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TitleFerrocement: applications in developing countries
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Total Pages108
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40 FERROCEMENT: APPLICATIONS IN DEVELOPING COUNTRIES FIGURE 17 Types of reinforcing mesh commonly used for ferrocement. (R. B. Williamson, University of California, Berkeley) improve mortar workability. Current experience indicates that volcanic sands and beach sands are adequate, but sand should not have an excess of fme particles. Experiments need to be made in using coral sand as a substitute for regular sand, which is not readily available in some areas. Organic debris and silt that will not bond to the mortar reduce the strength of the ferrocement and should be washed out. Water containing these impurities should also be filtered and purified; otherwise, water quality is not critical in general practice. CONSTRUCTION The three major problem areas in ferrocement construction are mortar mixing, mortar application, and curing. The mortar must be dense and compact. A trained supervisor can teach the mixer operator to judge mortar quality from the way it tumbles or rolls off the mixer blades. A general mix

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FERROCEMENT MATERIALS TECHNOLOGY FIGURE 18 Mixing the mortar. (Noel D. Vietrneyer, tional Academy of Sciences) 41 is 1 part cement,
2 parts sand. Water is added to give the required pastelike consistency (roughly 0.4 parts water by weight). A horizontal, paddle-bladed mixer is recommended for highest-quality mixing; it is critical for deep-water boats. For land uses, experience shows that hand-mixing is also satisfactory. Determining the cement-to-water ratio can be done with adequate accuracy by observing the mortar's consistency. Sand normally does not have a fixed moisture content; even in the same sandpile, the bottom layers tend to be more wet than the upper ones. Fingers and trowels are used for mortar placement in the mesh structure. Mortar guns are not recommended because the heavier parts of the mortar (i.e., sand) tend to separate out. A certain amount of vibration helps to produce complete mortar penetration of the mesh and assure good paction. An orbital sander (a simple power tool used widely in woodworking) with a metal plate substituted for the sandpaper pad has been found to

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