mechanical properties of recycled asphalt shingles at constant and elevated temperatures
DESCRIPTION
Department of Civil and Environmental Engineering Recycled Material Resource Center (RMRC). Mechanical Properties of Recycled Asphalt Shingles at Constant and Elevated Temperatures. Ali Soleimanbeigi , PE PhD student, University of Wisconsin-Madison. - PowerPoint PPT PresentationTRANSCRIPT
Mechanical Properties of Recycled Asphalt Shingles at Constant and Elevated
Temperatures
Department of Civil and Environmental Engineering Recycled Material Resource Center (RMRC)
Ali Soleimanbeigi, PEPhD student, University of Wisconsin-Madison
80 % of homes are roofed by asphalt shingles
12 million tons asphalt shingle waste per year in US
400,000 tons in Wisconsin
Current applications reuses 10-20 % of asphalt shingle waste
RAS is a top priory for reuse (EPA, FHWA)
Recycled Asphalt Shingles (RAS)
Reuse application with large volume
Embankment fill
Retaining wall backfill
Shape and component of RAS
Plate like particles Highly angular Rough surface texture
Angular Rough surface texture Porous
RAS Bottom Ash (BA)
Mechanical Properties for Structural Fill
Shear Strength: stability
RAS:BA mixture or stabilized RAS has sufficient shear strength as structural fill (f> 32o)
Compressibility: settlement
Compressibility is limited by adding granular material like BA or by stabilization
Hydraulic Conductivity: drainage capacity
RAS:BA mixture or stabilized RAS has sufficient drainage capacity as structural fill, K > 10-4 cm/s
Effect of seasonal temperature change on mechanical properties of compacted RAS:BA mixture
RAS contains asphalt cement, therefore:
Thermo-mechanical system: Triaxial Cell
tT
T(t)Pump
Temperaturecontroler
Back pressure, u
Thermocouple, Tc
Thermocouple, Tb
Thermocouple, Ts
Heater
Heating bath
RAS:BA specimen
Taygon tubing (6 mm)
Loading cell
Copper coil (6 mm)DifferentialTransducer(Volume change)
Cell pressure, c
Load
LabView
Thermo-mechanical system: Consolidometer
Load Cell
Specimen
Circulating water
Cool/warm water
PVC Cell Consolidation ring
Tc Copper coil
Thermo-mechanical system: Permeameter
Copper tubing
Thermocouples
Heating bath
Effect of temperature change on shear strength of RAS:BA mix and stabilized RAS
9
Effect of Temperature Change on Shear Strength and Volume Change
0 5 10 15 200
100
200
300
400
500
600
700
T=5°CT=22°CT=35°C
Axial strain, ea (%)
Devi
ator
stre
ss, s
'd (k
Pa)
0 5 10 15 20-3
-2
-1
0
1
2
3
4
T=5°CT=22°CT=35°C
Axial strain, ea (%)
Volu
met
ric st
rain
, evo
l (%
)
0 2 4 6 8 10 12 14 16 18 200
150
300
450
600
750
900
T=5°CT=35°C
Axial strain, ea (%)
Devi
ator
stre
ss, s
'df (
kPa)
0 2 4 6 8 10 12 14 16 18 20-3
-2
-1
0
1
2
3
4
T=5 °CT=35 °C
Axial strain, ea (%)
Volu
met
ric st
rain
, evo
l (%
)
RAS Soil
T=5oC1015202530
T=35oC
Shear Strength of RAS:BA mixture at Different Temperatures
Compacted RAS:BA mixtures have sufficient shear strength for typical highway embankment fills
f tanc
c≈0 kPa at different T
Shear strength
Cohesion
Friction
0 5 10 15 20 25 30 35 400
10
20
30
40
50
0
30
60
90
Temperature, T (oC)
Fric
tion
angl
e, f
(deg
rees
)
Cohe
sion
, c (k
Pa)
0 10 20 30 400
100
200
300
400
500
600
Temperature, T (oC)
Com
pres
sive
