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placement process. If a well-planned worksite strategy is in place with appropriate material handling equipment, excellent lighting, and a well-trained shotcrete crew, the only limiting production factor will be the capacity of the shot- crete placement equipment. Some mines in northern Canada have had success supplying bulk preblended dry materials underground via the shaft and cage through the use of cassettes (removable bulk bins that can be interchanged on an underground haulage vehicle). These cassettes can be charged with preblended materials on the surface from a storage silo and sent underground via the cage. For a project with ramp access, an underground haulage vehicle (designed specifically for carrying the cassette) can off-load an empty cassette and reload a full cassette so the material can be hauled in bulk directly to the worksite. As is the case with delivery using bulk haulage equipment, the Fig. 2: Preblended dry shotcrete being loaded into a ship’s hull elimination of bulk bags and pallets is an obvious benefit for bulk haulage and cassette delivery. Ingenuity has brought us to the point where bins For cassette delivery, the negatives are the on the surface equipped with level sensors auto- capital costs of the cassettes and, of course, matically refill underground silos and inform the weight. Most cassettes will weigh 6600 to 11,000 lb supplier on their own. However, sometimes there (3000 to 5000 kg), which reduces the amount of is no substitute for keeping it simple and going shotcrete material that can be delivered per trip back to—or staying with—the basics. by that amount. By contrast, bags and pallets weigh very little. The use of a slick-line or bore hole from surface to a location underground has become a Craig McDonald is a Sales popular option for transporting both dry- or wet- Manager for the Mining Markets mix shotcrete on mining and tunneling projects. Division of King Packaged This option eliminates the costly use of ramp or Materials Co. Equipment. The cage time, eliminates the need for bags and pallets, wet- and dry-mix shotcrete and allows bulk delivery of wet- or dry-mix shotcrete process, as well as the mixing in an efficient, timely manner. The biggest and placing of dry-mix concrete detractor from the use of slick line or bore hole and grout products, are his delivery is the high capital cost related to the areas of expertise. He is a graduate of the haulage equipment and the installation of a slick Mechanical Engineering Technology program at line or bore hole. Depending on depth, the cost of Canadore College, North Bay, ON, Canada. a lined bore hole or slick line can reach well into seven figures, making it impractical unless large Julian Peña Cruz is a Technical volumes of shotcrete are anticipated for a long Sales Representative for King period of time. Mines with a long anticipated life Packaged Materials. His area that use shotcrete for primary ground support are of focus includes prepackaged, excellent examples of situations that can finan- ready-to-use cementitious cially justify the installation of a bore hole or slick mining materials, including line. For a mine that may possibly require possibly high-performance shotcrete, hundreds of thousands of cubic yards (cubic ultra-rapid-strength-gain meters) of shotcrete during its operational life, the shotcrete, fiber-reinforced shotcrete, specialized high initial investment can pay dividends over the cable-anchoring grouts, and more. In 2013, he life of the mine by reducing the use of the shaft graduated from the École de Technologie time, ramp time, and worker power required to Supérieure (Université du Québec) in Montreal, facilitate moving materials either in bags and QC, Canada, where he received his bachelor’s pallets or cassettes. degree in construction engineering. Cruz is a All things considered, there is not one system practicing junior engineer in Quebec, Canada, that can be effective for all locations. All sites and a member of the Ordre des Ingénieurs du have their own unique requirements and challenges. Québec (OIQ). Shotcrete • Fall 2015 23


2015FallShotcreteEMag
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