IV. Перекладіть наступні складові слова українською.

roadway, carriageway, road-making.

V. Перекладіть слова, які утворені за способом конверсії.

use /n/ - to use, strain /n/ - to strain, change /n/ - to change, advantage /n/ - to advantage.

VI. Перекладіть слова грецького походження українською.

economical, technique, thermal, horizontal.

VII. Перекладіть слова латинського походження українською.

vertical, principle, application, construction, relatively, limit, form, discussion, normal, structure, to induce, initial, compression, to incorporate, to balance, to classify, individual, experimental, section, laboratory, to separate, procedure, coefficient, essentially, friction, constant, condition.

VIII. Дайте українські еквіваленти наступних сполучень іменників.

tensile strength, expansion joint, subgrade friction, slab length, road slab thickness, construction material, road construction firm, safety precautions, prestressing process.

IX. Складіть англо-українські пари словосполучень, еквівалентних за значенням.

1. prestressed concrete pavement; 2. compressive stress; 5. rigid abutment; 4. to cast the slabs; 5. prestressed slabs; 6. riding quality; 7. to repair services.

1. плити з попередньо напруженого цементобетонну; 2. їздова якість; 3. стискаюче напруження; 4. ремонтувати комунікації; 5. покриття з попередньо напруженого цементобетонну; 6. жорстка опора; 7. відливати плити.

PRESTRESSED CONCRETE PAVEMENTS

Although the principle of prestressing has been widely used in other structural fields, its application to road construction has been relatively limited to-day. It appears that prestressed concrete roads may be economically comparable with other forms of construction. In one excellent discussion it is suggested that as constructional techniques improve, prestressed pavements may even become cheaper to build than normal reinforced concrete pavements.

The purpose of prestressing a concrete structure is to augment its tensile strength by inducing an initial compressive stress in the concrete before it is subjected, to loading. Prestressing is carried out by two main methods. In the first of these, steel tendons are incorporated in the concrete, stretched and subsequently fixed to the concrete in such a way that the induced tension in the steel is balanced by compression in the concrete. Stretching may take place before the concrete has hardened (pretensioning by wires) or after the concrete has hardened (post-tensioning by cables or bars placed in ducts). The second method of prestreesing is by casting the concrete between suitable rigid abutments, which are of sufficient strength to receive the prestressing thrust. Jacks are then placed between the abutments and the concrete and operated to compress the concrete.

Prestressed concrete pavements can be classified according to whether they are of the individual slab type or of the continuous type. With the exception of one experimental section of roadway designed by the Road Research Laboratory, it is probable that all of the prestressed concrete pavements built in Britain to-day have been of the individual slab type. The method of construction employed is to cast the slabs so that they are separated only at expansion joints, and to prestress the slabs by internal tendons or cables. This construction procedure allows each slab to expand or contract relatively freely and since the coefficients of thermal expansion for steel and concrete are similar, the prestress in each slab remains essentially constant, except of subgrade friction. At the present time it appears that slab lengths of up to 400 ft can be satisfactory constructed in this way. Prestressed slabs are especially suitable for use in roads having inferior subgrade conditions and curves. In contrast, the continuous type of construction is more suited to fairly straight level lengths of roadway over good subgrades. The continuous method utilizes jacks to apply the thrust and then, after the slab has been prestressed, the gaps in which the jacks are accommodated are filled, so that the strain remains in the slab. This means that, since the prestressed slab cannot expand between the abutments, the stress in it does not remain constant but varies with temperature and moisture changes.

The main advantages attributed to prestressing are reductions in the slab thickness, in the number of joints and in the amount of cracking. Reductions in road slab thickness can result in some saving in concrete, and this is important in area where good construction materials are not readily available. Fewer joints expedite and simplify construction of the road and result in the carriageway having a better riding quality. Fewer cracks result in a longer life and lower the maintenance cost for the roadway.

The principal disadvantages associated with the use of prestressing are the difficulties encountered in applying prestress on vertical and horizontal curves and, in urban areas, the difficulty of repairing services located beneath the road since the prestress is destroyed by cutting trenches. It should also be mentioned that at the present time the application of prestressing to road construction is still only the development stage and not all road construction firms are equipped to handle this form of road-making. Hence, prestressed pavements are still liable to be more expensive to construct than normal reinforced concrete pavements. A further disadvantage is that strict safety precautions must be introduced and enforced during the actual prestressing process.

Завдання I. Знайдіть в тексті слова, які закінчуються на - ing. Визначте, чи є кожне з них герундієм чи дієприкметником теперішнього часу та яку функцію воно виконує. Відповідні речення перекладіть українською.

Завдання II. Знайдіть речення, які містять пасивну конструкцію. Речення перекладіть.

Завдання III. Знайдіть речення, які містять дієприкметник минулого часу і визначте, яку функцію він виконує. Речення перекладіть українською.

Завдання IV. Поясніть, з якою ціллю цементобетонна конструкція підлягає напруженню.

Завдання V. Розкажіть, які існують основні методи попереднього напруження цементобетонну?