XÁC ĐỊNH THÀNH PHẦN VẬT LIỆU HỢP LÝ LỚP BÊ TÔNG NHỰA TẠO NHÁM MẶT ĐƯỜNG CẤP CAO

-0-

THE MINISTRY OF EDUCATION AND TRAINING
UNIVERSITY OF TRANSPORT AND COMMUNICATION

*****
NGUYEN PHUOC MINH

RESEARCH ON IDENTIFYING THE PROPER
COMPONENTS FOR THE FRICTION COURSES
ASPHALTIC CONCRETE COVER OF HIGH TYPE
ROADS IN VIETNAM
Major: Civil Engineering
Program Code: 62.58.30.01
SUPERVISORS
1-Dr. Tran Tuan Hiep, Assoc. Prof
2- Dr. Vu Duc Chinh, Assoc. Prof

ASTRACT DOCTORAL THESIS

Hanoi - 12/2013

Hanoi, December 2013


-1INTRODUCTION
1. Overview
To facilitate the social economy and the industrializing-modernizing process,
Vietnam has been investing in a high-type and motorway system.
The motorway system in Vietnam is due for completion in 2020 and will be
covering the whole country with a total length of 6000 kilometers. Arterial

motorway routes such as Hanoi – Ninh Binh, Hanoi – Lao Cai, Hanoi – Hai
Phong, Saigon – Trung Luong, HCM City – Long Thanh – Dau Day are on the
way to utilization.
The motorway routes allow vehicles to speed over 80km/h. With such velocity,
all motorway routes have to be up to standards, including high roughness,
eveness and dewatering capacity, among which roughness plays a crucial role.
In developed countries, motorway covers are constructed with hollow asphalt
possessing high roughness, which demands specialized and high-cost
technology.
In Vietnam, asphalt concrete covers have been put into use on some motorway
routes despite being at testing stage. Our country also suffers from having to
depend on expensive foreign technology.
The biggest question now is to fully grasp the manufacturing technology for
friction courses asphalt covers to meet the demand of thousands kilometers long
high type roads and motorways nowadays. This issue proves a serious challenge
for Vietnamese constructor.
To achieve mastery of the aforementioned technology, we must prioritize
researches into determining the proper components for friction courses asphalt
so that our constructions reach the right poroxity, the durability as well as the
required roughness and agree with specific conditions in Vietnam. The thesis
“Research into determining the proper components for the friction courses
asphalt cover of high type roads in Vietnam” exists to solve these urgent
practical scientific issues.
2. Research purpose: To determine the proper components used in constructing
friction courses asphalt covers for high type roads in Vietnam with Open Graded
aggregate, residual void ratio ranging from 16%÷18 and to give out technical
standards for the friction courses asphalt cover components in order to adapt the


-2designing, manufacturing and constructing technology, meanwhile suggesting

solutions to the enhancement of the friction courses concrete material for high
type roads in Vietnam.
3. Research subject and scope
 Subject: on friction courses asphalt components with high poroxity and Open
graded aggregate.
 Scope:
+ The study of friction courses asphalt components means to combine
highway engineering theories with asphalt components utilization
experiences both worldwide and in Vietnam, to investigate and evaluate
highway surface status, local material, geographical and climatic
conditions in the Southern area;
+ To carry out both in-lab and field empirical researches to suggest the
proper components of friction courses asphalt and other relevant matters
in order to raise the quality of friction courses asphalt components;
4. Theoretical and practical significances of the thesis
This thesis brings forth contents regarding:
 Theoretical significance
4.1 General researches on the utilization of friction courses concrete for
highways both worldwide and in Vietnam;
4.2 Establishing mixed components with specific technical requirements for
composite material and publishing technical regulations for friction courses
asphalt components;
4.3 Determining the proper components for friction courses highway asphalt on
the base of empirical researches to indentify physical-mechanical criteria for
friction courses asphalt mixtures;
4.4 Researching on solutions to the enhancement of the quality of friction
courses asphalt components through the following tasks:
 To research on determining the relation between the residual voide ratio
and the macro-texture of friction courses asphalt covers;
 To research on the relation between the macro-texture and the waterabsorbing quality;

 To research on the effects of the aquaplanning phenomenon on driving
conditions;


-3 To research on determining changes in the time-dependent macro-texture
of the friction courses surfaces of some motorway routes in Vietnam;
 To research on the effectiveness of increasing the macro-texture and the
water-absorbing level of road surfaces by employing high-pressure
cleaning technology; to establish and suggest a periodical maintenance
routine for friction courses road surfaces;
 To research on solutions to enhancement of the quality of friction courses
asphalt components utilization across all stages: manufacturing,
constructing; supervising; quality acceptance; management of friction
courses asphalt components utilization.
 Practical significances
 The thesis has generally considered utilized friction courses asphalt
components in other countries and in Vietnam;
 Drafting a designing workflow and a new method for determining proper
components for friction courses asphalt covers that agree with utilizing
conditions in Vietnam
 Drafting empirical methods of evaluating physical-mechanical criteria for
friction courses asphalt components; limiting technical requirements of
materials used for the design of friction courses asphalt components;
 Suggesting solutions to increase utilization quality of friction courses
asphalt covers for high type routes in the Southern area.
5. Structure
This thesis consists of the following chapters:
+ Chapter I: Overview of friction courses asphalt.
+ Chapter II: Establishment of friction courses asphalt components serving the
empirical research purpose.

