DOT600 Roadbed Water Content Meter 1/10 C o p y r i g h t © 2 0 1 0 C a m p b e l l S c i e n t i f i c , I n c .
Warranty and Assistance The DOT600 ROADBED WATER CONTENT METER is warranted by CAMPBELL SCIENTIFIC, INC. to be free from defects in materials and workmanship under normal use and service for twelve (12) months from date of shipment unless specified otherwise. Batteries have no warranty. CAMPBELL SCIENTIFIC, INC.'s obligation under this warranty is limited to repairing or replacing (at CAMPBELL SCIENTIFIC, INC.'s option) defective products.
DOT600 Table of Contents PDF viewers note: These page numbers refer to the printed version of this document. Use the Adobe Acrobat® bookmarks tab for links to specific sections. 1. General Description.....................................................1 2. What Parts Comprise the DOT600 .............................2 3. Specifications ..............................................................3 4. User Interface for Measurement and Control............4 4.1 The Keypad....................................
DOT600 Table of Contents Appendix A. Design and Calibration ........................................... A-1 A.1 A.2 A.3 A.4 A.5 A.6 A.7 Description of Basic Technology........................................................ A-1 Description of the Modified Device.................................................... A-2 Detailed Description of any Field and Laboratory Work.................... A-2 Displacement Sensor Calibration ........................................................
DOT600 Roadbed Water Content Meter 1. General Description The DOT600 is a portable device for measuring the water content of soils used in construction of roads, parking lots, foundations, etc. Samples collected from field sites are compacted using a vertical stress of (15-45 PSI), then the water content is measured using dielectric permittivity sensitive methods.
DOT600 Roadbed Water Content Meter 2. What Parts Comprise the DOT600 DOT600 components are housed in a rugged case. Contained in the case are: 1. 2. 3. 4. 5. 6. 7. 8. 9. 10.
DOT600 Roadbed Water Content Meter 3. Specifications Power Battery 2.9 Ahr rechargeable sealed lead-acid battery Operating temperature range: -20°C to 60°C Standby charge retention at 20°C for one year = 95% Lifetime approximately 500 cycles with discharge to 50% followed by recharge. See section Power System Scale Capacity = 1000 g Accuracy = ±0.032% Repeatability = 0.02% FS The scale has overload protection in both the up and down directions during shipping.
DOT600 Roadbed Water Content Meter 4. User Interface for Measurement and Control The Measurement and Control Datalogger has a built-in ruggedized membrane-switch keypad for control and a display with 8 lines and 21 characters per line. Measurement control uses a hierarchical structure of menus and submenus. 4.1 The Keypad The keypad keys that are commonly used or have special functions are listed in Table 1. TABLE 1.
DOT600 Roadbed Water Content Meter 4.2.1 Project Information A 9-digit alphanumeric value can be entered to identify the project. The current date is automatically set. The project information is written to the measurement report (see Measurement Report section). Data can be displayed in either Imperial or SI units. 4.2.2 Test ID Data The elements of this submenu allow the user to enter information about a set of measurements. Scroll to the element and press the Enter button to enter value.
DOT600 Roadbed Water Content Meter 4.2.3 Make Measurements Scrolling to and selecting Make Measurements allows selection of measurement steps and displays the results as measurements are made. See Measurement section for detailed description. 4.2.4 System Menu The System Menu allows user access to numerous settings and data. For operation of the DOT600, the only control of interest is System Menu/Configure, Settings/Display.
DOT600 Roadbed Water Content Meter Sample Vertical Stress Vertical stress applied to compress the sample CompressionForce Force applied to compress the sample batt_volt_Min Minimum system battery voltage during measurement period 5. Making Measurements with the DOT600 Level the DOT600 case using the built-in bubble. Turn DOT600 on and wait for program to compile and Main Menu to appear. After entering Project Information and Test ID Data values as desired, select Make Measurements in the Main Menu.
DOT600 Roadbed Water Content Meter 5.1 Tare Scale Place the empty sample chamber base and cylinder on the scale. CAUTION The scale is very sensitive. Do not pull up on scale during use. Doing so could permanently damage the scale. In the top level menu select Make Measurements, select Measurement, and then select Tare Scale. The display will then shift back to the Make Measurement menu. When the Measurement value is 0 the measurement is complete. Weighing measurements take about 3 seconds.
DOT600 Roadbed Water Content Meter 5.2 Fill Sample Chamber On a flat surface away from the case, place the sieve on the sample chamber and fill the sieve with material. Push the material through the sieve using fingers or tool. Do not pack the material into the sample chamber, only fill it. NOTE Sample depth measurement range is 0.4” (~1cm) to 1.0” (2.5cm). Once the material is pushed through the sieve, tap the sample chamber/sieve on a hard surface and remove the sieve.
DOT600 Roadbed Water Content Meter Select Measurement, select Weigh Sample. The display will shift to the Make Measurement menu. When the weighing process is complete the net sample weight is displayed next to Weight (g), and the process step will read “weigh”. If an accurate weight measurement is not made within 9 seconds, a “wind error” message will appear on the screen and the weighing process will need to be started again. 5.
