Durability of steel fiber reinforced shotcrete with regard. Hence, reinforcement of the fibres depends on the cause of the cracking. Steel fibre reinforced concrete is a castable or sprayable composite material of hydraulic cements, fine andor coarse aggregates with discrete steel fibres of rectangular crosssection randomly dispersed throughout the matrix. Construction s sustainable option harnessing fibres for concrete construction, dundee, scotland, 810 july 2008. Designing frc slabs on grade for temperature and shrinkage induced cracks. In the case of steel fibre reinforced concrete for shotcrete, the steel fibres are added to the basic shotcrete concrete mix. Recent advances in structural fibrereinforced concrete focused on. In order to solve the problem of low strength and easy cracking of shotcrete in permanent support of tunnel single shell lining, the effects of steel fiber reinforced siliceous on mechanical properties of wet shotcrete were investigated by the tests of compressive strength, splitting tensile strength, flexural strength, shear strength, and bending toughness. European federation of national associations of specialist contractors and. Lessons learned from bridge repair with steel fiber. A particular fibre type, orientation and percentage of fibers, the workability of the mix. Wharf pile repaired by form and pour technique showing cracks in repair. The present investigation has examined how the postcrack energy absorption of fibre reinforced shotcrete frs changes with aging and has found that some types of fibre exhibit dramatically different performance characteristics at late age compared to that displayed at 28 days. After the cracks were induced, the specimens were unloaded and the cracks relaxed.
Sprayed concrete more commonly known as shotcrete is a method of applying concrete or mortar projected from a nozzle at a high velocity on a vertical or sloping surface. Concrete fibers reduce shrinkage crack formation and crack widths whilst also increasing performance in energy absorption and fire resistance. The impact created by the application consolidates the concrete. Bernard tse pl, po box 763 penrith nsw 2751 australia, tel. Specimens were cracked to specified crack mouth opening displacement 0, 100, 200, 300, 400, and 500 m. Although the hardened properties of shotcrete are similar to those of conventional castinplace concrete, the nature of the placement process results in an excellent bond with most substrates, and rapid or. The sika range includes these new fibre brands including micro, macro and steel fibres. Design issues to construct shotcrete for a tunnel with a. Creep of cracked fibre reinforced shotcrete panels. Astm c 116, standard specification for fiber reinforced concrete, outlines four 4 classifications for fiber reinforced concrete. Fiberreinforced shotcrete ms significantly reduces rebound. Sep 07, 2017 fiber reinforced shotcrete frs also allows for a uniform thickness and uniform density following the contours of the receiving face. The shotcrete process is truly one of the most versatile processes available for the use of concrete in both new construction and repairs. Hanson fibrecretea range of fibre reinforced concretehanson fibrecrete is a range of fibre reinforced concrete.
Fibrereinforced cement is an attractive, resilient construction material thats ideal for all kinds of exterior and interior protective surfaces. A typical shotcrete test panel being shot during construction. Barchips synthetic fiber concrete reinforcement delivers a 70% reduction in carbon footprint compared with steel fiber and steel rebar reinforcement. Wong department of civil engineering, the university of hong kong, hong kong abstract. Macro synthetic fiber reinforced concrete or shotcrete is seen by many design engineers as offering a viable alternative to steel reinforcement in tunnel linings. Mechanisms of shotcrete roof support author creator. Shotcrete for underground support vi, american society of civil engineers, reston, pp. This study assessed the mechanical properties and durability of latexmodified fiber reinforced segment concrete polyolefinbased macrosynthetic fibers and hybrid fiber macrosynthetic fiber and polypropylene fiber for a tunnel liner application.
