F. 4. Read the text beams and say what materials were used for the construction of beams; what material is used now?

Already in the early the 3^rd millennium BC, in Zozer's tomb complex at Saqqara, blocks of stone were being deliberately shaped for use as ceiling beams instead of just used as found. The fact that their undersides were cut to a rounded form suggests an even earlier use of cut timber, probably palm logs.

This is to be expected, since timber is easier to cut and transport. Apart from its inferior durability, it is also a more appropriate material because the structural action of a beam involves internal tension as well as compression. Besides, timber, unlike stone, has a tensile strength along the grain to match its compressive strength. With stone there was only one possibility — the use of metal reinforcement at the bottom to improve the tensile weakness.

Iron beams became structurally important elements only in the late 18th century with the widespread introduction of cast iron.

Reinforced concrete became a highly versatile structural material, since the strength of the concrete, the overall geometry of the element, and the quantity and placement of the reinforcement rods were all under the designer's control.

Notes:

appropriate подходящий involve вызывать grain (зд.) волокно inferior худший (по качеству) log бревно

deliberately умышленно, нарочно durability прочность, стойкость along the grain по направлению волокна versatile многосторонний, гибкий

F. 5. Read the text Decorative Laminates and then discuss it

The large range of decorative plastics laminates now available to the architect and builder has brought about a revolution in interior and exterior design. These materials are no longer for decoration only, but are made to withstand severe outdoor conditions for varying periods of time and sufficiently rigid to stand on their own in certain cases without support. They can be worked by all the methods commonly employed by the builder. Many disadvantages have had to be overcome in the development of decorative laminates before they could be put on the market, particularly with respect to their weathering properties.

A laminate has been developed which is suitable for both inside and outside use. This consists of a paper filler impregnated with thermosetting resins, on top of which is laid similarly impregnated paper. The paper itself is topped with a melamine resin treated skin which gives a tough surface, this sandwich being then pressed and subjected to heat. The laminate formed is 5/8 in thick, and is claimed to stand up to severe exterior conditions for at least ten years without serious fading.

As a complete structural material in itself, it is recommended for exterior work on shop fronts, walls, entrances, doors and windows. Its chief advantage is that it needs no maintenance other than an occasional wipe down with a damp cloth. For interior use it is recommended for surfacing or sometimes as a structural material for kitchens, bathrooms and lavatory walls, for doors, staircase walls, window sills, etc.

Notes:	fading = loss of colour filler заполнитель surface поверхность tough жесткий	impregnate пропитывать laminate слоистый материал skin наружный слой, оболочка to stand up to = to withstand
	put on the market = put out for sale to stand on their own = to support themselves thermosetting resin термореактивная смола