+ Chapter III: Empirical researches on determining physical-mechanical criteria
for asphalt mixtures and selecting the proper components of these mixtures.
+ Chapter IV: Researches on increasing the utilizing quality of highway friction
courses asphalt components.
*********
Chapter 1: OVERVIEW OF FRICTION COURSES ASPHALT
General researches on high type highway and motorway routes friction courses
asphalt consist of the following points:


-41.1 The structure and components of regular asphalt v
a-Asphalt structure
● Microscopic structure: consist of plastic and mineral powder to form asphalt
binder.
● Neutral structure: consist of sand and asphalt binder, forming asphalt mortar.
● Macroscopic structure: consist of ballasts and asphalt mortar, forming asphalt
mixture.
b- Asphalt mixture components
+ Aggregate, with the greatest particle size.
+ Binde
1.2. Open Graded Friction Courses Asphalt
1.2.1 Aggregate
OGFCA (Open Graded Friction Courses Asphalt) is a form of skeleton
macroscopic structure (picture 1.3), the mixture consists of large aggregate, with
few or no small aggregate and mineral powder and is designed so that the
compacting component can achieve residual void ratio ranging from 18%÷25%;

Picture 1.1: The structure of OGFCA mixture and some images of regular
asphalt and OGFCA.
1.2.2 Binder: mostly use enhanced bitum.

1.3 Factors affecting the rugosity
1.3.1 Notion
+ Micro-texture: is the hard-to-see surface roughness of aggregate that can
eliminate the aquaplaning effect.
+ Macro-texture: create drain channels
1.3.2 The effect of aggregate on the rugosity
 Factors affecting macro-texture.
 Factors affecting micro-texture.
1.3.3 Other factors affecting the rugosity
Designing the material; construction process; utilizing characteristics.


-51.4 Overview on Open graded friction course asphalt
1.4.1 Concept of Open graded friction course asphalt
Open graded friction course asphalt has different names over the world such as:
Porous Asphalt (PA), Porous Friction Course (PFC), Open Graded Asphalt
Concrete (OGAC), Open Graded Friction Course (OGFC), Porous European
Mix (PEM).
1.4.2 Characteristics of Open graded friction course asphalt
a/ Reduce spray and spindrift, slips on wet road surfaces
b/ Reduce light reflection and head light glare
c/ Reduce vehicle noises
d/ Increase road surface sliding resistance
e/ Reduce wheel tracking
1.4.3 Analyzing and evaluating the utilization of Open graded friction
course asphalt in other countries
Open graded friction course asphalt has been utilized in other countries from the
1930s, most popularly in the late 1980s. The OGFCA utilizing statuses are as
followed.
a/ In America

● OGFCA from NCAT (National Center For Asphalt Technology-Mỹ)
States in America have had experiences in using OGFCA since the late 1970s.
+ Utilizing status of OGFCA in NCAT is as followed:
 Aggregate abrasion resistance PSV (Polish Stone value);
 Particle size dmax= 9,5÷19mm among which d=12,5 mm is used regularly;
 Using polymer; bitumen content varies from 5÷7%, and fibrous admixture.
 Residual void ratio of the mixture 15÷25%.
 The thickness are 2÷5 cm thinner than compacted asphalt
 Wheel tracking is averagely 1,25cm deep after 10-12 years.
 Utilizing life 8÷12 years with OGFCA depth h=5 cm.
 Maintaining OGFCA rugosity: by using high pressure pump to clean the
surface
● Arizona
Arizona has been experimenting Open graded friction course asphalt since 1954,
in the 1960 the result was positive, so OGFCA has been utilized across the
whole state.
● Oregon


-6In the late 1970 the State of Oregon-America (ODOT-Oregon Department of
Transportation) has been experimenting OGFCA on heavy load routes with
speed limit more than 80km/h and equipped with bitum polimer. ODOT has
susggested using OGFCA as a thin layer and does not audit the material to the
pavement structure.
● California and Georgia
In 1944 Caltrans-California Department of Transportation used OGFCA as a
surface dewatering layer. Caltrans used the mixture with particle size dmax=9,5;
12,5; 25mm, residual void ratio min 18%. The most regularly implemented
thickness is 3,0 ÷ 4,5cm; particle size dmax=25mm, allowing the increase of
thickness to 5,0 ÷ 8,0 cm, and since 2006 Caltrans has allowed the act of

directly covering OFGCA layer on compacted asphalt.
● Georgia
The State Georgia (GDOT-Georgia Department of Transportation) has been
using OGFCA since 1950. Currently there are two types of OGFCA that GDOT
uses:
Type 1- OGFCA with two different particle size dmax=9,5 and 12,5mm,
designed thickness 2,0 cm, mixed residual void ratio 18-20%;
Type 2- European-based OGFCA with thickness 3,0cm and mixed residual void
ratio 20-24%. GDOT uses OGFCA as the cover for interstate routes and
highways with two-way traffic volume reaching 25.000 vehicles daily on
average. With particle size dmax=12,5mm, utilizing life 10÷12 years.
Summary: OGFCA has been utilized since the 1930 and the material possesses
many strengths as a friction generating layer on motorway routes in America;
yet there are unsolved weaknesses, which is the ability to maintain residual void
ratio and the time-dependent dewatering capacity downgrade phenomenon.
Moreover, the technical criteria of designing components for OGFCA and the
thickness of component layers in the states of America have not been agreed
upon but rather depend on specific climatic, load conditions and material
availability.
b/ Europe
European countries such as Denmark, Holland, Australia, Belgium, Switzerland,
England and Spain have been using OGFCA for motorway routes. According to
an accumulated report by Huber-NCAT in 2000, Europe hasn’t had a single
designing criteria for OGFCA. The OGFCA mostly used in Europe is Porous


-7Asphalt – PA with noise-reducing quality. Two Porous Asphalt layers are
utilized on high speed routes. The material is suggested not to be used as layers
in city areas, with vehicle speed below 45km/h, which means the void layers in
these area become congested easily;