Additional benefits such as reduction or elimination of reinforcing steel and increased durability can also be seen. This guideline can only be used for steel fibre reinforced shotcrete, and not for synthetic fibre concrete with low modulus of young e fiber reinforced shotcrete. Typical applications for fiber reinforced shotcrete are for tunnel linings, surface coatings on rock and soil, slopes, structures, embankments, or other structures that may be subject to high deformations or where crack. For steel fibre reinforced shotcrete, different considerations apply, with most mix designs being arrived at empirically. Assessment of steel fibre concrete exposed for 14 years, fibre reinforced cement and concrete, ed. This change can have significant consequences for the design of ground support based on fibre reinforced shotcrete. One of the main factors affecting the durability of concrete is corrosion of steel reinforcement. At that time, it was considered to be one of the worlds most modern and straightforward handbooks on the design of steel fibre reinforced concrete structures. Fibers in concrete help reduce shrinkage cracks, increase strength, increase. The primary advantages of fibre reinforced shotcrete are. This means that the quality of the concrete in terms of durability was unaffected 31.
Traditional rebars are generally used to improve the tensile strength of the concrete in a particular direction, whereas steel fibers are useful for multidirectional. Proceedings shotcrete for underground support xii, october 11, 2015, singapore. Fibre reinforced shotcrete is used on exposed surfaces and, in many cases, the thickness of the shotcrete may be of the order of 100 to 150 mm. Later the cracked specimens were tested for low pressure water permeability. The tested macrosynthetic fiber reinforced concrete has a better strength than steel fiber reinforced concrete. It has grown in popularity with architects and engineers because of its ability to be formed into virtually any size, shape or profile such as the heydar aliyev center pictured above.
In the fight for longevity, cracking is one of the biggest challenges that structural engineers face in a. They increase energy absorption and fire resistance, whilst reducing shrinkage crack, fracture formation and crack widths. Durability low crack widths under service conditions. Fibre reinforced shotcrete lining at the covanca tunnel. Quality control for wetmix fiber reinforced shotcrete in.
Fiber reinforced concrete can be defined as a composite material consisting of mixtures of cement, mortar or concrete and discontinuous, discrete, uniformly dispersed suitable fibers. This can be attributed mainly to the huge improvement in post crack. Uniform fiber reinforced shotcrete thickness and reduced rebound results in significant reduction of shotcrete consumption. Jun 20, 2016 fiber reinforced concrete is a fibrous concrete to increase the structural strength of the concrete structure they can be circular or flat. The fibers hold the shotcrete together, preventing fragments of cracked shotcrete from falling out between the bolts and wire mesh. Drawpoints and orepasses drawpoints and orepasses require special considerations in terms of support design. This guideline can only be used for steel fibre reinforced shotcrete, and not for synthetic fibre concrete with low modulus of young e fiberreinforced concrete for reduced crack widths. Fibre reinforced concrete is inspired in ancient building techniques such as adobe, boasting greater ductility which allows it to deform under tensile stress, as well as greater energy absorption capacity despite cracking. Steel fibre reinforced shotcrete tunnel linings are widely used as a stateoftheart procedure. Chapter 2 types of shotcrete and applications corps of. The purpose of using steel fiber in bridge concrete repair materials was primarily to prevent or reduce repair cracks and to improve durability. Any product which meets the specification requirements of alberta transportation bridge services specification for the repair of bridges with fibre reinforced shotcrete b373 or bridge construction specification.
The results point out a cracking density of the optimized and modified shotcretes lower than that of the standard shotcrete. Agedependent changes in postcrack performance of fibre. Compared with steel mesh reinforcements, fiber reinforced shotcrete also has. Pdf the longterm durability of shotcrete repairs to wharf piles has been investigated. Apart from these materialstructural enhancements, the applications made by the steel fiber reinforced shotcrete sfrs, like the tunnel linings, have proven that sfrs can provide a viable technical, economical and practical alternative to conventional mesh reinforced shotcrete. Durability of reinforced concrete in different environmental. Recommendations for design and construction of high. Test method for flexural toughness and firstcrack strength of fiberreinforced. Fibre reinforced shotcrete frs reinforced with macrosynthetic fibres has now been used to stabilize ground in underground mines and tunnels, and for slope stabilization, for over 10 years. Fibers include steel fibers, glass fibers, synthetic fibers and natural fibers each of which lend varying properties to the concrete. The inclusion of meticulously researched, carefully engineered polyvinyl alcohol pva and specially selected cellulose fibres into the cementbased material provides a unique combination of.
