Deep cement mixing (DCM) is a

civil engineering Civil engineering is a professional engineering discipline that deals with the design, construction, and maintenance of the physical and naturally built environment, including public works such as roads, bridges, canals, dams, airports, sewage ...

deep foundation A deep foundation is a type of foundation that transfers building loads to the earth farther down from the surface than a shallow foundation does to a subsurface layer or a range of depths. A pile or piling is a vertical structural element ...

technique where a binder material, typically cement, is injected into the ground for ground stabilization and

land reclamation Land reclamation, usually known as reclamation, and also known as land fill (not to be confused with a waste landfill), is the process of creating new land from oceans, seas, riverbeds or lake beds. The land reclaimed is known as reclamati ...

. In ground stabilization applications it is typically used to obtain a better load bearing capability of the existing soil, e.g. in order to bear buildings and other structures. In land reclamation applications it is typically used when cheaper techniques such as

dredging Dredging is the excavation of material from a water environment. Possible reasons for dredging include improving existing water features; reshaping land and water features to alter drainage, navigability, and commercial use; constructing da ...

or draining cannot be applied because of environmental concerns due to contaminated soil that these two techniques would release. The expansion of the

Hong Kong International Airport Hong Kong International Airport is Hong Kong's main airport, built on reclaimed land on the island of Chek Lap Kok, Hong Kong. The airport is also referred to as Chek Lap Kok International Airport or ''Chek Lap Kok Airport'', to distinguish ...

and Tokyo's

Haneda Airport , officially , and sometimes called as Tokyo Haneda Airport or Haneda International Airport , is one of two international airports serving the Greater Tokyo Area, the other one being Narita International Airport (NRT). It serves as the primary ...

are examples of this. Deep cement mixing was first developed in Japan where first field tests began in 1970. Originally granular

quicklime Calcium oxide (CaO), commonly known as quicklime or burnt lime, is a widely used chemical compound. It is a white, caustic, alkaline, crystalline solid at room temperature. The broadly used term "''lime''" connotes calcium-containing inorganic ma ...

was used as binder to stabilize the underlying soil, but soon better results were obtained using

cement A cement is a binder, a chemical substance used for construction that sets, hardens, and adheres to other materials to bind them together. Cement is seldom used on its own, but rather to bind sand and gravel ( aggregate) together. Cement mix ...

slurry and cement mortar. Until the end of the 1980s, DCM was used only in Japan and Scandinavia. Since then it has gained popularity also in the United States and Europe. Deep cement mixing involves first extracting soil from the ground into which binder material is later to be injected. Typically this is done with an

auger Auger may refer to: Engineering * Wood auger, a drill for making holes in wood (or in the ground) ** Auger bit, a drill bit * Auger conveyor, a device for moving material by means of a rotating helical flighting * Auger (platform), the world's f ...

type machine in order to penetrate deeply but narrowly into the soil. Upon reaching the required depth, cement or sometimes another binder material is injected into the excavated hole. As the soil is soft, the binder material mixes with the soil diffusing back into the excavated hole, so it is important to choose a binder material appropriate for the specific soil, although in the vast majority of cases, cement works well. As the cement-soil mix begins to harden, further cement is added on top of the growing column until the column reaches all the way up to the start. During this process further excavation of the diffusing soil may be required. Finally the machinery is moved to the location of the next column where the process is repeated in order to form another column. Once fully hardened these columns are then able to bear much higher loads than the seabed (when using the technique to reclaim land) or the typically soft soil upon which one wants to build.

References

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External links

Part of Report of DCM used in Tokyo

Hong Kong Airport Technical Report

Video containing an animation of deep cement mixing as used in Hong Kong
Deep foundations