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1. Runway Resurfacing
And Repairing Using
Modern Materials and
Techniques
PRESENTED BY
AGLAIA

2. Introduction
 The Air craft Classification Number/ Pavement Classification
Number (CAN/PCN) system has been adopted by ICAO as the
standard for the international reporting of air field pavement
bearing strengths .
 The ACN- PCN system of rating air port pavements is
designated by the international civil aviation organization
(ICAO) as the only approved method for reporting strength.
 The ACN- PCN method came in to use in1981.
 The ACN- PCN system is simple to use.
 Each air craft is assigned a number that expresses the
structural effect on a pavement for a specified pavement type
and a sub grade category.
 Each air port operating authority reports site pavement
strengths using the same numbering system.

3.  The pavement is capable of accommodating unrestricted
operations provide the air craft load number is less than or equal to
the pavement strength number. Maximum tire pressure limitations
may also be applied to some pavements which may further restrict
certain air craft operations. The ACN is based on static application
on aircraft loads to the pavement surface making them somewhat
conservative in nature
 The ACN and PCN are defined as follows:
 ACN is a number that expresses the relative structural effect of an
aircraft on different pavement types for specified sub grade
strengths in terms of a standard single wheel load
 PCN is a number that expresses the relative load carrying
capacity of a pavement in terms of a standard single wheel load
 The system is structured so that a pavement with a particular
PCN value can support, without weight restrictions ,an aircraft that
has an ACN value equal to or less than the pavements PCN value

4. Asphalt Applications
 Airfield uses of asphalt
 Most of the world’s paved roads are surfaced with asphalt.
 Asphalt is obtained by fractional distillation of petroleum
crude.
 These materials are also widely used in the construction of
hard standing and parking areas for both light and heavy
vehicles.
 They are therefore eminently suitable for use in the
construction and surfacing of access roads, perimeter roads
and vehicle parking areas on airfields.

5.  Without hard paving, access may be difficult to the airfield,
flying may be restricted in inclement weather or the facilities
may not come up to the minimum standards required by the
regulatory authorities for passenger carrying aircraft. The
following areas on a typical airfield are likely to require hard
paving:-
 • runways
 • taxi-ways providing access to runways
 • aircraft parking, re-fuelling or servicing aprons
 • hanger floors
 • car, bus or commercial vehicle parking areas
 • access roads
 • edge drainage (French Drains) for runways and taxiways

6.  In each of these areas different considerations apply.
 For example, runways require good skid resistance and
surface water drainage for good braking, an even surface
regularity to ensure passenger comfort and minimum risk of
damage to delicate electronic components and adequate
strength to support the high wheel-loadings of modern aircraft.
 Where jet-engined aircraft operate, freedom from loose
particles is an additional, essential requirement to avoid the
expensive damage that can be caused to jet-engines from
ingestion of foreign objects (known as Foreign Object Damage
or FOD).
 This term may also be used for “Foreign Object Debris”
when referring to any detritus or loose particles on or near to
runways or taxiways.

7.  For aircraft parking areas the main requirement is adequate
stability under high wheel-loadings; for paved areas where
aircraft will undergo re-fuelling and servicing, the principal
considerations are adequate stability under wheel-loads and
heavy point loads from maintenance machinery as well as good
resistance to oil spillage.
 Runways need to be constructed with sufficient strength to
carry the moving aircraft. Runways require a higher degree of
resistance to skidding and aquaplaning in view of the higher
speeds involved.
 One means of achieving the latter, now employed on many
major runways in the UK, is to use an open-graded Porous
Asphalt surface course traditionally known as Porous Friction
Course as the running surfacing.
 This acts as a drainage layer to prevent surface water
adversely affecting aircraft tire grip on the surfacing in wet
weather.

8.  Beneath the Porous Friction Course a strong impervious
binder course of Hot Rolled Asphalt or a dense Asphalt
Concrete known as Marshall Asphalt is required laid to
adequate falls.
 Alternatively the new surface course may be laid directly on
an impervious existing surfacing.
 When resurfacing work is being undertaken on runways, it is
essential that the existing surfacing is of good regularity and
laid to adequate falls or the levels are corrected by applying an
appropriate regulating layer.
 This is of particular importance if a Porous Friction Course is
to be applied and ensures that water is not held in the new
surfacing to lead to heavy ice formation in winter.