DOT600 Roadbed Water Content Meter Place the compression cap on the sample chamber by aligning the pins in slots and twist to lock. Turn the compression nut clockwise by hand or with a wrench until you can feel the sample being compressed.
DOT600 Roadbed Water Content Meter Place the wrench on the compression nut and rotate clockwise. Compress the sample to a desired pressure (PSI), displayed on the logger screen. CAUTION 12 Do not compress sample beyond 45 PSI. NOTE When sample is compressed remove wrench from compression nut and place on foam away from the compression chamber. Failing to do so will create interference with the magnetic positioning sensors.
DOT600 Roadbed Water Content Meter When the target pressure is reached select Measurement, select Sample VWC. Press Enter to 1. 2. 3. 4. 5. measure volumetric water content, VWC record applied pressure measure sample volume calculate sample dry bulk density calculate gravimetric water content, GWC The values are displayed on the logger screen. Additional values can be seen by scrolling down with the arrow key (8 key). 5.3.
DOT600 Roadbed Water Content Meter 5.3.2 Start New Test Select Measurement, select New Sample. Press Enter to: 1. 2. zero all temporary values increment test # 5.4 Removing Samples Remove the sample chamber completely from the enclosure. Loosen the compression nut by turning the ratchet in a counter clockwise direction. Remove the compression cap. Remove the sample chamber ring from the sample chamber base. The sample can then be removed from the sample ring.
DOT600 Roadbed Water Content Meter 6. Detailed Description 6.1 Power System 6.1.1 Battery, Charger and Power Switch A 2.9 Ahr battery and a CH100 charger/regulator (manufactured by Campbell Scientific) are mounted beneath the panel as shown in Figure 1. A wiring harness distributes power and connects the charger to a jack located on the panel in the upper-left corner near the power switch. This jack mates with the wires from a wall transformer and allows charging the battery. The 2.
DOT600 Roadbed Water Content Meter A circuit board containing water content measurement electronics is mounted below the sample chamber and is electrically connected to a waveguide mounted in the bottom of the chamber. As water content of the sample increases, the oscillation frequency of the circuit decreases, and this frequency is related to water content through empirical calibration. 6.3.
Appendix A. Design and Calibration A.1 Description of Basic Technology The DOT600 is based on the design of the DMM600 Duff Moisture Meter also manufactured by Campbell Scientific. Both devices measure volumetric water content of a porous-media sample by placing the sample in a cylindrical sample chamber, compressing the sample to a known compaction and then measuring the water content using a method that is sensitive to dielectric permittivity.
Appendix A. Design and Calibration A.2 Description of the Modified Device The method of water content measurement used by the DMM600 is also used in the DOT600 but with several significant differences listed here. • The electronics for the dielectric measurement method are modernized to provide improved measurement accuracy and resolution. Surface-mount components are used to obtain higher speed measurements which directly improves water content measurement accuracy.
Appendix A. Design and Calibration Calibrating the DOT600 scale is a simple matter of placing objects of known weight on the scale and recording the output voltage. Precision calibration weights manufactured by Ohaus and checked on an independent scale were used. Figure 1 show the linear relationship Weighing scale calibration 700 600 y = 1065x - 80.773 R2 = 1 weight (g) 500 400 300 200 100 0 0.000 -100 0.100 0.200 0.300 0.400 0.500 0.600 0.700 voltage output (V) FIGURE A-1.
Appendix A. Design and Calibration Typical displacement sensor calibration 1.00 Displacement (inches) 0.80 0.60 0.40 0.20 -40.000 -20.000 0.00 0.000 20.000 40.000 60.000 80.000 Displacement sensor output (millivolts) FIGURE A-2. Typical calibration data for the displacement sensors. A.5 Sensitivity of Weight Position on Scale Surface Small weights (diameter = 3 cm, weight = 200 g) were placed at various locations of a symmetrically defined grid superimposed on the scale surface.
Appendix A. Design and Calibration volumetric water content (m^3 m^-3) 0.45 0.4 0.35 0.3 0.25 0.2 0.15 clay calib sand calib loam calib silt calib 0.1 0.05 0 15 20 25 30 35 40 Water content sensor output (microseconds) FIGURE A-3. Partial calibration set showing calibration data and equation. The effect of clay content on sensor response is apparent. A.
Appendix A. Design and Calibration weighted in a 10 mph wind there will be some error, so taring the scale and weighting the sample should be performed in the same environment. The enclosure should also be leveled, using the bubble level next to the scale, to have accurate weight measurements. Displacement Sensors/Sample Thickness/Compression Pressure Magnetic displacement sensors provide position of both the compression piston and the plate above the compression springs.
Campbell Scientific Companies Campbell Scientific, Inc. (CSI) 815 West 1800 North Logan, Utah 84321 UNITED STATES www.campbellsci.com • info@campbellsci.com Campbell Scientific Africa Pty. Ltd. (CSAf) PO Box 2450 Somerset West 7129 SOUTH AFRICA www.csafrica.co.za • cleroux@csafrica.co.za Campbell Scientific Australia Pty. Ltd. (CSA) PO Box 444 Thuringowa Central QLD 4812 AUSTRALIA www.campbellsci.com.au • info@campbellsci.com.au Campbell Scientific do Brazil Ltda.
