The Purposes Of Shotcreting In Construction
In general terms, the definition of shotcreting is an injection under pressure of fluid material into fractures and cavities in rock, soil or artificial structures. shotcreting in construction basically has three different main purposes: stabilization, strengthening, sealing.
Stabilization: Stabilization shotcreting is making a skeleton of grout in weak parts or areas of the ground and to avoid sliding in cracks, fissures or bedding planes. It can also be done as spot shotcreting at selected location. Stabilization shotcreting is also used when a future concrete casting is to be done. This is shotcreting to support a construction which will have a temporary status, like a pilot tunnel in a civil engineering project or a drift in a mine. This type of shotcreting is not meant to stop seepage or water intrusion. For foundation work, stabilization shotcreting is mainly done to create temporary roads, work site foundations, stabilize trenches, etc. It may later on form a part of a permanent support.
Strengthening: Strengthening shotcreting is when the grouted ground is connected together by the grout and acts as one body. Joins, fissures, shear faults and other voids in the rock are filled with grout. This is shotcreting to reinforce a structure that will be permanent, such as communication or water tunnels. In dam foundations, blanket shotcreting is a process of enhancing the mechanical properties of the ground itself, so it can act as the support of the structure. In most cases, it is less expensive to utilize the rock thus strengthened in situ instead of drilling, blasting, excavating, crushing, and mixing it with cement to form a concrete which then is cast to form a support for the excavation. The different variants of consolidation shotcreting may be considered as mainly strengthening shotcreting.
Sealing: Sealing is strengthening shotcreting developed to almost water tightness, when a tunnel is dry or the seepage underneath a dam negligible. Sealing is divided into different sealing classes, depending on the permissible inflow of water on the particular work site. Curtain and cover shotcreting are forms of sealing shotcreting. In most subsurface constructions. Sealing is done as pre-shotcreting, the grouted zone should always go beyond the excavation area disturbed by blasting. A concrete casted lining will not seal the ground or stop a ground water sinking unless it is combined with shotcreting or an impermeable membrane. The tunnel can act as a drainage pipe in the ground especially with the air pumping effect from traffic in the enclosed area.