Instrumentation

Instrumentation

  Instrumentation

Introduction

There are twenty-six strain gages installed in eleven separate locations throughout the pavement structure. Nine strain gage locations are in the concrete pavement with 2 strain gages at each location. The other two strain gage locations are in the flexible pavement with 4 strain gages at each location. Two temperature sensors were also installed capable of measuring the temperature at three vertical locations. One was embedded in the concrete and the other in the flexible pavement. Finally, two pressure cells and two multi-depth deflectometers were installed in the flexible pavement.

Strain Gages

The strain gages in the concrete pavement were placed with two sensors at each location. One sensor was placed 1' below the surface of the P-501 and the other was placed 1' above the bottom interface of the P-501. Within the flexible pavement, two locations consist of four strain gages. Gages were placed at 0.5', 4.5', 5.5', and 9.5' below the surface of the P-401 HMA surface course.


Placement of strain gages prior to placement of P-501 PCC surface mix.

Multi-depth Deflectometers (MDD)

Two MDD's were embedded with the flexible pavement structure. The MDD's were designed to measure pavement deflections at seven depth locations within the pavement. The sensors used for this project acquire data at 4.5', 9.5', 10.5', 16', 22.5', 50', and 77.5' below the surface of the P-401 HMA surface course.


Placement of a multi-depth deflectometer in flexible pavement at the NAPTF.

Pressure Cells

Pressure cells were embedded at two locations in the flexible pavement. One location consisted of six pressure cells acquiring data at the following depth locations: 4.5', 9.5', 13.5', 17.5', 21.5', and 25.5' below the surface of the P-401 HMA surface course. The other location consisted of three pressure cells acquiring data at 4.5', 9.5', and 23.5' below the surface of the P-401 HMA surface course.


Placement of a pressure cell at the top of a Dupont Clay lift in the flexible Round-Up pavement structure.

Temperature Sensors

Temperature sensors were placed in two locations for this project. One location was within the concrete pavement and the other within the flexible pavement. Each location consisted of three sensors collecting data at varying depths. The concrete temperature data was collected at 0.5', 4.5', and 8' below the surface of the P-501 PCC surface mix. The flexible data was collected at 0.5', 3', and 4.5' below the surface of the P-401 HMA surface course.


Temperature sensors in place during construction of P-501 PCC surface course for Round-Up project.