Hps900 pc is a highperformance synthetic macro fiber that is manufactured from 100% virgin copolymer resin. Applications with concrete fibers have expanded and new fiber materials are also. Fibre reinforced shotcrete lining at the covanca tunnel1 by j a r ortigao2. Since the 1980s, fibre reinforced shotcrete has been more often applied as a permanent hard rock lining. Shotcrete with sigunit accelerator to strengthen underground structures of mine. Type i steel fiber reinforced concrete or shotcrete astm a820 type ii glass fiber reinforced concrete or shotcrete astm c1666. Feb 12, 2019 glass reinforced concrete grc, or glass fibre reinforced concrete gfrc, is a construction material that is commonly used to form exterior cladding panels. It contains short discrete fibers that are uniformly distributed and randomly oriented. Fibre reinforced shotcrete frs reinforced with macrosynthetic fibres has now been used to.
Steel fibre reinforced shotcrete is substantially superior in toughness index and impact strength compared to plain concrete or mesh reinforced shotcrete. In addition, the character of fiber reinforced concrete. Shotcrete can be used in almost any concrete project and typically results in a significant savings of time and money. Durability of reinforced concrete structures, theory vs practice albert k.
In fact, durability of the concrete is improved to reduce in the crack widths. Fibermesh reinforced sprayed concrete can be used in both dry and wet applications. When frs is specified, flexural strength is evaluated using beams sawed from test panels tested in accordance with astm c1609c1609m and for residual strength in accordance with fig. Construction technology superseded rete guide to good practice steel fibre concrete bs en 148891, 2006 british standards institution, eurocode fibres for concrete. Comparison of methods for early age strength testing of shotcretehydroscaling an overview of a young technology. To provide additional support, fiberreinforced shotcrete frs is used instead of conventional shotcrete in the most extreme ground conditions pakalnis, 2010. The latter is often found to be a key element in controlling the extent of damages and providing. In scandinavian countries, shotcreting is done by the wet process and as much as 60% of ground support structures tanks and domes in norway are constructed using steel fibres. Stefan bernard in underground construction, minimum perfor. King construction products group launches ultra highperformance, fiber reinforced concrete uhpfrc upfx poly is the result of an excellent research and development program conducted by montreal polytechnique, a proud partner of king packaged materials company.
Shotcrete is often used for the construction and stabilization of tunnels and other underground structures, where it is susceptible to different forms of physical and chemical attacks affecting its durability. Mix design of very high strength steel fibre reinforced concrete vhs sfrc for tunnel liner. Fibrereinforced cement is an attractive, resilient material. A finishing layer of plain, small size aggregate shotcrete was applied to cover the steel fiber reinforced shotcrete. The decrease in conventional reinforcement leads to a much faster construction which can be crucial when dealing with instable soil and rock conditions. Aluminum fibre is also having some disadvantages such as light weight, high cost and low strength.
The decisive advantage of the ability to omit the installation of reinforcement operation is the predominant benefit of the shotcrete method. Offers three dimensional homogenous pumpable reinforcement, which is always positioned properly. B375 fibre reinforced shotcrete, repair of spcsp culverts. Definition, specifications and conformity dafstb, 2015 german committee for structural concrete commentary on the dafstb guideline steel fibre reinforced concrete. To meet the smoothness criteria for the ventilation tunnels, the finishing layer received a. Fiber reinforced shotcrete or wire mesh for tunnel support may 22, 20 tunnel support, uncategorized shotcrete, steel fiber, steel wire mesh chrys steiakakis when tunnels are excavated with conventional drill and blast operations or via mechanical excavation for softer material, the quickest way to support is the use of shotcrete. Quality control for wetmix fiber reinforced shotcrete in ground support. The primary benefit of synthetic fiber additions to shotcrete is to decrease width of shrinkage cracks in the material. Experimental study on basic mechanical properties of steel. Shotcrete is a method of applying concrete, projected at a high velocity on a vertical surface and microsilica is the product to support reduced rebounding material. Fiber reinforced cement composites with multiple fine cracks hpfrcc high performance fiber reinforced cement composites with multiple fine cracks hpfrcc show remarkably high ductility under uniaxial tensile stress and excellent performance distinguished from conventional. Zhang is an engineer at lzhang consulting and testing ltd. Tufstrand maxten fibers comply with astm c1116, standard specification for fiber reinforced concrete and shotcrete, and are specifically used for the reduction. These openings are generally excavated in undisturbed rock.
