4640-B Thin Layer Density Gauge

Product Features


Recognizing the need for an improved method of measuring the density of thin layer asphalt overlays, Troxler, the world leader in nuclear gauge technology, developed the first true thin layer density gauge, the Troxler Model 4640-B.

Designed to measure the density of thin asphalt and concrete layers from 2.5 to 10 cm (1 - 4 inches), the Troxler Model 4640-B Thin Layer Density Gauge accurately measures the overlay density without influence from underlying material. No nomographs or manual corrections are required in order to compute the true density of the overlay. With on-site results available in as little as one minute, the Model 4640-B can provide the user with test results when they are needed, not hours after compaction has been completed.

Advantages of the MODEL 4640-B

In as little as one minute, the 4640-B displays densities in pcf, kg/m3 or g/cm3 and in percent Marshall, percent voids, or percent of maximum density (voidless). Accuracies within 1.5 percent of core results have consistently been achieved.

ELIMINATES NEED FOR NOMOGRAPHS AND MANUAL CORRECTIONS : Variations in the density or composition of the base material do no affect the test results. No field calculations or charts are needed to determine density.

OPERATOR SELECTED DEPTH OF MEASUREMENT : Enter the thickness of the overlay into the gauge memory and then accurately measure the overlay density (compaction) without influence from the underlying material.

The 4640-B meets or exceeds all applicable ASTM standards.

CALIBRATION : Test equipment is only as good as its calibration. With 30 years of proven experience, the 4640-B calibration process is unbeatable  for its accuracy and results. For special materials, up to 11 field calibrations can be performed and stored.

USER FRIENDLY : The operator will find the 4640-B very easy to use. It was designed as a user friendly gauge with prompts to guide the operator through the test procedure.

DATA STORAGE - COMPUTER COMPATIBLE : Store up to 750 readings by location and project number. Transfer stored readings to a printer of computer via RS232 interface. Additional site information can also be stored with each test.



 Measurement Specifications
  Time (Min) Thickness kg/m3 pcf
 Gauge Precision (± std. deviation)
 at 2240 kg/m
3 (140 pcf)


2.5cm (1")
5.0cm (2")
6.3cm (2.5")
2.5cm( 1")
5.0 cm (2")
6.3 cm (2.5")
± 1.0
± 0.6
 Depth of Measurement   25-100
 Radiological Specifications
 Gamma Source  8 ± 1mCi Cesium-137
 Troxler Drawing Number  TEL A-102112
 Source Encapsulation  Stainless Steel
 Shielding  Tungsten and lead
 Surface Dose Rates  5 mrem/hour max. top ad sides of gauge,
 15 mrerm/hour max. bottom of gauge,
 gamma in shield position
 Shipping Case  DOT 7A, TYPE A,  Yellow II Label 0.2 Transport Index
 Source Seal Approval for Domestic and International Shipment  Cs0137, SPECIAL FORM Certificate
 GB: SFC 140
 Mechanical Specifications
 Case  Colored polycarbonate top shell with aluminum cast base
 Operating Temp. : Ambient
 -10 to 70º C (14 to 158ºF)
  175ºC (350ºF)
 Storage Temp.  -55 to 85ºC (-70 to 185ºF)
 Gauge Size (excluding handles)  472 x 231 x 158 mm (186 x 9.1 x 6.2 inches)
 Gauge Weight (including handles)  240 mm (9.5 inches)
 Weight  13.5 kg (29.7pounds)
 Shipping Weight  40.8 kg (90 pounds) with transport case
 Electrical Specifications
 Stored Energy  30 watt-hours
 Battery Recharge Time  14-16 hours (automatic cutoff)
 Battery Recharge  110/220 V, 50-60Hz or 12-14 VDC
 Power Consumption (avg.)  0.16 watt/hours
 Readout (LCD) LIQUID CRYSTAL DISPLAY  4 x 16 alpha-numeric
 Battery packs are fully protected against overcharge and overdischarge.
 Provided with RS232 interface.
 Cable of operation with D size alkaline batteries for emergency use.
 Calibration Specifications
 Accuracy of Density Standards  ±0.3%
 Calibration Range  1600-2700 kg/m3
 100-170 pct Density
 Field Data Conversion

 4640-D - Contains a microprocessor providing direct reading in engineering units in pcf, kg/m
3 or g/cm3 ;
 no calculation is required.
 Special Functions
 Automatic standard count comparison and storage. Determination of count time for selected precision. Field offsets of density.
 Field calibration for special asphalts. Calculator mode with storage. Self-test and service programs: Display, Keypad, and Ram
 Test; GM Tube Test; Statistical Stability and Drift Test; Gauge Identification Program.

 Supplied with the MODEL 4640-B : Air Gap Fixture. 1" Magnesium Block; AC Battery Charger; DC Charger Cord; Transport   

 Optional : PN 021140 Radiation Sign Kit; PN 102868 Leak Test Kit; PN 104262 Radiation Survey Meter; TLD Film Badge Service.

 Licensing and Training : The radioactive source contained in the 4640-B is a by-product material and requires a special license
 issued by the "Agreement State" of by the U.S. Nuclear Regulatory Commission. Troxler will assist the customer in obtaining
 and completing the proper license application. Troxler office or field training may be arranged for a fee covering the instructor's
 time and expenses. For international licensing and training information, consult Troxler International, Ltd. or the local
 Troxler Distributor.