Compaction tests · LWD · Light weight deflectometer
Dynamic Plate Load Test (LWD)
We check the compaction and bearing capacity of fill, road sub-base, railways and pipeline trenches on site. We measure the dynamic deformation modulus Evd to TP BF-StB Part B 8.3 and give the result in about 3 minutes per point.
Call us directly: +90 533 616 18 67
- ~3 minutes per point
- TP BF-StB B 8.3
- Since 2001 on site
- Works in narrow trenches too
- Falling weight, 10 kg
- Guide rod and release
- Spring damper
- Loading plate Ø300 mm, acceleration sensor
- Measuring unit, Evd on screen and printout
- Influence depth about one plate diameter
Definition
What is the dynamic plate load test?
The dynamic plate load test is a field test in which a 10 kg weight is dropped onto a 300 mm diameter plate placed on the ground and the settlement of the plate is measured. The result is given as the dynamic deformation modulus Evd (MN/m²). The device is called a light weight deflectometer (LWD) or light falling weight deflectometer.
A high Evd means the layer is well compacted and stiff; a low value means it is insufficiently compacted or soft. The test is used to check compaction on every layer of fill and of the granular layers under a pavement. Because no truck or plant is needed as a counterweight, it can also be used in narrow trenches. One person can operate it.
Suitable materials: granular fill with a maximum particle size of up to 63 mm, crushed stone and sub-base materials, and fine-grained soils of stiff consistency.
At a glance
| Standard | TP BF-StB Part B 8.3 (German road construction specification). Similar methods: ASTM E2583 and ASTM E2835. |
|---|---|
| Falling weight | 10 kg. Plate diameter 300 mm. |
| Impact | Maximum force 7.07 kN, duration 17 ms. Stress under the plate 0.1 MN/m². |
| Measuring range | Evd 15–70 MN/m². |
| Influence depth | About one plate diameter, 300 mm. |
| Duration | About 3 minutes per point. Result on site on screen and printout. |
Conditions of use
When is the LWD suitable and when not?
Suitable for
- Compaction checks on every layer of fill and sub-base
- Backfill checks in pipeline, cable and sewer trenches
- Large sites where many points must be measured quickly
- Narrow areas that a vehicle for static plate load tests cannot enter
- Finding weak zones quickly and choosing extra test points
Not suitable for
- Frozen ground and air temperatures below 0 °C or above 40 °C
- Soft or muddy fine-grained soils
- Materials with particles larger than 63 mm under the plate
- Surfaces with a slope of more than 6%
- Very stiff layers where Evd exceeds 70 MN/m². For these a static plate load test is carried out
On site
How is the dynamic plate load test carried out?
- The surface is preparedThe test point is levelled and loose particles are removed. If needed a few millimetres of dry sand are spread under the plate so that it sits fully. A dried crust or wet surface is removed.
- The plate is placedThe 300 mm plate is seated on the surface and rotated slightly for full contact. The guide rod and falling weight are fitted vertically on the plate.
- The measuring unit is connectedThe acceleration sensor on the plate is connected to the measuring unit by cable and the point number is entered.
- Three seating dropsThe weight is released three times. These drops seat the plate on the surface and are not included in the measurement.
- Three measuring dropsThe weight is released three more times and the settlement of the plate is measured at each drop. The weight is caught after each drop and is not allowed to strike a second time.
- Evd is calculated and recordedThe unit calculates Evd from the average of the three settlements, shows it on screen and prints it. Results are reported with a sketch of the points.
Reading the results
How is Evd calculated?
The impact creates a stress of 0.1 MN/m² under the plate. The unit takes the average settlement (s) of the three measuring drops and calculates Evd:
Evd = 22.5 / s
Here s is the average settlement in millimetres. For example, if the average settlement is 0.45 mm, Evd is 50 MN/m². The smaller the settlement, the higher the Evd.
Evd: 50,0 MN/m²
The acceptance value is set by the project specification. There is no single conversion between Evd and the Ev2 value of the static plate load test that is valid for every soil. If the specification requires Ev2, both tests are carried out side by side at a few points on site to establish a relationship for that material.
