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Minnesota's Cold Weather Road Research Facility

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Environmental

 

Concrete Maturity

IK

Crack Detection

CR

Displacement

FP | HC | TL | TT

Drainage Volume

FL | TB

Electrical Conductivity [Soil]

EC

Elevation Reference

IV | LA

Frost Depth

RP

Moisture [Concrete]

MH | MP | MR

Moisture [Soil]

EW | HD | NP | RE | TD | WM

Pressure [Soil]

PL | PT

Static Pore Water Pressure

SW

Environmental Concrete Strain

KB | VM | VG | VW

Temperature

ET | RT | TC | TH | XB | XD | XG | XH | XL | XM | XS | XT | XV

Water Table Level

OS | OC

 

 

Dynamic Load

 

Surface Layer Displacement

DT | PA

Soil Displacement

SC

Pressure in Soil

PG | PK

Dynamic Pore Water Pressure

DW

Strain [Dowel Bar]

SS

Strain [Asphalt]

AE | BL | BT | LE | TE

Strain [Composite/Overlay]

LF

Strain [Concrete]

CD | CE | CS | GD | MM

 

 

 

 

 

 

 

 

Sensor Catalogue

 

Pavement or surface layer sensors are installed on, embedded within, or placed immediately under the hot-mix asphalt or concrete layer of a pavement structure.

 

The sensors are linked by fiber optics to MnROAD’s computerized data collection system and the data is stored in a database at MnDOT Materials Research and Engineering Laboratory in Maplewood.

 

 

All sensors are designated by a two-letter code.

 

Specification and performance history for an individual sensor type is available upon request.

 

Environmental Effect Sensors

 

Concrete Maturity

 

IK Sensor

A. Function

i. An "IK" sensor measures the maturity of concrete as it hardens.

B. Description

i. The Concrete Maturity (IK) sensor consists of a miniature datalogger with an embedded temperature sensor, battery and processor. The temperature history of the surrounding concrete is tracked and used to calculate the strength "maturity" of the concrete.

C. Manufacturer

i. IK sensors: intelliRock Maturity Logger, manufactured by Engius.

D. Location

i. IK sensors are located at various depths in the concrete surface layer.

E. Current Status

i. IK sensors are only downloaded early in the life of a test cell. Only recently installed IK are still functional.

F. MnROAD Database Tables

i. Data has been collected during the early life of several test cells. Data has not yet been loaded into the MnROAD database as of March 2011. Once processed it will be loaded into the database table named: MNR.IK_VALUES.

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Crack Detection

 

 

CR Sensor

A. Function

i. A "CR" sensor monitored the presence of cracks in HMA pavement due to environmental effects. It was intended to break when a crack formed in the HMA.

B. Description

i. The Crack (CR) sensor is an electrical resistance "tape" mounted between HMA lifts. (Like burglar alarm tape on windows).

C. Manufacturer

i. Custom made by MnROAD staff.

D. Location and Quantity

i. CR sensors were installed between lifts in several HMA test cells.

E. Current Status

i. These sensors did not perform as intended. The tape tended to stretch rather than break, so the moment of a HMA crack forming could not be consistently be determined. These were removed when the HMA cells were reconstructed.

F. MnROAD Database Table

i. Data was collected and stored in the MnROAD database table: MNR.CR_VALUES

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Displacement

 

FP Reference Points

A. Function

i. A "FP" was not an electronic sensor, but a reference point used to periodically quantify frost heave of a pavement surface layer.

B. Description

i. There were two types of Frost Pin (FP) reference points. One consisted of small steel rods installed into the surface of test cells (sunken so tires and snowplow blades could not damage or move them). The other type consisted of a steel rod (reaching to just below the pavement surface) mounted on top of a square plate installed into a particular subsurface layer. Periodic elevation measurements were taken by placing a survey rod on top of the frost pins.

C. Manufacturer

i. The frost pins were designed and fabricated by MnROAD staff.

D. Location and Quantity

i. Frost Pins were originally placed in several test cells to allow characterization of frost heave in various surface and subsurface layers.

E. Current Status

i. Frost pin measurements were discontinued in spring 1997. F. MnROAD Database Table i. Data from frost pins can be found in the MnROAD database table: MNR.FP_VALUES.

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Concrete Joint Opening Horizontal Clip - HC

A. Function

i. A "HC" sensor measures the opening and closing of a PCC transverse contraction joint due to environmental forces. Data is automatically collected once every 15 minutes, due to the slow rate of change of the movement.

B. Description

i. The Horizontal Clip (HC) sensor is a U-shaped strip of metal to which strain gauges are mounted. As the strip of metal is flexed, measured strain in the metal strip is converted to represent the displacement (separation) of the two legs of the device. Each leg of the sensor is mounted to span across a transverse PCC joint.

C. Manufacturer

i. Tokyo Sokki model TML PI-5.

D. Location and Quantity

i. HC sensors were originally mounted within large holes, spanning across transverse joints, blocked out during the paving of the concrete slabs. Following installation of the sensors, a split steel cover, with a rubber disk underneath, was bolted to the surface to allow for movement of the joint and to provide protection to the 6 sensor. A modified installation procedure was implemented in 2000.

ii. There were originally 80 HC sensors located in 14 MnROAD PCC test cells. Newer PCC test cells at the MnROAD facility have also included the installation of Tokyo Sokki model PI-5 sensors.

E. Current Status

i. The original sensors performed very well for approximately 4 years, at which time the original mounting systems began to fail (rusted brackets or sand infiltration from the base below). The improved mounting technique appears to be performing for a longer period of time. Original (1993) sensors have been removed, but newer (2000) installations are still functioning.

F. MnROAD Database Table

i. Data has been collected automatically every 15 minutes over the life of each sensor. Data can be found in MnROAD database tables: Displacement=MNR.HC_VALUES; Raw voltage from sensor=MNR.HV_VALUES.

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Tiltmeter - TT/TL

A. Function

i. A "TL" or "TT" sensor measures the slope of a PCC slab in the direction in the direction of traffic. Data is automatically collected once every 15 minutes, due to the slow rate of change of the movement.

B. Description

i. The Tiltmeter (TT/TL) sensor uses precision electrolytic transducers to detect angular motion in two perpendicular directions. The transducers operate on the fundamental principle that a bubble suspended in a liquid-filled case, is always bisected by a vertical gravity vector. As the transducer tilts, the case moves around the bubble, linearly changing the electrical resistance measured through the electrolyte. Internally, there are two sensors, one oriented longitudinally(TL) and one transversely(TT) to traffic.

C. Manufacturer

i. Applied Geomechanics model 756-1129 Mid-range Miniature Tilt Sensor.

D. Location and Quantity

i. TT/TL sensors were mounted in one panel within test cell 39. The sensors were placed on top of a flat plate placed on the base, and paved over with the PCC, to become embedded near the bottom of the slab.

ii. There are 15 TT/TL sensors (15 TL and 15 TT) located in MnROAD PCC test cell 39. E. Current Status 7 i. Performance of the TT/TL sensor has been very good. All 15 sensors appear to continue to function.

