chang’an university, china august 3, 2015cem.uaf.edu/media/138741/feng-ma.pdf · issaest,...
TRANSCRIPT
ISSAEST, Fairbanks, AK, USA, August 2-5, 2015
L. Huang, A.M. Sha*, F. Ma, Z.Z. Liu and X.L. Zou
Chang’an University, China
August 3, 2015
The national or local standards of the asphalt stabilized
aggregates just provides a simple climate zone and
specifications of construction.
The application and construction in this area are facing with
unprecedented problems .
The applications in cold and high altitude region (Qinghai-Tibet
Plateau) reported can obviously provide a useful experience
to make sure the pavement with high service levels.
The practice could be also very helpful to improve the
national or local standards related with this issue.
This section is from the southern of the Bayan Har Mountains, ended at the north Qinghe.
Location Maduo County Qingshui
River Chengduo
County Yushu County
Average air pressure 605.1 593.7 650.2
Annual mean air temperature(°C) -3.8 -4.8 -1.7 3.2
Annual mean highest air temperature (°C) 3.5 3.3 11.7
Annual mean lowest air temperature (C) -10.3 -11.5 -3.2
Extreme maximum temperature (°C) 22.4 20.4 24.0 28.5
Extreme minimum temperature (°C) -48.1 -42.9 -33.0 -27.6
Long year average precipitation (mm) 321.6 511.1 388 485.9
Daily maximum precipitation (mm) 54.2 64.5 38.8
Long term average evaporation (mm) 1322.5 1127.4 1448 1302.9
Most large snow depth (cm) 16 22 14
Most large freezing depth (m) 2.77 2.52 1.04
Average wind speed (m/s) 3.2 2.9 2.5 1.0
Monthly mean wind speed in winter (m/s) 2.7 2.8 1.0
Most wind speed (m/s) 30.0 24 26
Dominant wind direction NE WNW W
Meteorological data of the main counties nearby the test section
Origin-
destination K629+800~
K630+800 K630+800~ K632+000
K632+000~ K633+200
K633+200~ K634+200
Upper layer AC-13C, 4cm AC-13C, 4cm AC-13C, 4cm AC-13C, 4cm
Lower layer AC-16C, 5cm AC-16C, 5cm AC-16C, 5cm AC-16C, 5cm
Base ATB-25, 12cm ATB-25, 18cm ATB-25, 18cm ATB-25, 18cm
Sub-base
4% cement treated crushed
aggregates, 24cm
2% cement treated crushed
aggregates, 18cm,
graded crushed aggregates, 18cm
geocell reinforced
graded crushed aggregates,
18cm
Cushion graded gravel,
20cm graded gravel,
20cm graded crushed
aggregates, 20cm
graded crushed
aggregates,
20cm
Length/m 1000 1200 1200 1000
Pavement Structure of the test section
Raw materials: Asphalt binder The binder used in this test section is Karamay110# asphalt, whose
technique properties is detailed in Table .
The results of asphalt
Test items unit Test results Specificatio
n Penetration 25°C, 100g, 5s 0.1mm 113.2 T0604-2011
Ductility 15°C, 5cm/min cm >100 T0605-2011
Softening point (Ring ball) °C 44.4 T0606-2011
Relative density (15°C) - 0.978 T0603-2011
Viscosity (135°C) Pa·s 0.525 T0625-2011
Viscosity (175°C) Pa·s 0.105 T0625-2011
Raw materials: Aggregate Four types of aggregated (provided by Zhalongqiong Quarries)
with a gradation of 0~3mm, 3~5mm, 5~10mm, 10~30mm were
used in the test sections. .
Test results of aggregate
Test items Test values Requirements Specification
Crushing value (%) 16.0 ≤30 T0316-2005 Needle and plate particle content (particle diameter> 9.5mm) (%) 10.2 ≤20 T0312-2005 Needle and plate particle content (particle diameter<9.5mm) (%) 9.2 ≤20 T0312-2005
Particle, <0.6mm Liquid limit (%) 21.5 <28 T0118-2007
Plasticity index 5.6 <9 T0118-2007
Raw materials: Mineral filler
The mineral filler used in this study was produced in Huashixia, and
the Table shows the main technique properties of the filler.
