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  • Roadbase Soil Stabilizer
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Nuclear Density Test Using Troxler 3440

Description

This test method is described as useful, rapid and non-destructive technique for in-place measurements of wet density and water content of soil and soil-aggregate and the determination of dry density.

The test method is used for quality control and acceptance testing of compacted soil and soil-aggregate mixtures as used in construction and also for research and development. The non-destructive nature allows repetitive measurements at a single test location and statistical analysis of the results.

The Troxler model 3440 surface moisture-Density Gauge measures the moisture content, density, compaction of soils, soil-stone aggregates, concrete, asphalt treated bases, asphalt surfacing and other materials and other materials that approximate similar ranges of density and/or moisture content .The model 3440 complies with the following American Society of Testing and Materials (ASTM) standard:

ASTM D6938-10:       Standard Test Method for In-Place Density and Water Content of Soils and Soil-Aggregate by Nuclear Methods (Shallow Depth).

Measurement Precision
Model 3440 Nuclear Moisture/Density Gauge
Direct Transmission(150mm) 15 sec 1 min 4 min
Precision at 2000kg/m³ +/-6.8 +/-3.4 +/-1.7 kg/m³
Composition error at 2000kg/m³ +/-20 +/-20 +/-20kg/m³
Surface error (1.25mm, 100%Void) kg/m³ -17 -17 -17kg/m³







                      The method appropriate for gauge operation for soils is Direct Transmission.

Apparatus

  1. Nuclear Density Gauge: Troxler model 3440.
  2. Standard Block: this is the block the gauge is placed on when obtaining daily standard counts, should be the block that came with gauge and have matching serial number.
  3. Scrapper Plate / Drill Rod Guide: this plate is used to smooth and prepare the site for testing and align the drill rod.
  4. Drill Rod: this is used to create the hole for the gauge’s source rod to be inserted into.
  5. Extraction Tool: this is used for removing the drill rod after driving.
  6. Moisture proof container. 
  7. Hammer.

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Procedure

  1. Calibrate the gauge before use if it is not calibrated for a year.
  2. Select a smooth test site free of surface irregularities where the gauge in test position will be at least six inches away from any vertical projection.
  3. Remove all loose and disturbed material as necessary to expose the top of the material to be tested.
  4. Smooth the test surface sufficiently in size to accommodate the gauge.
  5. The maximum void beneath the gauge shall not exceed approximately 1/8 inch.
  6. Use native fines or fine sands to fill these voids.
  7. Using the scraper plate, lightly tamp an area equal to the bottom of the gauge.
  8. Place the scraper plate with the drill rod on the test site.
  9. Place the drill rod into the drill rod guide and drive a hole at least two inches deeper than the desired test depth. The hole must be perpendicular to the prepared surface of the test site.
  10. Remove the drill rod by rotating and pulling straight up. The drill rod extraction tool may be used to facilitate the procedure. Do not loosen the drill rod by tapping with a hammer.
  11. Extend and place the source rod in the hole to the desired depth of measurement.
  12. Seat the gauge firmly by rotating it about the source rod while pulling gently on the gauge in the direction will bring the side of the source rod in firm contact with the side of the nearest the scale.
  13. Follow the manufacturer’s instructions to obtain the wet density
  14. Record all required information applicable to the gauge used.
  15. Follow the manufacturer’s instructions to obtain the percent moisture and dry density.
  16. Take a representative sample of the material from the test site and place in a suitable moisture-proof container.
  17. The material shall be thoroughly mixed and a moisture determination made doing proctor test.
  18. Record the moisture content to the nearest 0.1 percent.

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Calculation

  1. To determine the dry density the following equation is to be followed:
    dryDensity
  2. To determine percent maximum density the following equation is to be followed:
    maxdryDensity               
            NOTE 1 A minimum of 98% from Maximum Dry Density (MDD) must be achieved for adequate compaction on site