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2013FallShotcreteEMag

Sustainability Sustainable Shotcrete Using Blast-Furnace Slag By Philip Sawoszczuk, Dr. Michelle Nokken, and Dr. Marc Jolin tsupport. The sustainable shotcrete mixture ability of the shotcrete process.2 This article will-growing awareness of the high level of sustainexplore and discuss the performance of twowo shotcrete mixtures were designed basedon sustainability for use in mining ground contained both fine and coarse pelletized blast- shotcrete mixtures, designed to maximize sustain- furnace slag aggregates. The control mixture ability while meeting the performance criteria contained regular concrete sand as the fine aggre- required for underground ground support. gate and pelletized blast-furnace slag as the coarse aggregate. The cementing materials were the same Problem Definition and for both mixtures and consisted of 85% portland cement, 7.3% granulated blast-furnace slag, and 7.7% Research Significance silica fume. The sustainable shotcrete mixture— Industrial wastes can have detrimental impacts composed of a total of 77.71% recycled materials, to human health, the environment, and to society. including slag cement, slag aggregates, and silica Is it possible to use part of these wastes in ground fume—achieved an average compressive strength support shotcrete in a sustainable fashion? Pellet- of 4569 psi (31.5 MPa) at 28 days, in addition to ized and granulated blast-furnace slag aggregates a hardened density that was 7.6% lighter than the have not been studied in shotcrete previously and control mixture. The results indicate the potential offer a promising channel to increase the recycled and feasibility of the sustainable shotcrete mixture material content of shotcrete, as well as making for mining companies as they strive to meet more it less dense, offering further benefits to the yield stringent environmental regulations and expectations. of fresh shotcrete per weight of dry material. The research project will help qualify the feasibility introduction of using these aggregates in shotcrete mixtures Concrete and shotcrete are consumed at a rate for ground support. of 11 billion tons (9.98 billion metric tons) per year, making it the most consumed material on Earth.1 Objectives Incorporating waste materials such as blast-furnace The goal of this project was to investigate a dry- slag or silica fume into concrete and shotcrete can process shotcrete mixture design that: go a long way toward reducing concrete’s impact 1. Recycles various waste products; on the environment by recycling them into a useful 2. Meets standard safety criteria for shotcrete product and replacing new minerals. Disposing of materials; this waste has always been a concern for industry; 3. Meets performance criteria for underground until very recently, it has been dealt with by the ground support shotcrete; most economic means possible. Unfortunately, the 4. Meets durability criteria for underground most economical waste disposal methods were ground support shotcrete; and often damaging to the environment. Today, laws, 5. Meets economic and process feasibility criteria. regulations, treaties, and public pressure are increasingly forcing all industries to find more mixture Design environmentally and socially responsible ways to manage waste. As our scientific and technological ingredient Selection understanding increases, waste is being refashioned Blast-furnace slag from the iron refining into products looking for a purpose. In this light, industry has been widely used and accepted in the with some technical knowledge, waste can be concrete industry, is commercially available, and processed and used economically, with little or no already has been the subject of shotcrete research environmental impact. Adding to this trend is the as a cementitious ingredient in shotcrete under 32 Shotcrete • Fall 2013


2013FallShotcreteEMag
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