Steel reinforced polymers

SRP stands for steel-reinforced polymers and also steel-reinforced plastic. This acronym is used to define materials made out of steel carbon fibers in a polymer matrix. Like FRP, SRP also features excellent mechanical properties, good workload partition among fibers, and high bonding performances to the support, which are conveyed by the presence of a polymer matrix. Moreover, thanks to their... 

FIGURE 13.12 Composite coefficient of friction for polyester-based matrix material. Symbol legend Glass fiber-reinforced polymer O-parallel, A-antiparallel, Steel-reinforced polymer -parallel, A-antiparallel, H-normal, carbon fiber-reinforced polymer -parallel, A-antiparallel, B-normal. (Reprinted from Friction and Wear of Polymer Composites, Composite Materials Series, Friedrich, K., ed., 1, T. Tsnkizoe and N. Ohmae, pp. 212-220, Elsevier, New York, 1986, with permission from Elsevier.)... 

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. 

A conductive polymer electrode has been designed specifically for the cathodic protection of steel reinforcing bars in concrete and is marketed under the trade name Ferex . The anode consists of a 16 AWG stranded copper conductor surrounded by a carbon-loaded polymeric coating similar to that used on the Anodeflex system ) to provide a nominal anode diameter of 8 mm The manufacturer claims that at the maximum recommended current density of 0 08 Am the anode life in concrete will be 32 years with a proportionately longer life at lower current densities. 

Conductive paints (resins) have recently been used for the cathodic protection of steel reinforcing bars in concrete, but they are always used in conjunction with a primary anode material, e.g. platinised-niobium or platinised-titanium wire or a conductive polymer rod. 

The initial evaluation showed that utilizing fiber-reinforced polymer (FRP) for pipelines is a feasible alternative to steel pipelines with regard to performance and cost [35]. From the cost analysis, an FRP pipe is quite attractive, especially in the regional or distributed service. Currently, spoolable piping manufacturers could install a composite pipeline for serving a 100,000 population for a cost of 250,000-500,000/mi. (does not include the cost for right-of-way), which is well below the DOE s capital cost target in 2017 of 800,000/mi. [35]. From this estimate and cost analyses, it is seen that FRP pipe economics is very attractive, especially for the distribution service. 

Subclass B2 is formed by the so-called structural composites, in which an outspoken mechanical reinforcement is given to the polymer. Subgroup B21 consists of blends of polymers with compatible anti-plasticizers subgroups B22 are the most important the fibre-reinforced polymer systems. The two components, the polymer matrix and the reinforcing fibbers or filaments (glass, ceramic, steel, textile, etc.) perform different functions the fibrous material carries the load, while the matrix distributes the load the fibbers act as crack stoppers, the matrix as impact-energy absorber and reinforcement connector. Interfacial bonding is the crucial problem. 

IMaterials and Scaling Issues. Two aspects of the basically simple desalination process require special attention. One is the high corrosivity of seawater, especially pronounced in the higher temperature distillation processes, which requires the use of corrosion-resistant, and therefore expensive, materials. Typical materials in use are copper—nickel alloys, stainless steel, titanium, and, at lower temperatures, fiber-reinforced polymers and special concrete compositions (39). It is noteworthy that in quest of a lower initial cost, the use of inadequate materials of constmction in many locations combined with poor operation by virtually untrained hands led to rapid deterioration and failure of plants long before their estimated design life. Adequate experience suggests by now how to avoid such failures. The other aspect is scale formation (40,41), discussed in mote detail below. 

Paraffins, PE and metals, such as Pb and Sn, have microhardness values below 100 MPa. Semicrystalline polyoxymethylene, PET, chain-extended PE, poly(ethylene 2,6 naphthalate) and metals, such as Al, Au, Ag, Cu and Pt, have values between 100 and 300 MPa. The microhardness values of carbon-fibre-reinforced polymer composites are about 900 MPa and those for the common metals Zn and Co are 2000 and 4000 MPa, respectively, while for white steel it is 5000 MPa. 

Coefficients of linear expansion of polymer concrete and steel reinforcements... 

It is necessary to note that this value exceeds the adhesion of furfurolacetate polymer concrete or usual cement concrete by approximately 10 times. Such high adhesion of the RubCon matrix to steel reinforcement is apparently related to the nature of the diene oligomer that is used as binder. 

FIGURE 2.36 Influence of reinforcement ratio p and aspect ratio L/d of the steel fibers on compression strength of fibrous RubCon. (Reprinted from Yu. Potapov, Yu. Borisov, D. Panfilov, O. Figovsky, and D. Beilin, Research of Polymer Concrete Based on Low Molecular Polybutadiene, Part VII Strength of Continuously Reinforced Polymer Concrete with Various Kinds of Fibers, J. Scientific Israel Technological Advantages 6, nos. 3-4 (2004) 71-74. With permission.)... 

The destructive action of acids is caused by their nature, concentration, pH of water solutions, presence of oxidizing properties, temperature of the environment, and solubility of formed corrosion products at their interaction with polymer concretes and steel reinforcement. 

Ohama, Y., Kan, S., and Sugahara, T., Flexural Behaviour of Steel Fiber Reinforced Polymer-Modified Mortars (in Japanese), pp. 67-70, Nihon-Kenchiku-Gakkai Tohoku-Shibu Kenkyu-Hokol hu, No. 38 (Nov. 1981)... 

Unsaturated polyesters (UP), epoxies and formaldehyde-containing polymers are those most frequendy reinforced with fibrous fillers. The polymer component is often referred to as the matrix. The advantages of reinforcing UP, particularly with respect to tensile strength and stiffness (E-modulus) properties, can be clearly seen in Table 3.5. Their low densities allow reinforced polymers to compete with traditional construction materials such as wood and steel (Aurer and Kasper, 2003). 

Y. Ohama, S. Kan and T. Sugahara Physical properties of steel fiber reinforced polymer-modified mortars, in Proceedings of the 25th Japan Congress on Materials Research, The Society of Materials Science, Japan, Kyoto (1982), pp.234-238. 

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