Types of Polymer Concretes

A wide variety of monomers and prepolymers are used to produce PC. The polymers most frequently used are based on five types of monomers or prepolymer systems  

The typical range of properties of PC products made with each of these polymers will be scrutinized in next part of this chapter. 

Let us look more specifically at PC based on the kinds of binders previously listed. 

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The polymer concretes are distinguished by the nature of the binder e.g., furan, polyester, epoxy, phenol formaldehyde, carbamide, and so on. The classification of the main types of polymer concrete according to the kind of synthetic resins involved is shown in Figure 1.2 [7],... 

Polymer concretes based on carbamide resins have a low toxicity and are favorable in manufacturing. However, the content of the polymer matrix in these PCs is high (up to 30%) and their physical and mechanical properties are low in comparison to other types of polymer concretes. 

The mechanical properties, the corrosion stability, and some useful properties are the reasons for the continuous interest shown in polymer-concrete composites by various design, research, and production organizations. The most important types of polymer-concrete composites are polymer-impregnated concrete (PIC), polymer-cement concrete (PCC), and polymer concrete (PC). 

Other types of polymer concretes, that is, PC (polymer concrete) and PCC (polymer cement concrete), also give various possibilities for adjusting mechanical properties to the required ones. 

A composite concrete material containing polymers and cement has superior properties to those of conventional concrete. Several types of polymer concretes have been fabricated and examined for their... 

We mentioned the main models for generation, transfer, and recombination of the charge carriers in polymers. Very often, these models are interwoven. For example, the photogeneration can be considered in the frame of the exciton model and transport in the frame of the hopping one. The concrete nature of the impurity centers, deep and shallow traps, intermediate neutral and charged states are specific for different types of polymers. We will try to take into account these perculiarities for different classes of the macro-molecules materials in the next sections. 

Most latex-modified mortars and concretes have good adhesion to most substrates (tile, stone, brick, steel and aged concrete) compared to conventional mortar and concrete. In general, bond strength in tension and flexure increases with an increase in the polymer-cement ratio, irrespective of the type of polymer used [87,94,98],... 

Polymer concrete, as highly filled polymer compositions, can be prepared on any synthetic binding. However, due to the requirements for density, strength, deform-ability, chemical resistance, and other characteristics, about 10 different types of monomers or oligomers are used in practice. In combination with modifying additives, they provide more than 30 varieties of polymer concrete. 

The most effective scopes of polymer concrete application, depending on the type of polymeric binder, are shown in Table 1.6. 

FIGURE 2.45 Structural diagram of RubCon samples at compression (1) samples type A, (2) samples type B. (Reprinted from Yu. Potapov, O. Figovsky, Yu. Borisov, S. Pinaev, and D. Beilin, Creep of Polymer Concrete at Compressive Loading, J. Scientific Israel Technological Advantages 5, nos. 1-2 (2003) 1-10. With permission.)... 

Organic coatings are used to block the penetration of carbon dioxide or chloride ions. They form a continuous polymeric film on the surface of the concrete, of a thickness ranging from 100 to 300 pm. The binder can already be present in the liquid paint as a polymer, or the polymer can be formed due to chemical reactions between monomeric components that are mixed just before application. Modem coating systems are usually built up of several layers applied consecutively. They are compatible with the alkalinity of the concrete and are based on various types of polymers (e. g. acrylate, polyurethane, epoxy), pigments and additives, and are made suitable for application by the addition of solvents or diluents. 

Several types of polymer-modified mortars and concretes, i.e., latex-redispersible polymer powder-, water-soluble polymer-, liquid resin-, and monomer-modified mortars and concretes, are produced by using the polymers and monomers shown in Fig. 2.1. Of th, the latex-modified mortar and concrete are by far the most widely used cement modifiers. 

PIC is a precast and cured portland cement concrete that has been impregnated with a monomer that is subsequently polymerized in situ. This type of cement composite is the most developed of polymer-concrete products. PCC, on the other hand, is a modified concrete in which a part (10%-15% by weight) of the cement binder is replaced by a synthetic organic polymer. It is produced by incorporating a monomer, prepolymer-monomer mixture, or a dispersed polymer (latex) into a cement-concrete mix. To effect the polymerization of the monomer or prepolymer-monomer, a catalyst (initiator) is added to the mixture. The process technology used is very similar to that of conventional concrete. So, unlike PIC which has to be used as a precast structure, PCC can be cast-in-place in field applications. PC can be described as a composite that contains polymer as a binder instead of the conventional portland cement. 

Density tests. Referring to Table 2 below, the densities of all the trial mixes ranged from just above 1000 kg/m to 1073 kg/m. The addition of polymers into the trial mixes had a negligible effect on the densities of the concrete. The control mix, CL had a density of 1034 kg/m which is very close to the densities of the other trial mixes thus the density of the concrete is affected more by the lightweight aggregate and cement binder content rather than by the quantity or type of polymer addition. 

The method of producing precast polymer concrete is similar to that of precast Portland cement concrete. The extremely short hardening period of polymer concrete is an obvious advantage over Portland cement concrete. Form removal may be as short as 40 seconds, depending on the type of monomer used [11]. The formwork, vibrators and mixers used in producing polymer concrete precast elements are no different to those used for Portland cement concrete precast elements. Flowever, it should be noted that the formwork should be durable, smooth surfaced and must be able to withstand the heat developed during the exothermic polymerisation process. 

The pore structures of latex-modified mortar and concrete are influenced by the type of polymers in the latexes used and the polymer-cement ratio. Examples of their pore size distribution are illustrated in Fig. 4.60. Generally, the porosity or pore volume of the latex-modified mortar and concrete reduces in the large radii of 0.2 pim or more, and increases greatly in the smaller radii of 75 nm or less compared to unmodified mortar and concrete. The total porosity or pore volume tends to decrease with an increase in the polymer-cement ratio. This contributes to improvements in the impermeability and durability of the latex-modified mortar and concrete. 

This chapter reviews the chemistries, properties, and commercial uses water-containing ionicaUy conductive polymer systems. In medical applications, these polymers serve as the conductive interface between the patient s skin and the medical equipment. These electrolyte systems are commercially produced in gel, paste, or sheet form using either natural or synthetic polymers. Regardless of the physical form, these systems are typically formulated to a conductivity range of 10 to 10 S cm to provide acceptable performance. A new plication of this type of polymer is reported recently in the prevention of steel rebar corrosion in concrete structures. 

The earliest distinction between types of polymers was made long before any concrete knowledge of their molecular structure. It was a purely phenomenological distinction based on their reaction to heating and cooling. 

Researchers also have found that the properties of concrete can be greatly improved by adding fibers of various kinds, including those made of steel, glass, and carbon-based polymers. One type of fiber concrete—called slurry infiltrated fiber concrete (SIFCON). which is tough enough to be used to make missile silos and can be formed into complex shapes—may be especially nsefnl for stmctures in earthquake-prone areas. 

Combinations with polymers can be obtained by impregnation of the hardened composite (polymer impregnated concrete - PIC) or with a polymer latex which is added during mixing (latex modified cement - LMC) [137]. Both types of polymer incorporation would be expected to increase the matrix strength and the fibre-matrix bond. However, their influence on the other matrix properties is quite different. In PIC, the matrix has a higher modulus of elasticity and becomes more brittle, while in LMC the matrix will be more ductile with a lower modulus of elasticity. 

Clock-type induction periods occur in the spontaneous ignition of hydrocarbon-oxygen mixtures [2], in the setting of concrete and the curing of polymers [3]. A related phenomenon is the induction period exhibited... 

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