9.  Where relatively light aircraft are involved standard
road surfacing materials, namely Hot Rolled Asphalt,
close-graded/dense Asphalt Concrete or Stone Mastic
Asphalt specified using the guidance from PD 66911 and
the appropriate European Asphalt Standard will provide
good durability and adequate performance.
 If Hot Rolled Asphalt is employed, a 35% stone
content mix without the application of pre-coated
chippings should give good performance and durability

10. Modern Asphalts
 Most runway resurfacing is carried out at night, with contractors given
access for just a few hours. They do the work in short bursts, completing a
section each night and reopening it the next day.
 It is not surprising, given these constraints, that designers and
contractors tend to stick with tried and tested mixes for the new runway
surface – usually Marshall Asphalt, a continuous graded aggregate mix that
gives a harder surface than traditional hot rolled mixes.
 Nynas has, over the years, developed a number of products that can be
used in runway surfacing and other heavily trafficked areas within airports.
These include binders with high resistance to damage by fuel oils and de-
icing fluids – a major issue for airport managers – as well as binders for thin
surfacing and foam mixes.
 One fuel damage resisting product Nyguard , was used at Bristol Airport
to bring two redundant runways back into use as taxiways and for aircraft
refueling and parking(fig.1). These ancillary areas are seen as lower risk.

11. Nyguard, was used at Bristol airport to bring two redundant runways back
in to use
Nynas has developed the product further to produce Nyguard HR(fig.2), a hot
mix binder specifically designed for heavy duty areas like airfields, docks and
bus bays. As well as its fuel damage resisting properties, the binder gives
cohesion values up to five times greater than equivalent paving grade bitumen,
making it much more resistant to shearing forces and resulting scuffing, tearing
and deformation.

12. Nyguard HR, a hot mix binder specifically design
for heavy duty areas

13.  One issue that may make airport owners more willing to
look at non-traditional mixes for runways is sustainability.
 With local authorities setting targets for recycling, and
commercial firms increasingly aware of waste and energy
consumption, there is increasing pressure to reuse material in
runway resurfacing.
 In a recent contract at Liverpool Airport, Tarmac reused
runway planings for sections of recycled pavement.
 These areas – the outer strips of the runway – were re-
constructed using Nyfoam, a binder specifically developed by
Nynas for foam mixes and used last year on the UK’s largest
road recycling contract on the A38 in Devon.
 The successful application of the technique at Liverpool is
likely to lead to other airports considering recycling for future
resurfacing projects.

14.  While Nynas’ specialist products have so far mainly been
used on ancillary areas, such as taxiways and parking bays,
the company also has experience of supplying specialist
materials for main runways. At Exeter Airport, for example, its
Nypol TS polymer modified binder was used by Bardon in the
construction of a “Super AirMat” runway – a thin surfacing
alternative to traditional Marshall Asphalt.
 Super AirMat contains a 10mm nominally sized grit-stone
with a very high polished stone value to give the surfacing a
high level of grip. The Nypol TS is designed to give good
adhesion and cohesion with the stone, and extra durability
comes from adding cellulose fibres to the asphalt mix.
 The Super AirMat mix was designed specifically for
airfields, and is laid in a single pass, making it a very efficient
way to surface large areas in a relatively short time.

15. Rubber Removal Techniques
The most common methods of pavement retexturing
are:
 High Water Pressure,
 Ultra High Water Pressure (Track Jet),
 Chemical,
 Shot Blasting,
 Mechanical Process.

16. High Pressure Water blasting
(HPW)
 Rubber is removed by means of rotary devices that move along
the surface as it cleans.
 This is done utilizing up to 30 gallons of water per minute at
pressures of between 100 to 1,000 bar .
 The water that penetrates the surface effectively cleaning
rubber deposits creates an hydraulic effect.
 This helps to increase the frictional values and surface texture
of the pavement.
 A combined suction part or a sweeper that picks up the rubber
debris during its operations usually accompanies it.
 This allows for the pavement to be easily and quickly returned
to operations and is especially advantageous in airport operations
where time constraints and short possession time is common.

17. Benefits
 The speed at which rubber is removed (1,200 m² per hour
are claimed).
 The cost efficiency of the process (water is generally
provided).
 The improved friction characteristics of the pavement due
to penetration of the water and the removal of rubber.
 The ease of getting off the runway in the event of an
emergency.
 Its usage is independent of weather and can be operated in
cold, damp wintry conditions.

18. Disadvantages
 Noise from the operation requires the wearing of hearing
protection.
 Eye protection should also be worn in the vicinity of the
machine while in operation.
 Appropriate disposal of waste material is required.
 Does loosen surface matrix encouraging the loss of fine
materials.
 Cleaning rate is 70% with one run.
 Heavily damages certain asphalt types like antiskid.
 Damages grooves and pavement surfaces over time (8
years).
 Damages sealing.
 Cannot be used to clean AGL.

20. Chemicals
 Environmentally friendly chemicals have been developed that are safe
and effective in cleaning rubber from contaminated surfaces. This is done by
spraying the chemicals onto the pavement surface and then scrubbing,
brushing and working them into the rubber deposit over several hours. The
chemicals break down the polymerized rubber into a soft jelly like substance.
 The substance is then flushed off the runway by water blasting when the
process is completed. During this process, the runway cannot be reopened
until the process is completed due to the runway surface being slippery.
 The debris cannot be swept up using conventional sweepers since the
chemicals will react with the rubber seals within the sweeper. Even though
the debris is considered to be biodegradable, the chemical is not and as a
result, the usual method of clean up is: flush the soapy residue off the
pavement surface onto the surrounding soil after completion of works.
 Over time, the debris accumulates and may eventually cause an
environmental problem requiring remediation. The cost of chemical removal
is usually double the cost of HPW and Track Jet due to the cost of the
chemicals.

