EVALUATION OF HOT MIX ASPHALT WITH HIGH DURABILITY
HEE JIN PARK, KATSUYA TOKUMITSU, AKIHIRO KAJITANI
Department of Technical Research Institute, THE NIPPON ROAD CO., LTD., Japanhijin.paku@nipponroad.co.jp , katsuya.tokumitsu@nipponroad.co.jp，
akihiro.kajitani@nipponroad.co.jp

ABSTRACT
Straight-run asphalt has been used as a main binder for asphalt pavement in Japan. The
Hot Mix Asphalt using polymer modified binder (MII-HMA) has set up to resist severe ruttingwith increasing heavy traffic and development of economic activity. Severe rutting has beenstill one of the problems, and then solutions including epoxy asphalt are proposed. Epoxycontaining Hot Mix Asphalt (E-HMA) was developed for the heavy traffic place. E-HMA havehigher rutting resistance than asphalt pavement of polymer modified binder (PMB) butworkers at asphalt plants are sometimes poisoned by epoxy resin. Therefore, the authors
developed polyester additive that can solve the problem of workers safely using highperformance E-HMA.
In this study, we carried out laboratory tests and field constructions to evaluate theperformance of polyester-containing Hot Mix Asphalt (P-HMA). From the results oflaboratory tests and field constructions, P-HMA is confirmed that this has higher
performance than MII-HMA and has the equivalent performance of E-HMA. Therefore, it isconsidered that P-HMA can be applied to the similar construction sites for E-HMA, and thisshould be one of the solutions for the deteriorated sites paved with MII-HMA.
1. INTRODUTION
Hot Mix Asphalt using polymer modified binder (MII-HMA) has been generally used at
highways and national roads that traffic is high volume and/or the logistics parking lots inJapan. However, MII-HMA has problems of severe rutting due to increasing heavy traffic
volume accompanying the development of economic activity, and increase of cargo quantity
in the logistics parking lots. Then, the authors developed epoxy-containing Hot Mix Asphalt(E-HMA) as a countermeasure against severe rutting. The E-HMA has high performanceagainst mixture rutting, stripping, cracking and deflection. Therefore, the E-HMA has beenused for high volume traffic roads and/or logistics parking lots. The epoxy resin used in EHMA is a solid type and it is an oil resin composed of base resin and curing agent, and melts
in high temperature environment. Also, when manufacturing E-HMA at the plant, workers
throw the epoxy resin into a mixer. Then, E-HMA has problems that the epoxy must be putin the refrigerator with inventory below 20℃, and workers are sometimes poisoned by epoxy
resin when manufacturing E-HMA at the plants. Then it is required to develop new materials
for workers’ safety and manageable materials.
The authors developed polyester as new material. It is safer and easier to handle than epoxy.
It is expected that polyester-containing Hot Mix Asphalt (P-HMA) has high pavement
performance. So, it is considered that has high performance as mixture rutting resistance,moisture-susceptibility, flexible deflection resistance, static load resistance.
The performance of P-HMA evaluate in this paper by comparing with E-HMA and MII-HMA
through laboratory tests and field constructions.

[1]26th World Road Congress2. BRIEF DESCRIPTION OF DEVELOPED POLYESTER ADDITIVE
The Picture-1 shows a condition of polyester. Polyester has
high molecules, and it is composed of two kinds ofmolecules; average molecular weight (Mn) 3,800 and weightaverage molecular weight (Mw) 13,000.
The polyester’s characteristics are powder type with particle
size of 1~2mm, glass-transition temperature (Tg) is 57.8℃
and melting point (Tn) is 103.6℃. This is hardened afterpaving because this is a thermoplastic resin.

Picture-1 Polyester
powder

3. LABORATORY TEST
Table-1 shows the evaluated mixtures. The performance of developed P-HMA is evaluatedand compared by using other two kinds of binders.
Table-1

Evaluated Mixtures

Mixtures typeNoteA

・Hot mix asphalt using polyester (P-HMA）

B

・Hot mix asphalt using polymer-modified Ⅱtype (MⅡ-HMA）

Comparison Mixture 1

C・Hot mix asphalt using epoxy (E-HMA）

Comparison Mixture 2―3.1. Test outline
3.1.1. HWT test
Rutting resistance has been generally evaluated using
a wheel tracking test which was originally developed byTransport Research Laboratory (TRL) in Japan. The
wheel tracking test is executed at a temperature of 60℃
and on the dry condition only.
However, in this study, rutting resistance and moisturesusceptibility are evaluated with HWT test as Picture-2
shows. The HWT test is carried out according toAASHTO T324-04 [1], and the test temperature is set
Picture-2 HWT test
at 60℃.This test was carried out using specimens witha diameter of 15cm, a thickness of 6cm, and air void 7% compacted using Superpave
Gyratory Compactor. The HWT test condition is listed in the Table-2. Results of HWT test
are evaluated by rutting depth at the travel completion of 10,000 cycles and stripping
inflection point (SIP). Moreover, rutting resistance index (RRI) is applied to evaluatecharacteristic of rutting resistance and moisture-susceptibility resistance of each mixture inthis study. RRI is showed in Equation 1 [2].

