Reinforcement and Polymer Concrete Matrix

The combination of steel reinforcement and a composite matrix depends on the following  

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FIGURE 2.12 Test unit for determination of coefficient linear expansion of RubCon (1) temperature chamber, (2) RubCon sample, (3, 4) steel plates, (5) pile, (6) indicator, (7) leg of indicator, (8) thermometer. (Reprinted from Yu. Potapov, O. Figovsky, Yu. Borisov, S. Pinaev, and D. Beilin, Joint Work of Reinforcement and Polymer Concrete Matrix, J. Scientific Israel Technological Advantages 4, nos. 3-4 (2002) 14-19. With permission.)... 

Potapov, Yu., Figovsky, O., Borisov, Yu., Pinaev, S., and Beilin, D. Joint Work of Reinforcement and Polymer Concrete Matrix, J. Scientific Israel Technological Advantages 4, no. 3 1 (2002) 14-19. 

Large particle reinforced composite systems are utilised with all three types of materials (metals, ceramics and polymers). Concrete is a common large particle strengthened composite where both matrix and particulate phases are ceramic materials. 

REINFORCED PLASTICS. Reinforced plastics are commonly referred to as composites or, more specifically, polymer composites, Not all composites are reinforced plastics ceramic/metal-matrix composites and concrete are good examples of nonpolymeric composites. Reinforced plastics are also referred to RP, FRP (fiberglass-reinforced plastic), and GRP (glass-reinforced plastic) interchangeably. 

The modification of cement concretes and mortars by polymers and resins is aimed at improvement of their mechanical properties compressive and tensile strengths, matrix-reinforcement bond, impermeability, corrosion resistance, etc. There are three main groups of polymer modified concretes ... 

Moreover, applied to concrete, the silicate platelets provided by the clay, being pozzolanic in nature, react with the calcium hydroxide crystals in the concrete matrix to produce C-S-H units, providing all of the associated benefits, i.e., increased strength, reduced permeability Additionally, these new C-S-H crystals form around the polymer chains, resulting in what is essentially a fiber reinforced concrete, though the reinforcing is at a scale and consistency never before achieved. The result of this latter effect is an increase in ductility of the concrete during failure (5). 

A significant amount of waste composites is generated each year and the need for a recycling method is becoming a necessity. Environmental Technical Services has developed, with the support of the University of Missouri-St.Louis, a method for recovering valuable constituents from composite materials. The process converts the polymer matrix to lower chain hydrocarbons and fuel gas leaving behind fibres. Mechanical tests of BMC panels, reinforced concrete and compression moulded panels made with recovered fibres were carried out. 10 refs. USA... 

Cement and Concrete Concrete is an aggregate of inert reinforcing particles in an amorphous matrix of hardened cement paste. Concrete made of portland cement has limited resistance to acids and bases and will fail mechanically following absorption of crystal-forming solutions such as brines and various organics. Concretes made of corrosion-resistant cements (such as calcium aluminate) or polymer resins can be selected for specific chemical exposures. 

Cement is a binder that sets and hardens by itself or binds other materials together. The most widely known application of cements is in construction a second one is the area of bone cements. Cements used in construction are characterized as hydraulic or nonhydraulic and mostly for the production of mortars and concrete. Hydraulic cements set and harden after combining with water. Most construction cements are hydraulic and based on Portland cement, which consists of calcium silicates (at least 2/3 by weight). Nonhydraulic cements include the use of nonhydraulic materials such as lime and gypsum plasters. Bone cements and bone cement composites refer to compounds that have a polymer matrix with a dispersed phase of particles. For instance, polymethylmethacrylate (PMMA) is reinforced with barium sulphate crystals (for radio-opacity) or with hydroxyapatite... 

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. 

In most of the two-component systems discussed so far, such as rubber-reinforced polyblends, the density or specific volume is approximately an average of the values for each component. There may be some exceptions to this generalization for example, if the smaller component fills free volume available in the major phase (Chander, 1971 Harmer, 1962 Huang and Kanitz, 1969). A similar but more important phenomenon exists when the volume available for filling by a monomer comprises not only free volume elements, but also gross pores, which may range in size from tens of angstroms to the order of micrometers or more. Examples of matrices may include partially sintered polymers, ceramics or metals, cement, concrete, minerals and rocks, paper, and wood (American Chemical Society, 1973). Clearly such systems tend to be complex even the matrix itself is often a multiphase material. 

FRPs are composite materials made of a polymer matrix reinforced with fibers. In comparison to concrete (that is also a composite material), the fibers may carry and transfer both compressive and tensile stresses. The polymer matrix bonds these fibers together, prevents budding of the fibers in compression, transfers stresses between discontinuous fibers, protects the fibers from environmental impact, and maintains the overall form of the resulting composite material. 

Fibre reinforced polymers (FRPs) are composed of a reinforcement material (glass, aramid or carbon fibres) surrounded and retained by a (thermoplastic or thermosetting) polymer matrix (unsaturated polyester, epoxy, vinyl ester, or polyurethane). FRPs were first used in the rehahiUtation of reinforced or pre-stressed concrete, but they have also been widely used in the reinforcement of timber structures. 

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