Test items Unit Test value Specificatio
n
Density g/cm3 2.705 T0352-2000
Moisture content % 0.4 T0332-2005
Hydrophilic coefficient —— 0.77 T0353-2000
Technique properties of the mineral filler
The passing rate of the aggregate used in this study is shown in the
Table . Passing rate of the aggregates
Mineral
aggregate
Passing proportion (%)
37.
5 31.5 26.5 19 16 13.2 9.5 4.75 2.36 1.18 0.6 0.3 0.15
0.0
75 1#(10-30mm) 100 97.3 82.7 47.6 31.6 16.6 1.6 0.6 0.5 0.5 0.5 0.4 0.2 0.2 2#(5-10mm) 100 100 100 100 100 100 95.2 7.8 1.6 1.1 0.9 0.8 0.7 0.4 3#(3-5mm) 100 100 100 100 100 100 100 88.9 6.5 2.8 1.8 1.5 1.3 0.9 4#(0-3mm) 100 100 100 100 100 100 100 100 77.5 55.9 39.2 27.6 19.8 9.9
Mineral
powder 100 100 100 100 100 100 100 100 100 100 100 100 97.4 78
Raw materials: Aggregate
Raw materials: Asphalt stabilized aggregates
The gradation of the asphalt stabilized aggregates used in this
study is shown in the Table .
Gradation of the asphalt treated crushed aggregate
Gradation type
Passing proportion (%)
37.5 31.5 26.5 19 16 13.2 9.5 4.75 2.36 1.1
8 0.6 0.3 0.15
0.0
75
Upper limitation 100 100 100 80 68 60 50 42 34 28 20 17 12 6
Lower limitation 100 100 90 62 52 42 36 28 22 16 10 7 4 2
Mean value 100 100 95 71 60 51 43 35 28 22 15 12 8 4
Composite
gradation 100 98.5 90.1
70.
1 61 52.5
43.
5 35.3 24
18.
1 13.7 10.6 8.3 5.1
To obtain the best engineering performance of the asphalt stabilized aggregates, the
optimal asphalt content (OAC) was determined by the large scale Marshall test, in
which the cylinder specimens (Φ152.4×95.3mm) were measured.
Results of the large-scale Marshall test
Test items Unit Requirements
construction criterion design criterion Nominal maximum
aggregate size mm 26.5 ≥31.5 ≥26.5
Specimen size mm Φ101.6×63.5 Φ152.4×95.3 Φ152×95.3 Double-sided beat
numbers number 75 112 112
Porosity % 3~6 3~6 4~6 Stability, ≮ KN 7.5 15 18 Flow value mm 1.5~4 measured measured
Asphalt saturation % 55~70 55~70 55~70
Voids in mineral
aggregate, ≮ %
design air voids ATB-40 nominal maximum
aggregate size requirement
4 11 26.5 12.5 5 12 31.5 12 6 13 37.5 11.5
The OAC could be determined based on the data in the Table in
which five asphalt contents were investigated.
Test results of large scale Marshall test
Asphalt-
aggregate
ratio(%)
Theory
relative
density
Integrated
relative
density VV (%) VFA(%) VMA (%) MS (kN)
FL
(0.1mm)
2.5 2.597 2.310 11.0 40.1 18.4 9.71 17.50
3.0 2.576 2.430 5.7 61.2 14.6 11.66 12.30
3.5 2.556 2.443 4.4 69.6 14.6 16.13 6.60
4.0 2.536 2.471 2.6 81.8 14.0 13.43 19.20
4.5 2.517 2.488 1.1 91.8 13.8 11.76 15.50
As a result, the optimal asphalt content (OAC) and corresponding
technical targets are concluded, as shown in the Tables.
Asphalt-
aggregate
ratio (%)
Theory relative
density (g/cm3)
Integrated
relative density
(g/cm3)
VV
(%) VFA
(%) VMA
(%) MS
(kN) FL
(0.1mm)
3.4 2.560 2.452 4.2 70.2 14.2 15.3 6.30
Optimal asphalt content and density
Aggregate mix proportion optimal asphalt content
Mixture
type
Proportion (%) Asphalt-
aggregate ratio
(%) 1# 2# 3# 4# Mineral powder
ATB-25 57 8 6 26 3 3.4
Practice and application
Construction preparation
Mechanical debugging
Mixture mixing
Mixture transportation
Mixture spreading Roller-Compaction.
