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Cofra roller compaction (CRC)

Compaction techniques form part of Cofra’s portfolio since 2005. Since that time we have compacted several tens of millions cubic meters with our compaction techniques. Our three compaction techniques are complementary to each other and are often used together on compaction projects. Our CRC rollers have the lowest depth of influence from our compaction techniques and are able to compact the top 2 to 3 meters of the subsoil and perform amongst other application areas often the ironing pass after vibro compaction works. Our specialists are more than happy to tell you more about it.

What it is

The Cofra Roller Compaction (CRC) method, also referred to as High Energy Impact Compaction (HEIC), is a technique that densifies loose granular materials up to a depth of 2 to 3 meters below the surface by pulling a non-circular roller over the surface of an area.

How it works

The compaction of the underground is initiated by vibrations, which lead to the rearrangement of the particles. These vibrations are generated from the impact of a weight onto the surface. The CRC method is in essence a light form of dynamic compaction in which densification is achieved by lifting and dropping a weight from a specified height. The shape of the non-circular drums of the CRC equipment cause in this case the lifting and dropping motion of the drum weight as the equipment travels over the site. 

 

Verdichting

Why it's used

Compaction is required to mitigate liquefaction risks or improve the bearing capacity and settlement behavior under loading of the underground. The roller compaction is, due to it’s shallow application, mainly used to improve the bearing and settlement characteristics of the top layers. 

Applying CRC will result in the following effects:

  • Soil densification due to vibration and particles re‐organization
  • Friction angle increase
  • Stiffness increase
  • Bearing capacity increase (Modified dry densities of 95% and 98% MDD can be reached with the system)
  • Liquefaction mitigation
  • Limitation of settlement when applying load

Application area

Cofra roller compaction is used in the following markets: 

  • Infrastructure: The roller is for example used for the compaction of embankments for roads, railways, runways and aprons for airports and port areas
  • Dredging and land reclamation: CRC is often used to compact the top layer of the reclamation up to specification
  • Mining: CRC can be used to compact roadways for the heavy mining trucks or to allow for higher production in the filling of spoils.
  • Construction: Cofra Roller compaction is used in the construction to compact terrains but also to investigate the areas for weak spots that need treatment
  • Liquefaction mitigation: CRC is used for liquefaction mitigation in areas where loose saturated granular soil occurs near the surface

  The following soil types are suitable for the use of CRC:

Website Diagram CRC V2

What sets us apart

Makassar CRC 13

Choice of compaction techniques

Cofra has the choice out of three complementary compaction techniques. This makes it able to choose the best compaction method for your project. Feel free to ask for your specific project situation and requirements.

Loggerdata

GPS quality control

The CRC technique compacts the underground fast, homogeneously and with high accuracy due to the use of a GPS guided monitoring system. The main parameter of interest is the deceleration of the impact, which is related to the compaction level of the subsoil. Overviews of the deceleration, as schematically indicated in the image above, create insight into the areas that require further attention.

IMG 6374 1 2

In-house engineering

Our in house geotechnical department is involved in every compaction project. The geotechnical engineers of Cofra are at hand to review data and make the site-specific correlations between the monitoring data and the hand over criteria. They will also perform the final testing if required.

Matarbari CRC 21

Platform control

Our CRC rollers are also used to compact working platforms.

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Fast response

Due to the ability to deploy three CRC units, we are often able to response to urgent compaction problems with a fast mobilization.

How it is installed

The roller is pulled at speeds between 10-15 km/h to generate the most optimal effect. The method has the highest surface production rate of all compaction methods known today, with a coverage in a single pass over 100.000m2 a day. The CRC technique compacts the underground fast, homogeneously and with high accuracy due to the use of a GPS guided monitoring system. The main parameter of interest is the deceleration of the impact, which is related to the compaction level of the subsoil. Overviews of the deceleration, as schematically indicated in the image below, create insight into the areas that require further attention.

Csm CRC Wide 2 7A7bf25c87

Contact us (regional contacts on our contact page)

Business development Cofra

For new opportunities or partnering

Estimation Department Cofra

If you require a quotation or need a budget for your project for any country in world outside our home markets

Technical Sales Cofra

For design questions or technical information

A selection of our compaction projects

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CRC compaction for the Hartel Tank Terminal

We have used our CRC roller to compact backfilled material up to a depth of 3m on the Hartel Tank Terminal in Rotterdam in 2019.

Matarbari_CRC_21

CRC compaction Matarbari powerplant

We have executed CRC roller compaction to assure platform stability and check for soft spots on the Matarbari powerplant construction site before installation of vertical drains commenced.

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CVC compaction for stability slopes

We have compacted the slopes for a pipe pull in Borselle, the Netherlands, from a barge up to a depth of 30m deep.

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CDC compaction for Bessamer Park Sheffield, UK

Cofra Ltd Compacted 11,500m2 for the development of a new warehouse in 2019.

P1020271

CDC compaction for UK Battery Industrialization Centre

Cofra Ltd compacted 12,500 m2 for the development of a new warehouse in 2019.

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CDC compaction for the Bahrein steel factory, Bahrein

Our Cofra Middle East crews compacted in 2022, 40,000m2 for the reclamation to expand the Bahrain Steel Factory.