MCC Columns are carried out in several following stages:
- Piling section – depending on the characteristic of the ground and surrounding buildings, a vibratory probe is used, that is a vibroflot for vibro compaction or CFA auger, which allows us to obtain the planned depth;
- Concreting – when the device reaches the planned depth, there begins concrete mix injection process in areas of organic or cohesive soils. The load-carrying medium is injected under high pressure through vibroflot nozzles previously attached to the vibroflot. Cementing process in non-bearing soils is accompanied by the compression of soil through injected cement mixture;
- Compaction – sandy soil lying over the organic or cohesive soil layer are compacted with vibroflot with an extra soil gradation improvement.
The application of MCC usually depends on the same geological profile, therefore it is recommended to perform in-depth assessment of geological profile before the decision to apply MCC method is made. This technology can be successfully applied to organic soils (aggregate mud, peats), but also to soft-cohesive soils (loams, dusts) as well as to non-cohesive soils (sands). They are often used as reinforcement for road embankments and other infrastructure facilities, and also have applications under the foundations of different structures (buildings and halls).
Depending on the soil parameters (particularly, lateral resistance of soft soils) and the pressure of concrete mix, concrete columns reach diameters ranging from 0.4-1.2 m, whereas, in non-bearing soil layer they are larger in diameter in proportion to columns in load-bearing soils. MCC columns are arranged on a square or triangular grid, reaching a depth uo to 30 m.
- Effective combination – MCC columns are the solution combining the advantages of soil compaction using vibroflotation method and concrete columns. On the one hand, the soil is not over-stiffen and on the other there is no risk of column dilution in organic soils;
- Adjusted to ground conditions – MCC method is designed for places where under the layer of average-parameter soils there are weak and non-bearing soils, amenable to improvement;
- Cost-effectiveness – the concrete column core is performed only in the area of non-bearing soils, which significantly reduces the material consumption as compared with other technologies of soil improvement;
- Improvement on a global scale – improving the mechanical properties of soil between the columns takes place during their formation by displacement/densification.