In Holland, Denmark, Belgium and France, OGFCA are used or experimented
dual-layered, including: the below void layer has particle size d=11-14 mm with
thickness from 4,0 to 5,0 cm, the upper compacted layer has particle size d= 6-8
mm with thickness 2,5-3,0 cm.
Designed void ratio from 19÷25%, polimer is the binder, bitumen contentfrom
4,5% to 6,5%, thickness 3,0÷4,0 cm. The material is used for noise reduction
and dewatering purpose.
● Belgium, Spain, England
OGFCA is used as the cover for motorway routes.
Designed void ratio from 18÷ 25%, aggregate size dmax=9,5÷12,5mm; bitum
polimer is used, bitumen contentfrom 4,5% to 6,5%, OGFCA thickness
3,0÷5,0cm. Used for noise-reduction and dewatering purpose.
Aggregate and mixture technical criteria include:
+ Polished Stone Value PSV, attrition value Los Angeles ≤ 20%;
+ Puddled Marshall 50 tampers/layer; + Residual void ratio ≥ 20%.
+ Attrition value Cantabro: ≤ 30%;
+ Compaction model based on the Marshall 50 tampers/layer method.
Summary: European countries have been using OGFCA from the 1980 on
motorway routes and this proves highly effective for increasing surface sliding
resistance; additionally for noise reduction and dewatering capacity.However,
there are weaknesses in the decreasing residual void ratio of OGFCA, which is
hard to control and can negatively affect the rugosity; OGFCA is also not listed
as part of the pavement structure thickness calculation.
c/ South Africa
South Africa requires the aggregate as followed: PSV > 50%, the amount of
water absorbing the aggregate < 1%; equivalent sand ES > 45%, dual-sided
grinding 90-100%,
Compaction model: based on the Marshall 50 tampers/layer method; residual
void ratio: 18-22%; unregulated gum melting index, Cantabro loss: max 25%30%; bitum polimer is used:SBR-Styren Butadien Rubber, synthetic fiber and
natural rubber.

-8d/ Australia
The designed OGFCA consists of three mixtures; symbol: OG-10, OG-14 and
OG-20. OG-I and OG-II differ in the designed traffic volume; between which
OG-II has an additional use of fibrous admixture and is recommended for routes
with traffic volume higher than 5x106 standardized vehicles and over 500
vehicles/lane/day.
Technical criteria and requirements:
Attrition Losangeles, LA, %: max 12%, dual-sided grinding, %: max 100.
bitum polimer serves as binder: 80/100 + SBS hoặc or synthetic fibrous
admixture, rubber powder; bitumen content(%): 4,0% - 6%; compaction model:
based on the Marshall 50 tampers/layer method; residual void ratio, %: min
18%-23%; unregulated gum melting index; attrition value max 25%-30%;
unregulated waterproof index.
e/ Asia
● Japan, Korea, India, Malaysia
Japan, Korea, India and Malaysia consider this material highly due to its benefit
when used as friction generating layer on motorway routes. They have adapted
the European technical criteria and apply the material. The tar used is polimer,
aggregate and fibrous admixture; Marshall 50 tampers/layers compaction model.
Technical criteria for OGFCA in Japan include:
Residual void ratio: 18-22%; bitumen content: 4,4÷4,6%; waterproofing
capacity: 52÷56 mm/sec; gum melting index: ≤ 0,3%; Cantabro loss: 17÷23%;
indirect tensile strength (ITS): 5÷10 kg/cm2;
Summary: Australia or South Africa or the countries of Asia can develop the
use of OGFCA on motorway routes thanks to the utilizing experiences in
America or in European countries. Although OGFCA is utilized effectively;
most technical criteria for designing components, component layer thickness,
utilizing life characteristic evaluation have not been agreed upon, but rather are

decided from practical uses.
 Collecting and analyzing the overview result from other countries’
researches
1) Design method: Marshall method, design residual void ratio min 18%;
2) Cantabro loss value or gum melting index is used as the limiting value when
designing the OGFCA;


-93) Technical criteria for OGFCA are not agreed upon, OGFCA is also not listed
as part of the pavement structure loadbearing calculation. This are the main
characteristics that need thorough study due to the conditions in Vietnam.
f/ Utilization of friction courses asphalt in Vietnam
In Vietnam, the use of friction courses asphalt has been experimented to
enhance the surface rugosity since 1994. The overview status of researching on
friction courses asphalt in Vietnam is as followed.
1-Experiementing hollow asphalt on the section connecting Northern Thang
Long – Noi Bai
In 1994 The Institute of Transport Science and Technology cooperated with
ESSO to carry out preliminary researches and construct a pilot section using
hollow asphalt as the OGDM (Open Graded Drainage Mix) throughout the
section beween Northern Thang Long – Noi Bai.
3-Friction courses asphalt produced with Novachip technology
The thin layer using Novachip technology as a friction courses layer on
motorway routes or high type roads, Novachip layer thickness from 1,25÷2,5cm,
this layer is not added to the calculation of pavement structure loadbearing
capacity. The layer has been built for the motorway route between HCM City –
Trung Luong.
4- Asphalt with high rugosity based on 22TCN 345-06
High rugosity asphalt with thickness from 2,0 to 3,0 cm are used for: motorway,
high type roads (speed limit over 80km/h), in order to increase the rugosity and

the surface sliding resistance. This is the material used to construct the friction
courses layer for the motorway route between HCM City – Long Thanh – Dau
Day.
1.5 Chapter 1 conclusion
There are many positive benefit as well as limitations to the utilizing
characteristics of OGFCA as the road covers on motorway routes or high type
roads; so from the result of general researches, some conclusions can be drawn:
1. Countries using OGFCA with the maximum aggregate size, limiting
technical criteria, thickness, residual void ratio depend much on their own
conditions.
2. In Vietnam friction courses asphalt has been implemented; the residual void
ratio of friction courses asphalt ranges from 12÷16%. OGFCA is only at the


