asphalt Pavement rehabilitation through recycling

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Asphalt Pavements
Rehabilitation through
Recycling
PRESENTER:
• RAJA ABUBAKAR KHALID
• 2K15-MS-PT-TRANS-05
TAXILA INSTITUTEOF TRANSPORTATIONENGINEERING,UNIVERSITYOF ENGINEERINGAND
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Contents
Introduction.
Advantages of Asphalt Recycling
RAP
Uses of RAP
Addition of additives.
Various Methods of Asphalt Pavement Recycling
Cold Recycling
Hot Recycling
References

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Introduction
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Transportation Modes In Pakistan
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Pavement Distress
Rutting
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Pavement Distress
Cracking
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Existing Practice for Rehabilitation
For the rehabilitation process , existing practice is to mill the
pavement up to the required depth
After that the milled material is dumped at the dumping site.
Thus tons of material is wasted which can be reuse using different
recycling process
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Asphalt Pavement Recycling
Asphalt Pavement Recycling is one way to stretch
existing budgets to maintain, preserve, rehabilitate and
reconstruct more kilometers of roadways.
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Advantages of Asphalt
Recycling
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Advantages of Asphalt Recycling
Conservation of natural resources
Better pavement performance
Reduced traffic disruption, maintained pavement geometry and
thicknesses
Removes cracked and aged pavement layers
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Advantages of Asphalt Recycling
Improves pavement smoothness and cross‐slopes
Maintains curb heights, drainage inlets, and bridge clearances
Creates a rough texture that bonds better with the overlay
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Materials savings will depend on...
Virgin binder cost
Asphalt content of the mix design
Aggregate cost
RAP cost
Asphalt content of the RAP
Percentage of RAP
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Executive Summary of Maintenance /
Rehabilitation Expenditure on NHA Network
Serial No. Maintenance Activity Year
2007-08
Year
2008-09
Year
2009-10
1 Rehabilitation 1,416.55 2,248.23 4,413.93
2
Structural Overlay
(Periodic Maintenance)
1,637.92 1,898.59 1,425.70
3
Functional Overlay
(Periodic Maintenance)
1,676.43 1,812.60 1,973.12
4 Routine Maintenance 809.92 1,278.82 1,190.46
5 Highway Safety 410.00 469.0 650
6
Emergency Maintenance
Allocation
900.00 1,000.00 1,000.00
Total (1 to 6) Rs. Million 6,850.82 8,707.24 10,653.21
Network Length KM 9,893 11,569 11,897
Asphalt Production Cost Categories
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Energy Consumption Related to Road
Construction and Maintenance.
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Economical benefits
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RAP
(Reclaimed Asphalt Pavement)
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What is RAP
RAP= Reclaimed Asphalt Pavement
Removed and/or reprocessed pavement
materials containing:
binder (5%) and aggregates (95%)
Old asphalt pavement that has been removed
from the roadway by either full depth removal or
milling
 High RAP is > 25% by weight of mix.
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RAP as a base material
Roughly equal to granular base with some additional value.
RAP as a Roadbeds
Value is roughly equal to granular
base Replacement Value Plus…
Reduced Haul if processed in place
Conservation of aggregate resources
Overall economics (Fuel Consumption
& Equip. Savings)
This historically accounted for the
largest recycling tonnage
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RAP used in Shoulders
Shoulders Value is greater than
granular material + increased structural
number.
Reduced Haul when processed and left
in place
Conservation of aggregate resources
 Overall economic benefit and less
shoulder maintenance
Energy savings vs. paved shoulders
 Safety of wider shoulder
RAP in new pavement
 Replaces portion of expensive virgin binder and aggregate
Virgin aggregate + asphalt value
costs
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Use of Recycle Pavement in Pakistan
Hot-In-Place Recycling
In the initial instance, projects of Hot-In-Place Recycling were launched on
different locations of Motorway M-2 (M-2 Contract No 207-2006).
Hot Recycling Works on M-2 (Km 90 to 330), July 2007.
Cold In-Place Recycling was experimented on
Kharain–Rawalpindi Project (51 KM, Contract No 13),
 Mian Channu-Sahiwal-Okara (72 Kms, Contract Package No.11b).
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Use of additives
Foamed Bitumen
Used as a binder for
Cold mixes with reclaimed Asphalt
pavement (RAP) materials.
Specialist surface dressing
Conventional cold mixes with good
quality or marginal aggregates

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Foamed bitumen
The product of hot bitumen meeting with
small amount of cold water ,
 creating thin bubbles of bitumen to bond
 with pulverized base materials.
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Emulsified Bitumen
A mixture of asphalt cement, water and emulsifying
agent (free flowing liquid at ordinary temperature).
These three constituents are fed simultaneously into
a colloid to produce extremely small globules (5-10µ)
of asphalt cement, which are suspended in water.
The emulsion contain about 50% - 65% bitumen.
Has low viscosity at ambient temperature, it
generally can be used without additional heat.

