MSC columns for soil improvement, belong to the group of displacement technologies. This means that during forming the column core, soil is not extracted to the surface, but displaced horizontally towards the hole centerline. To make MSC columns, the most commonly used are specifically adjusted steel pipe, which is connected at the hardware unit junction with a tool which generates vertical vibrations. Tool weight, vibrations and pressure of the machine result in sliding down the pipe at the planned depth. Once the pipe has reached the desired level, the tool is hoisted up while pumping properly selected grout. The result is a composite of the soil and columns, operating as a homogeneous structure with enhanced bearing capacity. The column process of column implementation does not cause any damages to the area, and the low-frequency vibrations generated in a vertical plane do not affect the construction of buildings even when the works are carried out in a compact development. Work efficiency comes to a few hundred running meters per work shift. During the MSC implementation process, the following parameters of the column are registered: the depth of MSC placing, the consumption of grout and power consumption of the vibrator. Active analysis of these readings allows us to control the quality of column installation and to verify the soil conditions on the concerned site.
MSC column technology has a very broad and economically justified use when we have to work with cases of layers of organic soil (eg. peats, aggregate mud, gyttjas) and cohesive soils with a degree of plasticity IL> 0.6 of a thickness up to 6.0 m. Due to the possibility of installation of a.m. columns on a very dense grid, this method is applicable in soil improvement under the floors in large-surface buildings, warehouse halls and sales floors as well as useful for different types of foundation slabs allowing for their cost-effective reinforcement. It is also used to improve soil under parking lots, walking routes and roads, particularly, when we are dealing with very low banks or inability to construct an appropriate transmission layer.
As a load-carrying medium of a colum shaft, it is used carefully compound grout (cement, lime, cement-lime with ash and chemical additives, or cement-sand/cement-lime-sand mix), the parameters of which are selected in line with the design requirements. The column shaft has a minimum diameter od 0.15 m to 0.30 m depending on the condition of improved soil and their lateral vulnerability. The most frequent column spacing ranges from 1.0 m to 2.5 m, using rectangular or triangular arrangement.
- High performance – MSC technology means very high performance, reaching up to several hundred running meters of columns a day (using a single hardware unit);
- Lack of excavated material – during column formation process there is no excavation of the material onto the surface. In the process there is no need to remove and dispose large amounts of soil;
- Environmentally friendly – no excavated material, excessive noise and fast-paced work make MSC technology really friendly to the environment;
- Mobile – compact hardware unit makes MSC technology applicable in places inaccessible to most of piling machines;
- Economic – due to the high efficiency of works, mobility and the option to choose the optimal grout, MSC method is very competitive to both well-known technologies of soil improvement and traditional soil exchange;
- Comprehensive improvement – MSC columns improves the foundation of the building structures by reducing the overall soil compressibility. Unlike pile solutions, designed as load-bearing rigid elements, MSC columns are designed and made so that the load could spread on the ground (5 – 40 percent loads) and on a column.