Non-Destructive Testing in Quality Assurance of Concrete for Assessing Production Uniformity

Abstract

Non-destructive testing (NDT) methods can be particularly valuable in assessing concrete quality at early ages as they are associated with reduced testing time and cost. A national study focusing on the potential use of NDT in quality assurance (QA) of concrete has recommended the adoption and/or use of such testing methods when these have low level of testing variability. Thus, objective of this study was to build on such recommendation and assess the response of specific well-developed and mature NDT methods in relation to their testing variability for detecting such production defects such as honeycombing and segregation. Recognizing the extensive knowledge and experience in assessing concrete with such methods over the years, the selected NDT methods considered were: ultrasonic pulse velocity (UPV); resonant frequency analysis (RFA); and, rebound hammer. Each of these NDT methods could be used for a specific assessment within QA as identified later on within the manuscript. The results indicated that indeed UPV is able to identify the presence of such defects with acceptable accuracy and repeatability. RFA also provided acceptable testing variability and thus can be used as complementary assessment to UPV in both lab and field-cured samples. The rebound hammer, as expected, was characterized with high testing variability and thus its use could be limited to a quick and only initial forensic assessment. Overall, the use of these NDT methods in QA will provide the opportunity to test a larger portion of concrete without a significant increase in QA cost and testing time.