Introduction – The quality of each material incorporated into a construction project is controlled by sampling and testing, comparing tests results with specification requirements, determining compliance status, and then responding accordingly. On the surface that sounds like a pretty simple and straight forward statement; however, for those of us entrenched in the “Quality” assessment sector of the construction management and oversight industry, we know differently. As it turns out, on a given project, the activities described above are often performed by multiple parties, at different frequencies, in different locations, and for different purposes. To further complicate matters, there is “Quality” terminology associated with all the roles and responsibilities that are involved in the activities above, and that terminology is often used incorrectly, incompletely, out of context, and inconsistently. Hey, believe me, I understand and appreciate that the “Quality” terminology is not always intuitive; however, as an industry member running a company whose project scope is often directly and significantly affected by the manner in which “Quality” terminology is used in RFPs, bid documents, and contracts, I have an interest in at least trying to clarify the basics. My goal here is not to generate more, or less, need for materials testing, on any given project. My only goal here is to have “Quality” terminology used correctly and consistently so that my potential future clients can more accurately convey the magnitude of the materials testing services that they seek. Once all parties are speaking the same language, and are interpreting terms in the same manner, the ultimate result will be a much better alignment between the client’s project service expectations and the materials testing firm’s proposed project budget.
If you have 10 to 20 hours to kill, and an interest in the all inclusive concept of quality programs as applied to major design and construction efforts, let me suggest the Federal Transit Administration (FTA) document entitled Quality Assurance and Quality Control Guidelines (available on the fta.dot.gov website). If you only have a couple hours to kill, and want an implementable materials testing example of the same type of content, tailored for a highway department, try Series 900 of the Arizona Department of Transportation (ADOT) Materials Testing Manual, Materials Quality Assurance Program. Of course the CODE OF FEDERAL REGULATIONS, 23 CFR 637, Subpart B, “Quality Assurance Procedures for Construction” is another good source. But, if you just have 10 minutes and only want a few quick and applicable definitions, read on. Keep in mind that a “Quality” organization deals with any and all products and services , but in my discussion below, I have attempted to relate the definitions to materials testing, and have also touched on how these concepts are supposed to compliment each other.
Quality Control (QC) – The operational techniques and activities that are used to fulfill defined requirements for quality. QC is carried out by the operating or producing forces, which in most cases means the Contractor and those under his contractual umbrella. In the context of materials testing, QC refers to the act of taking measurements, testing, and inspecting a placement process or end product to assure that it meets specification. QC also includes documentation of measurements and observations by QC personnel, reporting compliance status to production forces for them to act upon, and ultimately verifying that any non-complying work has eventually been brought into compliance. QC is NOT just the act of testing, but also includes the follow-up actions taken by production forces in response to testing. When testing indicates compliance, the Contractor’s production activities are validated; however, when testing indicates non-compliance, the Contractor is expected to adjust his own production methods, equipment, materials, or other activities in search of specification compliance. QC is an internal operation conducted by the Contractor in order to satisfy himself that his production activities are producing a product that achieves the defined and measurable quality requirements. When Contractors approach QC as a valuable tool for refining their operations in an attempt to avoid costly re-work and delay, they will commit the resources that it takes to actually control the quality of their product in real time. While many Contractors take this regimented and formalized approach to quality on their own, the construction industry trend since the 1970s has been a gradual shift of more and more risk and responsibility to Contractors on public works projects, and as a result, Owner Agency mandated Contractor QC programs have become the norm.
Quality Assurance (QA) – All planned and systematic actions that are necessary to provide adequate confidence to “management” that a product or service will satisfy the defined requirements for quality. In this case, “management” is a designated higher level entity or authority such as Quality Oversight, Quality Surveillance, or most often the Owner Agency. QA emphasizes upstream actions that directly improve the chances that QC actions will result in a product or service that meets the requirements. Upstream actions include ensuring that the project requirements are appropriate for the intended product and ensuring that contractors are capable of performing tasks related to project quality, ensuring that they do carry out quality requirements, and ensuring that they do document quality efforts and compliance status. At this point in the discussion, in order to stay within my self prescribed 10 minutes, I am going to have to draw the line. On a massive, billion dollar, design-build or P3 type project, even the function of creating and implementing an all encompassing higher level Quality Assurance Program, that contains the Quality Control Program, is assigned to the Contractor. But QA programs on such mega projects, while effective, are quite complex and often significantly hybridized. I am honestly trying to keep this simple, so for the remainder of this conversation, let’s assume that the QA role belongs to the Owner Agency.
Acceptance Testing – Even though Contractor QC testing is being conducted to control the product during production, the Owner still has a responsibility to assure himself, any higher level funding agencies, and the taxpayers, that he is only accepting and paying for work after his own verification efforts to confirm compliance. In the old days, there was no such thing as Contractor QC testing, there was only Acceptance testing. Owner agencies were sufficiently staffed and so inclined to perform materials testing on a near continuous basis, which in effect, means that Owners were performing the testing portion of the QC function for the Contractor. As the shift toward formalized Contractor QC became more prevalent, Owner Agencies did not stop Acceptance testing altogether, they just reduced their testing frequency, and in some cases changed the name to Verification testing. Over the years, since this second level testing is part of the QA Program, some began incorrectly referring to Verification testing as QA testing, but for all intents and purposes, it is still just Acceptance testing. The theory is that if Contractor QC tests are performed on a very frequent basis, and Acceptance testing of the same material under the same usage conditions is performed on a less frequent, but statistically significant basis, then the test results produced by each entity are related to each other. In theory, when frequent QC testing is consistently demonstrating compliance, then less frequent, but well distributed, Acceptance testing of the same material can be used to verify the QC results. For example, if a single QC test characterizes 200T of a specific material, and five consecutive passing tests are combined to define a 1000T quality lot of material that is claimed to be in compliance, then a single Acceptance test taken randomly within this same 1000T can be utilized to verify the entire quality lot, and hence can form the basis for acceptance. The numbers may vary from those used in this example, but the concept of Acceptance and QC interdependence remains intact. NOTE: This example is intentionally oversimplified for demonstration purposes. In reality, while the assumed ratio between QC and Acceptance may be reasonable, a valid statistical comparison between two data sets requires larger populations.
Independent Assurance (IAS) Program – This program consists of IAS testing and Correlation testing performed for the purpose of establishing an unbiased and independent evaluation of the sampling and testing personnel, equipment and procedures used in the acceptance program. Who performs these IAS actions is a function the project specific organizational structure, but key features are that IAS functions are performed by entities who do not have direct responsibility for Contractor QC or Owner Acceptance testing, and IAS testing is not used for determining the quality and acceptability of materials or workmanship. This type of program certainly comes into play at the State Highway program level, on select very large projects, and nowadays even at the smaller local public agency level where federal funds are involved. But that is about as much as I will elaborate on this topic.
End Result, Quality Assurance Program – The reality is that I have only scratched the surface here when it comes to “quality” terminology; however, I hope that one key point is clear. All of the materials testing functions discussed above represent a hierarchy for determining materials quality and each level gains confidence from the others. At the project level, the Contractor QC program involves the smallest quality lots, and if uniformity and compliance is consistently demonstrated at that level, the Acceptance program can have confidence that their less frequent verification conclusions are valid. Likewise, if the IAS and Correlation testing is statistically confirming the accuracy of the Acceptance testing across all of the projects within an agency program or major project defined corridor, then the Quality Assurance Program within which all of these activities exist is functioning properly, at least with respect to materials testing.