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2013WinShotcreteEMag

Corporate Member Profile Fibermesh® Concrete Solutions by Propex Fibermesh 150 fiber provides a three-dimensionalIncorporating a relatively small amount of protection system throughout the concrete and Explosive Problem. rect form of permeability that is required to relieve-ONLY when there is a fire do they create the cor Explosive Spalling the steam pressure that is created inside the con- As the world’s most widely used construction crete. Despite the claims of some manufacturers, material, concrete offers many advantages to it is not only the number of fibers that determines building and civil engineering projects, including how much resistance to explosive spalling is versatility, strength, and durability. However, it is provided but also the optimized balance of the known to present problems when exposed to high- best type of fiber and the number of fibers—and temperature fires. that has been built into Fibermesh 150. Several major tunnel fires, including the The ability of Fibermesh 150 fibers to prevent Channel Tunnel (1996), Mont Blanc (1999), explosive spalling of concrete has been indepen- Kaprun (2000), and Gotthard (2001), have dently verified at several internationally renowned raised questions about the properties of concrete fire test laboratories, including SP Technical in fire situations and prompted much research Research Institute (Sweden), Efectis/TNO (the into its behavior at high temperatures. Investiga- Netherlands), IBS (Austria), Hagerbach Test Gal- tions into fires in concrete structures have lery (Switzerland), and BRE (United Kingdom). determined that a significant loss of cross-sec- Fibermesh 150 microsynthetic fibers are tional area in the tunnel lining can occur due to manufactured to ISO 9001 Quality Assured Stan- the explosive spalling of concrete when exposed dards from 100% virgin polypropylene containing to very high temperatures. no reprocessed materials and are engineered Explosive spalling occurs when moisture in the specifically for use as concrete reinforcement. concrete is heated faster than it can migrate from Fibermesh 150 microsynthetic fibers are European the heat due to a rapid temperature rise, as in Standard EN 14889-2:2006 compliant and carry hydrocarbon-fueled fires. As the heat of the con- CE marking. crete increases, moisture in the concrete pores In addition to providing explosive spalling experiences a phase change to vapor. This vapor resistance, Fibermesh 150 fibers will provide causes an increase in pore pressure, which is resistance to early-age shrinkage cracking, unable to escape from the concrete mass. As this improve impact and abrasion resistance, and process continues, vapor pressure rapidly builds reduce rebound in sprayed concrete applications. up and exceeds the tensile capacity of the concrete, causing explosive spalling. Explosive spalling in concrete creates Effective Solution. 1. A health and safety risk for the emergencythree main consequences: Fibermesh® 150 services; Fibermesh® Concrete Solutions by Propex has 2. The structural integrity of the tunnel is placed spent many years researching how micro-poly- at risk; and propylene fibers function in concrete when 3. Huge economic damage caused by major exposed to fire. We have built up a very detailed disruption and enormous repair costs. understanding of the mechanism by which certain types of fiber can provide this valuable function. This research knowledge has been used to develop Fibermesh 150, a quality-assured fiber that provides the highest performance against explosive spalling yet, at the same time, is user- friendly to the concrete producer and contractor. Fibermesh® concrete Solutions By Propex Unlike several other competitors’ fibers that 6025 Lee Hwy are offered for this application, Fibermesh 150 has Chattanooga, TN 37421-3099 minimal effect on both the workability and air (423) 553-2245 content of the concrete. www.propexglobal.com 76 Shotcrete • Winter 2013


2013WinShotcreteEMag
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