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.
Cofra Roller Compaction
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.
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
Bearing capacity increase (Modified dry densities of 95% and 98% MDD can be reached with the system)
Limitation of settlement when applying load
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
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:
What sets us apart
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.
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.
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.
Our CRC rollers are also used to compact working platforms.
Due to the ability to deploy three CRC units, we are often able to response to urgent compaction problems with a fast mobilization.