78Transportation Research Record: J

78
Transportation Research Record: Journal of the Transportation Research Board,
No. 2408, Transportation Research Board of the National Academies, Washington,
D.C., 2014, pp. 78–85.
DOI: 10.3141/2408-09
Recently, so-called warm technologies have provided the paving industry with a considerable amount of versatility by increasing the options
available to perform a given project. The ability to mix at traditional
hot-mix temperatures and to compact at warm-mix temperatures is one
of these options, because doing so can allow for long-haul distances.
Warm technologies are fairly new to the United States, and documentation of their use on long-haul-distance projects is not abundant. This
paper presents successful full-scale use of an instrumented probe system
developed to simultaneously measure temperature at multiple locations
within an asphalt mix while it was hauled for an extended period of
time (10 h1). The data collected spanned haul distances far beyond
those needed for any conceivable conventional application and likely
exceeded distances needed for any emergency application. Probe temperature measurements appeared to be as reliable as well-accepted temperature measurement with asphalt thermometers. For representation
of most of the mix in a truck with cooler material near the edges, a laboratory short-term aging protocol was recommended for long hauls of
6 h or less that held mixes at 158C to 208C below their mixing temperature
for all but the last few minutes before they were progressively cooled to
the desired compaction temperature. Additional findings illustrated the
significant amount of time that most of a truck’s asphalt could retain
heat and provide temperature gradient measurements from just inside
the truck bed to near the center of the truck bed.
Recently, warm-mix technology has emerged as an approach that
can be effectively incorporated into paving projects through multiple avenues. One method is to lower the mixing temperature of
hot-mix asphalt (HMA) on the order of 35°C and produce warmmix asphalt. Another method is to mix at HMA temperatures and
compact at lower temperatures to extend haul distances. At least
45 states either actively use warm-mix technology or have investigated its use through a trial project (1). So-called warm technologies, however, are fairly new to the United States and many other
parts of the world. Additional information needs to be collected
about them, especially on their application to long-haul distances
(or long-haul times) on which less emphasis has been placed than
on items such as rutting and moisture damage (2, 3).
One consideration for long-haul distances (e.g., 6 h), are the
temperature conditions and gradients within the mix in the truck
bed. Neither temperatures under these conditions, nor equipment
configurations needed to measure them, appear to be prevalent in
the literature. Some relevant temperature data are available, such as
those of Brock and Jakob (4), but they do not include multiple and
simultaneous measurements in real time for a long haul. Brock and
Jakob reported that nine factors affected heat loss during transport
and that the relatively low thermal conductivity of an asphalt mix
slowed heat transfer rates from the middle of the mass to the edges
(4). An outer crust of mix that was relatively cooler than the center
developed, which resulted in an insulating effect.
Brock and Jakob collected asphalt mix data in a truck with a thermal imaging camera (4). The center of the mass was above 116°C
while the cooler outer crust was on the order of 82°C. An instance
was cited in Australia where mix was transported by truck 240 km.
Upon arrival at its destination, the truck’s outside body temperature
was 80°C, the exposed top of the mix was 96°C, and the center temperature of the mix mass was 152°C. Data of this nature are useful.
Even more useful would be simultaneous measurements from the
edge of the truck bed into the middle of the mix at multiple depths
over an extended haul.
This paper presents full-scale results from an instrumented probe
system capable of measuring temperature within an asphalt truck at
multiple locations in real time. Data were collected for two key purposes: (a) provide guidance for short-term aging protocol (STAP) in
the design of mixes for long-haul distances and (b) make available
to researchers and practitioners these data, which have a wealth of
potential applications that do not appear to be readily available. This
paper focuses on data collected with the use of the instrumented
probe system, while a companion paper presents the design, fabrication, and verification efforts that led to the final configuration of the
instrumented probe system (5).
Companion ReseaRCh
Howard et al. performed a laboratory study on the use of HMA
with warm-mix technology for emergency paving (6). One component of the study was documentation of construction projects
with the use of warm-mix technology in cases in which haul distances were up to 4 h, mixing temperatures (Tmix) were 113°C to
152°C, and compaction temperatures (Tcomp) were 80°C to 127°C.
Initially, laboratory performance testing for long-haul distances was
performed with specimens that experienced STAPs as reported in
Howard et al. (6, 7). Four types of cooling rate experiments were
conducted that eventually led to the STAPs. The approach selected
Measurement of Asphalt Concrete
Temperatures During Transport with
the Use of an Instrumented Probe System
Isaac L. Howard
Department of Civil and Environmental Engineering, Mississippi State University,
235F Walker Engineering Building, Mail Stop 9546, 501 Hardy Road, Mississippi
State, MS 39762-9546. [e-mail].
