPART ONE•• Environmental considerationsEnvironmental considerations•• Cold in situ recyclingCold in situ recycling•• Site evaluationSite evaluation•• Design of recycled materialDesign of recycled material•• Pavement designPavement design•• Specification Specification •• ConstructionConstructionPART TWOPART TWO•• SpecificationSpecification•• Notes for GuidanceNotes for Guidance


FLOW CHART A: SITE EVALUATIONFLOW CHART A: SITE EVALUATIONNo

Conventional reconstructionIs site of sufficient area?

Is depth sufficient? Can levels be raised?

No

Can subgrade be included?

Import supplementary aggregateYes

Is material OK for pulverisation?

Is aggregate consistent?

Are services deep enough?

Is strength/stiffness OK?

Central plant recycling

Cold in-situ recycling

YesNo No

Yes Yes

No

Yes

No

YesNo

Recycle as alternative materialYesNo

Yes


FLOW CHART B: PRIMARY BINDER FLOW CHART B: PRIMARY BINDER SELECTIONSELECTION

Structural maintenance by cold in-situ recycling

YesIs the pulverised aggregate

too fine and plastic?Pre-treat with hydrated lime or cement

to produce non-plastic aggregate

Is there any doubt about the binder to use?

Is groundwater a problem?

Is subgrade free from seasonal ground movement?

Portland cementFoamed bitumen

Overriding preference of engineer

No

Yes

NoYes

No

Yes

No



LIMITATIONSLIMITATIONS

•• Limited to in situ recyclingLimited to in situ recycling•• restricts depth of recycled layerrestricts depth of recycled layer

•• Generally limited to cement and Generally limited to cement and foamed bitumen binders used foamed bitumen binders used separatelyseparately

•• Prescriptive in naturePrescriptive in nature


SMART PROJECTSMART PROJECT

SSustainable ustainable MAMAintenanceintenance of roads of roads using cold using cold RRecycling ecycling TTechniquesechniques


MATERIAL ‘FAMILIES’MATERIAL ‘FAMILIES’

Unbound

Fullyvisco-elastically

bound

FAMILY 1‘HYDRAULIC’ BINDERS

Family 2(a)Foamix only mixtures

Family 2(b)Emulsion only mixtures

FAMILY 2‘VISCO-ELASTIC’ BINDERS

Family 3(a)Foamix + cementitious/pozzolanic mixtures

Family 3(b)Emulsion + cementitious/pozzolanic mixtures

FAMILY 3‘VISCO-ELASTIC / HYDRAULIC’ BINDERS

Fullyhydraulically

bound


TEST METHODS TO BE CARRIED TEST METHODS TO BE CARRIED FORWARDFORWARD

•• PRIMAPRIMA

•• Norwegian Torsion MeterNorwegian Torsion Meter

•• Geogauge Geogauge

Controls:•• German Dynamic PlateGerman Dynamic Plate•• FWDFWD•• Nuclear Density GaugesNuclear Density Gauges


A36 TOTTON: NTM TESTINGA36 TOTTON: NTM TESTING


NTM: SPIKED BASENTM: SPIKED BASE


GEOGAUGE TESTINGGEOGAUGE TESTING


PRIMA TESTINGPRIMA TESTING


COMPARISON OF IN SITU TEST COMPARISON OF IN SITU TEST EQUIPMENTEQUIPMENT

0

100

200

300

400

500

600

700

800

A1 A2 A3 B1 B2 B3 C1 C2 C3 D1 D2 D3 E1 E2 E3 F1 F2 F3 G1 G2 G3 H1 H2 H3 I1 I2 I3 J1 J2 J3

Locations

Stif

fnes

s, M

pa

0

50

100

150

200

250

300

350

400

Torq

ue, N

.m

PRIMA 29/11PRIMA 30/11GDP 29/11torsion meter 29/11


CONCLUSIONSCONCLUSIONS

•• The development of a performance The development of a performance based specification should broaden based specification should broaden the use of cold recyclingthe use of cold recycling

•• Recycled cold mix material can be Recycled cold mix material can be cored during early lifecored during early life

•• After achieving its design life, the After achieving its design life, the recycled material is in place to be recycled material is in place to be recycled againrecycled again


GORGEOUS BIRDGORGEOUS BIRD

uk experience of in situ recycling with cement for the

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