Bentonite for civil engineering

Bentonite as well as bentonite-base suspensions are widely used in a wide range of construction works:

• Tunneling, including for the metro;
• Construction of facilities using the “Slurry wall” method;
• Sealing cracks and filling voids, including during the construction of Hydropower plants;
• Waterproofing for the construction of foundations;
• Construction (installation) of waterproofing screens.

When constructing tunnels in difficult geotechnical conditions (unstable soils, significant groundwater pressure, etc.), slurry type tunneling machines are used.

Fig. 1 Tunneling machine mode of operation

During the tunneling operation with tunneling machine EPB type, a bentonite suspension with strictly defined properties is injected into the borehole area under the pressure, which is penetrated into the soil under the pressure, compacts the tunnel face, excluding subsidence and rock collapse. In addition, the functions of the bentonite suspension are to remove cuttings from the face, lubricating and cooling the sinking equipment.

During the construction of structures, with dense buildings, bentonite suspensions are used as part of the “slurry wall” technology.

Fig. 2 Slurry wall installation

The essence of the <>strong“slurry wall” technology in the construction of underground structures is that in order to prevent the walls from collapsing the trench is filled with clay mud as the soil is removed from it. The clay mud with low viscosity and high mudding ability penetrates into the soil and fills the walls of the trench, forming a thin - 0.5-3 mm and fairly dense and strong crust on their surface, preventing the wall of the trench from collapsing before the reinforcing cage is lowered and the trench is filled by the concrete. After the concrete has gained strength, the finished structure can serve as the supporting element of the foundation, the enclosing structure of the walls of the underground structure, as well as a groundwater cutoff that excludes the access of groundwater to the buried operated structure.

Due to the sealing, plasticizing and penetrating properties, bentonite is widely used in injection and cementitious mortars, which are effective for filling cracks and filling voids. That is why bentonite is an important material for the construction of hydroelectric power stations, dams and weirs, canals, ponds, basements of residential and industrial buildings.

For the whole range of construction works, the following grades of bentonite produced by Kurgan Bentonite Limited are successfully used: PBM-18, PBM-20, PBM-22. For the foundation waterproofing a unique waterproofing material - GCL is used.