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Various Methods of Asphalt
Pavement Recycling
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Various Methods of Asphalt Pavement
Recycling
To describe the various asphalt recycling methods, six
broad categories have been defined by Asphalt Recycling
and Reclaiming Association (ARRA), U.S. Department of
Transportation, Federal Highway, Administration.
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Cold Planning (CP)
Cold planning is the controlled removal of an existing
pavement to a desired depth, longitudinal profile, and
cross-slope, using specially designed equipment. The
resulting textured surface can be immediately used as a
driving surface, can be further treated with one of the other
asphalt recycling methods, or once cleaned and tack coated,
overlaid with HMA or recycled mix. In addition, CP can be
used to roughen or texture pavements to restore low
friction numbers and eliminate slipperiness.
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Hot Mix Asphalt Recycling (Central Plant)
Hot recycling in central plant is the process of removing the
existing pavement, combining RAP with new or “virgin”
aggregates, new asphalt binder, and/or recycling agents (as
required) in a central plant to produce a recycled mix. Hot
recycling of RAP currently is the most widely used asphalt
recycling method in the world.
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Cold Mix Asphalt Recycling (Central Plant)
In this process RAP material is mixed with new asphalt binder
and new aggregate (if needed) to produce cold, recycled mix
without application of heat. Recycled mix is produced at a
central location using a stationary clod mix plant. The cold
central plant recycling mix can be used immediately or it can
be stockpiled for later use in such applications as maintenance
blade patching or pothole repair.
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Full Depth Reclamation (FDR)
The recycling method where all of an asphalt pavement section, and
a predetermined amount of underlying materials, are treated to
produce a stabilized base course. In this process existing pavement is
pulverized, introduce additive and mix, mixed material are compacted
and a wearing course is finally applied on it.
Distresses and problems like loss of bonding between pavement
layers, stripping loss of surface integrity due to raveling, potholes,
bleeding, excessive shoulder drop off, inadequate structural capacity
are effectively treated with this method.
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Cold In-place Recycling (CIR)
In this process existing pavement materials are removed,
mixed with stabilizing agents, virgin materials (if required) and
reused in place. Cold in-place recycling is undertaken on site
and generally uses 100 percent of the RAP generated during
the process.
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Cold in-place Recycling
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Single pass Equipment Train
The usual components are
A cold milling machine,
 Portable crusher,
Travel-plant mixer,
Laydown machine
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Cold in-place Recycling
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Initial compaction by Screed Compaction of CIR layer
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Cold milling machine
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Portable Crusher attached to Cold-milling Machine.
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Laydown machine
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CIR Train at work
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Hot In-place Recycling (HIR)
In this process existing asphalt surface is heated, soften and
scarified to a depth, typically from 20 to 60 mm (25 mm most
common). Scarified material is combined with virgin aggregates,
asphalt binder, and/or recycling agent on the requirement basis
and finally compacted.
Mostly surface defects i.e. Raveling, Potholes, Bleeding, Friction
number, Rutting, Corrugations, Shoving, Slippage, longitudinal
transverse and reflection cracking, poor ride quality caused by
swells, bumps, sags, and depressions are effectively treated with
this method of recycling.
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Hot-in-place Recycling (HIR)
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Pre Heating Unit Wirtgen’s recycling train

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Re mixing Unit
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Scarifying / Heating unit

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New HMA placedin remixing unit
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References
Asphalt Pavement Recycling with Reclaimed Asphalt Pavement
(RAP),Stephen J. Cooper Federal Highway Administration NWPMA, 18th
Annual Fall Pavement Conference.
Basic Asphalt Recycling Manual, 2001
Development of guidelines for Asphalt Recycling in Pakistan, Pak-U.S, S&T
cooperative program Symposium,2013.
Reclaimed Asphalt Pavement in Asphalt Mixtures: State of the Practice,
Publication No. FHWA-HRT-11-021,April 2011.
Utilization of RAP, North Dakota Asphalt Conference April 7, 2010 Bismarck.
Wirtgen Cold Recycling Technology, 1st Edition 2012.
http://www.pavementinteractive.org/article/hot-in-place-recycling/

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asphalt Pavement rehabilitation through recycling

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