F. MnROAD Database Table

i. Data has been collected automatically every 15 minutes over the life of each sensor. Data can be found in MnROAD database tables: MNR.TL_VALUES, MNR.TT_VALUES.

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Drainage Volume

 

FL Sensor

A. Function

i. A "FL" or "flout" sensor measures the volume of water passing through drains in the pavement. Data is automatically collected once every 15 minutes.

B. Description

i. The Flout (FL) sensor consists of floating container within a 30 gallon collection barrel. As water fills the barrel, the floating container rises until water over-tops an opening in the container. Water then fills the container until the weight of the water exceeds the floating force, which then causes the container to fall and the water exits the system through an outlet in the container. A magnetic proximity sensor is triggered each time the container nears the roof of the barrel. Each time the container falls and empties, 16 gallons is released from the system, and the proximity sensor records the event (as a count).

C. Manufacturer

i. This device was designed and manufactured by MnROAD facility staff.

D. Location and Quantity

i. FL sensors are located to measure water drained by the curb system (or any water collected after surface clogging) in the pervious pavement cells.

E. Current Status

i. The FL sensors continue to function.

F. MnROAD Database Table

i. Data has been collected automatically every 15 minutes since the installation of the FL sensors. Data can be found in MnROAD database table: MNR.FL_VALUES.

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Tipping Bucket - TB

A. Function

i. A "TB" or tipping bucket sensor measures the amount of water draining from the outlet of an edge drain.

B. Description

i. The Tipping Bucket (TB) device consists of a divided "bucket" and an electronic counting switch. Water from a pavement edge drain falls into one side of the divided "bucket" until it is filled, at which point the bucket tips or "rocks", such that the other side of 8 the bucket then begins to collect the drain water. An electronic switch counts the number of tips of the bucket. Knowing the quantity of water in the bucket and the time between tips, edge drain flow rates can be determined.

C. Manufacturer

i. The original tipping buckets (TB) were designed by Mn/DOT and constructed by a consultant hired to manufacture and install the MnROAD sensors.

D. Location and Quantity

i. TB sensors are installed at the end of the outlet of edge drains in several MnROAD test cells. ii. There were originally 14 TB sensors located in 5 PCC and 2 hot-mix asphalt MnROAD test cells. Newer test cells have also been equipped with TB sensors.

E. Current Status

i. Automated readings from the original TB sensors ceased after June 2003. Sensors in newer cells continue to function.

F. MnROAD Database Table

i. Data has been collected automatically every 15 minutes over the life of each sensor. Data can be found in MnROAD database tables: MNR.TB_VALUES, MNR.TB_ERRORS, MNR.TB_CALIBRATIONS.

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Electrical Conductivity [Soil]

 

EC Sensor

A. Function

i. A "EC" sensor is designed to measure three soil moisture components: Volumetric water content, designated by model "EW"; soil temperature, designated as model "ET", and electrical conductivity, designated by model "EC". Data is automatically collected from each of the three sensors every 15 minutes.

B. Description

i. The "ECHO" (EC) soil moisture sensor consists of three probes (in one unit) used to measure volumetric water content, temperature, and electrical conductivity in soils. Water content is determined using capacitance/frequency domain technology to measure the dielectric constant of the soil.

C. Manufacturer

i. ECHO, ECH2O-TE, and 5TE Soil Moisture sensors manufactured by Decagon.

D. Location and Quantity

i. EC sensors have been installed in several test cells, typically at multiple depths to measure moisture in pavement base and subgrade layers.

E. Current Status 9

i. Early ECHO sensors did not function well. Later models continue to function.

F. MnROAD Database Table

i. Data is being collected automatically every 15 minutes over the life of each sensor. Data can be found in MnROAD database tables: MNR.EC_VALUES, MNR.ET_VALUES, EW_VALUES.

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Elevation Reference

 

 

IV Reference Rods

A. Function

i. An "IV" is not an electronic sensor, but a long rod installed into the ground to serve as a fixed reference point for displacement or elevation measurements.

B. Description

i. The Invar Reference (IV) rod consists of an 8 to 12 foot long, ½ to ¾ inch diameter, metal rod, partially jacketed by a 1.5 inch diameter PVC pipe filled with waterproof grease. A wider 2" diameter "head" is attached to the top of the narrow rod, such that displacement or elevation devices can be placed on top. The 6 to 8 foot long grease-filled PVC jacket is designed such that frost heave and soil settlement forces will not grab and move the reference rod.

C. Manufacturer

i. The invar (IV) rods and PVC pipes were cut and machined by Mn/DOT and MnROAD facility staff members.

D. Location and Quantity

i. IV rods have been installed in several test cells, typically near the lane and shoulder joint. ii. IV rods have been moved to others cells to suit various studies.

2. LA Reference Rods

A. See IV Reference Rods for description and details. The only difference is that LA Reference Rods are made out of stainless steel rod, instead of invar rod.

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Frost Depth

 

Resistivity Probe - RP

A. Function

i. A "RP" sensor measures the depths of freezing and thawing fronts in the granular base and subgrade. Data for the original installations was collected manually at various times. Some installations became automated.

B. Description

i. The Resistivity Probe (RP) sensor is a vertical series of electrical resistivity gauges used to indicate when a substantial portion of the pore water in a soil has frozen.

C. Manufacturer 10

i. RP sensors were designed by MnROAD staff and fabricated by Shannon and Wilson, the instrumentation consultant involved with the original construction of MnROAD.

D. Location and Quantity

i. RP sensors were originally placed in several locations within a test cell to characterize frost profiles. ii. There was originally at least one RP sensor installed in each of the 40 MnROAD test cells. Each probe had 41 sensors, giving a total of 4223 measurement points.

E. Current Status

i. The use of RP sensors was discontinued in spring 1999. Data collection and processing was found to be very labor intensive.

F. MnROAD Database Table

i. Data from original RP sensors can be found in the MnROAD database table: MNR.RP_VALUES.

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Moisture [Concrete]

 

Concrete Moisture - MH

A. Function

i. A "MH" sensor is designed to measure the humidity inside a concrete slab. Included within the MH sensor is a temperature sensor, designated as model "TH" or "XH". Data is automatically collected once every 15 minutes.

B. Description

i. The Moisture Humidity (MH) is a custom fabricated sensor consisting of a small digital humidity and temperature sensor mounted inside a plastic tube.

C. Manufacturer

i. The MH sensors at MnROAD were custom designed and fabricated by MnROAD staff. The sensor consists of a digital humidity and temperature sensor mounted inside a plastic pen tube with one end sealed and the other covered by a GoreTex fabric to prevent liquid water from entering the tube.

ii. The digital humidity and temperature sensor, model SHT75. is manufactured by the Sensirion Company.