Acceptance monitoring
♦ main procedures
During the construction of the asphalt stabilized aggregates in the
test section, the machinery allocation is as detailed as Table.
Machinery allocation
Equipment Number Remark
Intermittent mixing Plant 1 possessing production capacity Asphalt paver 3
Bitumen-spraying car 1
Tandem steel wheel vibrator roller (13t) 2
Wheel roller(26t) 2 Dump truck 13 charging about 40t per car
Synchronous surface dressing machine 1
Practice and application
♦ Mixture producing and transportation
►The mixtures (ATB-25 asphalt mixtures) were mixed for 45s.
► Generally, it takes about 30 minutes to produce asphalt stabilized
aggregates to fill a dump truck under a normal condition
► the distance was about 6.3 ~ 10.7 km, which needs about 25 ~ 30
minutes to transport the mixtures.
Heating temperature of asphalt 150°C~155°C
Heating temperature of mineral aggregate 180°C~185°C
Factory temperature of mixture 165°C~170°C
Storage temperature of mixture ≤10°C
Discarded temperature of mixture >185°C
Temperature requirement of asphalt stabilized aggregates
Practice and application
♦ Paving procedure
The field paving equipment is showed below
Tandem steel-wheel
vibrator roller Rubber-wheel
roller
Asphalt paver
Practice and application
♦ Paving procedure The rolling strategy of machines, temperature controlling is
detailed in Tables Rolling strategy of machines and temperature controlling
Rollin
g
proces
s
Type of roller Running
speed(km/h)
Rollin
g
cycles
Rolling
tempera
ture(°C)
Initial
pressur
e
two 13t tandem steel
wheel vibrator roller
(static pressure) 2 to 3 2 ≥150
Repres
s two 26t wheel
roller(vibration) 3 to 5 8 to 9 ≥140
Final
pressur
e
two 13t tandem steel
wheel vibrator roller
(static pressure) 3 to 6 2 to 3 ≥120
Producing and mixing temperature
(°C)
165°C
~170°C
Arriving temperature (°C), ≥ 160
Spreading temperature (°C), ≥ 155
Initial compacting temperature
(°C), ≥ 150
Re-compacting temperature (°C),
≥ 140
Final compacting temperature
(°C), ≥ 120
Final temperature
of the surface
(°C), ≥
Wheel roller 115
Tire roller 105
Requirement of rolling temperature
Field measurements ♦ Compactness The core samples were taken from the field test sections, as shown in Figs. The thickness and compactness of core samples can be found in Table .
Coring samples in the field
Detection results of compactness
Base type Thick
ness Requir
ement Compa
ctness
Requir
ement
K629+800~K630+800(12cmATB)
9.57 ≥11.4 92.64
≥92
K630+800~K632+000(18cmATB)
14.08
≥17.1
91.47
K632+000~K633+200(18cmATB)
15.75 91.47
K633+200~K634+200(18cmATB)
16.76 94.53
Field measurements
♦ Deflection
Detection results of deflection
Base type K629+800~K630
+800 K630+800~K632
+000 K632+000~K633
+200 K633+200~K634
+200
Deflection 39.3 26.9 40.2 55.8
Field measurements ♦Test conclusion and analysis
1) Insufficient and uneven thickness
►The smoothness of sub-base is inadequate.
►the edge of the asphalt stabilized aggregates may be
thin.
►The differences of compaction thickness.
2) Insufficient and uneven compactness
►the segregate during charging, moving, discharging and paving.
►Temperature reducing because the roller did not compact in
time.
►The limitation of roller machines caused the rolling speed could
not keep up with the paving speed.
Existing problems
► Temperature caused segregation
►Gradation caused segregation
Un-compacted core sample Surface segregations after compaction
Strategies
The low temperature, great temperature difference, severe freeze-
thaw cycles and short construction period in cold and high altitude
regions affect the construction of asphalt stabilized aggregates.
This case study provides a reasonable guidance for asphalt stabilized
aggregates in cold and high altitude regions.
It suggests that the asphalt stabilized aggregates should obtain
suitable compositions and structures based on the material
optimization and optimal mixture design. Besides, effective and
efficient temperature control, construction technology and organizing
manage could guarantee the engineering performance of mixtures.
Feng Ma PH D, Associate Professor Vice Chair of Highway Engineering Department, Highway School, Chang'an University, China (+86)15829939683 E-mail,[email protected]