“Acceptance” is a formal procedure used to decide whether work should be accepted, rejected, or accepted at a reduced payment (Freeman and Grogan, 1998). Specifically, it is the monitoring method used to determine whether or not a particular process is meeting quality standards; it is not, however, a form of quality control. Acceptance procedures simply accept or reject things based on their quality; they do not ensure proper quality standards. Thus, they should never be used as a method to control or improve quality; process controls are used to control and systematically improve quality (Montgomery, 1997). Often, the term “quality assurance” is used to refer to what is here defined as “acceptance”. While this is fine (and many organizations do this) the standard AASHTO definitions are used here meaning that the term “quality assurance” refers to the all-encompassing idea that includes “quality control”, “independent assurance” and “acceptance” as its three key components.
Acceptance procedures can take one of the following three broad forms: (Montgomery, 1997):
- Accept with no inspection is generally used when there is no economic justification to look for defective units or material.
- 100 percent inspection is generally used where components or material are extremely critical and passing any defective components or material would result in an unacceptably high failure cost.
- Acceptance sampling is generally used when there is some economic justification to look for defective material and either (1) some small finite percentage of defective material is acceptable or (2) it is not economical or practical to use 100 percent inspection. Acceptance sampling uses statistics to estimate information about a large amount of material from a small random sample.
Pavement construction typically uses acceptance sampling and thus, many specifications are statistically based. Statistical Acceptance Specifications takes a more in-depth look at these types of specifications.