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49
CHAPTER SEVEN
QUALITY CONTROL AND QUALITY ASSURANCE
AND PERFORMANCE MEASURES
INTRODUCTION (The results of independent assurance tests are not to be
used as a basis of product acceptance.)
A key element of microsurfacing projects is the quality control · Verification. The process of determining or testing the
and quality assurance (QC/QA) philosophy and procedures truth or accuracy of test results by examining the data
applied. In both cases, an independent assurance element may and/or providing objective evidence. [Verification sam-
be applied. QC/QA is a major issue with the highway agencies pling and testing may be part of an independent assurance
that are considering implementing contract pavement mainte- program (to verify contractor QC testing or agency accep-
nance. This topic also relates to microsurfacing performance tance) or part of an acceptance program (to verify con-
risk allocation that was covered in chapter four. Because micro- tractor testing used in the agency's acceptance decision).]
surfacing design is laboratory-based and those tests were · Quality Management (QM). The totality of the system
covered in chapter three, this chapter will confine itself to used to manage the ultimate quality of the design as well
the construction QC/QA process. Specific QC/QA testing as the construction encompassing the quality functions
requirements for both the materials and the finished product described above as QA, QC, independent assurance, and
are summarized and analyzed in this chapter. verification (Committee on Management of Quality
Assurance 2005).
QUALITY DEFINITIONS
MICROSURFACING QUALITY REQUIREMENTS
For the purposes of this synthesis, Transportation Research
Circular E-C074: Glossary of Highway Quality Assurance
Field quality management in microsurfacing consists of two
Terms (Committee on Management of Quality Assurance
primary activities. First, the contract for the project will spec-
2005) will be used to define the quality assurance terms in
ify a certain amount of QC/QA sampling of materials for test-
this report. Quoted here are the major definitions.
ing to occur in the field. The primary reason for field sam-
pling is to verify that the materials being installed conform
· Quality. The degree to which a product or service sat-
to the same standards as in the contract. For example, on
isfies the needs of a specific customer, or the degree
large microsurfacing projects where the aggregate and other
to which a product or service conforms to a given
materials are produced over a series of weeks rather than all
requirement.
at one time, the inherent variability that occurs in nature can
· Quality assurance (QA). All planned and systematic
change the engineering properties of aggregate and emul-
actions necessary to provide confidence that a product
sion (ISSA 2010a). Thus, field sampling seeks to ensure
or facility will perform satisfactorily in service. (QA
consistency of the mix as it is being applied. The second
addresses the overall problem of obtaining the quality
major quality management activity is the monitoring and
of a service, product, or facility in the most efficient,
correcting of defects in workmanship. A perfect microsurfac-
economical, and satisfactory manner possible. Within
ing mix that has passed all the laboratory tests can still be
this broad context, QA involves continued evaluation of
improperly installed in a manner that prevents it from reach-
the activities of planning, design, development of plans
ing its desired service life. "Therefore, good decisions and
and specifications, advertising and awarding of contracts,
careful quality control are necessary from initial selection of
construction, and maintenance, and the interactions of
the treatment type through final acceptance of the completed
these activities).
project" (Jahren and Behling 2004).
· Quality control (QC). Also called process control. Those
QA actions and considerations necessary to assess and
adjust production and construction processes so as to con- Field Testing Practice
trol the level of quality being produced in the end product.
· Independent assurance (IA). A management tool that The survey and the content analysis specifically sampled
requires a third party, not directly responsible for process for information on how public highway agencies distribute
control or acceptance, to provide an independent assess- the responsibility for conducting various quality manage-
ment of the product and/or the reliability of test results ment tasks. At this point it is important to remember from
obtained from process control and acceptance testing. chapter three that most agencies assign the responsibility for
