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New Zealand Airfield Pavement Surface Types – Evaluation, Design, Maintenance and Rehabilitation

John MarshGeneral Manager Airports, Beca Infrastructure Ltd

2010 FAA Worldwide Airport Technology Transfer Conference

April 20th 2010

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Beca Group

Multi disciplinary engineering and management consultancy

Founded in 1917

2,500 employees

Main groups in New Zealand, Australia and Asia

Proud history of successful airport projects since the 1970’s

Over 70 focused and dedicated airport experts

Current major projects in Auckland, Christchurch, Melbourne, Brisbane, Adelaide, Perth, American Samoa, Marshall Islands and various Defence airfields

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New Zealand

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New Zealand

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New Zealand

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New Zealand

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New Zealand

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New Zealand

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Facts and Figures Population 4 million

7 international airports, plus many smaller regional ports

Auckland– 13 million PAX– 156,000 movements

Christchurch– 6 million PAX– 136,000 movements

Wellington– 5.5 million PAX– 112,000 movements

Variety of aircraft from A380 and B777 to small turboprops and GA

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Pavement Surfacing Types

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Pavement Maintenance Issues

Predominantly flexible asphalt pavements other than concrete at Auckland Airport

Usual range of issues with weathering, ageing, fatigue cracking, bleeding and stripping, groove closure, rutting, fuel damage, concrete spalling and fatigue

Challenges of weather extremes from sub- tropical in the north to cooler temperate and alpine conditions in the south

Range of airfield pavement management systems adopted, from simple inspections to more rigorous pavement management systems

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Innovation and Sustainability

Lower population and associated economic challenges has led to a culture of innovation and sustainability

Material recycling– Crushed concrete

– (RAP) Recycled asphalt pavement

– Other fillers considered

Lower grade aggregates– Stabilisation with cement, lime and bitumen

– Used in low importance pavements or base layers

Innovative solutions to construction e.g. slab removal Low energy asphalt mixes

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Auckland Airport: Concrete Technology

Auckland Airport has over 13 million passengers per year

Concrete pavements originally constructed in the 1960’s

Single Runway 05/23 3,635m (11,925’) long

By the early 1990’s pavements exhibiting fatigue cracks and spalling

Areas of slab replacement completed under displaced threshold

Critical central portion needed a new solution

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Auckland Airport

Main Runway 23L-05R

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Epoxy Underslab Injection

Methodology developed to form a stiff beam along each free edge of the cracked slab to delay the time until further deterioration

Challenges with open graded scoria subbasecourse

Laboratory trials, dynamic trials and full scale test strips

Deflections reduced by approximately 15%

Over 1,000 slabs have now been injected

>90% success rate

10 year extension until eventual slab replacement required

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Epoxy Underslab Injection

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Epoxy Underslab Injection

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Expedient Slab Removal

Modified mining loaders

Customised forks

Cutting and lifting slabs

Less noise and debris

600% productivity gains

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Expedient Slab Removal

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Concrete Thermal Monitoring

Research project to determine cumulative temperature hours to develop required flexural strengths

Laboratory testing programme

Concluded insitu 2000 ºC-hours would be sufficient to develop >4.8MPa (700psi)

Monitoring during construction demonstrated required strength achieved in 48 hours

Early opening of the runway reduced disruption to operations

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Concrete Thermal Monitoring

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Christchurch Airport: Asphalt Technology

Christchurch International Airport has over 6 Million passengers per year

Primarily thin asphalt pavement surfacings over unbound gravel base layers and a natural gravel subgrade

Main runway 02-20 with a cross wind runway 11-29 Annual programme of airfield maintenance Collaborative approach to maintenance established with an

airfield works framework with owner, designer and contractor Goal is to safely and cost effectively implement the annual

pavement maintenance works whilst implementing a number of airfield paving innovations and minimising disruption to airfield operations

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Environmental Considerations

Environmental objectives set for the project

Meeting CIAL’s environmental goals (the Southern Hemisphere’s first CarboNZero airport)

Use of recycled materials and low energy asphalt on airfield pavements

Minimal impact on airport neighbors

Establishment of Environment Management Plans

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Sustainable Asphalts

Recycled asphalt pavements

15% to 30% RAP on shoulders and taxiways

Coolpave ™ warm mix AC trialed over the last 3 years

Combination of both

50% to 90% RAP in the future?

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RAP Asphalt Mix Properties

RAP mixes found to be less consistent than traditional mixes

Lower workability and tendency to cool more rapidly

Higher temperatures and softer bitumens have been trialed.

Further evaluation of durability

Mix (Lab Trials) Stability (kN) Resilient Modulus (MPa)

Wheel Tracking (mm)

AC14 14.5 3,500 2.9

AC14 with 15% RAP

18 5,000 1.0

AC14 with 30% RAP

17 5,100 <1.0

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Warm Mix AC Properties

Coolpave ™ technology by contractor Fulton Hogan using LEA Co. System

Placement temperatures under 100ºC (212ºF)

40% reduced energy, lower emissions and safer

Encouraging results, although lower stiffnesses to date and more compactive effort required

Mix (Field Results) Modulus at 4 weeks (MPa)

Modulus at 1 year (MPa)

AC14 2,400 2,900

AC14 with Coolpave 2,000 2,500

AC14 with 15% RAP 3,500 4,200

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Christchurch Airport AC Paving