RepairUndergroundStructuralSilica Fume in Shotcrete
John Wolsiefer, Sr., and Dudley R. Morgan
Read MoreSilica fume is a highly pozzolanic mineral admixture that has been used mainly to improve concrete durability and strength and as portland cement replacement. Silica fume has been used primarily in the United States, Canada, and the Scandinavian countries, but is now finding increasing use
UndergroundDevelopment of a Centrifugal Sprayed System for Shotcrete Application
Hiroshi Yamachi, Masataka Uozumi, Yuji Nagano,Youichi Nakano, and Shunsuke Sakurai
Read MoreA new Japanese Ministry of Health document provides regulations and guidelines for the allowable dust concentration in tunnel works. The recommended maximum concen-tration should be less than 3.0 mg/m3 (2.3 mg/y3) at 50 m (164 ft) from the tunnel face. To observe this guideline, it
UndergroundStructuralSteep Slope Stabilization with Fiber-Reinforced Shotcrete
Michael Ballou
Read MoreFor the past 150 years or so, roads have been built through the mountain passes in the western U.S. and Canada. Sometimes these roads led to mines; sometimes they started as logging roads. Some were built for access roads for the railroad. Many were built
UndergroundStructuralSpecification of Shotcrete Toughness
Roland Heere and Dudley R. (Rusty) Morgan
Read MoreFiber-reinforced shotcrete has become an established material for ground support in tunnelling and mining applications as well as in new construction and infrastructure repair. Designers and speciï¬ers frequently require such shotcrete to maintain some quantiï¬able postcrack strength or toughness. Until the newly published round panel
UndergroundInnovative Shotcrete Application Over Geofoam Structure Supporting Boston’s Central Artery Tunnel
David Jamieson
Read MoreThe objective of Boston’s Central Artery/Tunnel (CA/T) Project is to ease the congestion of approximately 190,000 vehicles per day traveling through the city of Boston. This objective is being achieved through the total reconstruction of Interstate Highway I-93 as it passes through the heart of
UndergroundSteel Fibrous Shotcrete: A Summary of the State-of-the-Art
Charles H. Henager
Read MoreSteel fibrous shotcrete has been used for mine and tunnel linings, for rock slope stabilization, in dam construction, for repair deteriorated surfaces and arches, for fire protection coatings and in thin-shell dome construction.
UndergroundRelease of New ASTM Round Panel Test
Stefan Bernard
Read MoreFollowing a 3-year development period, a new test for post-crack performance assessment of ï¬ber-reinforced shotcrete (FRS) and ï¬ber-reinforced concrete (FRC) based on round panels was passed by ASTM Committee C 09 in June 2002. The standard test method, known as C 1550-02, œStandard Test Method
UndergroundInternationalShotcreting in Australian Underground Mines: A Decade of Rapid Improvement
Matthew Clements
Read MoreOver the last decade, dramatic improvements in spraying technology have allowed shot-crete to become the first-choice ground support in many underground mines in Australia. Before 1994, only a very small amount of dry spray shotcrete was used. Since then, the increased use of wet-mix ï¬ber-reinforced
UndergroundDetermination of Early-Age Ductility of Steel Fiber-Reinforced Shotcrete Lining System at INCO’s Stobie Mine
Jean-Francois Dufour, J. Denis P. O'Donnell, Sr., and Michael Ballou
Read MoreThe state of technology in shotcrete materials has evolved steadily throughout the world and particularly in North America during the last 20 years. The use of supplementary cementing materials such as silica fume, fly ash and slag, the new generations of chemical admixtures, and the
UndergroundCombining Shotcrete Mixes for Maximum Performance
J. Denis P. O’Donnell, Sr.
Read MoreRebound is an essential element in the application of shotcrete. Rebound is deï¬ned as follows: œMainly large aggregate with some sand and cement that bounces or ricochets off the receiving surface and falls on to lower surfaces.1 There is a vital function that is achieved