Howard 79
was to cool the asphalt along the general trend described in the
temperature–time relationship for the duration of interest to a temperature of 6°C above the desired compaction temperature (Equation 1). Ultimately, these STAPs were reported to need further study
at full scale, because they had their basis in laboratory cooling
rate experiments. Equation 1 is compared with the data from the
instrumented probe system described later in this paper.
T t = + 0.0005( ) 2 2 – 0.39( ) t R 177 = .99 (1)
where T is the asphalt temperature (°C) and t is the time elapsed
since the asphalt was mixed (minutes).
A study by Howard et al. (8) was part of the same experiment discussed in this paper, and built on an earlier study by Howard et al. (6),
which investigated haul time effects in terms of asphalt absorption,
binder grades, Fourier Transform Infrared Spectroscopy, workability,
and repeated creep. Asphalt was hauled 1.0 to 10.5 h to investigate
binder behavioral changes. The overall conclusion was that haul times
up to 8 h did not produce any major aging differences for a given binder
type or between binder types. Neat PG67-22, foamed PG67-22,
and Evotherm 3G modified PG67-22 were studied. The findings of
Howard et al. were encouraging for long-haul distances in terms of
performance, because no major aging differences were observed (8).
Howard presented all pertinent developmental efforts that led to the
full-scale instrumented probe system used here (5). Howard et al. provided tabular lists of all major parts needed to build the truck-mounted
system (9). Generally speaking, two metal probes (D-tube samplers)
are pushed into the asphalt mix on the truck’s passenger side, which
are subsequently opened to expose a series of bead thermocouples
directly to the asphalt inside the truck. The probes reach approximately half way into the truck and allow temperature measurement
from the center of the mix to the edge of the truck bed. Temperature
is monitored in the truck cab in real time by a data acquisition system
securely mounted to prevent jarring from loosening connections.
Figure 1 provides photographs of the instrumented probe. Figure 2
provides a probe schematic that shows temperature measurement
locations relative to the inner edge of the truck bed, alongside a thermocouple bundle. Durable, yet efficient, quick connections were key
components of the system. All paths from a thermocouple to the data
acquisition system were a continuous series of either copper or constantan. Pins and sockets were used to create all connections. Bundles
were made of thermocouples protected with heat-shrink tubing with
different lead lengths wired to a quick connection that connected to a
trunk line that connected to the data acquisition system.
After a thermocouple bundle was placed in the probe by bonding
the area near the thermocouples to the probe with a JB Kwikweld,
the remaining cavity was filled with room temperature vulcanizing
silicone to minimize air flow. This type of silicone also was used
to fill all remaining space in the hole at the end of the probe where
wires exited the probe. The prohibition of air flow to or from the
outside of the truck bed was a key aspect of the system. A series
of laboratory experiments described by Howard was performed to
evaluate the probe and to select thermocouple orientations that isolated any effects of the probe itself from temperature measurement
(5). These experiments used asphalt in buckets and large-capacity
ovens. Ultimately, curving thermocouples (Figure 1, middle photo)
were selected and successfully tested in the laboratory. Some of
Tip Closed
Prior to Cavity Filling
Overall View of Probe When Closed
L2
Thermocouples (Prebonding)
Thermocouples (Postbonding)
Cavity Filled
Tip Open
L1
Cavity
Filled
FIGURE 1 Instrumented probe system.
Driving Tip
Cavity Filled
Inner Edge of Truck Bed
2.5 cm
5.1 cm
138.4 cm
125.7 cm
Two Bead TCs
Location 3 (L3)
Two Bead TCs
Location 4 (L4)
3.8 cm
38.1 cm
38.1 cm
Two Bead TCs
Location 1 (L1)
Two Bead TCs
Location 2 (L2)
12.7 cm
38.1 cm
L1
L2 L3
L4
Thermocouple
Bundle That Is
Placed Inside
Metal Probe
FIGURE 2 Thermocouple probe locations and bundle.
80 Transportation Research Record 2408
the Figure 1 photos show thermocouple beads covered

Kết quả (Anh) 2:

78
Transportation Research Record: Journal of the Transportation Research Board,
No. 2408, Transportation Research Board of the National Academies, Washington,
DC, 2014, pp. 78-85.
