The group of polymers

Synthetic polymers can be divided into three separate class - thermoplastic, heat-resistant and elastomers.
Thermoplastics, such as polystyrene and polyvinyl chloride (PVC), can be repeatedly soften when heated. This is because the chain molecules in them are moveable relative to each other. The mobility increases with increasing temperature. In heat-resistant polymers (bakelite and epoxy resin) cross-links between the chains inhibit this process, so they when heated, not softened.
Elastomers - rubber and similar polymers, natural and synthetic rubber. To obtain the necessary number of links between the molecular chains of these materials are subjected to special treatment. As a result, they gain flexibility, i.e. the ability to be stretched, and after removal of the load to take its original shape.

Wood

The demand for wood is always great: she's on hand spraying, just to give a desired form, the details of the wood are easily attached to each other, and the products have a beautiful look.
Each type of wood gives a unique fibration of the wood with its natural pattern. This pattern is evident for the longitudinal cutting of the barrel when the outcrop of the internal structure of the wood fibers and cells.
Another specific feature of the surface of the wood has labels irregular round or oval shape. The outline of each such a bitch depend on the angle at which the sawed timber. Bitches come across where the trunk of the tree to leave the branch. Every living branch over time if grows in the barrel, and educated it swirls harden in his column; conversely, each dead branch forms a knot, which during the processing is eliminated.

Hard and soft wood

The wood is hard or soft. Give soft wood conifers - pine, spruce, fir, dads, and hard - deciduous, particularly beech, birch, maple, oak and poplar. In the tropics solid wood is produced from black ebony, mahogany, teak and other valuable species. Beautiful to look at and also solid wood has always been appreciated in the circle of manufacturers and buyers of furniture. Unfortunately, the trees of firm breeds grow slowly, and in the rainforests they are becoming less. For example, in Thailand in 1945. tropical forests accounted for 70% of all land, and by 1989 this figure had fallen to 18%; therefore, the Thai government banned logging. In many industrialized countries, there are calls on the reduction of import solid wood.

Logging

Usually, the trees are felled with the aid of powerful circular saws, then cut off the branches and dumped them on the treatment site for further transportation, involving cranes, crawler tractors, bulldozers. If the wood is to be transported by land, using cranes load it on a wheeled transport, although in India and Burma, to drag felled trees, as in ancient times used elephants.
In some regions the forest is easier to float along the rivers; felled trees are to the rafts and push the water by means of cranes. Then hundreds of rafts linked together and towed to sorting and labelling. In remote areas, where rivers no traffic, just the logs floated downstream up to the destination party wood.
In many countries, especially those where the harvest solid wood, not enough powerful technique for the cutting of the forest. For timber in logs export to the industrialized countries for wood processing plants.
The timber mill deck primarily free from bark, and then mechanical saws cut into billets of a certain size. At this stage of processing, the wood still contains SAP and require drying. A natural process is possible, but takes almost a year of time, so the wood normally sent to a quick lesso drying in special dryers. As a result of such artificial drying, shrinkage occurs and sometimes even warping of the wood; therefore, wood is processed only after the complete drying, when it becomes relatively stable (assuming again wet).
Sawn timber for further processing to be used in the construction and surfaces from the outside, require proof. Often, the boards transmit to longitudinal cutting, painting or etching the surface of the boards. Attractive wood is cut into very thin sheets - a veneer facing that he then glued to the base of plain wood.
Plywood consists of several sheets of wood glued together so that the fibers of adjacent sheets formed a right angle. Plywood sheet is much stronger made of ordinary wood, it is difficult to bend and split; the probability of warping is also negligible.
In the woodworking industry wastes little man found a use for everything. The slats of wood of low quality is placed between sheets of high quality wood, producing Blockboard and residual scrap is crushed into sawdust impregnated with glue and compressed to particleboard - wood chipboard plate.

Building

Ancient crafts, such as masonry, as before play an important role during the construction of houses. However, modern methods of shotcrete (layer-by-layer sketches) of the concrete mix or the installation of prefabricated structures require new knowledge and skills.
The oldest homes were built of locally available materials: branches, turf, stones and clay. All this can be cut and trim to give the desired shape with the help of primitive tools like stone axes and knives. Adobe bricks, fashioned by hand from clay with addition of straw and dried in the sun, was first used in the Eastern Mediterranean about 6000 years BC that was a significant step forward.