stre
ngth
s'df
(kPa
)
fff
sin1sin2cos2 '
3'
c
df
Stabilized RAS
Outwash Sand
f
c
Shear Strength of Stabilized RAS at Different Temperatures
Sufficient shear strength at elevated temperatures for structural fill
f tanc
Effect of temperature change on compressibility of RAS:BA mix or stabilized RAS
Long Term Compressibility
v
Time, t (log scale) tp
1Ca
tp : End of primary consolidation time
Ca : Secondary compression ratio
Soil
v
v
h
hh
v
Variation of strain over time under constant load
tc
log
a
Compressibility at Elevated Temperatures
0 5000 10000 15000 200000
1
2
3
4
'v200 kPa T=35°C
Time, t (min)
Verti
cal s
trai
n, e
v (%
)
24 h
Increase of temperature increases the vertical strain and vertical strain rate
0
1
2
3
4
T=35°CT=22°CT=5°C
Time, t (min)
Stra
in (%
)
)(, log
o
o
TTK
TT e
tc
a
0 5 10 15 20 25 30 35 400
0.02
0.04
0.06
0.08
0.1
0.12
Measured, RAS:BA (50:50)Predicted, RAS:BA (50:50)
Temperature, T (oC)
cae
RAS (%) K
25 0.157
50 0.168
Model Verification
0 5 10 15 20 25 30 35 40 45 500.000
0.005
0.010
0.015
0.020
0.025
0.030
0.035
0.040
0.045
'v200 kPa35°C30°C25°C20°C15°C10°C5°C
RAS content (%)
Seco
ndar
y co
mpr
essio
n ra
tio, c
ae
Variation of ca with RAS Content and Temperature
1000 10000 1000000
2
4
6
8
10
12
T=35-22 °CT=22 °C
Time, t (min)
Verti
cal s
trai
n, e
v (%
)
’v=25 kPa
50 kPa
100 kPa
200 kPa100 kPa
200 kPa
50 kPa
25 kPa
Ca= 0.0080
Ca= 0.0004
T=35 oC T=22 oC
Effect of Thermal Preconsolidation-RAS:BA (25%:75%)
Material caClay 0.01Wisconsin outwash sand 0.0003RAS:BA (25:BA)-thermally preconsolidated 0.0004
Construction at warm seasons greatly reduces the long term compressibility of RAS:BA mixture
Effect of Thermal Preconsolidation-Stabilized RAS
0 10000 20000 30000 40000 50000 600000
0.5
1
1.5
2
Time (min)
Verti
cal S
trai
n, e
v (%
)
T=35oCT=22oC
T=22oC
T=22oC
ca=0.0002
ca=0.0016
Material ca
Clay 0.01
Wisconsin outwash sand 0.0003
Stabilized RAS (thermally precompressed) 0.0002
Stabilized RAS 0.0016
Construction at warm seasons greatly reduces the long term compressibility of stabilized RAS
Effect of Temperature on Hydraulic Conductivity
0 10 20 30 400.0000
0.0003
0.0006
0.0009
0.0012
0.0015
0.001835 kPa70 kPa140 kPa280 kPa
Temperature, T (oC)
Hydr
aulic
con
ducti
vity
, K (c
m/s
)
Hydraulic conductivity of RAS:BA mixture increases with increase in temperature
Hydraulic conductivity increases with temperature
Conclusions
Sufficient shear strength of RAS:BA mix or stabilized RAS is maintained due to seasonal temperature change
Thermal cycle increases shear strength and stiffness of RAS:BA mix Secondary compression ratio is an exponential function of temperature
Construction of embankment fills using RAS:BA mix or stabilized RAS is recommended during warm seasons
Use of RAS will contribute to more sustainable roadway construction
QUESTIONS?
0 2 4 6 8 10 12 14 16 18 200
100
200
300
400
(b)
T=22°CT=22-35-22°C
Axial strain, ea (%)
Devi
ator
stre
ss, s
'd (k
Pa)
9% reduction of a
Effect of Thermal Cycle
Thermal cycle increases the shear strength and stiffness of the compacted RAS:BA mixture
0 1000 2000 3000 4000 5000 6000 7000
-8
-7
-6
-5
-4
-3
-2
-1
0(a) T=22°C
T=22-35-22°C
Time, t (min)
Volu
met
ric st
rain
, evo
l (%
)
T=35oC 22oC22oC