Concrete has relatively high compressive strength, but significantly lower tensile strength and as such 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 as it matures concrete shrinks. All concrete structures will crack to some extent, due to shrinkage and tension. Concrete which is subjected to long-duration forces is prone to creep.
Concrete would almost always fail from tensile stresses – even when loaded in compression. The practical implication of this is that concrete elements subjected to tensile stresses must be reinforced with materials that are strong in tension.
Concrete can also be prestressed (reducing tensile stress) using internal steel cables (tendons), allowing for beams or slabs with a longer span than is practical with reinforced concrete alone. Inspection of concrete structures can be non-destructive if carried out with equipment such as a Schmidt hammer, which is used to estimate concrete strength.
GLASS:
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.
Most common glass has other ingredients added to change its properties. Lead glass or flint glass is more 'brilliant' because the increased refractive index causes noticeably more specular reflection and increased optical dispersion. Adding barium also increases the refractive index. Thorium oxide gives glass a high refractive index and low dispersion and was formerly used in producing high-quality lenses, but due to its radioactivity has been replaced by lanthanum oxide in modern eye glasses Iron can be incorporated into glass to absorb infrared energy, for example in heat absorbing filters for movie projectors, while cerium(IV) oxide can be used for glass that absorbs UV wavelengths.
MARBLE:
Properties:
One of important properties of marble is understood from its name — from Greek, 'marmaros' means «a brilliant stone». It is the property of marble to change in beams of the sun, to be new to an eye every time, unique play of light that drew attention of ancient Greeks to this material, and caused them to erect dozens of temples of it, to make statues so graceful and plastic that we admire it hundreds years later.
Moreover, marble possesses a lot of properties due to which it remains one the most popular natural building materials:
Convenience of processing. Marble is plastic and easily polishing. It is viscous and strong enough, therefore it does not break at once, allowing cutting products of various forms;
Durability. The first signs of white marble ageing appear only after
Water resistance. Water absorption factor of marble is low
Frost resistance. Marble practically does not absorb moisture — therefore, there will be no microcracks from liquid freezing under low temperatures. Products of marble can be used safely in cold premises;
Thermostability. Heat does not influence on marble, so it can be used for fireplaces or to finishing of premises, where temperatures essentially exceed usual temperature;
Ecological compatibility. Marble is classified as a first class material by its level of natural radio-activity, and it can be applied in construction of all types of objects. Being a natural material, it is porous and is capable of «breathing» — it creates a favourable microclimate in a room;
Universality. Both large elements of an interior — ladders, wall panels, columns, and finer, and decorative details — table-tops, window sills, figurines, vases can be made of marble.
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