Fibre-reinforced concrete

This section is limited to the application of methods of mathematical optimization to materials with cement-based matrices, like ordinary concretes, polymer concretes, fibre-reinforced concretes, etc. Other methods of improving the material design by separate analyses of particular aspects and criteria, or by computer assisted comparisons of a number of designs to select the best one, are mentioned only briefly. 

There are less exotic ways of increasing the strength of cement and concrete. One is to impregnate it with a polymer, which fills the pores and increases the fracture toughness a little. Another is by fibre reinforcement (Chapter 25). Steel-reinforced concrete is a sort of fibre-reinforced composite the reinforcement carries tensile loads and, if prestressed, keeps the concrete in compression. Cement can be reinforced with fine steel wire, or with glass fibres. But these refinements, though simple, greatly increase the cost and mean that they are only viable in special applications. Plain Portland cement is probably the world s cheapest and most successful material. 

Glass fibre reinforced enamels BS 4147 BS 4164 BS SI4 AWWA/ANSI C203 Hot applied in factory and in field by line travel 2-5-6 Asphalts prone to water absorption and root damage. Coal tar resistant to oil products and root damage. Long successful service record, particularly coal tars. Proven under concrete weight coatings. 

The use of inorganic CERASHELL, a sandwich composed of cellular or foamed straw insulation between two fibre-reinforced high-strength dense materials, surpasses the characteristics of the foam/concrete composite. Pneumatic placement of a non-woven fibre matte as the outer shell results in a low-cost shelter in the first stage prior to placement in later stages of the insulative and structural components. The costs of steel reinforcement and urethane are eliminated, whilst extremely safe buildings of remarkable wind, earthquake, and fire-resistance are produced. 

Fibre Bragg grating sensors are a type of optical sensor that has received considerable attention in recent years. They are used for monitoring the structural condition of fibre-reinforced composites, concrete constructions or other construction materials. 

It is possible to use glass fibre reinforcements in order to increase the thickness or, where necessary, to bridge fine cracks in the substrate. Some coatings are also formulated to be used on damp concrete surfaces which cannot be dried. 

Green, M. F., Bisby, L. A., Beaudoin, Y., and Labossiere, P., Effect of Freeze-thaw Cycles on the Bond Durability between Fibre Reinforced Polymer Plate Reinforcement and Concrete, NRC Canada, Journal of Civil Engineering, Vol. 27, 2000. pp. 949-959. Neville, A. M., Concrete Maintenance and Repair, John Wiley Sons, Inc.. New York, NY, 1995. 

Man-made composites fall into three broad classes, depending on whether the main part of the composite, the matrix, is a polymer, a metal or a ceramic. Often, but not always, the composite combines materials from two classes, as in glass-fibre-reinforced plastics. However, the most widely used composite material, concrete, is a ceramic -ceramic composite. The most important classes of artificial composite are described below. The mechanical properties of composites are discussed in Section 10.4. Biological composites are very varied and will not be considered here. 

If concrete removal is not required or supplementary reinforcing bars cannot be used, external reinforcement can be applied. For instance, steel bars may be encased in a shotcrete layer or steel plates may be bonded onto the concrete surface. Recently, the use of steel plates has been substituted by fibre-reinforced plastics (F. R.P.), that are composite materials with glass, aramide or carbon fibres embedded in a polymeric matrix (usually an epoxy system). F. R.P. are available in the form of laminates or sheets that are bonded to the concrete surface using an epoxy adhesive [11]. They are typically used to improve the flexural and shear strength or to provide confinement to concrete subjected to compression. The... 

Polyurethane foam is used with facings such as paper, glass fibre, plasterboard or glass fibre reinforced concrete. The facings and foam are layers connected in series, so the temperature drop across each layer is added for the steady-state heat flow. If layer i has thickness Lj and conductivity ki then the overall U-value of the product is given by... 

Ahmed, S.F.U. and Mihashi, H. (2007). A review on durability properties of strain hardening fibre reinforced cementitious composites (SHFRCC). Journal of Cement and Concrete Composites, 29(5) 365-376. 

Kawamata, A., Mihashi, H. and Fukuyama, H. (2002). Material design of hybrid fibre reinforced cementitious composites. Journal of Advanced Concrete Technology, 1(3) 283-290. 