D. Location and Quantity

i. MH sensors have been installed in several PCC test cells, typically at multiple depths to measure moisture gradients within slabs.

E. Current Status

i. The most recent installation of these sensors took place in Cells 70-72.

F. MnROAD Database Table

i. Data is being collected automatically every 15 minutes over the life of each sensor. Data can be found in MnROAD database tables: MNR.MH_VALUES, MNR.XH_VALUES, MT_VALUES, TH_VALUES.

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MP Sensor

A. Function

i. A "MP" sensor is designed to measure the water potential inside a concrete slab. Data was collected both manually and automatically.

B. Description

i. A Psychrometer (MP) sensor consists of two thermometers mounted within a ceramic screen bulb (to only allow passage of water vapor) used to determine relative humidity via the relationship between dew point and temperature.

C. Manufacturer

i. Wescor, Inc. psychrometer model PST-55-15-SF.

D. Location and Quantity

i. MP sensors have been installed in several PCC test cells, typically at multiple depths to measure moisture gradients within slabs.

E. Current Status

i. MP sensors are no longer used. Measurements and calibration were found to be difficult.

F. MnROAD Database Table

i. Data was collected both manually and automatically shortly after installation. Data will eventually be loaded into the MnROAD database table: MNR.MP_VALUES.

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MR Sensor

A. Function

i. A "MR" sensor is designed to measure the moisture content inside a concrete slab. Included within the MR sensor is a temperature sensor, designated as model "RT". Data is automatically collected once every 15 minutes.

B. Description

i. The Moisture Resistance (MR) sensor is a gypsum block based (soil moisture) sensor that uses electrical resistance to determine moisture content.

C. Manufacturer

i. ELE EI23-7724 Soil Moisture Block manufactured by ELE International.

D. Location and Quantity

i. MR sensors have been installed in several PCC test cells, typically at multiple depths to measure moisture gradients within slabs.

E. Current Status

i. MR sensors ceased to function in 2008.

F. MnROAD Database Table

i. Data was being collected automatically every 15 minutes over the life of each sensor. Data can be found in MnROAD database tables: MNR.RM_VALUES, MNR.RT_VALUES.

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Moisture [Soil]

 

EW Sensor

A. Function

i. An "EW" sensor measures volumetric water content in soil. It is one of the 3 parts of an EC sensor. See the EC sensor for more details. Data is automatically collected from each of the three sensors every 15 minutes.

B. Description

i. Soil water content is determined by an EW sensor using capacitance/frequency domain technology to measure the dielectric constant of the soil.

C. Manufacturer

i. ECHO, ECH2O-TE, and 5TE Soil Moisture sensors manufactured by Decagon.

D. Location and Quantity

i. EW sensors have been installed in several test cells, typically at multiple depths to measure moisture in pavement base and subgrade layers.

E. Current Status

i. Early EW sensors did not function well. Later models continue to function.

F. MnROAD Database Table

i. Data is being collected automatically every 15 minutes over the life of each sensor. Data can be found in MnROAD database tables: MNR.EW_VALUES, MNR.EC_VALUES, ET_VALUES.

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HD Sensor

A. Function

i. A "HD" sensor uses a heat dissipation method to indirectly measure soil water matric potential. Data is automatically collected from each sensor once every 12 hours.

B. Description

i. A Heat Dissipation (HD) Matric Water Potential sensor consists of a cylindrically-shaped porous ceramic body, with a heating element and thermocouple inside. Soil water matric potential is determined using the principals of thermal conductivity, heat dissipation, and water content..

C. Manufacturer

i. Campbell Scientific model CS229.

D. Location and Quantity

i. HD sensors were installed in test cells 27 and 28.

E. Current Status

i. HD sensors continue to function.

F. MnROAD Database Table

i. Data is being collected automatically every 12 hours over the life of each sensor. Data can be found in MnROAD database tables: MNR.HD_VALUES.

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NP Access Tube

A. Function

i. A "NP" was not an electronic sensor, but a vertical access tube that allowed a neutron moisture sensing probe to be lowered within various soil layers to measure soil moisture content.

B. Description

i. The Neutron Access (NP) Tube consisted of a 2 inch diameter, 8 foot long, PVC tube vertically installed into various base and subgrade layers. A neutron moisture sensing probe was then periodically lowered to measure the moisture content at various layers in a pavement test cell. When the fast neutrons produced by the probe collide with hydrogen present in the soil, they lose much of their energy. The detection of slow neutrons to the probe then allows an estimate of the amount of hydrogen present. Since water contains two atoms of hydrogen per molecule, this therefore gives a measure of soil moisture.

C. Manufacturer

i. The PVC tubes were fabricated by MnROAD staff. The neutron probe device manufacturer was Troxler.

D. Location and Quantity

i. NP access tubes were installed in many of the original test cells.

E. Current Status

i. NP readings were discontinued shortly after they were begun. The tubes filled with water and it was found PVC was a material not suitable for such measurements.

F. MnROAD Database Table

i. No data has been loaded into the MnROAD database.

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RE Sensor

A. Function

i. A "RE" sensor measures volumetric water content using time-domain measurement methods. Data is automatically collected from each sensor once every 12 hours.

B. Description

i. A Water Content Reflectometer (RE) sensor consists of two parallel stainless steel rods (attached to electronics) that can be inserted into a soil and used to measure the dielectric constant, which can then be converted to volumetric moisture content. This particular sensor does not require the typical reflectometer (cable tester) used for similar sensors.

C. Manufacturer

i. Campbell Scientific model CS616.

D. Location and Quantity

i. RE sensors were installed in test cells 19, 27 and 28.

E. Current Status

i. RE sensors continue to function.

F. MnROAD Database Table 14

i. Data is being collected automatically every 12 hours over the life of each sensor. Data can be found in MnROAD database tables: MNR.RE_VALUES.

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Time Domain Reflectometer - TD

A. Function

i. A "TD" sensor measures the moisture content of base and subgrade materials. Data was collected manually from 1993-1998, but has since been collected automatically every 15 minutes.

B. Description

i. The Time Domain Reflectometer (TD) [or TDR] sensor measures changes in the dielectric constant of the soil due to changes in the soil moisture content. The device is excited by a high frequency electromagnetic pulse, which is sent down 2 or 3 parallel wave-guides or prongs. The velocity of the reflected wave (located at its "apparent length [LA]") is measured and correlated to soil moisture content.

C. Manufacturer

i. Original TD sensors were designed by Mn/DOT researchers and fabricated by a consultant hired during the original construction of MnROAD. More recent installations have used Campbell Scientific models CS605, CS610, or CS645.

D. Location and Quantity

i. TD sensors were originally placed in each of the test cells in the outer wheelpath and/or at the centerline of the roadway. Some cells had replicated installations that included additional TD sensors in the shoulder area.

ii. TD sensors are typically installed in a vertical stack of sensors to capture the moisture content at various layers below the pavement surface.