21. Stress Absorbing Membrane
Interlayer(SAMI)
 Asphalt interlayer system consist of a wide variety of products and
processes, each with unique benefits and specific placement methods to
ensure good adhesion to the underlying pavement. The products may be
classified in a number of categories such as; sand asphalts, grids,
nonwovens, steel reinforcements and SAMIs.
 In general, a SAMI is placed on top of an existing pavement and
subsequently capped with a hot mix asphalt overlay (Fig.6).Its purpose is to
delay the propagation of cracking that originates in the pre-existing pavement
that will eventually reflect through to the new surface layers. Cracking in the
surface layers allows penetration of water, salt and other deleterious materials
that can accelerate the deterioration of the entire pavement structure once it
penetrates the aggregate base.

22. SAMI within the pavement structure

23. “A saturated asphalt concrete is typically unaffected
structurally by water unless the asphalt aggregate is stripping
prone.
In contrast, a saturated base aggregate loses about 40% of
its strength when saturated.”( source: Pavement Preservation
Task Group of Caltrans)
In effect each crack will allow a certain amount of water to
enter the road base hence negatively impacting the original
engineered design.
An effective SAMI should therefore; provide additional tensile
strength to the pavement to combat reflective cracking, be
flexible enough to allow it to move within the pavement
structure as well as providing a waterproof barrio for the
ingress water from the surface to the pre-existing pavement.

24. Constructing a SAMI using the
FiberMat process
 FiberMat is a flexible, waterproof membrane that incorporates
asphalt emulsion and fiberglass strands to combat reflective cracking,
meeting all three requirements of an effective SAMI. Patented
equipment, developed specifically for the FiberMat process, ensures
even distribution of the materials and precise computer controls to
allow adjustments in application rates while the machine is in motion.
 This equipment is contained within a trailer that houses several
spools of fiber glass, the patented cutter assembly system, an asphalt
emulsion pump and distribution spray nozzles, plus the computer
system that controls the application rate of each component (figure7) .
 The unit is pulled by an asphalt emulsion tanker, connecting the
output lines of the tanker to the Fiber Mat machine’s emulsion
pumping system

25. Fig:7. The fiberMat , Application System

26.  The fiberglass strands are pneumatically blown
between two separate layers of asphalt emulsion
(figure8) ensuring complete and even coverage of both
fiberglass and asphalt emulsion(figure9).
 The even distribution of emulsion and fiberglass is
achievable in a swath up to 4m wide (easily covering an
entire lane width).Computer synchronized nozzles and
cutters allow the operator to vary the application width to
accommodate changes in pavement width, tapered
sections and turning lanes. It is possible to place
FiberMat as narrow as 1m to a maximum of 4m (150mm
increments)

28.  To complete the process, it is necessary to imbed a
layer of aggregate in to the second layer of asphalt
emulsion. Aggregate is placed with a traditional chip
spreader and seated using pneumatic rollers.
 The purpose of the aggregate layer is to protect the
newly constructed membrane from vehicular traffic and
construction equipment. The completed FiberMat (SAMI) is
capable of accepting traffic within 20 minutes, and should
be overlaid with hot mix asphalt prior to the onset of
freezing temperatures.
 The unfinished road, FiberMat and aggregate.
 The entire ‘ train’ of equipment consists of the emulsion
tanker, FiberMat trailer, chip spreader, aggregate trucks
and rubber tire rollers

29. CONCLUSION
 Runway rehabilitation scheme requires in-depth study of
problems of formulate repair scheme and to choose suitable
materials and techniques for repair.
 Use of new materials like modern asphalts, SAMI(FiberMat
Type B) to delay propagation of reflection cracks are found to
be a lasting solution.
 However, its long-term performance in context of Indian
climatic conditions is yet to be established and proven.
 However, no guidelines are available with respect to
various methods.
 These are the fields, which needs further studies. In
future, these materials are likely to find extensive usage in
highway and runway work.

30. REFERENCES
 Devendra Kumar., “Runway Maintenance Using modern
Techniques”, IRC Journal of Indian Highways, March 2005,
pp.31-39
 Pawan Kumar and A K Sriinivastave., “Glass Fibre
Reinforced plastic”, Civil Engineering Construction,
November 2002,pp.45-50
 ICAO Aerodrome Design Manual Part 3
 Defence Estates Specification 013 – Marshall Asphalt for
Airfields


31. For more…. Mail to aglaiaconnect2018@gmail.com