Glass is an amorphous (non-crystalline) solid material. Glasses are typically brittle and optically transparent.
The most familiar type of glass, used for centuries in windows and drinking vessels, is soda-lime glass, composed of about 75% silica (SiO2) plus sodium oxide Na2O from soda ash, lime CaO, and several minor additives. Often, the term glass is used in a restricted sense to refer to this specific use.
Glass is in widespread use largely due to the production of glass compositions that are transparent to visible wavelengths of light. In contrast, polycrystalline materials do not in general transmit visible light.[45] The individual crystallites may be transparent, but their facets (grain boundaries) reflect or scatter light resulting in diffuse reflection. Glass does not contain the internal subdivisions associated with grain boundaries in polycrystals and hence does not scatter light in the same manner as a polycrystalline material. The surface of a glass is often smooth since during glass formation the molecules of the supercooled liquid are not forced to dispose in rigid crystal geometries and can follow surface tension, which imposes a microscopically smooth surface. These properties, which give glass its clearness, can be retained even if glass is partially light-absorbing i.e. colored.[46]
Glass has the ability to refract, reflect, and transmit light following geometrical optics, without scattering it. It is used in the manufacture of lenses and windows. Common glass has a refraction index around 1.5. According to Fresnel equations, the reflectivity of a sheet of glass is about 4% per surface (at normal incidence in air), and the transmissivity of one element (two surfaces) is about 92%. Glass also finds application in optoelectronics e.g., for light-transmitting optical fibers.
Brick
A brick is a block, or a single unit of a ceramic material used in masonry construction, usually stacked together, or laid using various kinds of mortar to hold the bricks together and make a permanent structure.[1] Bricks are typically produced in common or standard sizes in bulk quantities. They have been regarded as one of the longest lasting and strongest building materials used throughout history.
In the general sense, a "brick" is a standard-sized weight-bearing building unit. Bricks are laid in horizontal courses, sometimes dry and sometimes with mortar. When the term is used in this sense, the brick might be made from clay, lime-and-sand, concrete, or shaped stone. In a less clinical and more colloquial sense, bricks are made from dried earth, usually from clay-bearing subsoil. In some cases, such as adobe, the brick is merely dried. More commonly it is fired in a kiln of some sort to form a true ceramic.
Appointment brick defines certain material properties that allow it to apply in a given field. And the appointment of a brick can be building, facing and special.
Building bricks used for building exterior and interior walls. Facing brick outer surface has an excellent quality, which allows to withstand various influences.
A special type is used for special operating conditions. The following property, which characterizes the brick, is emptiness. Hence, this building material can be hollow (hollowness can reach up to 45%), solid centers (bricks without voids) and aerated (except structural voids formed mikropustoty, while ensuring ease). Quality insulation from porous brick is much higher than that of a hollow or corpulent, and therefore, the walls are thinner.The size of bricks can be divided into four types: it can be single, one and a half, double and non-standard (this includes the European sizes, the four-, eight-, restoration, etc.). The following property of brick is its density, which is defined as any other matter density, ie, dividing the mass by the volume. What density will be higher, the properties of thermal insulation will be lower. The strength of brick is determined by the ability of a construction material does not collapse under the influence of external forces, which, naturally, cause internal stresses. Brick, as is known, varies by make and define it as a testing time for compression and bending.
Resistance to low temperature is an important property, especially in the edges with a temperate climate. This ability is as follows. The material is saturated with water, then it undergoes repeated freezing and thawing alternately (freezing at -15 ° C, thawing at room temperature), then there should be no meaningful technical damage, and should not happen deterioration of properties. The thermal conductivity of bricks is a property of the material to transfer heat when the temperature difference between inside and outside the structure. Thus, if the thermal conductivity is lower, the heat in the house will be greater. The thickness of the wall does not act as such a property of brick, however, to her are required in this regione.Sleduyuschim property of brick is its water absorption. Is the ability to absorb the material, and then retain moisture in its pores. This is necessary because the saturation water main properties are falling, however, as prochnost.Vazhnym parameter brick supports resistance to fire. It consists in resisting high temperatures, that is, is the preservation of the bearing capacity in case of fire. Brick is a truly unique fire resistance. And as if the main generalize the properties include durability of brick. Depends on the quality of resistance building material impacts of external and internal factors.
Concrete
Concrete is a composite construction material composed primarily of aggregate, cement, and water. There are many formulations, which provide varied properties. The aggregate is generally a coarse gravel or crushed rocks such as limestone, or granite, along with a fine aggregate such as sand. The cement, commonly Portland cement, and other cementitious materials such as fly ash and slag cement, serve as a binder for the aggregate. Various chemical admixtures are also added to achieve varied properties. Water is then mixed with this dry composite, which enables it to be shaped (typically poured) and then solidified and hardened into rock-hard strength through a chemical process called hydration. The water reacts with the cement, which bonds the other components together, eventually creating a robust stone-like material. Concrete has relatively high compressive strength, but much lower tensile strength. For this reason it is usually reinforced with materials that are strong in tension (often steel). Concrete can be damaged by many processes, such as the freezing of trapped water.
Concrete has relatively high compressive strength, but much lower tensile strength. For this reason is usually reinforced with materials that are strong in tension (often steel). The elasticity of concrete is relatively constant at low stress levels but starts decreasing at higher stress levels as matrix cracking develops. Concrete has a very low coefficient of thermal expansion and shrinks as it matures. All concrete structures crack to some extent, due to shrinkage and tension. Concrete that is subjected to long-duration forces is prone to creep.
Tests can be made to ensure the properties of concrete correspond to specifications for the application.