E. Current Status

i. Data from the TD sensors was manually collected from 1993-1998. The operational status of the original TD sensors is unknown at this time. Since 1999, many new TD sensors have been installed and connected to an automated data collection system.

F. MnROAD Database Table

i. Data can be found in MnROAD database tables: MNR.TD_VALUES.

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Moisture Block - WM

A. Function

i. "WM" sensors at MnROAD have been used to measure both soil moisture content and frost depth in base and subgrade layers. Data is automatically collected from each sensor every 15 minutes.

B. Description 15

i. The Watermark (WM) sensor measures changes in electrical resistance due to changes in the soil moisture content.

C. Manufacturer

i. Watermark 200-x manufactured by the Irrometer.

D. Location and Quantity

i. WM sensors were originally placed next to the TD sensors in each of the test cell. This included replicated installations in several test cells.

ii. Similar to TD sensors, WM sensors were installed in a vertical stack of 7 sensors to capture the moisture content at various layers below the pavement surface.

E. Current Status

i. These sensors perform very well, with many of the original WM sensors still functioning. These sensors continued to be installed into new test cells to measure moisture and frost depth.

F. MnROAD Database Table

i. Data was been collected automatically every 15 minutes over the life of each sensor. Data can be found in MnROAD database table: MNR.WM_VALUES.

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Pressure [Soil]

 

Static Soil Pressure Cell - PL (& PT)

A. Function

i. A "PL" or "PT" sensor measures horizontal or vertical pressure in base and subgrade layers caused by environmental loads (moisture, temperature, settlement). A "XL" or "XT" sensor, mounted within the PL or PT sensor, respectively, is a thermistor necessary for temperature correction of the measured pressure. Data is automatically collected once every 15 minutes.

B. Description

i. The Lateral Soil Pressure (PL) and Vertical Soil Pressure (PT) sensors consist of two 6 inch (152 mm) diameter steel plates (welded together around their rims) connected by a steel tube to a vibrating wire sensor. The space between the plates and within the tube is filled with a liquid. The vibrating wire sensor responds to changes in pressure applied to the plates by the material in which the sensor is embedded.

C. Manufacturer

i. Geokon 4800E Earth Pressure Cell.

D. Location and Quantity

i. PL/PT sensors are embedded into the base and subgrade layers near the centerline of the roadway of both asphalt and PCC test cells.

ii. There were originally 13 PL (&13 XL) and 53 PT (&53 XT) sensors located in 4 PCC, 6 hot-mix asphalt, and 1 aggregate surface MnROAD test cells. As test cells have been constructed, both new and "recycled" PL/PT sensors were installed.

E. Current Status

i. These sensors have performed well. Most PL or PT sensors have not been tested for functionality recently, therefore their status is unknown.

F. MnROAD Database Table

i. Data has been collected both manually and automatically during the life of each sensor. Data can be found in MnROAD database tables: MNR.PL_VALUES, MNR.XL_VALUES, MNR.PT_VALUES, MNR. XT_VALUES, FT_VALUES.

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Static Pore Water Pressure

 

Static Pore Water Pressure Cell - SW

A. Function

i. A "SW" sensor measures slowly changing positive pore water pressure in oversaturated soils. A "XS" sensor, mounted to the SW sensor, is a thermistor necessary for temperature correction of the measured pressure.

B. Description

i. The Static Pore Water Pressure Gauge (SW) is a pore water pressure-sensing device consisting of a pressure sensitive diaphragm with a vibrating wire attached to it.

C. Manufacturer

i. Geokon 4500SL Vibrating Wire Piezometer.

D. Location and Quantity

i. SW/XS sensors were embedded into the base and subgrade layers near the centerline of both asphalt and PCC test cells. ii. There were originally 49 DW (and 49 XD) sensors located in 4 PCC, 6 hot-mix asphalt, and 1 aggregate surface MnROAD test cells.

E. Current Status

i. SW/XS sensors last reported data in November 2010.

F. MnROAD Database Table

i. Data has been collected automatically every 15 minutes over the life of each sensor. Data can be found in MnROAD database tables: MNR.SW_VALUES, MNR.XS_VALUES.

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Environmental Concrete Strain

 

Concrete Strain Transducer - KB/XB

A. Function

i. A "KB" sensor measures the strain in a PCC slab due to material shrinkage and environmental forces. A "XB" sensor, mounted within the KB sensor, is a thermocouple necessary for 17 temperature correction of the measured strain. Data is automatically collected once every 15 minutes.

B. Description

i. The KB sensor is a strain transducer, with an active gage length of 100 mm, and a low modulus case designed to measure strain in materials undergoing a transition from a compliant state to a hardened state (like concrete). The sensor is self-temperature compensated, having a linear thermal expansion coefficient similar to concrete. The attached "XB" thermocouple sensor permits temperature measurement at the exact location of the sensor.

C. Manufacturer

i. Tokyo Sokki KM-100BT.

D. Location and Quantity

i. KB sensors are embedded into the concrete surface layer near the top and bottom of the slab.

ii. There are 4 KB sensors in MnROAD test cell 60.

E. Current Status

i. These sensors have performed very well and continue to report data.

F. MnROAD Database Table

i. Data has been collected automatically every 15 minutes over the life of each sensor. Data can be found in MnROAD database tables: MNR.KB_VALUES, MNR.XB_VALUES, MNR.KB_INITIAL_VALUES.

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Concrete Vibrating Wire Strain Gauge [low modulus] - VM/XM

A. Function

i. A "VM" is a Geokon 4200L sensor, similar to a VW sensor except the metal case is constructed of a low modulus material. An attached thermistor "XM" sensor is used for temperature correction of the strain due to differences in coefficient of thermal expansion between the steel sensor and the concrete it is embedded into. See the description for VW more details. These sensors are only located in Test Cell 60.

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Concrete Vibrating Wire Strain Gauge [short gauge length] - VG/XG

A. Function

i. A "VG" sensor measures the strain in a PCC slab due to material shrinkage and environmental forces. A "XG" sensor, mounted to the VG sensor, is a thermistor necessary for temperature correction of the measured strain. Data is automatically collected every 15 minutes.

B. Description

i. The VG sensor is a small (active gage length = 51 mm) vibrating wire stain gauge consisting of a taut wire that is anchored between two end flanges and surrounded by a protective tube. The wire is electro-mechanically excited, causing it to vibrate at its natural 18 frequency. The resonant frequency of the wire changes with the tension. Thus the strain exerted on the flanges by movement in the PCC slab changes the frequency of vibration, which can be correlated to strain. The attached thermistor (XG) sensor is used for temperature correction of the strain due to differences in coefficient of thermal expansion between the steel sensor and the concrete it is embedded into.

C. Manufacturer

i. Geokon 4202 Vibrating Wire Strain Gauges.

D. Location and Quantity

i. VG/XG sensors are embedded into the concrete surface layer near the top and bottom of a slab.

E. Current Status

i. These sensors continue to function.