Tufstrand maxten is a 100% virgin blended copolymer synthetic macro fiber successfully used as an alternate to steel fibers, welded wire mesh and conventional reinforcing bars in a wide variety of secondary reinforcement applications. Addition of steel fibers into the concrete improves the crack resistance or ductility capacity of the concrete. The main standards for fiber reinforced concrete are astm c 116 and en14889. Cast concrete lining, cca references on request via. Plastic fibre reinforced concrete structuralstructural fibres plastic are manufactured. Request pdf on apr 2, 2001, erik nordstrom and others published durability of steel fiber reinforced shotcrete with regard to corrosion. Fiber reinforced shotcrete can be applied quickly since the reinforcement is premixed into the sprayed. Recommendations for design and construction of high performance. Design of fibre reinforced shotcrete linings with microsynthetic fibres. The technology is now commonplace for primary and permanent ground support in both mining and civil tunnel applications. Shotcrete repair on dam structures a durable method. Pdf embrittlement of fiberreinforced shotcrete researchgate.
Hanson fibrecrete is available from all of our static and mobile production plants. The use of steel fibre reinforced shotcrete for the support. Recommendations for future developments in shotcrete. Glass reinforced concrete designing buildings wiki. Durability of fiber reinforced concrete in a severe marine environment jan. Fiber reinforced concrete are of different types and properties with many advantages. Fiberreinforced concrete is ideal for improving the durability and toughness. Correlations in the behaviour of fibre reinforced shotcrete beam and. History of sfrc steel fibre reinforced concrete sfrc was introduced commercially into the european market in the second half of the 1970s. Proceedings of the second international conference on engineering developments in shotcrete, october 2004, cairns, queensland, australia. Typical mix designs for steel fibre shotcrete are given in table 2. What is the use of carbon fibre reinforced concrete. Mechanical properties and durability of latexmodified.
Rebound reduction in steel fiber reinforced drymix shotcrete through matrix modifications. Our environmental impact assessment shows that by using our fiber concrete and fiber shotcrete you will minimise your environmental impact using proven concrete reinforcement technologies. Continuous meshes, woven fabrics and long wires or rods are not considered. Fiber reinforced concrete and shotcrete for repair and. The swedish concrete association published a report on steel fibre reinforced concrete in 1995.
The use of macrosynthetic fiberreinforced shotcrete in. Crimped and hooked end steel fibre of length 50 mm and an aspect ratio equal to 50 was added to concrete in different proportions i. Ideal for mining and tunneling environments when faststrength gain and longterm durability are desired. Fiber reinforced shotcrete frs also allows for a uniform thickness and uniform density following the contours of the receiving face. In particular the study proved the efficiency of plastic fibre reinforced shotcrete towards the climatic variations changes both at short and long term. The present investigation has examined how the post crack energy absorption of fibre reinforced shotcrete frs changes with aging and has found that some types of fibre exhibit dramatically different performance characteristics at late age compared to that displayed at 28 days. Barchips synthetic fiber reinforced concrete will never suffer from corrosion or.
