Recycled Asphalt Pavement– what to look out for?
KATSURA ENDO, DR. ON ENGINEERINGCHIEF RESEARCHERTECHNICAL RESEARCH INSTITUTE
THE NIPPON ROAD CO., LTD.

Prepared for the Argus Pavement Technology Asia 2018, 17-19 October, Pan Pacific Singapore

Topics
1. Introduction
2. Recycled Asphalt Pavement in Japan
3. Recycled Asphalt Pavement Production
4. Point at Issue – what to look out for5. Summary and Recommendations

1. Introduction

Statistical Information of Japan
Area : 378,000km2
Population : 127 million (as of 2016)
Prefectural governments : 47
Nominal GDP : JPY 555.607 trillion (April 2018)
Real GDP : JPY 537.849 trillion (April 2018)
Road network : 1,222,319 km (as of 2016)
Asphalt plant : 914 (as of 2017) = 1.2 plant/500km2- 805 member firms of JAMA only

Changes in Actual Road Length
Total actual road length : 1,222,319 km(as of 2016)
1,000,000

Prefectural road : 185,168 km
Municipal road : 1,028,375 km
 Road length keeps increasing Asphalt pavement is about 95%

Actual Length (km)Expressway : 8,776 km
National highway : 55,565 km

Total Length : 1,222,319km as of 2016

800,000

600,000
First expressway in 1963
400,000

Municipal Roads
Prefectural Roads
Nationa Highway
Expressway

200,000

01956 1961 1966 1971 1976 1981 1986 1991 1996 2001 2006 2011 2016
Fiscal Year

Source : Ministry of Land, Infrastructure, Transport and Tourism, Japan

Changes in HMA Production

41,640 million tons at 2016
Recycled Asphalt Pavement (HMAwith RAP) Production
Increased after 1992

90

With RAP

80

Without RAP

70
60
50
4030
20
100

1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016

Peak was 80,838 million tons at1992

Amount of HMA Production(million ton)Total HMA Production

Source : Japan Asphalt Mixture Association

Changes in Recycled Asphalt Pavement
Production
Adopted by 47 prefectures
With RAP

Exceeded 50%
Exceeded 70%

1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016

% of HMA with RAP

Recycled Asphalt Pavement has beenused as one of the road pavement 100
materials since late 1970s in Japan 90
80
70
It has been used by every 4760
prefectures since 1995
5040
Its amount was exceeded 50% in3020
1998
10
Its amount was exceeded 70% in02005
Its amount is about 76%

Source : Japan Asphalt Mixture Association

Why Recycled Asphalt Pavement Used?
Small national area and very limited landfill
Limited good quality of natural resources, i.e. virgin aggregates‘Waste Management and Public Cleansing Act’ in 1970
Severe regulation of industrial waste including used asphalt concrete3R (Reduce, Reuse, Recycle) policies
‘Law for Promotion of Effective Utilization of Resources’ in 1991
‘Construction Material Recycling Act’ in 2000

 ‘Law Concerning the Promotion of Procurement of Eco-Friendly Goodsand Services by the State and Other Entities’ (Green Purchasing Law) in2001Recycled Asphalt Pavement is one of the procured goods
 Very limited and severe budgetRecycled Asphalt Pavement is cheaper than virgin HMA

2. Recycled Asphalt Pavement in Japan

Recycled Asphalt Pavement
RAP (Reclaimed asphalt pavement)
Virgin aggregatesVirgin asphalt
Rejuvenator Sometimes not used when virgin asphalt has higher penetration value
Note : RAS (Recycled Asphalt Shingles) is not used in Japan

RAP (Reclaimed Asphalt Pavement)
Existing asphalt pavement is removed by milling or removal works
Removed material is hauled to a recycling plant and temporary stored in astockpile
Stockpiles usually do not have roofs

The stored material is crushed and screened, then stored in other stockpilesagain Such stockpiles usually have roofs
 Most maximum size is 13mm in Japan• R13-0 : aggregate size is 13mm to 0mm• R13-5 : aggregate size is 13mm to 5mm• R5-0 : aggregate size is 5mm to 0mm

Specification of RAP in Japan‘Old’ asphalt content : 3.8% or higher by weightPercentage of fine aggregate passes 0.075mm sieve : 5% or less by weightPenetration value of ‘old’ asphalt at 25oC : 20 (1/10mm) or greater
orSplitting strength ratio at 20oC : 1.70 MPa/mm or lessNote: Splitting strength ratio has been specified since 2010.
Above specifications are for R13-0, and it can be calculated from two valuesof both R13-5 and R5-0.