F. MnROAD Database Table

i. Data has been collected automatically every 15 minutes over the life of each sensor. Data can be found in MnROAD database tables: MNR.VG_VALUES, MNR. XG_VALUES.

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Concrete Vibrating Wire Strain Gauge [low modulus] - VW/XV

A. Function

i. A "VW" sensor measures the strain in a PCC slab due to material shrinkage and environmental forces. An attached thermistor "XV" sensor is used for temperature correction of the measured strain. Data is automatically collected every 15 minutes.

B. Description

i. The VW sensor is a medium (active gage length = 153 mm) vibrating wire stain gauge consisting of a taut wire that is anchored between two end flanges and surrounded by a protective tube. The wire is electro-mechanically excited, causing it to vibrate at its natural frequency. The resonant frequency of the wire changes with the tension. Thus the strain exerted on the flanges by movement in the PCC slab changes the frequency of vibration, which can be correlated to strain. Strain values from VW sensors are relative, in that one can only compare the change in value over time, or the change since the initial set of the concrete around the sensor. Initial VW values (at the time of concrete set) can be found in the database table MNR. VW_INITIAL_VALUES. The attached thermistor (XV) sensor is used for temperature correction of the strain due to differences in coefficient of thermal expansion between the steel sensor and the concrete it is embedded into.

C. Manufacturer

i. Geokon 4200 Vibrating Wire Strain Gauges.

D. Location and Quantity 19

i. VW/XV sensors are embedded into the concrete surface layer near the top and bottom of the slab at several locations in a test panel.

E. Current Status

i. These sensors have performed very well, and many original VW/XV sensors continue to function.

F. MnROAD Database Table

i. Data has been collected automatically every 15 minutes over the life of each sensor. Data can be found in MnROAD database tables: MNR.VW_VALUES, MNR.XV_VALUES, MNR.VW_INITIAL_VALUES.

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Temperature

 

ET Sensor

A. Function

i. An "ET" sensor is a thermistor sensor attached to a EC/EW sensor. See the "EC" or "EW" sensor descriptions for more details.

B. MnROAD Database Table

i. Data has been collected automatically every 15 minutes over the life of each sensor. Data can be found in MnROAD database table: MNR.ET_VALUES.

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RT Sensor

A. Function

i. The "RT" designation has been used for two unique sensor types. One represents the thermocouple attached to an MR sensor. The other represents the thermistor attached to a PT sensor. See the "MR" or "PT" sensor descriptions for more details.

B. MnROAD Database Table

i. Data has been collected automatically every 15 minutes over the life of each sensor. Data can be found in MnROAD database table: MNR.RT_VALUES.

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Thermocouple - TC

A. Function

i. A "TC" sensor measures the temperature of a material in which it is embedded. Data is automatically collected every 15 minutes.

B. Description

i. The Thermocouple (TC) sensor is a pair of dissimilar metal alloy wires (copper and Constantine) connected together near the point of measurement. Thermocouples generate an open-circuit voltage, called the Seebeck voltage, which is proportional to the temperature difference between the hot (point of interest) end and a reference junction.

C. Manufacturer

i. Omega Type-T thermocouple wire, fabricated into "trees" by MnROAD staff.. 20

D. Location and Quantity

i. TC sensors within pavements are typically mounted on a vertical "tree". This mounting method allows vertical temperature profiles to be determined, which are very important to the understanding of pavement response.

E. Current Status

i. These sensors continue to function.

F. MnROAD Database Table

i. Data was been collected automatically every 15 minutes over the life of each sensor. Data can be found in MnROAD database tables: MNR.TC_VALUES (current year), MNR.TC_VALUES_#### (where #### indicates one year of values); or the database view: TC_VALUES_ALL.

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TH Sensor

A. Function

i. A "TH" sensor is a temperature sensor attached to a MH sensor. See the "MH" sensor description for more details.

B. MnROAD Database Table

i. Data has been collected automatically every 15 minutes over the life of each sensor. Data can be found in MnROAD database table: MNR.TH_VALUES.

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XB Sensor

A. Function

i. A "XB" sensor is a thermocouple sensor attached to a KB sensor, to aid in temperature compensation. See the "KB" sensor description for more details.

B. MnROAD Database Table

i. Data has been collected automatically every 15 minutes over the life of each sensor. Data can be found in MnROAD database table: MNR.XB_VALUES.

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Thermistor in Dynamic Pore Water Pressure Cell - XD

A. Function

i. A "XD" sensor is a thermistor attached to a DW sensor to aid in temperature compensation. See the "DW" sensor description for more details.

B. MnROAD Database Table

i. Data has been collected automatically every 15 minutes over the life of each sensor. Data will eventually be loaded into the MnROAD database table: XD_VALUES.

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XG Sensor

A. Function

i. A "XG" sensor is a thermistor sensor attached to a VG sensor, to aid in temperature compensation. See the "VG" sensor description for more details.

B. MnROAD Database Table 21

i. Data has been collected automatically every 15 minutes over the life of each sensor. Data can be found in MnROAD database table: MNR.XG_VALUES.

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XH Sensor

A. Function

i. A "XH" sensor is a temperature sensor attached to a MH sensor. See the "MH" sensor description for more details.

B. MnROAD Database Table

i. Data has been collected automatically every 15 minutes over the life of each sensor. Data can be found in MnROAD database table: MNR.XH_VALUES.

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Thermistor in Lateral Pressure Cell - XL

A. Function

i. A "XL" sensor is a thermistor sensor attached to a PL sensor, to aid in temperature compensation. See the "PL" sensor description for more details.

B. MnROAD Database Table

i. Data has been collected automatically every 15 minutes over the life of each sensor. Data can be found in MnROAD database table: MNR.XL_VALUES.

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XM Sensor

A. Function

i. A "XM" sensor is a thermistor sensor attached to a VM sensor, to aid in temperature compensation. See the "VM" sensor description for more details.

B. MnROAD Database Table

i. Data has been collected automatically every 15 minutes over the life of each sensor. Data can be found in MnROAD database table: MNR.XM_VALUES.

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Thermistor in State Pore water Pressure cell - XS Sensor

A. Function

i. A "XS" sensor is a thermistor sensor attached to a SW sensor. See the "SW" sensor description for more details.

B. MnROAD Database Table

i. Data has been collected automatically every 15 minutes over the life of each sensor. Data can be found in MnROAD database table: MNR.XS_VALUES.

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Thermistor in Soil Pressure - XT

A. Function

i. A "XT" sensor is a thermistor sensor attached to a PT sensor. See the "PT" sensor description for more details.

B. MnROAD Database Table

i. Data has been collected automatically every 15 minutes over the life of each sensor. Data can be found in MnROAD database table: MNR.XT_VALUES.

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XV Sensor

A. Function

i. A "XV" sensor is a thermistor sensor attached to a VW sensor, to aid in temperature compensation. See the "VW" sensor description for more details.