M. Taylor, F.D. Lydon and B I G. Barr Toughness Measurements on Steel Fibre-Reinforced High Strength Concrete, Cement and Concrete Composites Vol. 19 (1997), p. 329-340. 

K.R. Venkatesh et al. Experimental evaluation of the fire behaviour of insulated fibre-reinforced-polymer-strengthened reinforced concrete columns. Fire Safety Journal, Vol.41, (2006), pp.547-557... 

Fibre reinforcement. Asbestos fibre reinforced products were extremely popular in the recent past but owing to the inherent health risks its use is now restricted or even prohibited. This restriction has led to much research into alternative forms of reinforcement for thin concrete... 

O. Weichold, M. Moller Development of a cement-in-polymer dispersion for improved adhesion in continuous glass-fibre reinforced concrete. 1. Aachen-Dresden Textiltagung, Aachen, 29.-30. Nov. 2007... 

Another example given by Meier et al [21] was related to the reinforcement of the City Hall of Gossau. Here a hole had to be cut in a concrete slab to accommodate an elevator. It was reported that the edges of the hole were strengthened with carbon fibre reinforced plastics sheets instead of thick steel plates. This helps retain the aesthetics of the building and after painting, the presence of carbon fibre reinforced plastic sheets was completely disguised. 

The Japanese are also active in the application of fibre reinforced plastics to reinforced concrete structures to improve their earthquake resistance. Kabatake et al [22] reported on 14 cases in which chimneys were retrofitted with fibre reinforced plastics and were judged by the Building Disaster Prevention Association of Japan to be one of the most effective retrofitting methods. In this retrofitting programme, carbon fibre tapes impregnated with an epoxy resin were wound and adhered to the exterior of the chimney. Sumida et al [ 23] have described experiences with aramid reinforced... 

As it is commonly known and applied for a long time, the properties of paste can be improved by reinforcement with the fibres. For example, the production of asbestos-cement materials started 80 years ago. The fiber reinforcement technology has been developed extensively for the last 20 years and the other fibres has been taken into account, first of all the steel fibres, but also the carbon, glass, resin, polypropylene and cellulose fibres as well. The fibres reinforcement gives the pos-sibihty to enhance the flexural and tension strength, as well as the impact resistance. The fibre composite modifies the properties of concrete by control cracking and the mode of failure by means of post—cracking ductility. 

The improvement of concrete properties by fibre reinforcement is primarily attributed to markedly higher fibre resistance to rupture, as it is shown in Table 6.1 according to Hannant [57]. 

Qian, C.X. Stroeven, P. (2000). Development of hybrid Polypropylene-Steel Fibre Reinforced Concrete, Cement and Concrete Research, Vol. 30, No.l, pp. 63-69, ISSN 0008-8846. 

Singh, S.P. Kaushik, S.K. (2003). Fatigue Strength of Steel Fibre Reinforced Concrete in Flexure, Cement and Concrete Composites, Vol. 25, pp. 779-786, ISSN 0958-9465. 

The well-known possibilities of the use of textiles and fibres in construction have developed into fields of application ranging from geotextiles to fibre-reinforced concrete, concrete reinforcing armatures made of fibre-reinforced polymers, usually carbon fibre composites (CFCs), textile membranes and sheeting and to constructions made of fibre-reinforced polymers as multi-layer composites. The present book is dedicated to the spectrum of building geotextiles are excluded, since they are less commonly used for building construction and are more common in earthworks, transit structures and landfills. 

Fibre reinforced poiymer (FRP) composite materiais for strengthening of existing concrete structurai members (flexural, shear, confinement)... 

Externally bonded flexural reinforcement (EBFR) for the strengthening of concrete members using unstressed fibre reinforced polymer (FRP) strips... 

Abbasi, A. and P. J. Hogg (2004). Fire testing of concrete beams with fibre reinforced plastic rebar. In Advanced Polymer Composites for Structural Applications in Construction, ed. L. C. Hollaway, Cambridge, UK, Woodhead Publishing, pp. 445-456. 

Blontrock, H., F. Taerwe and S. Matthys (1999). Properties of fibre reinforced plastics at elevated temperatures with regard to fire resistance of reinforced concrete members. Fourth International Symposium on Fiber Reinforced Polymer Reinforcement for Concrete Structures, Farmington HUls, MI, pp. 43-54. 

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