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What is DCP testing and how does it compare to CPT?

January 9, 2021 by Vertek Team

Dynamic Cone Penetration (DCP) testing is used to measure the strength of in situ soil and the thickness and location of subsurface soil layers.

Dynamic Cone Penetration

It is similar to CPT (cone penetration testing) in that a metal cone is advanced into the ground to continuously characterize soil behavior.

In DCP, however, the cone is driven by a standard amount of force from a hammer, and how far the cone moves with each blow is used to determine the soil density and properties at that level.

In DCP testing, the pushing force is applied by manually dropping a single or dual mass weight (called the hammer) from a fixed height onto the push cone unit.

dcp data

The resulting downward movement is then measured. Unlike CPT systems, basic DCP equipment is hand-portable and may be limited to test depths of 3-4 feet: this makes it a good choice for shallow testing applications such as roadbed construction and maintenance.

Since DCP is essentially hand-powered, it is cheaper and more portable than CPT equipment, but the possibility of human error makes it trickier to obtain consistent and accurate data.

Historically, one of the largest difficulties associated with DCP has been obtaining accurate depth difference measurements with a hand rule after each blow of the hammer.

As you can imagine, taking these measurements by sight and recording them by hand can be slow, finicky work.

Plus, to measure the total depth, the sum of these measurements is calculated, so it is easy to accumulate a troublesome amount of error if each measurement is even slightly off.

Fortunately, handheld electronics technology has alleviated these issues to a great extent. Vertek’s Smart DCP System uses a smartphone app and a laser rangefinder to automatically count blows and measure, record, and plot depth.

From the smartphone, this data can be easily graphed in the field and transferred to a computer or client for reporting and analysis.

Automatic data collection saves time, increases accuracy, and means that the test can be efficiently completed by one person.

vertek automated dcp testing

To further increase the repeatability and efficiency of DCP testing, Vertek offers automatic DCP (ADCP) testing systems. ADCP rigs can be mounted on lightweight trailers, commercially available trucks, or ATVs.

Automated tests are both faster and more consistent than their manual counterparts, and also decrease physical labor for the operator.

DCP and ADCP testing and data analysis is a broad subject, so we’ll return to it in another blog.

In the meantime, be sure to check out the DCP testing information and video demonstrations on our site! You can also download our catalog to see the full specifications and capabilities of Vertek’s Smart DCP and ADCP equipment.


Have questions about whether DCP is right for you?

Click here or give us a call at 1-800-639-6315 to discuss your needs and our solutions.


DCP FAQs

What is a dynamic cone penetrometer?

The Dynamic Cone Penetrometer (DCP) is used to determine underlying soil strength by measuring the device’s penetration into the soil after each hammer blow.

How does a cone penetrometer work?

A cone penetration test rig pushes steel cone into the ground, generally up to 20m below the surface or until the cone reaches a hard layer. The steel cone contains an electronic measuring system that records tip resistance and sleeve friction.

What is DCP testing?

Dynamic Cone Penetration (DCP) testing is used to measure in situ soil’s strength and the thickness and location of subsurface soil layers. It is similar to CPT in that a metal cone is advanced into the ground to characterize soil behavior continuously.

What is DCP in the construction industry?

Dynamic Cone Penetrometer, or DCP, is a tool used for evaluating the strength of soils on site. It also helps with monitoring the condition of granular layers and subgrade soils in pavement sections over time.


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Filed Under: CPT Tagged With: DCP testing

Why do Dynamic Cone Penetration (DCP) Testing?

January 25, 2020 by Vertek Team

Assessing the level of compaction of sub-surface soils can be essential to designing and building structures, particularly those subject to transient or cycling loads. A perfect example is roadways.

If the soil beneath a roadway is not compacted sufficiently, then over time the cycling loads of passing traffic will compact the soil further, leading to surface failures such as large cracks, potholes, and displaced pavement. Assessing the compaction of non-cohesive soils such as fine sands is a particularly difficult challenge.

As we’ve noted in other blog posts, removing a sample from the ground and sending it to a lab is not only time consuming and expensive, but can be highly inaccurate in non-cohesive soils because the samples by necessity are disturbed from their sub-surface condition.

This is where dynamic cone penetration (DCP) testing comes in. Read on to learn more about the importance of DCP testing and what solutions are available.



CPT platforms designed for Cone Penetration Testing.

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The Dynamic Cone Penetration (DCP) test is one of many forms of in-situ soil characteristic tests that are designed to assess soil density.

It shares some characteristics of both SPT and CPT testing, which enables it to provide a useful and in the right application can deliver a complementary data set and is less expensive and troublesome than Nuclear Density testing.

The Standard Penetration Test (SPT) is done by using a sample tube which has thick walls to prevent deformation during the test.

To conduct a test, a borehole is drilled to a specified depth. The sample tube is driven into the bottom of the borehole using a drop hammer of a defined weight dropped a defined distance.

The number of blows (N) needed to drive the sample tube 6, 12 and 18 inches is recorded. The SPT provides a rough indication of the soil density at depth. As noted in previous posts (link here), getting accurate data for soil density can be a complex challenge.

SPT provides an estimate but is not as accurate as CPT and is more expensive due to the need to drill boreholes and the time and labor to do each sample test.

Cone Penetration Testing is a more efficient and accurate way to assess soil density at depth. However, for a small number of shallow tests, dynamic cone penetration testing will provide a more accurate result than SPT and will be less expensive than hiring a CPT rig.

Nuclear Density testing requires a radiation source such as Cesium or Radium. The instrument emits a beam of particles that either are reflected back or pass through whatever is being tested for density.

Using a calibrated sensor and gauge the density of a variety of different materials, including soils, can be determined.

While Nuclear Density testing is relatively efficient because it uses radioactive materials operators must be specially trained and licensed. It is also riskier to manage at a worksite, which again is a good reason to consider DCP.

DCP uses a cone similar to CPT, which provides specific advantages in how the instrument behaves in the soil while measurements are being taken vs. SPT.

Because SPT readings are taken at defined depth and the output is ‘how many blows to travel a specific distance, the test is limited in scope. DCP testing by contrast can reveal a more continuous profile as the tool is driven deeper into the soil to a maximum depth of one meter.

Vertek’s Smart DCP kit and Automated DCP system gives users the ability to conduct three and eight times the number of tests, respectively, compared to standard DCP testing.

So for certain specific test scenarios, dynamic cone penetration can be the test of choice. It is generally more accurate at assessing soil density (compaction) than SPT, is less expensive for certain applications than CPT and is safer and less complicated to administer than Nuclear Density testing.

While DCP results will be consistent for a specific set of soil conditions, it is recommended that the test be calibrated to a specific geology to ensure that data interpretation is accurate.

Filed Under: DCP Tagged With: DCP, DCP testing

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