B. MnROAD Database Table

i. Data has been collected automatically every 15 minutes over the life of each sensor. Data can be found in MnROAD database table: MNR.XV_VALUES.

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Water Table Level

 

OC Sensor

A. Function

i. An "OC" sensor allows automated measurement of the level of the water table at a particular location. Data is collected every 12 hours.

B. Description

i. The Water Table Pressure (OC) sensor consists of a pressure transducer placed near the bottom of a 15-foot deep PVC pipe, drilled with holes to allow the water table level to stabilize within it. Higher pressure readings equate to water table levels closer to the surface of the pavement.

C. Manufacturer

i. Campbell Scientific CS425- Druck PDCR 1830-8389.

D. Location and Quantity

i. OC sensors have been installed in several test cells.

E. Current Status

i. Some "OC" sensors continue to function.

F. MnROAD Database Table

i. OC data can be found in MnROAD database tables: MNR.OC_COAX_RAW_VALUES, OC_TRANS_RAW_VALUES.

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Open Stand Pipe - OS

A. Function

i. An "OS" sensor allows measurement of the level of the water table at a particular location. Data for the original installations was collected manually at various times. More recent installations are automated with an "OC" sensor and collected once every 12 hours.

B. Description

i. The Open Standpipe (OS) sensor consists of a 15-foot deep PVC pipe, drilled with holes to allow the water table level to stabilize within it. Originally, measurements were obtained by lowering a water-sensing probe into the pipe. More recent installations have included automated pressure "OC" transducers inserted into the bottom of the tube. See the "OC" description for more details.

C. Manufacturer

i. OS are fabricated by MnROAD staff.

D. Location and Quantity

i. OS sensors were originally placed 25 feet from the roadway centerline (just beyond the shoulder). More recent installations have included an OS sensor underneath the centerline of the roadway.

ii. There was originally one OS sensor installed in each of the 40 MnROAD test cells. Newer test cells have added additional OS sensors.

E. Current Status

i. Manual readings of the OS sensors ceased after March 2002. Some newer test cells have "OC" sensors installed to automate the measurements.

F. MnROAD Database Table

i. Manual OS data can be found in MnROAD database table: MNR.OS_MANUAL_VALUES.

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Dynamic Load Sensors

 

 

Displacement of Surface Layer

 

 

Linear Variable Differential Transducer - DT

A. Function

i. A "DT" sensor measures surface layer (HMA, PCC, or COMPOSITE) displacement due to dynamic loads.

B. Description

i. The Linear Variable Differential Transducer (DT) sensor is an electro-mechanical device that produces an electrical output proportional to the displacement of a separate, moveable core. Displacements are measured relative to a fix reference point (a buried stainless steel or invar rod).

C. Manufacturer

i. Several models of DT sensors have been used: Schaevitz model HCD-500 or Macro GHSAR 750-250.

D. Location and Quantity

i. DT sensors were originally mounted to an expansion ring within holes cored into hot-mix asphalt and concrete surface layers. Most displacement reference points were 12 foot long steel rods driven into the subgrade below the sensor, and jacketed by a PVC tube to prevent frost heave action. Other length reference rods were installed to monitor displacement at various layers within the pavement structure.

E. Current Status

i. These sensors were installed full time into the original tests cells and performed well for approximately 5 years. Once maintenance of the core hole areas became too demanding, the sensors were removed and installed as needed for load testing sessions. Newer DT sensors are only installed during load test events. 24

F. MnROAD Database Table

i. Data continues to be collected during various load response testing sessions, and some has been processed and loaded into the MnROAD database. Data is located in database tables named: MNR.DYNAMIC_LOAD_TEST_VALUES and MNR.DYNAMIC_LOAD TEST DESCRIPTIONS.

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Piezo-Accelerometer - PA

A. Function

i. A "PA" sensor measures the vertical acceleration of a PCC pavement surface subjected to a moving vehicle. The vertical deformation of the pavement surface can then be calculated from measured acceleration using double integration analysis.

B. Description

i. A Piezo-Accelerometer (PA) sensor is a small, cylindrical, acceleration device with a magnetic base. A series of six of these sensors were magnetically attached to lag bolts installed into recessed slots formed during the paving of the PCC slabs. The PA sensors were only attached to the pavement during special load testing sessions.

C. Manufacturer

i. Kistler Model 8628B50 Piezo-Accelerometers.

D. Location and Quantity

i. PA sensor attachment locations were formed using blockouts during the paving of the PCC slabs. They were located to allow for measuring joint efficiencies under traffic loads.

ii. PA sensor attachment locations were originally installed in 7 MnROAD PCC test cells.

E. Current Status

i. These sensors have been installed and tested only a few times since 1994. It is doubtful the original connection wires running to the attachment locations are still functional.

F. MnROAD Database Table

i. Limited data has been collected from this type of sensor. Data is not readily accessible at this time, but any future data will be input into the MnROAD database table: MNR.PA_VALUES.

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Displacement [Soil]

 

SC Sensor

A. Function

i. A "SC" sensor measures soil compression due to dynamic loads. Data from these sensors is only collected during load testing.

ii. A Soil Compression (SC) Gage consists of a 1 inch stroke potentiometer mounted inside a set of sliding brass tubes that have flat circular plates attached to their ends.

B. Manufacturer

i. Soil Compression Gage manufactured by CTL Group.

C. Location and Quantity 25

i. SC sensors were installed in three directions (longitudinal and transverse to traffic, vertical) to characterize dynamic soil compression under traffic loads. ii. SC sensors were installed in Cells 16-19 and Cells 77-79.

D. Current Status

i. These sensors have been found to be fragile, and many no longer function.

E. MnROAD Database Table

i. Data has been collected during load test events. Data has to be processed first, but then is loaded into the MnROAD database tables: MNR.DYNAMIC_LOAD_TEST_VALUES and MNR.DYNAMIC_LOAD TEST DESCRIPTIONS.

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Pressure in Soil

 

Dynamic Soil Pressure Cell - PG

A. Function

i. A "PG" sensor measures vertical pressure in base and subgrade layers subjected to dynamic loads.

B. Description

i. The Dynamic Pressure Gauge (PG) is a pressure-sensing device consisting of two 6 inch (152 mm) diameter steel plates (welded together around their rims) connected to an electrical pressure transducer by a steel tube. The space between the plates and within the tube is filled with a liquid. The transducer responds to changes in pressure applied to the plates by the material in which the sensor is embedded.

C. Manufacturer

i. Geokon 3500 Dynamic Soil Pressure Cells with Ashkroft K1 Transducers.

D. Location and Quantity

i. PG sensors are embedded into the base and subgrade layers near the wheelpaths of both asphalt and PCC test cells.

ii. There were originally 106 PG sensors located in 8 PCC and 7 hot-mix asphalt MnROAD test cells. As test cells were reconstructed, functioning PG sensors were removing and reinstalled into newer test cells.

E. Current Status

i. These sensors have performed well.

