Published: Jan 1966
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Quality is defined as “an attribute, characteristic, or property” also “class, kind, or grade.” In considering, then, the quality of testing, thought should be given to the characteristics of the kind of testing desired, how this kind of testing can be recognized, and how it can be obtained. That testing of concrete and concrete materials is important and necessary has been demonstrated many times, especially when one reads of the spectacular structural failures caused by inferior materials. But there are other failures too, not so spectacular, but nevertheless serious and costly to the owner. Examples are popouts, cracking, and unsoundness of concrete resulting from the use of aggregates containing inferior constituents—constituents that would be revealed by proper tests, properly performed. Adequate quality control of materials, including laboratory and field tests, informs the engineer, architect, contractor, and owner of the properties of materials proposed for construction and serves as a guide to the producer in maintaining his product within specification limits. There was a time, many years ago, when the engineer or architect depended entirely on his own experience in judging the quality of materials; the stick poked into an earth embankment, how far the concrete would flow in a form, and similar methods of evaluation. These methods are still good. Knowledge gained through experience is still, and always will be, a vital part of engineering proficiency. However, the engineer today finds it not only desirable but also necessary to rely upon laboratory tests to inform him of the suitability of a material. Different materials, new materials, and new usages for old materials all contribute to the need for reliable, impartial tests to point the way for correct use of these materials. This is especially true in the field of concrete construction where we see the development of bold and sophisticated structures that were not considered possible a few years ago. Ultimate strength design, thin shells, new lightweight materials, and exposed aggregate finishes are typical of modern trends in the use of concrete.
Waddell, J. J.
Technical services engineer, Riverside Division of American Cement Corp., Los Angeles, Calif.