Eine Plattform für die Wissenschaft: Bauingenieurwesen, Architektur und Urbanistik
Eine Plattform für die Wissenschaft: Bauingenieurwesen, Architektur und Urbanistik
Shotcrete with high early strength, over 2 MPa at the age of 10 minutes, has been developed for enhancement of rock support, improvement of safety, increase of excavation speed, and decrease of total cost in tunneling. The high early strength shotcrete is achieved by use of a calcium-aluminate based powder accelerator and calcium-sulfate based powder additive. The calcium-aluminate based powder accelerator is hydro-reactive and exhibits self-hardening properties on reacting with water. Ettringite (3CaO-Al2O3-3CaSO4-32H2O) is observed by reaction of the accelerator and calcium-sulfate based powder additive, together with cement and water. Formation of Ettringite is thought to enhance the strength development in the early stages of hydration in shotcrete. Shotcrete experiments in a model tunnel resulted in very high strength from early to later ages, 4.0 MPa after 10 minutes, 19.3 MPa after 1 day, and 58.8 MPa after 28 days. Application of the high early strength shotcrete can decrease the required thickness of shotcrete, exclude the need for steel ribs in some applications, shorten the excavation period, and decrease the total tunneling cost.
Shotcrete with high early strength, over 2 MPa at the age of 10 minutes, has been developed for enhancement of rock support, improvement of safety, increase of excavation speed, and decrease of total cost in tunneling. The high early strength shotcrete is achieved by use of a calcium-aluminate based powder accelerator and calcium-sulfate based powder additive. The calcium-aluminate based powder accelerator is hydro-reactive and exhibits self-hardening properties on reacting with water. Ettringite (3CaO-Al2O3-3CaSO4-32H2O) is observed by reaction of the accelerator and calcium-sulfate based powder additive, together with cement and water. Formation of Ettringite is thought to enhance the strength development in the early stages of hydration in shotcrete. Shotcrete experiments in a model tunnel resulted in very high strength from early to later ages, 4.0 MPa after 10 minutes, 19.3 MPa after 1 day, and 58.8 MPa after 28 days. Application of the high early strength shotcrete can decrease the required thickness of shotcrete, exclude the need for steel ribs in some applications, shorten the excavation period, and decrease the total tunneling cost.
Shotcrete with High Strength at Early Age
Ishida, A. (Autor:in)
10th International Conference on Shotcrete for Underground Support ; 2006 ; Whistler, British Columbia, Canada
Shotcrete for Underground Support X ; 110-119
25.08.2006
Aufsatz (Konferenz)
Elektronische Ressource
Englisch
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