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Shotcrete is an all-inclusive term for spraying concrete or mortar with either a dry or wet mix process. However, shotcrete may also sometimes be used to distinguish wet-mix from the dry-mix method. The term shotcrete was first defined by the American Railway Engineers Association (AREA) in the early 1930s. [6]
The volumetric mixer varies in capacity size up to 12 m 3 and has a production rate of around 60m 3 an hour depending on the mix design. Many volumetric concrete mixer manufacturers have innovated the mixer in capacity and design, as well as added features including color, multiple admixes, fiber systems, and the ability to do gunite or shotcrete.
The primary advantages of fibre-reinforced shotcrete are: Addition of steel fibers into the concrete improves the crack resistance (or ductility) capacity of the concrete. Traditional rebars are generally used to improve the tensile strength of the concrete in a particular direction, whereas steel fibers are useful for multidirectional ...
Shotcrete is also used for applications where seepage is an issue to limit the amount of water entering a construction site due to a high water table or other subterranean sources. This type of concrete is often used as a quick fix for weathering for loose soil types in construction zones. There are two application methods for shotcrete.
The new Austrian tunneling method (NATM), also known as the sequential excavation method (SEM) or sprayed concrete lining method [1] (SCL), is a method of modern tunnel design and construction employing sophisticated monitoring to optimize various wall reinforcement techniques based on the type of rock encountered as tunneling progresses.
Flow table with a grip and a hinge, 70 centimetres (28 in) square. In the American version of this test, the table is 10 inches (25 cm) diameter per ASTM C 230.; Abrams cone, open at the top and at the bottom - 30 centimetres (12 in) high, 17 centimetres (6.7 in) top diameter, 25 centimetres (9.8 in) base diameter.
The main interest of dry shotcrete is the capacity to pump the mortar over a long distance and this is needed when the access points are distant. Perhaps the longest dry shotcrete distance is a job site in Australia in 2014, where 100% calcium aluminate mortar was air transported over 800 meters before being sprayed. The main drawback with dry ...
Putzmeister was founded by Karl Schlecht in 1958. [3] Schlecht designed a mortar machine based on his diploma thesis at the University of Stuttgart. [4]In 1986, Putzmeister 52Z's were used in the Chernobyl nuclear accident, pumping over 300,000 m 3 (390,000 cu yd) of concrete to entomb reactor number 4, setting a world record at the time for volume pumping.