HEXAGON SHELL

In recent years, people's interest in solving the situation has increased, especially in cities where noise concentrations are higher because of extremely high traffic and industry development. Problems associated with noise in such environment are constantly increasing and therefore people require somehow protect their buildings or working spaces.  For this reason, it is necessary to take care about the selection of materials with improved sound insulation just during the construction of building. The ability of building materials to absorb sound waves usually depends on their stiffness, density and porosity. A number of plasters are used in plastering, among them gypsum plaster offers better advantages, in terms of  smooth finish coat, strength, curing time, good insulation, shrinkage crack resistant, light weight and resistant to fire .  Gypsum plaster, is a typically cheaper material. It exhibits good thermal insulation and acoustic attenuation. Owing to its thermal p...

Calcined gypsum is capable of reacting with water to form calcium sulfate dihydrate which is a fairly hard and rigid product and which is referred to herein as "Gypsum Plaster." A number of plasters are used in plastering, among them gypsum plaster offers better advantages, in terms of  smooth finish coat, strength, curing time, good insulation, shrinkage crack resistant, light weight and resistant to fire . An example of a common gypsum product is gypsum board, which is widely used as a structural building panel. Speaking generally, gypsum board comprises a core made from an aqueous slurry of calcined gypsum which hydrates to form set gypsum. Typically, the board has a a paper sheet lining adhered to both of its faces. A characteristic of gypsum is that it has a tendency to absorb water. To illustrate, a gypsum core containing no water-resistant additives can absorb as much as 40 to 50 wt. % water when immersed therein at a temperature, of 70° F for about two hours. In appli...

Pres-historic man did not recognize the value of plaster as a fire resistant material. Several factors affect the behavior of a plastered building element, when exposed to fire. A number of plasters are used in plastering, among them gypsum plaster offers better advantages, in terms of smooth finish coat, strength, curing time, good insulation, shrinkage crack resistant, light weight and resistant to fire . It is due to the physical property of gypsum plaster, consisting of 66 percent of hemihydrate calcium sulfate plus other two materials added at the factory to control setting time and working qualities. When exposed to fire the fully hydrated gypsum is calcinated   or will change back to hemihydrate calcium sulfate at about 130 Celsius and changes to anhydrous calcium sulfate at about 175 Celsius. Both these phase changes are endothermic. Also, the chemically combined water released, representing 21 percent by weight of the original material, plus additional free water ordina...