The Problem of Durability in Building

1. Durability Is known to be a very elusive property. If the problem is regarded critically the question may well be asked: What is the degree of durability required?

2. The durability of any material or method of construction (if we regard walls) depends upon the conditions of exposure. External weathering with rapid alterations of temperature and moisture content results in deterioration of structures and materials which would be unaffected over very long periods if used inside. It is necessary to take account of the increased severity of exposure to the weather.

3. In selecting materials the practice of experience is not enough. Many disastrous failures arc supposed to have resulted from the supposition that an unfamiliar combination of familiar materials can be used with complete freedom. The technique of scientific testing of materials is considered to be more reliable. It has accumulated dolinite principles on which an appraisal of durability is made.

4. The durability of it walling material in service is affected by its chemical composition, pore structures and to some extent by its mechanical strength. Materials vary in the extent to which their pores will be filled with water on immersion. In some materials nearly the whole of the pore space is filled.

5. In certain cases the effects of frosts may be rendered more severe by the presence in a material of certain salts in solution. We assume chemical attacks and pore structures to be interrelated.

6. Thus, it is the technique of scientific testing that should be used when the problem of reliance is concerned in the sphere of building materials.

VI. Read the 4 paragraph of the text and choose the correct answer to the question

What factors affect the durability of a walling material in service ?

1. Chemical composition, pore structure and mechanical strength affect the durability of walling material in service.

2. Weather conditions affect the durability of walling material in service.

3. Previous behaviour affects the durability of walling material in service.

4. Rapid alterations of temperatures affect the durability of walling material in service.

Contents

1. Text: Some facts about building materials………………………………..5

2. Text: Metals, glass and plastics as building materials…………………....7

3. Text: Cement……………………………………………………………..8

4. Text: Concrete…………………………………………………………...10

5. Text: Getting the best from prestressed concrete………………………..12

6. Text: Civil engineering…………………………………………………..14

7. Text: From the history of civil engineering………………………………16

8. Text: The design of residential areas……………………………………..17

9. Text: Something about cementing materials………………………………19

10. Text: The problem of durability in building………………………………..21