Sika Corporation: Concrete Reinforcing Fibers for Shotcrete
Sika Group has subsidiaries in 101 countries around the world and manufactures in over 200 factories. Sika Corporation is headquartered in Lyndhurst, NJ, and employs more than 1,700 people in 22 locations throughout the country. Sika Corporation is a specialty chemical and industrial materials company serving construction and industrial markets. Its technologies are focused on sealing, bonding, damping, reinforcing, and protecting. Sika’s product lines include roofing, concrete admixtures, specialty mortars, epoxies, structural strengthening systems, industrial flooring, sealants, adhesives, specialty acoustics, and reinforcing materials.
In March of 2019, Sika acquired King Packaged Materials Co. King is a well-established manufacturer of products for the construction and mining industry. Their portfolio includes shotcrete solutions, grouts, and repair and masonry mortars. The company has an excellent reputation for its recognized brands, its high quality & reliable product solutions, and its strong technical sales expertise. Sika has developed a new business unit STM – Shotcrete Tunneling & Mining, where King now has access to many other Sika products, including fiber reinforcing for shotcrete.
Fibermesh, a Sika brand, manufactures SikaFibers for concrete and shotcrete reinforcement, in a 129,000 sq ft production facility, located in Chattanooga, TN. Fiber reinforced concrete is ideal for improving the durability and toughness of the concrete matrix. Fibers in concrete help reduce shrinkage cracks, increase strength, and increases energy absorption.
Fiber reinforced concrete is not a new concept. Since biblical times fibers were used in cement-based construction materials in the form of straw and horsehair. Today, there are a large variety of fiber options for reinforcing concrete available in the marketplace. These include micro and macro synthetic fibers, steel, and blended fibers.
The fibers are mixed in the concrete matrix and have no significant effect until the hardening process begins; they inhibit the emergence of cracks and hold cracks tightly together through their tensile strength and anchorage. Where there is greater strain, the fibers prevent larger cracks by causing them to dissipate into more numerous, very fine and generally harmless ones. Macro and micro synthetic fibers can inhibit early age shrinkage cracking. Macro synthetic and steel fibers can inhibit long term cracking due to drying shrinkage and stress cracks from loading. Because fibers are easy to handle and dose for mixing, and they have a good bond in the matrix, they are ideal for improving the performance of concrete and mortar for many applications.
Unlike traditional reinforced sprayed concrete, the SikaFibers are distributed three-dimensionally throughout the mix and are always positioned properly. Traditional reinforced shotcrete can develop voids behind the welded wire mesh which can lead to water migration behind the shotcrete. This will lead to eventual rusting of the traditional reinforcing and spalling of the shotcrete. Macro synthetic fiber reinforced shotcrete develops a uniform bond to the rock face and does not corrode while removing the hazard of working directly in front of the exposed surface.
The addition of fibers increases the ductility of sprayed concrete. For instance, if the sprayed concrete lining of an excavated tunnel support is cracked due to high flexural stresses such as rock burst, the fibers can accommodate the tensile forces. This interaction between sprayed concrete and fibers increases the mechanical capacity of the lining. The time-consuming steel fixing operations which interrupt the workflow are then eliminated. By eliminating the traditional reinforcement, the sprayed concrete is also applied without ‘spray shadows’ and rebound is reduced. The result is the optimization of the application process, improved quality of the structure, and a quicker, less expensive tunnel excavation.
Sika has developed synthetic macro fibers specialized for sprayed concrete applications with large displacements. The SikaFiber Force fibers are continuously embossed for the perfect anchorage for sprayed mining applications. The fiber comes in 48, 54, and 60 mm lengths. The fibers have been developed as a best-in-class fiber for increased site safety, increased toughness, increased ductility, a more economical solution, and no worries of potential corrosion which all lead to faster mine development.
Sika is an ideal partner because of the wide range of products and applications we offer for almost any site construction requirements. Sika specialists and our Technical Support team can advise and help meet challenges with the right solution. Find out more today! Please visit us at our website at usa.sika.com/STM.