CONSTRUCTION AND ARCHITECTURE/4. Modern construction materials
Vyrezkova A. V.
Irkutsk National
Research Technical University
The 21st
century is the century of postindustrial society characterized by
highly-productive industry and the industry of knowledge. Scientific
achievements become the main driving force of economics, the base of industry
of knowledge. A lot of new inventions and discoveries have been made in
different fields of science giving us food for thought.
Glass is the material that has always drawn attention of scientists and
engineers. Glass is defined as the state of amorphous substance produced by
solidification of supercooled liquids. It is not easy to define the term of
glass or glassy state, as there is a nonstop transition between glass and
liquid on the one hand and glass and crystal on the other hand. So, it is
better to define glass as a solid substance with densely packed atoms, in which
by the existence of middle order there is no long-range order. Regarding glass
as a building material it is possible to make its classification, to
characterize different kinds of glass and to conduct a comparative analysis. It
is possible to determine differences in toughness, durability, design
resistance of different types of glass, the advantages and disadvantages of new
developments in this field.
The term “glass” is usually associated with transparent, solid material, which
is very brittle and easy to break. The importance of glass in our lives can be
explained by its properties, which make it different from all other well-known
materials. There is no doubt, that the most attractive quality of glass is its
transparency. To understand the index of glass transparency we can imagine 1 cm
thick plate, made from high- quality glass. It can transmit 99% of light.
The second important quality of glass is its chemical resistance. In fact,
there is only one substance that can be of any harm for glass. It is
hydrofluoric acid. All other chemical compounds have no effect on glass or can
only make a very little damage to its surface. Extremely high chemical
resistance of glass can perfectly protect glassy products from so called
atmospheric agents such as rain, frost and sunrays.
The main branch, where glass has found its wide application is construction
business. A great deal of smelt glass is refined for buildings glazing. The
second large group of glass articles is so called “hollow” glass, vessels of
different kinds, shapes and functions used for liquids, powders, gases, food
products, chemicals etc. Glass is also extensively used in food industry for
making bottles, jars, household tableware etc. Glass is really irreplaceable
when it comes to the storage of active chemical substances, for example in
laboratories, which cannot do without chemical glassware. Transport industry
also requires a large amount of sheet glass for glazing of cars, planes,
trolley-buses, trams, railway wagons and ships. Glass is widely used to produce
glass wool and glass fiber. Another application of glass is painting art.
With the development of new technologies glass finds more and more new branches
for its application. In September, 2015 in China a unique glass bridge was
brought into operation. The length of the bridge is 260 meters, its height is
180 meters. Engineers, who designed the bridge, claim that one square meter of
the bridge can withstand up to 800 kilograms. However, the Chinese mass media
have published the news recently, that the glass got a crack, when one of the
tourists dropped metal thermos with water. Officials assured the tourists that
the cracks were of no danger, as only one layer of glass had been damaged.
But more often glass is used in shop windows and in doorframes. The most common
type of glass is applied for these purposes – common flat window glass with a
high index of ability to reflect the light. The surface of such sheet window
glass is covered with a special semitransparent sheeting, made of titanium
oxide, which reflects the light. Radioprotective sheet glass is also applied in
windows glazing and has a screen sheeting on its surface. Reinforced glass is
produced by continuous rolling with simultaneous rolling of the sheet metal
mesh. Reinforced glass can have a smooth or patterned surface, can be colored
or transparent. All these types of glass can be used as window glass.
Glass-ceramics is sheet glass of different texture, covered with ceramic
crystals of various colors on one side. It is made of unpolished window glass
or rolling glass. Glass-ceramics is used as a decorative material in buildings
in both exterior and interior application as well as in production of panels
and floor tiles.
Reinforced glass is a sheet glass with metal mesh, safe and fire resistant,
able to resist smoke and hot gases. Though it can get cracked by fire, fitting
prevents it from replacing and thus prevents the fire from expanding. Broken
glass does not fall out even if there are several cracks. Although, such type
of glass belongs to the inventions of the last century, it is still in demand
due to its reasonable price.
Toughened glass is more resistant than reinforced glass and ten times more
resistant to breakage than common glass. Thermal tempering process is conducted
in a following way: a heated sheet of glass is rapidly cooled by cold air. As a
result it is resistant both to frost and heat. However, if you give it a hard
blow, it will crumble into many pieces. Toughened glass has broad application
for automobiles, buses and other vehicles, front doors and partitions in
houses.
It is well-known nowadays that substances of different nature can be
transformed in a glassy sate. These are the melts of different pure oxides and
a great variety of their combinations, salt melts such as chalcogenide, halide,
nitrate and others. Many organic substances can be also easily transformed in a
glassy state. Glass is easily produced from water solution of different salts
and their mixtures. Metal glass, produced by rapid cooling of the alloys of
different metals, was introduced in the last decade. In this way, a glassy
state can obtain substances of different chemical properties with different
types of chemical bonds – covalent, ion, metal and different physicochemical
properties.
Chinese and English scientists produced metal glass on the basis of cerium with
quiet unusual properties for such a substance. Metal glass is an amorphous
substance. It is generally produced by rapid cooling of melt. As a result
material does not get crystallized, but solidifies in the amorphous state.
Though crystallized states are the most thermodynamically favourable for
alloys, amorphous structure has a very high index of durability – tens and
hundreds of years. In several cases metal glass has unique mechanical and
magnetic properties such as toughness, resistance to stretching and others)
that explains its wide application. However, by indoor temperature all types of
metal glass are very brittle.
The other type of amorphous materials much more widely applied in industrial
production is polymer glass. Possessing less toughness they have much lower
temperature of glass transition than metal glass and are easily treated by
heating due to the high index of flexibility.
Researchers of the laboratory of material science in Berkl headed by Robert
Richi have found the ways to eliminate the faults typical for such types of
glass. They produced glass on the basis of palladium, amorphous by its
structure, possessing the same fatigue strength like common structural
materials with polycrystalline structure on the basis of steel, aluminum and
titanium. Now, when additives of palladium made it possible to eliminate its
main technological fault, such type of glass can rightfully be called the
material of the 21st century.
Nowadays scientists pay great attention to such material as glass, as its
unique properties make it possible to use glass in those branches where no
other material can be used.
There are different types of glass and they are applied for different purposes,
but perhaps, there is no other material as popular and as indispensable as
glass. New materials can be invented with the course of time, but we still
cannot do without glass.
Reference
list
1. Kachalov N.
"Glass" of 1959.
2. Gridnev S. A. "Dipolar
glasses" 1998.
3.
https://ru.wikipedia.org/
4.
http://www.festivalnauki.ru/
5.
http://tribuna.ru/
6.
http://realty.newsru.com/