- 10 stage of experimenting the technical criteria in-lab and checking field
rugosity;
3. Based on the researches on friction courses asphalt both worldwide and in
Vietnam, along with thorough analysis; the thesis has been able to
determine the proper component for friction courses asphalt as well as
suggest technical requirements on the components and the technical criteria
for friction courses asphalt for high type roads in Vietnam.
***********
Chapter II: ESTABLISHING THE FRICTION COURSES ASPHALT
MIXTURES TO SERVE EMPIRICAL RESEARCH PURPOSES
To establish the proper mix of the components, two steps need to be taken:
+ Step 1: Establish some options for the components of friction courses
asphalt mixtures serving empirical researches;
+ Step 2: Perform in-lab experiments, prepare samples, compress samples
according to different mix options from step 1 and counter samples
(chapter 3) to determine the essential physical-mechanical criteria of

friction courses asphalt so that proper components for friction courses
asphalt can be determined.
2.1 Basic requirements for friction courses asphalt
Ensure utilizing life; reduce yieldings and cracks caused by fatigue, avoid
segregation when spreading due to the major raw aggregate which plays an
important role to the friction surface structure.
2.2 Selecting aggregate
2.2.1 Technical characteristics required for aggregate
Quality requirements for aggregate: wear-resistant quality; cubic, angular (onesided grindind index), mixed aggregate.
2.2.2 Aggregate requirements for OGFCA
+ Maximum particle size and OGFCA mixture:
The doctoral student suggests the maximum particle size Dmax of OGFCA in
Vietnam as 9.5mm, named Open Graded Friction Course Asphalt-OGFCA;
symbol: OG-X.d: with X as the suggested mix, d as the maximum particle size.
OG types suggested: OG-A.9,5, OG-B.9,5 and OG-C.9,5
+ Mixed components


- 11 Components in OGFCA mixture include: Raw aggregate: from 4,75mm to Dmax,
fine aggregate: from 0.075mm to 2.36mm mostly from crushed stone; mineral
powder: below 0.075mm and grinded from limestone.
+ Mix aggregate chracteristics
The target function of OGFCA researches is to create residual void ratio Va=
16-18%.
+ Sussgesting aggregate mixture for OGFCAin Vietnam
Table 2.1: OGFCA mix suggested for research in Vietnam.
Sieve mesh size
(mm)

OG-A.9,5

12.5
9.5
4.75
2.36
1.18
0.075

100
87
12
5
-

100
100
42
14
-

3

6

RESEARCHED MIX
OG-B.9,5
100
96
42
-

100
100
67
-

14
0

24
6

OG-C.9,5
100
95
26
12
-

100
100
46
26
-

3

8

100

Lîng lät qua sµng (%)

90
80
70
60

OG-A.9,5
OG-B.9,5
OG-C.9,5

50
40
30
20
10
0

Cì sµng (mm)

0,075

2,36

4,75 9,5 12,5

Hình 2.1: Researched mix OG curve.
+ Selecting aggregate for mixture design
● Raw aggregate (ballast): originally from Tan Cang-Dong Nai stone mine.

● Fine aggregate: grinded from từ bedrock; no use of natural sand in creating
friction courses asphalt.
2.3 Binder: The author suggests using bitum polimer PMB-I and ensures all
technical requirements of Polimer 22TCH 319-04 standard are met.
2.4 Mineral powder: grinded from limestone with CaCO3 content >85% (Ha
Tien mineral powder with CaCO3 content>90÷95% is recommended).
2.5 Designing friction courses asphalt mixture components
2.5.1 Designing mixture components by Marshall method


- 12 Casting process, machinary, testing equipment and sampling order.
2.5.2 Testing the friction courses asphalt mixture components
+ Estimating the necessary bitumen content(experiment appendix IV, V)
Table 2.2: The necessary bitumen contentfor the three suggested mixes
The bitumen content according Suggestion for the
to the surface rate (%) varied
estimated bitumen
OG Type
by mixture mass.
content (%) according
to mixture mass
Lower bound Upper bound
OG-A
OG-B
OG-C

4,2
3,9
4,3

4,0÷5,5
4,0÷5,5
4,0÷5,5

4,7
4,8
4,9

+ Testing to determine the physical-mechanical properties of samples
(Appendix VI)
+ Determining the optimum bitumen content(Appendix VIII)
Table 2.3: Suggesting the limiting technical value for the researched mixture.

Required
techinical
criteria
VTO
(22TCN 345-06)
Suggested OG

Voids in
Mineral
Aggregate
VMA

Melting
gum
index

Stability

Plasticity

Air
voids
Va

(kN)

(mm)

(%)

(%)

(%)

>6

2÷4

12÷16

≥ min.22

≤ 0,2

>6

2÷4

16÷18

≥ min.22

≤ 0,2

Results for determining the optimum bitumen contentare in the table below.
Table 2.4: Optimum bitumen contentfor the three mixtures suggested.
NO

OGFCA
Type

OGC according to
mixture mass (%)

OGC according to
aggregate mass (%)

1

OG-A

4.8

5.0

2

OG-B

5.2

5.5

3

OG-C

5.2

5.5

Collecting the experiment results:


- 13 Table 2.5: Collecting results and selecting the suggested mixes
Suggested technical limit

OG-A
OG-B
OG-C

(kN)
9,82
15
15,76

(mm)