Price
Dynamic plate load test price
The price depends mainly on the number of points and the project location.
- The more points, the lower the price per point
- For layer-by-layer checks the number of visits affects the price
- Sand cone, nuclear density or CBR tests can be added at points with low results
- Travel and accommodation are added for sites outside Istanbul
Fill in the details and your message opens ready to send on WhatsApp. Add your specification and a sketch of the test points to the same chat if you have them.
Before the test day
What we need on site
- The layer to be tested must be placed, compacted and levelled
- There must be no standing water or frost on the surface
- Test point locations, a sketch or chainage must be agreed
- Send us the acceptance value and test frequency in the specification, if any
- Plant must be ready to recompact points with low results
After the test
What is in the report?
- Settlements of the three measuring drops and the Evd value for each point
- Test point locations and layer information
- Pass or fail against the specified acceptance value
- Printouts from the measuring unit
- Recommendations for zones with low results
Applications
Where is the dynamic plate load test used?
Comparison
Which compaction control test should you choose?
| Test | What does it measure? | When to choose it? |
|---|---|---|
| Dynamic plate load test (LWD) | Dynamic deformation modulus Evd | Fast checks at many points, narrow areas and trenches |
| Static plate load test | Deformation moduli Ev1, Ev2 and the Ev2/Ev1 ratio | When the specification requires Ev2, and on stiff layers. A truck or plant is needed as reaction |
| Nuclear density test | In-situ density and moisture content, degree of compaction against Proctor | When a degree of compaction is required, fast density checks |
| Sand cone test | In-situ density | Where the nuclear gauge cannot be used or verification is required |
| CBR | California bearing ratio | Bearing capacity of materials for pavement design |
Frequently asked questions
About the dynamic plate load test
What is the dynamic plate load test?
A field test in which a 10 kg weight is dropped onto a 300 mm diameter plate placed on the ground and the settlement of the plate is measured. The result is given as the dynamic deformation modulus Evd and shows the compaction and bearing capacity of the fill.
What does LWD mean?
LWD stands for Light Weight Deflectometer. The test is also called the light falling weight test, deflectometer test or dynamic plate load test.
Which standard is the dynamic plate load test carried out to?
In Turkey the German road construction specification TP BF-StB Part B 8.3 is most often used. Similar methods are described in ASTM E2583 and ASTM E2835.
How is Evd calculated?
The device takes the average plate settlement from three measuring drops. For a 300 mm plate, Evd = 22.5 / s, where s is the average settlement in millimetres. For example, a settlement of 0.45 mm corresponds to an Evd of 50 MN/m².
What should the Evd acceptance value be?
The acceptance value is set by the project specification and depends on the position and material of the layer. The range that can be measured with the LWD is 15–70 MN/m². Where a higher value is required, the static plate load test is carried out.
Is there a relationship between Evd and Ev2?
There is no single conversion valid for every soil. If the specification requires Ev2, dynamic and static plate load tests are carried out side by side at a few points on site to establish a relationship for that material. Checks then continue with the faster LWD.
How long does the dynamic plate load test take?
About 3 minutes per point. The result is seen on site on the device screen and a printout is produced.
Where can the dynamic plate load test not be used?
On frozen ground, soft fine-grained soils, materials with particles larger than 63 mm under the plate and surfaces with a slope of more than 6%. The air temperature must be between 0 and 40 °C.
What is the difference between the dynamic and static plate load tests?
In the static test the plate is loaded in steps with a hydraulic jack and a truck or plant is needed as reaction; the result is Ev1, Ev2 and the Ev2/Ev1 ratio. In the dynamic test the load is applied once by a falling weight, no vehicle is needed and the measurement takes a few minutes; the result is Evd.
How deep does the test check?
The influence depth is about one plate diameter, i.e. around 300 mm. Each compacted layer must therefore be checked separately.
Let us check your fill before the next layer
Send us the number of points, the type of work and the project location. We will plan the day on site 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)