DOI: 10.3141 / 2408-09
Recently, So-Called warm technologies have given below the paving industry with a Considerable amount of versatility by Increasing the options
available to thực a given project. The ability to mix at traditional
hot-mix temperatures and warm-mix to compact at temperatures is one
of những options, vì doing than for long-haul can allow distances.
Warm technologies are fairly new to the United States, and ask for their documentation of use Long-haul-distance on projects is not abundant. This
paper presents successful full-scale use of an instrumented probe system
to simultaneously measure temperature Developed multiple locations at
an asphalt mix trong khi it was hauled for an extended period of
time (10 h1). The data spanned haul distances far beyond thập
needed for any conceivable conventional những application and Likely
exceeded distances needed for any emergency application. Probe temperature measurements to be as reliable as appeared, well-accepted temperature measurement Thermometers with asphalt. For Representation
of nhất of the mix in a truck near the edges with cooler material, a short-term laboratory aging protocol was recommended for long hauls of
6 h or less at 158C mà giữ mixes mixing temperature to 208C below chúng
for all but the last FEW minutes trước They were progressively cooled to
the desired temperature compaction. Additional findings Illustrated the
the significant amount of time mà nhất of a truck's asphalt could retain
heat and cung temperature gradient measurements from just inside
the truck bed to near the center of the truck bed.
Recently, warm-mix technology has emerged as an approach mà
intervention Be Incorporated Into effectively paving projects through multiple avenues. One method is to lower the mixing temperature of
hot-mix asphalt (HMA) on the order of 35 ° C and tạo warmmix asphalt. Another method is to mix at HMA temperatures and
compact at lower temperatures to extend haul distances. At Least
45 states hoặc actively use warm-mix technology or have investigated its use through a trial project (1). So-Called warm technologies, Tuy nhiên, are fairly new to the United States and many other
parts of the world. Additional information needs to be thập
about add, Especially on Long-haul ask for their application to distances
(or of long-haul times) less emphasis on Đã đặt mà coal
on rutting and moisture như items damage (2, 3).
One Consideration for Long-haul distances (eg, 6 h), are the
temperature gradients trong conditionsEND_SPAN and mix in the truck
bed. Neither under những conditionsEND_SPAN temperatures, nor equipment
needed to measure added configurations, vẻ to be prevalent printed
the literature. Some data are available the relevant temperature, như
như Brock and Jakob (4), but do not include multiple chúng and
print Simultaneous real time measurements for a long haul. Brock and
Jakob Reported mà nine Factors AFFECTED khi transport heat loss
and low thermal conductivity Relatively rằng of an asphalt mix
slowed heat transfer rates from the middle of the mass to the edges
(4). An outer crust of coal mix That Was Relatively cooler the center
Developed mà resulted in an insulating effect.
Brock and Jakob thập asphalt mix in a truck data with a thermal imaging camera (4). The center of the mass was above 116 ° C
while the cooler outer crust was on the order of 82 ° C. An instance
was cited in Australia where the mix was transported by truck 240 km.
Upon arrival at its destination, the truck's outside body temperature
was 80 ° C, the exposed top of the mix was 96 ° C, and the center temperature of the mix mass was 152 ° C. Data of this nature are ích.
Even more ích Simultaneous measurements would be from the
edge of the truck bed Into the middle of the mix at multiple Depths
over an extended haul.
This paper presents results from full-scale safety instrumented probe
system capable of measuring an asphalt truck trong temperature at
multiple locations to print real time. Data Collected for two key là Purposes: (a) for short-term guidance cung aging protocol (STAP) in
the design of mixes for long-haul distances and (b) make available
to researchers and Practitioners These data, have a wealth of mà
mà potencial applications do not readily available to be vẻ. This
paper focuses on data with the use of the thập instrumented
probe system, while a companion paper presents the design, fabrication, and verification efforts into mà led to the final configuration of the
instrumented probe system (5).
Companion Research
Howard et al. Performed a laboratory study on the use of HMA
with warm-mix technology for emergency paving (6). One component of the study was documentation of construction projects
with the use of warm-mix technology print là Cases chứa haul distances up to 4 h, mixing temperatures (Tmix) là 113 ° C to
152 ° C, and compaction temperatures (Tcomp) 80 ° C to 127 là ° C.
