Compaction tests · Nuclear density · % Proctor
Nuclear Density Test
We measure compaction on site on fill, road layers and controlled fill under buildings. We determine in-situ density and moisture content with a nuclear gauge to ASTM D6938 and report the result as degree of compaction against the laboratory Proctor value.
Call us directly: +90 533 616 18 67
- NDK-licensed gauge
- ASTM D6938
- Proctor test in an accredited laboratory
- TANAP, Istanbul Airport
- Handle for lowering the rod
- Display: density, moisture content, % Proctor
- Gamma source, inside the drilled hole
- Gamma detectors, in the base
- Neutron source and detector, at the surface
Definition
What is the nuclear density test?
The nuclear density test is a field test that measures the in-situ density and moisture content of compacted soil with a gauge containing radioactive sources. The measured dry density is divided by the maximum dry density from the laboratory Proctor test of the same material to give the degree of compaction.
Density is measured with gamma rays and moisture content with neutrons. On site it is also called the nuclear gauge test, nuclear Proctor or, after the gauge brand, the Troxler test.
It is used to check every compacted layer on highways, airport runways, railways, pipelines and controlled fill under buildings. The result is seen on site, at the test point, straight away.
At a glance
| Standard | ASTM D6938 (in-place density and water content by nuclear methods). |
|---|---|
| Measured values | Wet and dry density, moisture content, % Proctor. |
| Measurement depth | Up to 300 mm in direct transmission. Backscatter mode from the surface as well. |
| Sources | Caesium-137 (density), americium-beryllium (moisture). |
| Prerequisite | Proctor test in an accredited laboratory on a sample of about 10 kg of the material. |
| Licence | The gauge is used under a licence from the Turkish Nuclear Regulatory Authority (NDK), by a trained operator with a dosimeter. |
Two stages of the test
Laboratory first, then the field
Proctor test
A sample of about 10 kg is taken from the fill material and the Proctor test is carried out in an accredited laboratory. The standard or modified Proctor test gives the maximum dry density and optimum moisture content of the material. Field measurements are assessed against this value.
Nuclear density measurement
A hole is made in the compacted layer with a steel rod and the gauge rod is lowered into it. The gauge measures wet density and moisture content and calculates dry density and degree of compaction. Points below the specified value are recompacted and tested again.
On site
How is the nuclear density test carried out?
- The Proctor value is enteredThe maximum dry density and optimum moisture content from the laboratory are entered into the gauge.
- A standard count is takenThe gauge is checked with a daily standard count on its own reference block.
- The surface is preparedThe test point is levelled so that the base of the gauge sits fully on the surface.
- The hole is madeA hole slightly deeper than the test depth is made with the guide plate and steel rod.
- The rod is lowered and measuredThe gamma source is lowered to the required depth and the gauge measures density and moisture content.
- The result is recordedDry density and % Proctor appear on the display and are recorded with the point number and location, then reported.
Reading the results
How is the degree of compaction calculated?
The gauge measures wet density (γn) and moisture content (w). Dry density and degree of compaction are found as follows:
γd = γn / (1 + w)
Compaction = γd / γd,max × 100
The acceptance value is set by the project specification. The specification also states which Proctor test (standard or modified) is used.
Price
Nuclear density test price
The price depends mainly on the number of points, the duration of the service and the project location.
- One-off testing, or a gauge with operator by the day or month
- For long fill works a monthly service lowers the cost per point
- If no Proctor test has been done, the laboratory fee is added
- Travel and accommodation are added for sites outside Istanbul
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Why use a service
Hiring a service instead of buying a gauge
Because a nuclear density gauge contains radioactive sources, a licence from the NDK is needed before buying one. The licence requires a compliant storage area, a radiation detector with dosimeter for each gauge and trained staff.
- The licensed gauge and trained operator come from us
- Storage, transport and dosimetry obligations are ours
- We also organise the Proctor test in an accredited laboratory
- One-off, daily or monthly work as needed
Limits of the test
When is care needed?
