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2016FallShotcreteEMag

Sustainability Rethinking Shotcrete Mixture Design through Sustainable Ingredients By Antoine Gagnon, Isabelle Fily-Paré, and Marc Jolin Awareness of the environment has increased in recent years because the world we built over the past century has left us with several environmental challenges. On one hand, the picture is far from bleak because numerous breakthroughs in science and technology have contributed to improve our health, our comfort, and our productivity. On the other hand, however, we consume more and more resources as the population grows, and we have yet to find a clearly sustainable way to reuse most of these resources. Concrete can be a valuable asset when it comes to dealing with post-consumer waste materials. There have been numerous research efforts conducted in the last couple of decades to evaluate the potential of alternative materials in concrete mixtures. Some of these alternative materials are postconsumer waste products and are presently collected for reuse in some countries. Unfortunately, there are still very few ways to bring these waste materials back into the cycle of consumption. As a solution, the use of these materials to replace or supplement cementitious materials (or aggregates) in concrete is a great way to deal with two sustainability issues. First, it gives a solution for productive use of the increasing generation of waste materials, as it represents an inexpensive and efficient way to give a second life to many products normally sent directly to landfills. Secondly, it lowers the need for consuming natural resources in producing concrete. However, when using new ingredients with significantly different properties than those of traditional constituents, some new and unusual behaviors may be observed and have to be considered. Recently, some of these alternative materials have been evaluated as potential replacement ingredients in dry-mix shotcrete mixtures in the Laval University’s Shotcrete Laboratory (Fily- Paré and Jolin 2013; Gagnon 2016). The key in this kind of study is to think outside the box—any material we have ever put our hands on has the potential to become a suitable ingredient in shotcrete mixtures. It is only a matter of understanding, evaluation, and engineering creativity. New Materials Glass is one of the post-consumed materials that has been tested in dry-mix shotcrete mixtures over the last few years (Fily-Paré and Jolin 2013). Glass bottles are widely used in North America, but there has not been much interest in finding them a second life, sending most of the collected glass to landfills. Less than 30% of the collected glass is actually recycled and the rest is discarded (EPA 2012). However, crushing glass into powder is a way to create a new ingredient for shotcrete, offering a more sustainable future for these used glass bottles (Fig. 1). The use of glass powder (GP) as 20% cement replacement in shotcrete has shown interesting Fig. 1: Glass powder from crushed bottles (white), silica fume (gray), and cement 28 Shotcrete • Fall 2016


2016FallShotcreteEMag
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