[2]

26th World Road CongressTable-2 HWT test condition
Wheel load(N)Travel speed(cycle/min)Completion travel(cycle)

Temperature(℃)

Air voids of specimen(%)

Condition

Tire70525

10,00060

7

Dry and Water

Stainless steel

RRI = N ×( 1 — RD ) ・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・Equation 1.
Where,RRI : rutting resistance Index
RD : rut depth at completion of the test in, inch. The RD is typically less than 1inch.
N : number of cycles at completion of the test. The maximum N is 10,000 cycles in the test.
3.1.2. Bending test
To evaluate the cracking resistance at low temperature, the bending test [3] has been
conducted in japan. The bending test uses specimens as Figure-1 shows. 30cm×30cm×5cm
size of specimens is prepared first, and this is cut into 4 parts as Figure-1. Then two
30cm×10cm×5cm size of specimens are used for the bending test. The test is done aftercuring at chamber temperature of -10℃ for more than 6 hours. Loading speed is 50mm/min.
Notion of the bending test show in Figure-2.

30cm
Cutting line

10cm

50mm/min

5cm

10cm

20cm

c'b'a'

Compacted direction

cba

10cm

30cm

30cm

From test results, the load and the deformation at
the time of breaking are obtained. And the bending
strength and strain at break can be got from
Equation 2. and 3. with reference to Figure-3.
σ (Pa) = (3l/(2bh2)) × P・・・・Equation 2.

ε (mm/mm) = (6h/l2) × d・・・・Equation 3.

Figure-2 Notion of bending test
PLoad, N

Figure-1 Cutting method of specimen

dStrain, mm

Figure-3 Example of load-strain curve
Where σ is the bending strength of when breaking, b is the width of specimen (mm), ε isstrain of when breaking, h is the thickness of specimen (mm), l is distance between
supporting points (mm), P is the load when breaking (N), d is the center deformation of when
breaking (mm)[3]26th World Road Congress3.1.3. Bending Creep test
In order to evaluate the static loading resistance ofthe asphalt concrete mixture, a bending creep test
was carried out. Applied load is 1/10 of the bending
strength, and the constant load is maintained until
specimen breaks. The specimens are evaluated bytime and deformation amount to specimen broke.
Figure-4 is conceptual of bending creep test, andTable-3 shows conditions of the bending creep test.

408.7N

5cm

10cm

20cm

30cm

Figure-4 Conceptual bending
creep test

Table-3 Conditions of bending creep test
Bending
Strength(MPa)OccuredStress(MPa)50.5

SpanSpecimenwidthb (cm)Loaded loadL (cm)Specimenthicknessh (cm)20510408.7

P (N)

Test
temperature(℃)

203.1.4. Oil resistance test
Figure-5 shows oil resistance test. Thespecimens for the Marshall stability testare prepared. The test specimens forthis test have 3 specimens per mixtures.
These specimens are immersed intogasoline at 20℃ for 48 hours and these
specimens are immersed into water at60℃ for 30 minutes. Finally Marshallstability test [4] is carried out.

20℃, 48h60℃, 30min

gasoline

water

Figure-5 Oil-resistance test

3.2. Test results
The results of the HWT test, bending test, bending creep test, and oil-resistance test aredescribed below.
3.2.1. HWT test
HWT test results in the condition of water and dry are shown in Figure-6. From the HWT test
results on the dry condition, P-HMA showed 1/2 of rutting depth or less of MII-HMA, and has
the same rutting depth as E-HMA. From the HWT test results on the water condition, MIIHMA occurred the SIP at 4,500 cycles and the rutting depth of 4,500 cycles was 5.2mm(0.2inch). E-HMA and P-HMA do not occurred SIP, and P-HMA was 1.3mm less than EHMA. From the above results, RRI is taken and shown in Figure-7. From the Figure-7, PHMA had the high performance than MII-HMA, and P-HMA and E-HMA were found to havehigh of the mixture rutting resistance and the moisture-susceptibility resistance.