F. MnROAD Database Table

i. Data continues to be collected during various load response testing sessions, and some has been processed and loaded into the MnROAD database. Data is located in database tables named: MNR.DYNAMIC_LOAD_TEST_VALUES and MNR.DYNAMIC_LOAD TEST DESCRIPTIONS.

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Dynamic Soil Pressure Cell - PK

A. Function

i. A "PK" sensor measures vertical pressure in base and subgrade layers subjected to dynamic loads.

B. Description

i. The Dynamic Pressure Gauge (PK) is a small diameter, soil stress cell consisting of a liquid-filled hollow steel cell approximately 50.8mm (2") in diameter and 12.7mm (.5") thick, with an electrical pressure transducer housed within the cell. The transducer responds to changes in pressure applied to the surface of the sensor by the material in which the sensor is embedded.

C. Manufacturer

i. Kulite model 0234 Soil Pressure Cell.

D. Location and Quantity

i. PK sensors are embedded into the base and subgrade layers near the wheelpaths of both asphalt and PCC test cells.

ii. There were originally 66 PK sensors located in 4 PCC, 11 hot-mix asphalt, and 4 aggregate surface MnROAD test cells.

E. Current Status

i. These sensors have performed well. Recent status is unknown.

F. MnROAD Database Table

i. Data were collected during various load response testing sessions, and some has been processed and loaded into the MnROAD database. Data is located in database tables named: MNR.DYNAMIC_LOAD_TEST_VALUES and MNR.DYNAMIC_LOAD TEST DESCRIPTIONS.

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Dynamic Pore Water Pressure

 

 

Dynamic Pore Water Pressure Cell - DW

A. Function

i. A "DW" sensor measures rapidly changing positive pore water pressure in over-saturated thawing base and soil layers subjected to dynamic loading conditions. A "XD" sensor, mounted to the DW sensor, is a thermistor necessary for temperature correction of the measured pressure.

B. Description

i. The Dynamic Pore Water Pressure Gauge (DW) is a pore water pressure-sensing device consisting of a semi-conductor strain gauge piezometer.

C. Manufacturer:

i. Geokon 3410S Dynamic Pore Water Pressure Gauge.

D. Location and Quantity

i. DW/XD sensors were embedded into the base and subgrade layers near the wheelpaths of both asphalt and PCC test cells. ii. There were originally 52 DW (and 52 XD) sensors located in 4 PCC, 6 hot-mix asphalt, and 1 aggregate surface MnROAD test cells.

E. Current Status

i. DW/XD sensors have been used very little since installation. Many have been removed during the reconstruction of test cells.

F. MnROAD Database Table

i. Very limited data has been collected from this type of sensor. Data is located in database tables named: MNR.DYNAMIC_LOAD_TEST_VALUES, MNR.DYNAMIC_LOAD TEST DESCRIPTIONS, and XD_VALUES.

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Strain [Dowel Bar]

 

 

Steel Strain Gauge - SS

A. Function

i. A "SS" sensor measures the strain in steel dowel bars in PCC transverse joints due to dynamic vehicle loads.

B. Description

i. The Steel Strain (SS) sensors consist of four weldable resistance strain gauges mounted to the top, bottom, and both sides of a dowel bar. As a dowel bar flexes under load, strain levels can be measured and used to determine potential bearing stresses on the surrounding concrete.

C. Manufacturer

i. Micro-Measurements Group model LWK-06-W250B-350. Installed on the dowels by MnROAD staff.

D. Location and Quantity

i. SS sensors were originally mounted on the dowel bars prior to placement of the PCC.

ii. There were originally 180 SS sensors (45 dowels x 4 gauges per dowel), located in 7 MnROAD PCC test cells.

E. Current Status

i. Performance of the SS sensors cannot be assessed, since they were connected and recorded a very limited number of times. None of the SS sensors remain functional at this time.

F. MnROAD Database Table

i. Limited data was collected during various load response testing sessions, and some has been processed and loaded into the MnROAD database. Data is located in database tables named: MNR.DYNAMIC_LOAD_TEST_VALUES and MNR.DYNAMIC_LOAD TEST DESCRIPTIONS.

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Strain [Asphalt]

 

 

AE Sensor

A. Function

i. An "AE" sensor measures hot-mix asphalt strain response due to dynamic loads.

B. Description

i. The Angled Asphalt Strain (AE) sensor is an electrical resistance (full bridge) strain transducer, utilizing a nylon rod with transverse steel anchors at each end to form an H-shape.

C. Manufacturer

i. AE sensors: Model ASG 152, manufactured by CTL Group.

D. Location

i. AE sensors are located at the bottom of the hot-mix asphalt layers. They are oriented at a 45 angle to direction of traffic.

E. Current Status

i. Some AE sensors are still in service as of February 2011.

F. MnROAD Database Tables

i. Data has been collected during various load response testing sessions, and some has been processed and loaded into the MnROAD database. Data is located in database tables named: MNR.DYNAMIC_LOAD_TEST_VALUES and MNR.DYNAMIC_LOAD TEST DESCRIPTIONS.

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Biaxial Strain Gauge - BS (BL/BT)

A. Function

i. A "BL/BT" sensor measures hot-mix asphalt strain response due to dynamic loads.

B. Description

i. The Biaxial Strain (BL/BT) sensor consists of four electrical resistance strain gauges embedded in an asphalt mastic mix. Two of the strain gauges within a biaxial strain sensor are orientated in the longitudinal direction (with traffic) and designated as "BL". The remaining two gauges are oriented in the transverse direction (90º to traffic) and designated as "BT". Data is stored in the database under the designations "BL" and "BT". Physical dimensions of the biaxial strain sensor are: 152.4mm x 152.4mm x 12.7mm (6" x 6" x 1/2").

C. Manufacturer

i. BL/BT sensors were manufactured by the Alberta Research Council.

D. Location and Quantity

i. BL/BT sensors are located at the bottom of the hot-mix asphalt layers. They are mounted on top of the base layer and paved over with the asphalt layer, to become embedded into the bottom of the asphalt layer.

ii. There were originally 40 Biaxial Strain sensors installed into test cell 26.

E. Current Status

i. Due to reconstruction of Cell 26 in 2000, these sensors were removed.

F. MnROAD Database Tables

i. Data was collected during various load response testing sessions, and some has been processed and loaded into the MnROAD 29 database. Data is located in database tables named: MNR.DYNAMIC_LOAD_TEST_VALUES and MNR.DYNAMIC_LOAD TEST DESCRIPTIONS.

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Bituminous Longitudinal Embedment or Transverse Embedment Strain Gauge - LE or TE

A. Function

i. A "LE" or "TE" sensor measures strain response in hot-mix asphalt due to dynamic loads.