Initially, laboratory performance testing for long-haul distances was
Performed with specimens mà experienced as Reported print STAPs
Howard et al. (6, 7). Four types of cooling rate Experiments Were
Conducted mà Eventually led to the STAPs. The approach selected
Measurement of Asphalt Concrete
Temperatures During Transport with
the Use of an instrumented Probe System
Isaac L. Howard
Department of Civil and Environmental Engineering, Mississippi State University,
Walker 235F Engineering Building, Mail Stop 9546, 501 Hardy Road, Mississippi
State, MS 39762-9546. [e-mail].
Howard 79
was to cool the asphalt along the general trend tả in the
temperature-time relationship for the duration of interest to a temperature of 6 ° C above the desired compaction temperature (Equation 1). Ultimately, những STAPs Were Reported to need Further study
at full scale, vì chúng laboratory cooling hda print có basis
Experiments rate. Equation 1 is sánh with the data from the
instrumented probe system later in this paper tả.
T t = + 0.0005 () 2 2 - 0:39 () t R 177 = .99 (1)
where T is the asphalt temperature (° C) and t is the time elapsed
since the asphalt was mixed (minutes).
A study by Howard et al. (8) was part of the same experiment Discussed in this paper, and built on an earlier study by Howard et al. (6)
investigated haul mà time terms of asphalt Absorption print effects,
binder Grades, Fourier Transform Infrared Spectroscopy, workability,
and repeated creep. Asphalt was hauled 1.0 to 10.5 h to Investigate
binder behavioral changes. Conclusion The overall haul was mà times
up to 8 h did not tạo any major for a given binder aging Hiệu
giữa binder type or types. Neat PG67-22, foamed PG67-22,
and Evotherm 3G là modified PG67-22 studied. The findings of
Howard et al. Encouraging for long-haul là distances print terms of
performance, no major aging vì Hiệu Were Observed (8).
Howard hiển all pertinent developmental efforts into mà led to the
full-scale instrumented probe system used here (5). Howard et al. given below tabular lists of all parts needed to build major truck-mounted the
system (9). Generally speaking, two metal probes (D-tube samplers)
are pushed Into the asphalt mix on the truck's passenger side, mà
are subsequently opened to expose a series of bead thermocouples
to the asphalt trực Inside the truck. The probes Reach Approximately half way Into the truck and allow temperature measurement
from the center of the mix to the edge of the truck bed. Temperature
is monitored in the truck cab print real time by a data acquisition system
securely mounted to Prevent jarring from loosening connections.
Figure 1 provides Photographs of the instrumented probe. Figure 2
provides a schematic probe temperature measurement shows mà
locations relative to the inner edge of the truck bed, alongside a thermocouple bundle. Durable, yet Efficient, quick connections là key
components of the system. All paths to the data from a thermocouple
acquisition system a continuous series of hoặc là or Constantan copper. Pins and sockets used to create all connections là. Bundles
là made ​​of heat-shrink thermocouples protected with tubing with
lead lengths khác wired to a quick connection to a connected có
có trunk line connected to the data acquisition system.
After a thermocouple probe in the bundle was đặt by bonding
the area near the thermocouples to the probe with a JB Kwikweld,
the cavity was filled with còn room temperature vulcanizing
silicone to minimize air flow. This type of silicone was used cũng
còn to fill all space in the hole at the end of the probe where
the probe Wires exited. The prohibition of air flow to or from the
outside of the truck bed was a key aspect of the system. A series
of laboratory Experiments Performed tả by Howard was to
evaluate and to select the thermocouple probe orientations mà any effects of the probe isolated from temperature measurement Itself
(5). These Experiments asphalt used buckets and large-print khả
ovens. Ultimately, curving thermocouples (Figure 1, middle photo)
selected and successfully Were Tested in the laboratory. Some of
Tip Closed
Cavity Filling Prior to
Overall View of Probe Closed When
L2
Thermocouples (Prebonding)
Thermocouples (Postbonding)
Cavity Filled
Open Tip
L1
Cavity
Filled
Figure 1 instrumented probe system.
Driving Tip
Cavity Filled
Truck Bed Inner Edge of
2.5 cm
5.1 cm
138.4 cm
125.7 cm
Two Bead TCs
Location 3 (L3)
Two Bead TCs
Location 4 (L4)
3.8 cm
38.1 cm
38.1 cm
Two Bead TCs
Location 1 (L1)
Two Bead TCs
Location 2 (L2)
12.7 cm
38.1 cm
L1
L2 L3
L4
Thermocouple
Bundle That Is
Placed Inside
Metal Probe
Figure 2 Thermocouple Probes locations and bundle.
80 Transportation Research Record 2408
photos show the Figure 1 thermocouple beads Covered