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26th World Road Congress

1020

M II -PMA

Ｄｒｙ

E-HMA
P-HMA

P-HMA

Rutting depth(mm)Rutting depth(mm)8

M II -PMA

Ｗａｔｅｒ

E-HMA

64151052000

2,000

4,000
6,000
Travelling cycle（cycle)

8,000

10,00002,0004,000
6,000
Traveling cycle（cycle)

8,000

10,00010,000Dry condition RRI(cycles・inch)

Resistance for mixture rutting

HighFigure-6 HWT test results on the condition of dry and water

9,500

y = 0.2087x + 8087.7
R² = 0.9998
9,000

MⅡ-HMA
8,500

P-HMA

LOW

E-HMA
8,000

0

2,000

4,000

6,000

8,000

10,000

Water condition RRI（cycles・inch）

HighLOW

Resistance for mixture rutting in water

Figure-7 RRI with HWT test
3.2.2. Bending test
The results of the bending test are showed in Table-4. The P-HMA showed as samebreaking stain as MII-HMA. it showed the similar level of bending strength and breaking
strain as the MII-HMA. On the other hand, P-HMA is almost the same as the bending
strength of the E-HMA, but the breaking strain is somewhat low.
From the above, it is considered that the P-HMA has as same cracking resistance as MIIHMA at low temperature.
Table-4 Results of bending test
Mixture TypeBending Strength（MPa）

Breaking Strain

AP-HMA

11.5

4.9

B

MⅡ－HMA

11.4

5.1

CE-HMA

12.3

7.2（×103 ）

3.2.3. Bending creep testThe status and results of bending creep test are shown in Figure-8. From the Figure-8, it
was found that the deformation resistance of the P-HMA has relatively lower resistanceagainst static load of E-HMA but has about 2 times higher resistance against static load thanthe MII-HMA. Then it is considered that P-HMA has a harder performance than the MII-HMA.

[5]

26th World Road CongressElapsed time（h）
0.0

1.0

2.0

3.0

4.0

5.0

6.0

Deformation amount（mm）

04E-HMABroke time：5.3ｈ
812P-HMA
Broke time：0.8h

16M II-HMABroke time：0.46h
20Figure-8 Results of bending creep test
3.2.4. Oil-resistance test
Picture-3 shows the top surface of specimens after the oil-resistance test and Figure-9
shows the test results. P-HMA has lower oil immersion Marshall stability and oil immersion
residual stability than E-HMA. However, P-HMA showed 3.5 times oil immersion Marshallstability and 1.5 times oil immersion residual stability compared to MII-HMA. As a result, theoil-resistance of P-HMA was confirmed higher performance than MII-HMA and P-HMA canbe applied to a construction site where high oil-resistance is required.
MII -HMA

P-HMA

E-HMA

Picture-3 The specimens after test
100

Oil immersion Marshall Stability（kN）

97.3

50

80
704060

59.3
27.7

30
39.4

50
40

21.3

20

1090

30

20
6.1

Oil immersion Residual Stability（％）

60

1000
MⅡ－HMA

P－HMA

E－HMA

Figure-9 Result of resistance-oil test

[6]

26th World Road Congress4. EXAMPLE OF FIELD APPLICATIONS
From the results of laboratory tests, it was confirmed that P-HMA has high performance. So,
the authors applied P-HMA to the field and logistics center parking lot were selected at
Sakata city and Saitama city in Japan.
In the logistics center parking lot where loading and unloading of cargo are repeated at
designated places and severe rutting occurred (Figure-10). Therefore, the authors applied
P-HMA there. In this construction, MII-HMA also paved as a comparative object in order toevaluate P-HMA performance in the field.
Figure-11 shows the results of the survey after 13 months service of E-HMA and P-HMA.
Few rutting and cracking were found at not only parking area of E-HMA but also parking
area of P-HMA. E-HMA and P-HMA are considered having the similar performance.
Figure-12 shows the results of the survey after 6 months service of MII-HMA and P-HMA.
The rutting occurred at the tire position of heavy truck within the parking area of MII-HMA,
and rutting depth was about 8 mm and no cracking was found. The authors could not findrutting and cracking from the parking area of P-HMA.

E-HMA

P-HMA

Figure-11 The survey results after
13months of E-HMA and P-HMA

Figure-10 Condition before
construction

P-HMAMII-HMA

Figure-12 The survey results after 6 months of MII-HMA and P-HMA
5. CONCLUSION
This paper is concluded as follows,
1. From the laboratory test, P-HMA has high performance as mixture rutting resistance,
moisture-susceptibility resistance, flexible deflection resistance, static load resistance.
2. Based on the results of field constructions and survey, P-HMA showed significantly higher
performance than MII-HMA, and showed the same performance as E -HMA.
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26th World Road Congress3. Application of P-HMA is effective for the field requiring high pavement performance.

REFERENCES
1. AASHTO. AASHTO T324-16 : Standard Method of Test for Hamburg Wheel-Track
Testing of Compacted Hot Mix Asphalt(HMA).
2. TRASPORTATION RESEARCH BOARD. Long-Term Field Performance of Warm Mix
Asphalt Technologies. NCHRP RESEARCH REPORT 843(2017). p17
3. JAPAN ROAD ASSOCIATION. Pavement Survey・Test Method Manual Third volume.
pp69-73.2007.
4. JAPAN ROAD ASSOCIATION. Pavement Survey・Test Method Manual Third volume.
pp5-16.2007.

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26th World Road Congress