Materials in Construction

An Introduction

G. D. Taylor

• Editore: Routledge
• Anno: 2013
• ISBN:
  9781317879015
• Edizione: 3
• Argomento: Technology & Engineering
• Categoria: Construction & Architectural Engineering

Materials in Construction: An Introduction presents a clear and accessible introduction to the principles, practice and performance of construction materials. This new edition is being published as a companion to G. D. Taylor's Materials in Construction: Principles, Practice and Performance - an advanced text that will develop the topics presented in this book. The coverage of a wide range of construction materials provides a comprehensive foundation to the subject, and includes an overview of performance characteristics and standards for many materials. The text also reviews material properties, and examines and evaluates modes of deterioration while emphasising preventative techniques and remedial treatment. Throughout the text carefully devised example experiments and questions support the theory and practical information. Materials in Construction is an essential handbook for any student studying materials as part of a construction course at BTEC NC/D, HNC/D and undergraduate level.

1 Introduction

Chapter summary

● Stages in the life of a building.

● Performance criteria, standards and quality in relation to materials in construction.

● Important performance characteristics of materials, together with means of assessing them.

● Important environmental performance issues.

1.1 Stages in the life of a building

The successful operation of materials in buildings requires an understanding of their characteristics as they affect the building at all stages of its lifetime as follows:

● Design

Materials appropriate to the building design, function and environment must be selected; indeed, traditionally, consideration of the materials to be used was a coherent part of the design process. Today there is more choice but designers must be aware of the limitations as well as the opportunities associated with individual materials, and how they interact with each other.

● Construction

Builders are legally obliged to ‘build well’ and this includes a responsibility to use specified materials in the correct manner and to identify potential defects.

● Maintenance

Although some materials are virtually maintenance-free, the majority require some form of care during their lifetime. Effective maintenance depends upon knowledge of how materials react with their environment over the planned lifetime. It may in the long term be much more expensive to maintain certain materials if their initial quality is poor – for example, protective coatings to timber and metals.

● Repair

A wide choice of repair systems is now available for many materials. Informed and efficient use of such systems hinges upon an understanding of decay processes, how to arrest decay, and how the repair materials interact with the original materials.

● Demolition/recycling

These processes are increasingly being considered as a part of the overall selection procedure. The safety/environmental aspects of alternative materials are, in particular, now being included in assessments of overall suitability.

1.2 Performance criteria

Modern buildings are usually one-off structures of great complexity. They comprise many components, some pre-manufactured and assembled on site, while others, such as concrete, may be manufactured ‘in situ’. In each case, satisfactory operation of the building as a whole depends on the performance of the materials from which its components are made and on the interrelationships between them.

Before assessing the suitability of any one material for a given situation, the performance requirements for that situation must be identified. Such requirements might include:

● Structural safety

The ability to withstand stresses resulting from gravity, wind, thermal or moisture movement, or other sources.

● Fire

The material must behave acceptably in resisting fire spread, release of dangerous substances in fire and retaining satisfactory structural stability.

● Durability

The material should fulfil the above performance criteria as required for the planned lifetime of the building.

● Health/safety

There should be no risk to health due to chemical or physical effects of the material, both during and after construction.

There are a number of other important performance requirements; for example:

● Comfort

● Resistance to weathering

● Serviceability

● Appearance

These will be referred to as appropriate when individual materials are described.

In addition to the above performance requirements of materials within the finished building, the following might also have to be considered:

● Availability/cost.

● Ease with which material can be incorporated into the building (buildability).

● Environmental aspects – for example, energy demand of the material during manufacture and ability to conserve energy in use.

1.3 Materials properties: specifications, standards and regulations

Most new buildings are produced with the aid of some written specification, which may often take the form of detailed annotations to drawings, a bill of quantities, or separate documents which are part of the contract. Some form of written specification is highly desirable because it communicates to the construction team exactly what is required and provides the client with a basis on which unsatisfactory performance may be identified and remedied.

It is important to appreciate the background to the production of specifications, standards and, ultimately, regulations for a particular item or context. In order to be enforceable there is a need for each stage of the process to be precise and repeatable. The developmental stages that lie behind any specific standards or regulations are shown in Fig. 1.1.

Fig. 1.1 Developmental stages in the production of standards and specifications

To give an illustration of this, the resistance to fire spread through a walling component might be required. This is the identification stage, which might be defined in terms of how long (time in minutes) fire would take to penetrate the wall. This would be measured by carefully designed experimental tests, but if results are to have widespread applicability, all relevant aspects of the test procedure should be standardised. Standards may be confined to the method of test, but very often they also include acceptable levels of performance under the test.

Finally, a client or designer may specify performance levels by reference to the standard or, especially where health and safety are involved, a local authority or government may regulate use by requiring a given level of performance under the standard.

Most standards represent basic performance levels. When higher levels are required they may have to be drafted carefully for a given specification. Standards measure performance in a carefully defined reproducible manner, as explain...