3,9
3,2
3,3

(%)
16,44
13,59
14,29

Voids in Mineral
Aggregate
(%)
24,98
19,92
24,08

Suggested

> 8,0

3÷6

16 ÷ 18

≥ 22

OG Type

Stability Plasticity Air voids

Draindown
(%)
0,04
0,07
0,12
≤ 0,20

2.5.3 Establishing the mixture components and suggesting technical criteria
Through experiments, results are established into three components as the table
below.
Table 2.6: Establishing mixture components for research purpose.
No
1
2
3
4
5
6

Sieve size (mm)
12,5
9,5
4,75
2,36
1,18
0,075

Bitumen content
according to mixture mass
(%)

OG-A
100
87-100
12-42
5-14
3-6

OG-B
100
96-100
42-67
14-24
0-6

OG-C
Method
100
95-100
26-46 TCVN 88603-2011
12-26
3-8
TCVN 8860PmB-I: 4,0 ÷ 5,5
2-2011

Table 2.7: Suggestion of technical criteria for friction courses asphalt mixtures.
No

Properties

1

Air voids (%)

2

Bitumen content (%)

3

Permeability (10-3m/s)

4

Cantabro Loss

5

Indirect Tensile Strength
Ratio (ITSR) (%)

Value

Standard

Suggestion

Marshall compaction
2x50 tampers/layer
Marshall compaction

4,0÷5,5
2x50 tampers/layer
EN 13108-7- Marshall compaction
≥ 0,1
2006
2x50 tampers/layer
Marshall compaction
10÷20 EN 12697-17
2x50 tampers/layer
EN 13108-20- Marshall compaction
≥ 70
2005
2x50 tampers/layer

≥ 16÷18

EN 13108-7

2.6 Chapter 2 conclusion
Results from chapter 2 can help draw the following conclusions:
1. Aggregate mixture components were suggested;


- 14 2. Optimum bitumen contentfor the three asphalt mixtures has been determined;
with limiting technical criteria for component mixtures, in which air voids
vary from 16%÷18%.
3. Three friction courses asphalt mixture components for empirical research
purpose specifically in Vietnam’s condition have been established to
evaluate the physical-mechanical properties to select the proper components
for friction courses asphalt in chapter 3.

**********
Chapter III: EMPIRICAL RESEARCHES ON DETERMINING THE
PHYSICAL-MECHANICAL PROPERTIES OF FRICTION COURSES
ASPHALT MIXTURES AND SELECTING THE PROPER COMPONENTS
FOR THE MIXTURES
Chapter 3 covers empirical researches on evaluating the physical-mechanical
criteria. Through the experiment results, analyzing and countering samples;
evaluating OGFCA components according to the suggested technical criteria,
from which the proper components for highway friction courses asphalt in
Vietnam can be selected.
3.1 Graded mixtures suggested for experiments
To research on the properties of OGFCA for utilizing purpose, the doctoral
student has suggested the mix and the bitumens as listed by table 3.1.
Table 3.1: Suggestions of mixes and bitumens for research.
Bitumen use

TT

OGFC typeoptimum bitumen
content according to
mixture mass

PmB-I

Application criteria

1

OG-A-4,8%

X

Suggested by thesis

2

OG-B-5.2%

X

Suggested by thesis

3

OG-C-5.2%

X

Suggested by thesis

4

BTNNC.9,5

x

22TCN 345-06

3.2 Components preparation: must conform with regulating criteria, (Research
appendix III; IV and V).

- 15 3.3 Prepared sample: must conform with the directions of the experiment
process as with the required criteria.
3.4 Empirical researches on physical-mechanical criteria of the samples
3.4.1 Experiments to determine the elastic module of the components
Determine static module of elasticity for friction courses asphalt by pressing
circular cyclinders in unconfined compression condition (compress one
cyclinder, sample not placed in mould, the compressed version has equal
diameter with that of the sample)
The results are shown in picture 3.4 below
( Mpa)
450
400
350
300
250
200
150
100
50
OG-A
OG-B
OG-C

322
258

226 242 236

PmB-I
226
242
236

345 337

277 269

PmB-II
258
277
269

PMB-III
322
345
337

Picture 3.1: Result of the research on elastic module of three studied mixtures.
3.4.2 Experiment to determine indirect tensile strength (Appendix IX)
The result shows that: According to European criteria EN12697-12, the ITS
factor of the three research models all exceed 70% and are qualified. This is one
of the bases to assess and select the proper components for friction courses
asphalt.
Hệ số ITS (%)
BTNNC.12,5-4.8%-…

0.84

BTNP.9,5-4.8%-PmB.III

0.99

OG-C-5,0%-PmB.III

0.94

OG-B-5,0%-PmB.III

0.997

OG-A-4.8%-PmB.III

0.92

OG-C-5,0%-PmB-I

0.95

OG-B-5,0%-PmB-I

0.98

OG-A-4.8%-PmB-I

0.90
0.4

0.5

0.6

0.7

0.8

0.9

1

Picture 3.2: Indirect tensile strength (ITS) factor of the three mixtures for
researching and the counter samples.


