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New technology leads to savings on underwater pile encasements at Barron River BridgeStephen Day

Civil Engineer, Program Delivery and Operations |

Department of Transport and Main Roads

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Overview

1. Introduction/background2. Phase 1 – Initiation 3. Phase 2 – Options review 4. Phase 3 – Market exploration 5. Phase 4 – Monitoring 6. Phase 5 – Finding a solution 7. Phase 6 – Project delivery 8. Conclusion.

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Introduction

Purpose• Outline 15-year search for cost-effective treatment for

Alkali Silica Reaction (ASR) cracking in underwater piles• Provide information on Fibre Reinforced Plastic (FRP)

pile jackets• Highlight potential benefits of new technology

Cost savings Technical advantages.

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The structure

Barron River Bridge (ID 7779) on Captain Cook Highway• Seven-span prestressed concrete (PSC) bridge on

major arterial highway (16,000 vehicles per day)• Constructed in 1977• 176.5 m long, 10.4 m wide• Blade piers founded on driven PSC piles (10 per pier).

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Barron River Bridge (BIS ID 7779) aerial view

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Barron River Bridge (BIS ID 7779)

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The structure

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The structure (cont.)

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Phase 1 –Initiation 2000–2003

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Project initiation 2000-2003

Date Work Activity Outcome

Nov 2000 Concrete Technology (CT) Report No.1 Investigation

Chloride induced corrosion Cracking in Piles

Nov 2001 Level 2 Inspection Bridge in poor condition

Jun 2002 CT Report No. 2 Remedial Works

Pier Repairs and Cathodic Protection (-> 2006)

Nov 2002 Underwater Inspection (Eight piles)

Vertical/horizontal cracks Up to 15 mm

Dec 2002 Treatment Options reviewed (Principal Engineer (CT)

FRP – no underwater epoxyReinforced Concrete (RC) encasement preferred

Jan 2003 Underwater Inspection (Seven piles)

Similar crackingProblems with spacing of piles

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The issue

ASR cracking in PSC piles in marine environment• Potential for premature corrosion – loss of service life• Uncertainty with extent of corrosion in prestressed steel • Other piles likely to suffer same fate.

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Preferred treatment

• Pile encasement Seal existing cracks Inhibit Cl, H2O, O2 ingress Increase internal pressure to limit ASR.

• Pile encasement options Traditional Reinforced Concrete (RC) FRP jacket.

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Ref: McGuffin et al. Feasibility of a New Pile Rehabilitation System

14 |14 | Engineering Technology Forum 2016 | 10 June 2016

15 |15 | Engineering Technology Forum 2016 | 10 June 2016

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Phase 2 –Options Review2004–2005

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Options review (2004-2005)

Date Work Activity OutcomeMar 2003 FRP Prototype Feasibility

Project concludedFRP prototype utilising mechanical (finger) locks not yet viable

May 2004 Options Review Meeting FRP Jackets preferredConsider staged repairs

Aug 2004 Remaining Piles Inspected 13 of 40 piles flagged for Stage 1 repairs

Aug 2005 2005 Technical Forum Paper by Carse/Hamilton

Awaiting market development in FRP Jackets

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Underwater inspections (2002-04)

• Three separate inspections summarised in a Defect Map

• 13 of 40 piles severely cracked

• Remedial treatment recommended for severely cracked piles.

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Benefits of FRP

• Potentially significant cost savings• Slimmer design (80 mm versus 200 mm)• No reinforcement• Simplified construction for placement of grout• Impermeable barrier • Excellent confinement strength.