Splitting Test
Cylindrical specimen : 100 mm in diameterand 63.5mm in thickness
Test temperature : 20oC
Loading speed : 50mm/min
2 Pwithin 30 secondTest must be completedσ =Splitting strength :tπ dL
σRss = tx

Splitting strength ratio :P : maximum load (N), d : thickness of specimen (mm), L : diameter of specimen (mm),x : specimen displacement at maximum load applied (mm)Note : This is a similar test method to determine tensile strength of specimen

Rejuvenator
Used to restore aged asphalt to original property
Totally true ?
Effective in second, third, fourth, … generation recycling ?
 Various compounds including oil-based materials

Mixture Design in JapanSet the target values of the design penetration value of combined asphalt orthe splitting strength ratio value
General design penetration value : 50 (1/10mm)
General design splitting strength ratio value : 0.75 (MPa/mm)
Calculate combination ratio of all aggregates including RAP to meet mixture
gradation
RAP content is usually limited by gradation and/or a plant equipment
Determine usage of rejuvenator or new soft asphalt
Rejuvenator is used when RAP content is relatively high, whereas new softasphalt is used when RAP content is relatively lowDetermine Usage of Rejuvenator or NewSoft Asphalt
Penetration Value MethodUsage of rejuvenator or new soft asphalt is determined to meet thedesign penetration value
100

Penetration value of 'old' asphalt(1/10mm)

Penetration value (1/10mm)

100

target penetration value : 50

10target penetration value : 50

1002
4
6810
1214
Percent of rejuvenator (by weight of 'old' asphalt)

16

020
40
60
80
Percent of new asphalt (by weight of all asphalt)

100Splitting Test Method

1.8Splitting Strength Ratio (MPa/mm)

Splitting Strength Ratio (MPa/mm)

Usage of rejuvenator or new soft asphalt is determined to meet thedesign splitting strength ratio value
1.6
1.4
1.2
1.0target value : 0.75

0.8
0.6
0.4
0.2
0.0
02
4
6
8
10
12
14
1618
Percent of rejuvenator (by weight of 'old' asphalt)

20

1.8
1.6
1.4
1.2
1.0
target value : 0.75

0.8
0.6
0.4
0.2
0.0
0

20

4060
Percent of RAP (by weight)

80

100

Determine optimum asphalt content by the Marshall volumetric design
method to meet mixture specifications
Confirm mixture property for rutting resistance by the wheel tracking
testWheel tracking test

• Specimen size : 300mm * 300mm * 50mm
• Tire : 200mm in diameter, 50mm in thickness• Load : 686N
• Loading speed : 42 passes/min• Test temperature : 60oC
• Testing time : 60 minutes or displacement is 25mm

Recycled asphalt pavement is ascribed to virgin HMA if all performanceof recycled asphalt pavement meets specifications for virgin HMA
Some properties like rutting resistance from wheel tracking test shows
greater result than virgin HMA. Is it acceptable ?

3. Recycled Asphalt Pavement Production

Recycled Asphalt Pavement Production inJapan
Almost asphalt plants are batch plants in Japan
Basically three methods
Indirect RAP heating methodDual dryer method
Drum dryer method
Note : Above expressions may not be correct

Indirect RAP Heating MethodVirgin aggregates : Heated by a dryer
RAP : Mixed with heated virgin
aggregates, asphalt and rejuvenatorin the mixer
Heat-exchange mechanism
General RAP content is 30% or less
The higher RAP content, the higher temperature of virgin aggregates
required. This leads to deterioration of recycled asphalt pavement.