- 16 3.4.4 Experiments on determining the coefficient of percolation [EN 131087] (Research appendix XI)
Thầm nước Kv-OG-A
Thấm nước Kv-OG-B
Thấm nước Kv-OG-C

Kv (10-3 m/sec)
5,0

4,6

4,0

4,0
3,0

3,5

3,1

2,3
1,6

2,0

0,9

1,0

1,0

0,6
0,4

0,0
4,0%

4,5%

5,0%

0,8
0,1
5,5%

Bitumen content (%) mixture mass

Picture 3.3: Perculation checking device and experiment results

Thấm nước: Water penetration
The results show that: According to the technical European regulating criteria
on void asphalt, the qualified coefficient of percolation is Kv ≥ 0,1 (10 -3m/s).
The results also show OG-A to be the components with the highest coefficient
of percolation, qualified for the void asphalt regulations.
3.4.5 Reseaches on determining Cantabro loss [EN 13108-7]
This research criteria is used for evaluating the wear-resistance of friction
courses asphalt compaction model at 250C, rotating 300 circles in revolver.
The results show that: Cantabro loss of OG components decreases when the
bitumen content increases; Cantabro loss type OG-A is greater than that of OGB and OG-C, still, the attrition value conforms with the criteria and is qualified
for being <20%.
The Cantabro loss checking results (appendix X) are as followed.
Cantabro Loss (%)
19,0
17,0
15,0
13,0
11,0
9,0
7,0
5,0
3,0
1,0

OG-A
OG-B
OG-C

4,0

4,5

5,0

5,5

Bitumen content (%)

Picture 3.4: Collecting Cantabro loss from the three studied mixtures.
3.4.6 Checking the wheel tracking on the studied components (AASHTO T324-04)


- 17 + Experimenting characteristic of wheel tracker : The wheel tracking device
operates by rolling a void-free rubber wheel with diameter of 203 mm, wheel
track 50 mm wide on the surface of asphalt sized 320mm x 260mm, the
thickness of the compaction model varies from 4,0÷10,0 cm; dried at 50ºC. The
experiment was carried out with the total number of wheel passing as 20.000
times/point or the maximum depth of wheel tracking as 12.5 mm.
+ Research purpose: testing the deformation strength of OGFCA, from which
the components and a proper thickness can be selected.
● Input:
The prepared sample for the device: OG-A; OG-B and OG-C sampling
thickness 4 and 5 cem, use PmB-I and PmB-III.

Picture 3.5: Wheel
tracking device and
compaction model.

+ The results are collected in the following table
From table 3.2, based on the test results and the regulated technical limit, the
author suggests mixture OG-A be the proper components for the selected
friction courses asphalt (table 3.3).
OG-C
Table 3.2: Collected results of physical-mechanical characteristics of the three mixtures.
No

Value

OG-A

OG-B

OG-C

Technical
requirements

Technical criteria

min 12
3÷6
min 85

AASHTO T24597 (2001)

1
2
3

4
5
6

Tampers/layer
Bitum
Bitumen content (%)
Stability (kN)
Plasticity (mm)
Stability at 60 C/at 25 C (%)

50
Bitum Polime: PmB-I
4,8
5,0
5,0
12,89
13,91
15,76
3,9
3,2
3,3
93,1
84,1
87,0

7

Air voids, Va (%)

16,44

13,68

14,07

16% ÷ 18%

AASHTO T26997(98)

8

Wheel tracking (mm)-Hamburg Wheel
Tracking Device (20.000 circles, pressure 6
daN/cm2, testing temperature 60oC)

5,2

1,2

1,7

max. 10

AASHTO T3242004

9 Permeability (10-3 m/s)
10 Cantabro Loss (%)
11 Indirect Tensile Strength Ratio (ITSR) (%)

3,7
17,5
91

0,4
7,8
99

1,0
9,5
94

≥ 0,1 (10-3 m/s)
≤ 20%
≥ 70%

EN 13108-7
EN 13108-7
EN 12697-12

o

0

Cỡ sàng vuông (mm)

Miền cấp phối

Thiết kế

12,5
9,5
4,75
2,36

100
87-100
12-42
5-14

100
94
27
10

Phương pháp thí
nghiệm
TCVN 8860-32011


- 18 Table 3.3: Proper components for the selected friction courses asphalt.
Sieve size (mm)
12,5
9,5
4,75
2,36
0,075
Bitum
Bitumen content (%)

Mix
Design
100
100
87-100
94
12-42
27
5-14
10
3-6
5
PmB-I
4,2÷5,5

Method
TCVN 8860-32011
22TCN 319-04

3.6 Conclusion
Results from chapter 3 help draw the following conclusion:
1. Technical criteria for OGFCA quality evaluation have been suggested;
among which are Cantabro loss checking criteria and coefficient of
percolation for friction courses asphalt suitable for the conditions in
Vietnam;
2. Required technical limitation for components have been collected, analyzed
and checked (table 3.2), OG-A was selected as the proper components for
friction courses asphalt for high type roads in Vietnam (table 3.3)
***************
Chapter IV: RESEARCH ON ENHANCING SOLUTIONS TO THE

UTILIZATION OF HIGHWAY FRICTION COURSES
ASPHALT COVERS
Air voids, macro-texture, surface water-absorbing level, etc are influenced by
loadbearing, climatic and environment factors. These properties suffer timedependent downgrade. The determination of air voids is difficult, through the inlab and field experiments, their relations are meaningful and essential, helping
engineers to grasp the criteria for friction courses asphalt throughout the whole
utilizing process.
Then, through the macro-texture criteria, with researched relations such as the
relation between macro-texture (average sanding depth) and air voids, between
air voids and water-absorbing level, determine the time-dependent change of
macro-texture; then the remaining air voids of asphalt component layers can be
calculated during the utilization process. The relations between these criteria can
help road managing engineers to indentify the downgrade of friction courses


0,60

y = 0,0002x + 0,9185
R² = 1E-05

0,55

y = 0,0011x + 0,4626
R² = 0,0428

0,50
0,45
0,40
0,35
0,30
4,79

4,31
4,27
4,64
5,50
4,79
8,55
5,30
4,62
8,55
5,78
5,78
4,62
6,60
5,78
4,75
5,66
5,78
4,13
5,12
5,53
4,84
5,45
4,60
5,43
5,64

1,10
1,05
1,00
0,95

0,90
0,85
0,80
0,75
0,70
0,65
0,60

Độ nhám vĩ mô Htb (mm)

Độ nhám vĩ mô Htb (mm)

- 19 asphalt covers and suggest proper managing solutions for the friction courses
asphalt cover.
4.1 Researches on some evaluating criteria for utilizing quality of friction
courses asphalt covers
4.1.1Researches on the relation between air voids and macro-texture
The author has collected figures at field from the construction organization 621Ho Chi Minh City Traffic work and stone work company during the package:
Construction of landing-take off strips of Can Tho Airport (appendix XV) and
in-lab prepared sample. The author has collected samples to make statistic of
two values: air voids and macro-texture.