Fibercon reinforced shotcrete offers a highly durable, timely and maintenance free support system that can be integrated into a ground support regime including rock bolts, cable bolts or steelsets. The toughness characteristics of shotcrete are enhanced by the presence of a high tensile steel fibre throughout the concrete. It incorporates fibre technology, added at the batching plant to enhance concrete performance and durability. Given that rc is the par excellence option for construction structures, it is of little. Influence of early age properties of shotcrete on tunnel construction sequence. Agedependent changes in post crack performance of fibre reinforced shotcrete linings article pdf available in tunnelling and underground space technology 49 june 2015 with 543 reads. In the design of steel fibre reinforced sprayed concrete. The lightness, strength, durability, and vibrationdamping impact properties of fiber reinforced thermoplastic composites make them attractive materials for sports equipment. The addition of fibers in shotcrete is a wellestablished practice in many underground applications. They have greatly contributed to a better characterization of steel fibre reinforced concrete sfrc, and have thus allowed to gain a better understanding of the behaviour of this material and to specify minimum, performance requirements for each project. Fiber reinforced concrete frc is concrete containing fibrous material which increases its structural integrity. Fibres are an ideal ingredient for improving the performance and durability of concrete and mortar. April, 2012 shotcrete, fibre reinforced 1 shotcrete, fibre reinforced. The repair contractor used a form and pour methodology.
Indeed, fiber reinforced shotcrete, or frs, typically exhibits improved resistance to crack opening as well as substantial energy absorption. Steel fibre reinforced concrete sfrc quality, performance. Due to above said limitations these fibres are rarely used in construction with concrete. Hps900 pc fibers are engineered and manufactured to exceed the requirements of astm c 1116 standard specification for fiber reinforced concrete and shotcrete, type iii synthetic fiber reinforced concrete. Our synthetic fiber concrete reinforcement is delivered to site ready mixed with the concrete, eliminating all costs associated with traditional steel reinforcement. The permeability of shotcrete is not affected by the presence. Founded in 1904 and headquartered in farmington hills, michigan, usa, the american concrete institute is a leading authority and resource worldwide for the development, dissemination, and adoption of its consensusbased standards, technical resources, educational programs, and proven expertise for individuals and organizations involved in concrete design. Use for vertical, horizontal, or overhead applications, such as. Agedependent changes in post crack performance of fibre reinforced shotcrete linings. In the construction of public infrastructure such as tunnels it has become.
Tunnel linings required to resist sustained ground stresses, or which may be subject to deformation associated with seismicity or ground movement at later ages, should be designed with consideration of a possible longterm loss of ductility exhibited by some types of fibre reinforced shotcrete. As a multidiscipline construction materials company, sika offers a full range of. More engineering developments, taylor and francis, london, e. Fiber reinforced shotcrete or wire mesh for tunnel support. Pdf performance of macro synthetic fiber reinforced. Consider for example that in 2016, the national association of corrosion engineers nace released a comprehensive report estimating the annual global cost of corrosion at 2. New index parameters such as the ngi tunnelling quality qmethod index barton et al. Fiberreinforced concrete enhances the durability of concrete by reducing crack widths typically due to plastic shrinkage, long term drying shrinkage and thermal changes. Durability performance of bicomponent polymer fibres under creep and in aggressive environments. Fiber reinforced concrete types, properties and advantages. It can be applied anywhere conventional dry processed shotcrete is used.
Durability of reinforced concrete structures,theory vs practice. When using the wwf, there is always the issue of uniform density of the shotcrete layer because if the shotcrete is not built up correctly around the wwf, voids in the shadow of the wwf become a concern. An analysis of flexural strength and crack width for fiber. A study on the effect of changes in fibre type and dosage rate on fibre reinforced shotcrete performance. Fiber reinforced shotcrete yields a strong bond to the earth surface which is required to make a system selfsupporting. It has for instance become the standard form of reinforcement in the australian mining industry, and has been. The ability of fibre reinforced shotcrete frs to rapidly achieve and then. Durable, long lasting, low cost concrete reinforcement. Initially, the work involved private contractors, government highway crews, various. Satisfactory structural performance of fibre reinforced shotcrete frs in. Durability properties of sprayed engineered cementitious composite. While this is generally true of the compressive strength of concrete it is not necessarily true. Steel fibre concrete composites for special applications. Using this approach to design, lining thickness, strength.
Design of sprayed concrete linings in soft ground a. Acr uses american concrete institute aci certified nozzlemen. Htf shotcrete is a fastsetting, fiber reinforced, and easy to use shotcrete formulation that sets fast without an accelerator. Shotcrete is a method of applying concrete projected at high velocity primarily on to a vertical or overhead surface.