Brick house

A lot of people around the world live in brick houses. Typical house of brick stands on a strip Foundation of concrete, poured into the pits. The Foundation covered with a layer of so-called concrete preparation. Flooring on the ground level can be concrete or wooden floorboards, laid across the ceiling beams. The ends of these beams rest on the outer walls of the house. Support joists of the first floor also serve as intermediate low brick wall built on a concrete preparation, over which is placed a wooden beam - lag. The floorboards are fastened by nails at right angles to the joists.
The ceiling usually consists of beams between the walls to which the bottom with nails to fasten the sheets of drywall. The boardwalk top floor nailed on top of the ceiling beams of the first floor. In older homes first nailed wooden slats (lath) across the ceiling beams. Between the strips leave gaps when attached to the plaster it could seep between them. After hardening of the mortar, the plaster firmly against the rail.
The wooden frame of the roof rests on the walls of the capital, the top is covered with a waterproof material such as roofing material. Across the roof lay the pieces of wood and nailed them to the inclined bars. Slate or tiles are fastened with nails or staples to Latham.
Partitions divide the building into rooms, but do not support design. They can be built of brick, lined with concrete blocks or stucco, nailed to a wooden frame.
Door frame is usually made of wood and window frames of wood, steel or aluminum. Over door and window openings shall be beams (lintels). They serve the upper leg of masonry which might otherwise SAG and collapse. Nowadays, jumpers are made of steel or concrete. In some houses put a wooden lintel.

Wood-frame house

While most of the work during the construction of a brick house, you need to perform on the building site, wooden frame houses can be mounted from prefabricated structures. Such standard elements as the frame units and wall panels are manufactured in factories. This greatly reduces the time that is spent on house construction, as most of the work on site is producing large prefabricated structures.
In areas where not enough timber frame cased with boards. In other cases, a wooden frame can carry the wall panels of concrete.

The use of concrete

Now instead of fixing pre-cast concrete panels to the frame is applied layer by layer throwing him on the concrete with subsequent retention. In some cases, the concrete had been sprayed on the lightweight precast frame, which plays a role of reinforcement. In another system used shotcrete concrete contains tiny fibres that give it even more strength. Concrete has become one of the most important materials for the manufacture of prefabricated structures such as beams and columns, floor slabs and roofs, staircases, cladding wall panels and load-bearing structure of the walls. In some structural systems, such wall elements support the weight of the entire building and there is no need in the bearing frame of columns and beams. Concrete panel exterior walls come from the factory ready with a decorative veneer and is often inserted by Windows.

The reinforcement of fiberglass

The individual elements are made on-site by pouring concrete into wooden forms (formwork) reusable. Recently appeared encasement of glass-fiber-reinforced concrete. This formwork becomes an integral part of the design of the house. It simply sets in the desired location and pour concrete.
One of the most common ways in high-rise construction is a method of the console Assembly from the Central hollow of the trunk of reinforced concrete, which are often available Elevator shaft. The Foundation for such a home is usually done in the form of massive concrete mortar. Concrete barrel built on this base plate, and a steel or concrete frame then mounted on massive beams projecting from the barrel.
Steel load-bearing frame elements are preferably I-beams. They provide greater stiffness of beams at their relatively low weight compared to expensive steel beams. In addition to high-rise buildings, steel frames are used for the construction of small industrial and commercial buildings, low-rise apartment buildings and ordinary houses.

Road

Many of the core elements of modern road construction developed by the Romans, who were famous for their engineering and build roads with solid Foundation, good drainage and a smooth surface.
Road network the Romans had been carefully planned, and on the main lines were equipped with stop like a modern service stations on motorways. After the decline of the Roman Empire the roads are not maintained in proper condition and gradually collapsed. However, a lot of trails that were used by the Romans, make today a basis of a considerable part of the European network of highways.
In England the science of road building flourished in the early nineteenth century. Thanks to the efforts of the Scottish engineers Thomas Telford and John Macadam. Telford supervised the construction of more Books roads and 1,200 bridges. And macadam, except for roads, published works on their building and invented a road surface known as tarmacadam, or tar concrete.
The expansion of the Railways interrupted the development of road construction in England, but interest resumed in the late nineteenth century. In connection with the invention of the car. The increase in the number of vehicles demanded the creation of a new road network. Therefore, in the early 1950s, the British began the construction of the motorway network.