15,83 15,83 15,10 15,10 16,64 16,64 16,44 16,44 18,00 18,00

Độ rỗng dư Va (%)

Độ rỗng dư Va (%)
a/
b/
Picture 4.1: Graphs showing the relation between air voids and macro-texture

a/in-lab and b/ at field
The results and the figure analysis provide a relation between air voids and
macro-texture through this formula:
+ In-lab experiment: Htb = 0,0002Va+0,9185 (4.1)
+ Field experiment:
Htb = 0,0011Va+0,4626
(4.2)
In which: Htb is the macro-texture (mm), Va is the air voids (%).
4.1.2 Researches on the relation between air voids and water-absorbing
level

12000
Độ hút nước Qt (cm3 )

11000

10000

Qt = 150.75Va + 7722.3
R² = 0.1101

9000

8000
7000

6000
5000

Stagnation

Drainage

4000
12.4 12.4 12.5 12.3 12.3 12.5 12.3 12.6 12.8 11.2

Độ rỗng dư Va (%)

Picture 4.2: Checking tools and graph showing the relation between air voids Va
and water-absorbing level Qt.


- 20 Analysis of the results provided the relation between water-absorbing level and
air voids of road surfaces through this formula:
Qt = 150,75Va + 7722,3 (4.4)
In which: Qt is the surface water-absorbing level (cm3); Va is the air voids (%).
Conclusion: The results from section 4.1.1 and 4.1.2 show the interrelation
between macro-texture (Htb), air voids (Va) and water-absorbing level (Qt) to
friction courses asphalt component.
4.1.3 Researches on the effect of aquaplanning phenomenon on driving
conditions
For researches on the effect of aquaplanning phenomenon on driving conditions,
the author carried out experiments at chainage KM4+500, package 1A, constructing
the motorway route between Ho Chi Minh City – Long Thanh – Dau Day.
1.8 kPa

1.6 kPa

1.4 kPa

1.11

1.07

1.00
0.80

0.64
0.63
0.65

0.60

0.62
0.56
0.62

0.40
0.20
0.00

50

55

60

65

70

Tốc độ xe (km/h)

75

80

2 Kpa
Hệ số bám φ (mặt đường ướt)

Hệ số bám φ (mặt đường khô)

2 Kpa
1.20

85

0.80

1.8 kPa

1.6 kPa

0.69

0.65

0.58

0.56
0.47

0.70
0.60

0.45

0.50
0.40

1.4 kPa

0.48

0.41

0.30
0.20
0.10
0.00

50

55

60

65

70

75

80

85

Tốc độ xe (km/h)

Picture 4.3: Vehicle wheel coefficient of adhesion with wet and dry road surfaces.

Field researches have reveal some issues:
1. When speeding over 80km/h on dry surfaces, the coefficient of adhesion
φ lightly varies 0,62÷0,65, on wet surfaces, the coefficient of adhesion
φ varies 10÷30% compared with dry surfaces.
2. When testing with 1,4kPa air pressure, the coefficient of adhesion value
is relatively high, causing discomfort for drivers.
4.1.4 Researches on the time-dependent changes of macro-textture on
motorway routes
In these researches, the author surveyed the macro-texture at chainage
Km37+00 and Km38+00 from HCM City to Trung Luong direction (Tien
Giang) to check on the rugosity in early November 2009 and early Jannuary
2010 (Appendix XIII).


- 21 Field reseaches show that: macro-texture (Htb) decreases by 3-7% in the first
four months at the beginning stage of utilizing the motorway route connecting
HCMC – Trung Luong. This result helps the author to suggest a periodical or
regular maintenance for the friction courses of the motorway route.
Picture 4. 4: Results for the macro-texture survey at chainage
Km37+550÷Km38+150.

1.60

ΔHtb=0,07

1.40
1.20
1.00
0.80
0.60

0.40
0.20

Độ nhám vĩ mô htbi năm 2009
Độ nhám vĩ mô htbi năm 2010
Htb năm 2010 (Htb=1.37)
Htb năm 2009 (Htb=1.44)

0.00

Độ nhám vĩ mô Htb (mm)

Độ nhám vĩ mô Htb (mm)

1.80

1.8
1.6
1.4
1.2

1
0.8
0.6
0.4
0.2
0

ΔHtb=0,03

Độ nhám vĩ mô htbi năm 2009
Độ nhám vĩ mô htbi năm 2010
Htb năm 2009 (Htb=1.41)
Htb năm 2010 (Htb=1.38)

Lý trình

Lý trình

Picture 4.5: Results for the macro-texture survey at chainage
Km37+550÷Km38+150 và Km38+150÷Km38+850.
4.1.5 Researches on increasing the rugosity by high pressure cleaning
technology
For these researches the author has experimented on utilizing the motorway
route connecting HCMC – Trung Luong at chainage Km37+550÷Km37+750.
There were two methods used:
a- Compressed air blast

a/
b/
Hình 4.6: Compressed air blasting a/ high pressure cleaning technology b/.

