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Quality Assurance

Quality has become one of the most important consumer decision factors in the selecting among competing products and services. This is true not only for individual consumers but also for large corporations, government organizations and the taxpaying public as a group. In its broadest sense, quality is a degree of excellence: the extent to which something is fit for its purpose. In the narrow sense, product or service quality is defined as conformance with requirement, freedom from defects or contamination, or simply a degree of customer satisfaction.

Taking a pavement core
Taking a pavement core
Using the ignition oven to measure asphalt content
Figures 1 and 2: Taking a pavement core for density quality control. Figure 3: Using an ignition furnace to determine asphalt content.

AASHTO and the FHWA subscribe to definitions that designate “quality assurance” as an all-encompassing term, to include “quality control”, “independent assurance” and “acceptance” as its three key components (TRB, 1999):

HDOT and the Counties use acceptance testing to monitor contractor quality.  Key acceptance parameters are asphalt content, aggregate gradation, in-place mat density and final mat smoothness.


Quality control, acceptance and independent assurance are wholly separate components of quality assurance. It is difficult, if not impossible, to influence one component, solely through actions within another component. For instance, acceptance procedures are essentially monitoring methods used to determine whether or not a particular process is meeting quality standards. As such, they can be used to accept or reject material based on its quality but they should never be used as a method to control or improve quality; quality will not necessarily improve based on increased or stricter monitoring alone. In short, no amount of inspection changes the quality of a product or service (IQA, 2001). Quality control (process control) is used to control and systematically improve quality. Furthermore, independent assurance test results should not be used for acceptance or quality control. If they are, the tests are no longer independent and should not be used as if they were.

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