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Prototype FRP solution

Source: A. Carse (2007) – Joint Project (DTMR/USQ )

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Prototype test – rupture of fins

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Phase 3 –Market exploration2006–2008

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Market exploration (2006-2008)

Date Work Activity OutcomeMay 2006 Expression of Interest

(EOI) process proposedWorks package – four sites (Barron plus three other bridges)

Mar 2007 EOI Called Four submissions (No FRP)

Jun 2007 Design Development (Double ECI (Early Contractor Involvement))

Two companies engaged

Aug 2007 Design submissionsPreferred design selected

Pricing for Barron piles 0.50m v $1.4m

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RC Encasement

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Market explorationDate Work Activity OutcomeOct 2007 Project split into 2 Contracts:

1. National Highway (three bridges)

2. State roads (Barron River bridge)

National Highways Contract awarded and completed

Feb 2008 Tendered Price for Barron R increases 400% to $2.0m

Barron River Contract abandoned pending developments in FRP jackets

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Phase 4 –Monitoring2008–2014

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Monitoring 2009-2014

Date Work Activity OutcomeVarious L2 Inspections

Aug 2014 Underwater Inspection 22 piles now crackedPiles cleaned

2014 Underwater Inspection• Total cost $0.15m

Installation of crocodile protection (30%) Cleaning (50%) Inspection (20%)

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Underwater inspection 2014

• Results overlaid on original Defect Map

• 22 piles now exhibiting severe cracking (previously 13)

• Other piles with minor cracks.

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Phase 5 –Finding a solution2014–2015

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Finding a solution 2014-2015

Date Work Activity OutcomeAug 2014 FRP Treatment Review PileMedic identified as a

candidate treatment

Oct 2014 PileMedic proposal Cost Estimate - $1.1m Project planning initiated

Feb 2015 Funding secured (Element 19 – Structure Rehab)

All 40 piles

Mar 2015 Structure Management Plan (SMP) submitted and approved

Project prioritisedFunding reallocated

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FRP solution – PileMedic

• Pilemedic jackets Thin preformed FRP laminate sheeting Seamless cylindrical shell (two layers) Underwater-curing epoxy

• Advantages• Rapid underwater installation• Impermeable barrier • High confinement strength• Cost savings

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FRP solution – PileMedic

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PileMedic pile jacket

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Phase 6 –Project delivery2015

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Project delivery

Date Work Activity OutcomeApr 2015 Contract – Materials Supply

Sole InviteeBuilding Services Brisbane/ Quakewrap($0.284m)

May 2015 Contract – Construction Sole Invitee

Roadtek($0.51m)

June 2015 Site works commenced

Aug 2015 Site works completed

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Supplementary specification

• Work Items 9001.01P - Cleaning of Piles 9002.01P - Install PileMedic Pile Encasement 9003.01P - Supply and Deliver Pile Encasement Material 9004.01P - Install Grout

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The economicsEstimate Year Value 2015 ValueInitial SMP Estimate (FRP) 2007 $0.75m $0.95m

RC Encasement OptionEOI Preliminary Design

(Alternate Supplier)2008 $0.5m

($1.4m)$0.61m($1.72m)

Tendered Price 2008 $2.0m $2.46m

Final FRP OptionProject Estimate 2015 $1.1m $1.1mFinal Project Cost 2015 $0.95m $0.95m ($24k/pile)

Estimated Savings - $1.5m (160%) over tendered RC, - $0.77m (80%) over RC alternative

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The project teamGroup Role Team member

TMR Far North District Project initiation, development and management

Stephen DayKarl Alolod

Structures Branch Technical review and approval

Faisal Mir

Roadtek Works delivery Coordination of works

Andrew Schelberg

Commercial Divers (JD Marine)

Underwater works

Product Supplier (Building Solutions Brisbane)

Technical advice Training of works team

Tony White

Manufacturer (Quakewrap) Technical support Professor Mo Ehsani

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Conclusion

Learnings• Significant savings can be achieved by utilising new

technologies• FRP pile jackets are a cost-effective option for pile

encasement, particularly for: underwater installation where access is restricted.

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Conclusion (cont.)

Learnings• The “do nothing” option can be an effective asset

management strategy • Explore and embrace new technology – but do your

homework• A good team working together is essential when

introducing new technology.

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Thank you