Conclusion: The results from field experimenting showed that there was an
unconsiderable increase in the macro-texture after compressed air blasting.
b- High pressure cleaning technology
Analyses and evaluations provide the following graph for macro-texture value
before and after high pressure cleaning process.


- 22 Conclusion: There was a considerable increase in the macro-texture Htb=6%
after high pressure cleaning process. From section 4.1.4, the downgrade
possibility in macro-texture in three months is 3-7%. Then a periodically 3
months high pressure cleaning process can maintain the utilizing quality for
friction courses asphalt component.
2.00

Độ nhám vĩ mô Htb (mm)

1.80
1.60
Htb1=1.31

1.40
1.20

Htb2=1.25

1.00
0.80

Độ nhám vĩ mô trước khi phun rữa cao áp

0.60

Độ nhám vĩ mô sau khi phun rữa cao áp

0.40

Htb1=1.31

0.20

Htb2=1.25

0.00

Lý trình

Picture 4.7: Macrotexture before and
after high pressure
cleaning process

4.2 Researches on solutions to enhancing the quality of friction courses
asphalt
4.2.1 Checking the production of friction courses asphalt at plants
a-Aggregate: Require well-operated grinding device from the mine producing
the aggregate and an aggregate evaluation process.
b-Mineral powder: CaCO3 content needs to exceed 90%, good bitumen
absorbing capacity, mineral powder percentage in mixtures must be as designed.
c-Binder: Suplliers must have quality certificate, recommend the bitum
temperature when using and stroring at plants.
4.2.2 Constructing solutions for friction courses asphalt

Component production at plants: as reported in section 4.2.1; strict supervision:
mixing temperature, mixture temperature after taken out of mixer;
Transport: time and distance must be limited, or a minimum constant
temperature must be kept when entering the construction site.
Placing: be advised to avoid segregation.
Compaction: must stay at a constant temperature; the road temperature
decreases fast, which mean compaction needs faster completion. Recommend
using tyred roller, vibratory roller, the use of compactor for friction courses
asphalt is not recommended.
4.2.3 Supervising, checking and accepting friction courses asphalt
Supervising process :at plants, construction sites.
Friction courses asphalt quality acceptance.


- 23 4.2.4 Utilizing management for friction courses asphalt
1) Periodical checking on the rugosity by sanding every 3 months;
2) Surface maintenance by high pressure cleaning technology.
4.3 Conclusion
1. Researches show that there are interrelation between criteria such as air
voids, macro-texture and water-absorbing level;
2. The macro-texture check (Htb) can help determine the values, especially the
air voids criteria which influences macro-texture and water-absorbing level;
3. The researches also prove that the effect of aquaplanning on driving
conditions is practical; helping engineers to see clearly the downgrade of air
voids and have directions and solutions to maintenance the road surfaces,
increasing utilizing quality of friction courses asphalt.
*************
CONCLUSIONS AND RECOMMENDATIONS
I- Scientific contributions of the thesis
The thesis focused on researching into a component with scientific significances

in constructing traffic work; the research has solved issues regarding high
scientific nature on the characteristics of friction courses asphalt covers, below
are matters that have been clarified:
1. Establishing three mixed components with specific technical requirements for
composite material and technical regulations for friction courses asphalt;
2. Selecting the proper mixture components for highway friction courses asphalt;
3. Researching on increasing the utilizing quality of highway friction courses
asphalt components; in which the following issues are determined
3.1 Determining the relation between air voids and macro-texture in friction
courses asphalt;
3.2 Determining the relation between air voids and water-absorbing level;
3.3 Determining the effect of aquaplanning phenomenon on driving conditions on
highways with different rugosity;
3.4 Determining the time-dependent change of macro-texture on friction
courses surface in Southern areas;
3.5 Determining the effectiveness of increasing the macro-texture and the
water-absorbing level of road surfaces by employing high-pressure cleaning
technology;


- 24 3.6 Establishing and suggesting a periodical maintenance routine for friction
courses road surfaces on the motorway route of high type roads;
3.7 Suggesting enhancing solutions to the utilizing quality of friction courses
asphalt across all stages: material, production at plants; constructing
technology; supervising; quality acceptance; management of friction courses
asphalt on high type roads.
II- Practical contribution of the thesis
1. Based on the results of the proper components for friction courses asphalt;
the production and mastery of friction courses asphalt under Vietnam’s
conditions is possible;

2. The thesis has suggested the design methods and limiting technical criteria
of OGFCA mixtures;
3. Researching on the relation between macro-texture and air voids, macrotexture and water-absorbing level, effect of aquaplanning phnomenon on
surfaces helps engineers to grasp the utilizing criteria for friction courses
asphalt for high type road covers, meanwhile having better management
measures;
4. Evaluating time-dependent friction courses quality and solutions to
enhancing utilizing quality of friction courses asphalt with high pressure
cleaning technology; establish and suggest management plan, periodical
maintenance for the friction courses layer, helping the managing and
utilizing centers to have better solutions to the periodical maintenance work
for friction courses asphalt road covers.
III-Weaknesses and Limitations
The thesis only researched in lab conditions with limiting OGFCA technical
criteria provided by reference materials as well as figures on manufacturing,
constructing, maintenance and repairing the OGFCA layer from other countries.
There is currently no realistic condition to produce and apply the technology in
the Southern area.
IV- Recommendations
Recommending a periodical maintenance regime for the rugosity of friction
courses asphalt motorway covers, then suggesting solutions to maintain the
working effect and a suitable repairing regime for friction courses asphalt.