- Not used on clean gravel and clean crushed stone because of the large surface voids
- The material must be uniform. On coarse or mixed fill, results can be verified with the sand cone
- Moisture measurement treats the hydrogen in the material as water. Other hydrogen sources such as organic matter can affect the result; if needed it is compared with the oven-dry method
- When the material changes the Proctor test must be repeated, otherwise the degree of compaction will be wrong
References
Projects where we carried out nuclear density tests
- TANAP Project, Harmancık site2018–2019
- TANAP Project, Gönen site2018–2019
- Istanbul AirportIstanbul
- Aksaray–Ankara MotorwayAksaray
- Balıkesir Organised Industrial Zone2021
- TOKİ Silivri housing2020
- İkitelli OPET2020
- Emet Boron WorksKütahya
- Çanakkale solid waste landfillÇanakkale
- Ereğli Iron and Steel, galvanising lineZonguldak
Comparison
Which compaction control test should you choose?
| Test | What does it measure? | When to choose it? |
|---|---|---|
| Nuclear density test | In-situ density, moisture content, % Proctor | When the specification requires a degree of compaction, fast checks at many points |
| Sand cone test | In-situ density | Materials unsuitable for the nuclear gauge, verification |
| Light weight deflectometer (LWD) | Dynamic deformation modulus Evd | When the specification requires a modulus, narrow trenches |
| Static plate load test | Ev1, Ev2 and Ev2/Ev1 | Bearing capacity and stiffness checks |
| Proctor test | Maximum dry density, optimum moisture content | Before field compaction control, for each material |
Frequently asked questions
About the nuclear density test
What is the nuclear density test?
A field test that measures the in-situ density and moisture content of compacted soil with a gauge containing radioactive sources. The measured dry density is divided by the laboratory Proctor value to give the degree of compaction.
Which standard is the nuclear density test carried out to?
ASTM D6938, which covers the in-place density and water content of soil and soil-aggregate by nuclear methods.
Is a Proctor test required for the nuclear density test?
Yes. The degree of compaction is the ratio of the field dry density to the maximum dry density from the Proctor test. A sample of about 10 kg of the fill material is therefore taken in advance and the Proctor test is carried out in an accredited laboratory.
What should the degree of compaction be?
The acceptance value is set by the project specification. It depends on the position of the layer, the material and the Proctor test used (standard or modified).
How deep does the nuclear gauge measure?
In direct transmission the gamma source is lowered into a drilled hole and measures to a depth of up to 300 mm. Each compacted layer is therefore tested separately.
Is the nuclear density test dangerous?
The gauge contains sealed radioactive sources and is used under a licence from the Turkish Nuclear Regulatory Authority (NDK). Measurements are made by a trained operator wearing a dosimeter. People are asked not to stand near the gauge unnecessarily during measurement.
Can I buy a nuclear density gauge?
A licence from the NDK is needed before buying one. The licence requires a suitable storage area, a radiation detector with dosimeter and trained staff. For those who do not want these obligations we provide a daily or monthly service with operator.
Which materials cannot be tested with the nuclear gauge?
The method is not used on clean gravel and clean crushed stone because of the large surface voids. On non-uniform, coarse fill, results can be verified with the sand cone test.
What is the difference between the nuclear density test and the sand cone?
Both measure in-situ density. The nuclear gauge also measures moisture content and gives the result at the point straight away. In the sand cone test the soil from the hole is weighed, moisture content is found separately and the test takes longer. The sand cone is used on materials unsuitable for the nuclear gauge and for verification.
What is the difference between the nuclear test and the light weight deflectometer?
The nuclear test measures density and degree of compaction. The light weight deflectometer (LWD) measures the stiffness of the layer as the dynamic deformation modulus Evd. The acceptance criterion in the specification decides which one is used.
Let us check your fill before the next layer
Send us a 10 kg sample of your fill material and we will have the Proctor test done in an accredited laboratory. We will plan the field measurements layer by layer and send our quote.
Sarıgöl Mah. Mezarlık Sk. C1 No: 108 İç Kapı No: 63
Gaziosmanpaşa, Istanbul, Turkey
Mobile / WhatsApp: +90 533 616 18 67
Phone: +90 212 369 00 16
info@zeminarastirma.com
Mon–Fri 08:00–19:00 · Sat–Sun 08:00–14:00 (GMT+3)