11. Quality Assurance
11.1 Introduction
Highway and airfield construction specifications are a means to an end. Their objective is to provide the traveling public with an adequate and conomical pavement on which vehicles and aircraft can move easily and safely from point to point. A practical specification is designed to ensure adequate performance at minimum cost; a realistic specification takes account of variations in materials and construction that are inevitable and characteristic of the best construction possible today.
Most agencies currently use a combination of method specifications, statistically based specifications, and end-result specifications, all of which will be discussed in Section 11.3. This combination shares the risk between agency and contractor, directly specifying some materials, equipment, and methods, but allowing the contractor to choose some also. What “acceptable” looks like is defined, and random sampling and statistical analysis of test results evaluate whether the contractor’s work is acceptable.
Although other QA topics will be introduced, the primary focus of this chapter will be on several elements of QC. The following subsections will discuss definitions of the primary aspects of QA.