VCC in central Berlin

VCCs are comparable in their quality and field of application with Continuous Flight Auger (CFA) piles, with the added benefit that for VCCs over 90 % of the soil is displaced in-situ rather than dug out. This assures a higher shaft friction and less waste disposal.

Vibro Concrete Columns

Different types of Vibro Concrete Columns

Vibro Concrete Columns can be classified as cast-in-situ displacement piles. This type of pile has a high bearing capacity due to a high mantle friction and the enlarged base that can be installed when dry concrete is used.
VCC constructed
using a truck mounted concrete pump

There are two main types of Vibro Concrete Columns :

  1. Vibro Concrete Columns (VCC) with pumped concrete.
  2. Dry Vibro Concrete Columns (DVCC) where the concrete is a dry mix.

Advantages of the DVCC Method over the VCC Method

The dry concrete is much less a liquid than the pumpable concrete that is used for the standard VCC method.

This allows the vibroprobe to transmit more vibration waves and thereby compaction energy through the concrete into the soil. The DVCC method is therefore advisable for projects where the load bearing capability of a pure stone column is not sufficient and compaction of the soil around the pile is desired (e.g. to prevent liquefaction in an earthquake). The DVCC pile offers the combined effect of high load bearing and soil compaction.

An enlarged gravel base can be formed to give the concrete column enhanced bearing capacity. It is also possible to build a partial stone and concrete column.

DVCC with dry concrete. Installation is done in the same way as a normal stone column.

The advantage is to be able to build an enlarged base and to be able to vary the column diameter.

Possible Disadvantage of the DVCC Method

Although comparison tests in the same soil have not yet been carried out. Columns installed with pumpable concrete (VCC) may have a higher maximum internal strength due to the characteristics of the concrete mix. However, very often the internal strength of the pile is not the critical factor and the better compaction of the surrounding soil may lead to higher overall load bearing capacity of the DVCC columns

Installation of VCC
  1. Locate rig over VCC point.
  2. Vibrate down to depth.
  3. Start the concrete pump.
  4. Build the enlarged base.
  5. Pull with constant speed while observing limit values for concrete pump pressure.