Prefabricated sheets

Reinforced (fiber glass) polyester is a common building material, that yields to PVC. It is useful in partitions, prefabricated sheets, pipelines, furniture and coatings. This unsaturated polyester is also an organic cement in flooring or adhesives. 

The term sheet and membrane tend to be interchangeable. By definition, a membrane refers to the finished built-up waterproofing layer comprising one or more prefabricated sheets. As such, a sheet becomes a membrane in a single-ply application and a modified bituminous membrane may have two sheets, base and cap. 

Data for thermal movement of various bitumens and felts and for composite membranes have been given (1). These describe the development of a thermal shock factor based on strength factors and the linear thermal expansion coefficient. Tensile and flexural fatigue tests on roofing membranes were taken at 21 and 18°C, and performance criteria were recommended. A study of four types of fluid-appHed roofing membranes under cycHc conditions showed that they could not withstand movements of <1.0 mm over joiats. The limitations of present test methods for new roofing materials, such as prefabricated polymeric and elastomeric sheets and Hquid-appHed membranes, have also been described (1). For evaluation, both laboratory and field work are needed. 

Insulation is widely used in laminate form with plasterboard, chipboard, cement board, and metal sheeting, etc. Applications are generally as lining board systems in buildings but prefabricated metal panels and ceiling tiles are also produced. 

Winningham MJ, Sogah DY. A modular approach to polymer architecture control via catenation of prefabricated biomolecular segments polymers containing parallel /8-sheets templated by a phenoxathiin-based reverse turn mimic. Macromolecules 1997 30 862-876. 

Techniques to deal with the cracks, instability and other problems caused by this dry condition have been developed in recent years by wood tank manufacturers. One procedure is the application of marine grade plywood sheets, with adequate nailing, to the entire inside surface of the wood tank. This may not be required when properly designed prefabricated PVC bag liners are to be installed, and such design may be used for other types of membranes. 

The chamber is constructed of mill finished stucco embossed aluminum with a 20 gauge heavy duty galvanized steel floor. The choice of an all aluminum structure was based on the lack of reactivity of formaldehyde with aluminum (9, observed adsorption of formaldehyde on steel sheet metal(10), and the availability of a prefabricated walk-in cooler. 

For shear strengthening, fabrics that are applied on the entire side of the webs, Fig. 4.18, or in the form of sheets with certain spacings, can be used. Prefabricated CFRP L-shaped strips, Figs 4.10 and 4.17, are also an alternative. 

Prefabricated polystyrene foam sheets are used mainly for thermal insulation and waterproofing in basements. Polyethylene foam is used, e.g. for pipe insulation, and is fixed with an adhesive or tape. Urea-formaldehyde foam was used for improving thermal insulation in old houses, but uncontrollable formaldehyde emissions have caused its use to be minimised. Polyurethane foam is used for thermal insulation as prefabricated foam forms, e.g. on pipes and as sheets on roofs or walls. In pipe insulation, adhesives may be used in fixing. Uncured diphenylmethane diisocyanate-based (MDI) polyurethane foam is sprayed on site (e.g. for window frames) or for technical applications (e.g. on large boilers). When spraying foam on boilers, good ventilation and personal protection is needed. Tools used in thermal insulation include knives, saws, scissors, jointing tools, etc. 

Existing RC columns can also be strengthened using prefabricated FRP shells. The shells are prefabricated imder controlled conditions using fibre strands or sheets. They can be fabricated in half cylindrical or rectangular shells. They can also be fabricated in a closed form with a vertical slit so that they can be opened up and placed around the columns. 

Structural rehabilitation of timber and concrete structures with composite systems can be generally accomplished in one of two ways (Karbhari and Seible, 2000) using wet lay-up or cured in-situ systems, by application of composite overlays, fabrics, sheets or fibre tows (Fig. 22.4) and using systems involving the bond of prefabricated APC materials, such as straight pultruded strips, and factory-made curved or shaped elements (Fig. 22.5). 

Reinforcement of the connection by internal or external bonding of prefabricated ARC materials (rods, plates or pultruded profiles) or wet lay-up of fabrics or sheets. - Perpendicular to wood grain reinforcement of the timber member, in the connection, by internal or external bonding of prefabricated ARC materials (rods, plates or pultruded profiles) or wet lay-up of fabrics or sheets. 

Sheet pile elements are bended steel plates with U- or Z-shaped sections and contain a side groove to connect next sheet pile elements. Some heavy-duty elements have l -shaped sections. The sheet pile elements can be driven along the wall layout line directly. Piles are premanufactured to be installed side by side and automatically connected to one another. Therefore, sheet pile retaining systems can be installed much quicker than other systems. Most sheet pile elements have connections that are water tight. As a result, sheet pile systems are commonly used in hydraulic projects. Steel is the most common sheet pile material. Presently, there are vinyl sheet pile products available in the market. For transportation projects, sheet pile systems are often used as a temporary shoring structure. When sheet piles are used as a permanent system, a wall cap on top shall be specified. Some manufacturers have their own prefabricated cap system. It is a common practice to build a concrete cap. If the wall was used as part of a support structure, the sheet pile wall can directly be embedded into the above structure s concrete base. 

There are two approved methods for the erection of a prefabricated tower scaffold - an advance guard rail system and the through the trap (3T) system. These systems have been developed by HSE and the Prefabricated Access Suppliers and Manufacturers Association and are described in detail on the HSE information sheet Tower scaffolds CIS No 10 (Rev 4). 

---