Civil Engineering and Construction / Boring - Civil Engineering and Foundations (Including Seepage Control)
Summary of uses
Various kinds of bentonite are used in various civil engineering and building foundation works including foundation works for architectural buildings, excavating and jacking works in tunnel or drainpipe works, and development of reservoirs or landscaping ponds. Bentonite is used as a material for a stabilizer to protect the wall surface of the excavated ground or as a material to fill cracks in the ground and increase its waterproof property. Bentonite is often used in combination with water and cement to fill cracks, reinforce the ground, or fix underground cores in civil engineering or construction works.
In piling works using drilling mud such as those conducted by the cast-in-place piling method (earthdrill method, reverse method, or boring hole method) or the cast in situ diaphragm wall method, bentonite is used as the chief material for a stabilizer to prevent the pile hole wall from collapsing.
In shielding works or jacking works carried out in tunnel excavation or sewerage pipe installation works, bentonite is used as an important material to effectively carry out excavation and jacking. A cement fluid made by combining bentonite with cement is also used as a back-filling material to fill gaps between tunnels or pipes and the ground and prevent land subsidence.
Bentonite is also used in the seepage control work for a reservoir, a landscaping pond, or a biotope to prevent water leakage or infiltration. Bentonite mixed mainly with on-site soil is laid around the pond and in the bottom and compacted by a compaction roller.
In monitoring wells, exploration wells, and holes made by the deep well method, crushed or granular bentonite is used in the impermeable layer on the bottom. Even in work to form an impermeable layer on the bottom of a several dozen meter deep hole, bentonite granules, which are uniformly shaped and coated with a water infiltration retardant, can be dropped with no concern for bridging to form an impermeable layer as designed just by throwing them into the hole from the ground.
Different construction methods and properties required of bentonite
|Major construction methods||Properties required of bentonite|
|Earth drill method||Viscosity, Wall forming property, Salt resistance|
|Underground continuous wall construction method||Viscosity, Wall forming property, Salt resistance|
|Soil mixing wall method Deep well method||Viscosity, Solid-liquid separation inhibiting property|
|Grout method||Viscosity, Solid-liquid separation inhibiting property|
|Shield method||Viscosity, Solid-liquid separation inhibiting property|
|Pile Construction method||【Drilling mud】Viscosity（Yield value）
【Cement milk】Viscosity, Solid-liquid separation inhibiting property, Strength
|Deep well method
（Formation of an impermeable layer on the bottom of a hole）
|Waterproof property, Water infiltration retardant property, Apparent specific gravity stability|
|Product name||Earth drill method||Underground continuous wall construction method||Soil mixing wall method Deep well method||Grout method||Shield method||Pile Construction method||Deep well method|
|EARTH GEL 1||◯||◯||◯|
|Product name||Dispersant||Thickener||Lost circulation materials|