B. Description

i. Sensor designation "LE" indicates a strain sensor was mounted longitudinally or parallel to the direction of traffic. A sensor designation "TE" indicates a strain sensor was mounted transversely or perpendicular to the direction of traffic. Two different sensor models have used the designation "LE" or "TE". Prior to 2008, the LE and TE strain sensors were an electrical resistance strain gauge embedded within a strip of glass-fiber reinforced epoxy, with transverse steel anchors at each end of the strip to form an H-shape. After 2007, the LE and TE strain sensors are an electrical resistance (full bridge) strain transducer, utilizing a nylon rod with transverse steel anchors at each end to form an H-shape.

C. Manufacturers

i. Pre 2008: Dynatest model PAST-2AC. Post 2007: CTL Model ASG152.

D. Location and Quantity

i. LE and TE sensors are positioned at the bottom of the hot-mix asphalt layers near wheelpaths.

E. Current Status

i. These sensors have performed very well, with a demonstrated life span of approximately 2 years. Original (1993) sensors have either ceased to function, or have been removed due to reconstruction of a test cell. Newer sensors remain in service.

F. MnROAD Database Tables

i. Data continues to be collected during various load response testing sessions, and some has been processed and loaded into the MnROAD database. Data is located in database tables named: MNR.DYNAMIC_LOAD_TEST_VALUES and MNR.DYNAMIC_LOAD TEST DESCRIPTIONS.

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Strain [Composite/Overlay]

 

 

LF Sensor

A. Function

i. A "LF" sensor measures hot-mix asphalt strain response due to dynamic loads applied to a whitetopping overlay.

B. Description

i. The "LF" sensor consists of a foil strain gage bonded to the bottom of an asphalt core that was removed and reinstalled prior to a bonded concrete overlay (whitetopping).

C. Manufacturer

i. LF sensors: BLH foil strain gage manufactured by Vishay Measurements Group.

D. Location

i. LF sensors are located at the bottom of the hot-mix asphalt layer under a whitetopping.

E. Current Status

i. These sensors no longer function.

F. MnROAD Database Tables

i. Data has been collected during various load response testing sessions, and some has been processed and loaded into the MnROAD database. Data is located in database tables named: MNR.DYNAMIC_LOAD_TEST_VALUES and MNR.DYNAMIC_LOAD TEST DESCRIPTIONS.

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Strain [Concrete]

 

 

Concrete Embedment Strain Gauge - CD

A. Function

i. A "CD" sensor measures concrete pavement (PCC) strain response due to dynamic loads.

B. Description

i. The Concrete Embedment (CD) strain sensor is an electrical resistance strain gauge embedded within a strip of glass-fiber reinforced epoxy, with transverse steel anchors at each end of the strip to form an H-shape.

C. Manufacturer

i. Model PAST-2PCC manufactured by Dynatest.

D. Location and Quantity

i. CD sensors are embedded into the concrete surface layer near the top and bottom of the slab at various locations throughout a particular panel.

ii. There were originally 128 CD sensors located in 8 MnROAD PCC test cells.

E. Current Status

i. These sensors were extracted (within cores) in 2003.

F. MnROAD Database Table

i. Data was collected during various load response testing sessions, and some has been processed and loaded into the MnROAD database. Data is located in database tables named: MNR.DYNAMIC_LOAD_TEST_VALUES and MNR.DYNAMIC_LOAD TEST DESCRIPTIONS.

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Concrete Embedment Strain Gauge - CE

A. Function

i. A "CE" sensor measures concrete pavement (PCC) strain response due to dynamic loads.

B. Description

i. The Concrete Embedment (CE) strain sensor is an electrical resistance strain gauge hermetically sealed between two thin resin plates.

C. Manufacturer

i. Tokyo Sokki Kenkyujo model PML-60 purchased from Texas Measurements, Inc.

D. Location and Quantity

i. CE sensors are embedded into the concrete surface layer near the top and bottom of the slab at various locations throughout a particular panel.

ii. There were originally 436 CE sensors installed into 14 MnROAD PCC test cells. Newer PCC and Composite test cells at the MnROAD facility have included the installation of additional Tokyo Sokki model PML-60 strain sensors.

E. Current Status

i. The original (1993) sensors were removed by coring in 2003. Newer sensors remain in service.

F. MnROAD Database Table

i. Data continues to be collected during various load response testing sessions, and some has been processed and loaded into the MnROAD database. Data is located in database tables named: MNR.DYNAMIC_LOAD_TEST_VALUES and MNR.DYNAMIC_LOAD TEST DESCRIPTIONS.

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CS Sensor

A. Function

i. A "CS" sensor measures concrete pavement (PCC) strain response due to dynamic loads.

B. Description

i. The Concrete Surface (CS) strain sensor is an electrical resistance foil type strain gauge mounted to a backing material suitable for bonding to a smooth concrete surface.

C. Manufacturer

i. Tokyo Sokki model FLM-60-11 purchased from Texas Measurements, Inc.

D. Location and Quantity

i. CS sensors were bonded to the side of concrete slabs at various depths.

E. Current Status

i. Some sensors remain in service.

F. MnROAD Database Table 32

i. Data continues to be collected during various load response testing sessions, and some has been processed and loaded into the MnROAD database. Data is located in database tables named: MNR.DYNAMIC_LOAD_TEST_VALUES and MNR.DYNAMIC_LOAD TEST DESCRIPTIONS.

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Geokon Dynamic Strain Gauge - GD

A. Function

i. A "GD" sensor measures PCC strain response due to dynamic loads.

B. Description

i. The Geokon dynamic (GD) concrete embedment strain sensor consists of a full bridge gauged proving ring, coupled between two flanges.

C. Manufacturer

i. Geokon model 3900 manufactured by Geokon, Inc.

D. Location and Quantity

i. Two GD sensors are embedded into the concrete surface layer near the top and bottom of the slab, in the wheelpath of one panel in Test Cell 60.

E. Current Status

i. These sensors continue to function.

F. MnROAD Database Table

i. Data continues to be collected during various load response testing sessions, and some has been processed and loaded into the MnROAD database. Data is located in database tables named: MNR.DYNAMIC_LOAD_TEST_VALUES and MNR.DYNAMIC_LOAD TEST DESCRIPTIONS.

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Concrete Embedment Strain Gauge - MM

A. Function

i. A "MM" sensor measures PCC strain response due to dynamic loads.

B. Description

i. The Micro-Measurements Concrete Embedment (MM) strain gauge is an electrical resistance strain-sensing grid hermetically sealed within a polymer concrete casing.

C. Manufacturer

i. Micro-Measurements models EGP-5-120 and EGP-5-350.

D. Location

i. MM sensors are embedded into the concrete surface layer near the top and bottom of the slab at various locations throughout a particular panel.

E. Current Status

i. These sensors are no longer functional.

F. MnROAD Database Table

i. Data was collected during various load response testing sessions, and some has been processed and loaded into the MnROAD 33 database. Data is located in database tables named: MNR.DYNAMIC_LOAD_TEST_VALUES and MNR.DYNAMIC_LOAD TEST DESCRIPTIONS.

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