Dual Dryer MethodVirgin aggregates : Heated by a dryer
RAP : Heated by another dryer
General RAP content is 30 – 60%

Drum Dryer MethodVirgin aggregates : Heated by a dryer
RAP : Heated by same dryer together
General RAP content is 60% or more

4. Point at Issue – what to look out fora. Mixture design
b. Rejuvenator or soft asphaltc. Recycled asphalt pavement production

Mixture Design
Penetration value of RAP is decreasing
Recycled several times
Increasing polymer modified asphalt (PMA)• Separating removed asphalt material using PMA from all material isimpossible
This is one of the reasons the splitting test method has been introducedSometimes hard to recover aged asphalt to a target penetration value
The splitting test method is under revising currently in Japan

Rejuvenator or soft asphalt
Penetration value is the only performance index for recovered asphalt inJapan
Does rejuvenator work well after only tens of seconds of wet-mixing
and/or tens of minutes of hauling?
Recovering compounds of asphalt (alkanes, aromatic hydrocarbons,resins and asphaltenes) is expected in the U.S.A. and other countries
Some rejuvenators to recover asphalt compounds are commerciallyavailable Is there any problem if RAP is considered as ‘black’ aggregate ?
The splitting strength ratio is thought to follow this concept
A chemical agent has been developed and used. This agent does not affect toasphalt property but acts like rejuvenator with very small dosage• Katsura Endo et.al. : STUDY ON QUALITY IMPROVEMENT OF RECYCLED ASPHALT PAVEMENT, 8th International
Conference on Maintenance and Rehabilitation of Pavements (MAIREPAV8), Singapore, 27–29 July 2016

Recycled Asphalt Pavement Production
a. Ensuring sufficient supply of RAP
b. RAP size control
c. Moisture control of RAP
d. Cost effective ?

Ensuring Sufficient Supply of RAP
RAP can not be produced without
removed existing asphalt pavement
Legislation maybe required
Producing 1 ton of RAP requires
several tons of removed asphalt
pavement
This leads to a kind of limitation ofRAP content
If you want to increase RAP content to drop in production cost ofrecycled asphalt pavement, it requires enough RAP storage

RAP Size Control
It is sometimes difficult to meet a target mixture gradation when uses
R13-0
R13-0 sometimes has small amount of fine particles passing 2.36mmsieve
Using classified RAP ,i.e. R13-5 and R5-0, is one of the solutions, but
R13-5 remains after R5-0 is consumed in this case• This is also one of the reasons that HMA with higher RAP is difficult
to produce

Moisture Control of RAP
Moisture content of RAP affects to heating temperature to evaporate
water well
Case1

Case2

Case3

Moisture Content of RAP (%)

146.5

154.5

163.0

Heated Temperature of RAP (oC)

3.4

2.64.0

Moisture Content of RAP after Heating (%)

2.5

0.40.0Remaining water in RAP leads to temperature drop during hauling HMA
to construction sites and makes recycled asphalt pavement workabilityworseHeating temperature affects to operation cost of a plant
121210864

Moisture Content : 8%
Moisture Content : 6%
Moisture Content : 3%

20

Fuel Consumption Rate (L/ton)

Fuel Consumption Rate (L/ton)

14108642

Note: dryer fuel efficiency is 80%0120140160180
Heating Temperature (oC)200

2200246Moisture Content (%)

810

HMA Production Capability (ton/h)Moisture content also affects to HMA production capability
250
200

Production capability is double,
if moisture content decreases
from 8% to 1.5%.

150
10050

Note: dryer fuel efficiency is 80%

00246Moisture Content (%)

810

Cost Effective ?
RAP producers get both removed asphalt pavement and its disposal fee
from waste generators
Then RAP is cheaper than virgin aggregates and recycled asphalt
pavement is cheaper than virgin HMA
Recycled asphalt pavement is more cost effective if well moisture control
takes place

Summary and Recommendations
1. Introduction• Recycled asphalt pavement has been used since late 1970s and now is amajor HMA in Japan• Recycling-related legislation supported popularization of recycled asphaltpavement

2. Recycled Asphalt Pavement in Japan• Specification of RAP is based on penetration value or splitting strength ratioof ‘old’ asphalt• Mixture design is base on a concept to determine rejuvenator volume ornew soft asphalt content to meet a target penetration value or splitting
strength ratio, and it is conducted through the Marshall volumetric designmethod• Recycled asphalt pavement is ascribed to virgin HMA if all performancemeets specifications for virgin HMA, however some test results arequestionable

3. Recycled asphalt Pavement Production• Most asphalt plants are batch-type and basically three methods in Japan• General RAP content depends on which method is adopted

4. Point at issue – what to look out for• Adaptive mix design to increasing RAP content, several generation ofrecycling and PMA• How to recover aged asphalt ideally with rejuvenator or soft asphalt ,orusing a new agent will be another option• How to ensure sufficient supply of RAP• Better moisture control of RAP leads to better quality of recycledasphalt pavement and more cost effective

Thank you for your kind attention.