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Good quality control (QC) practices are essential to obtain satisfactory pavements. Typical QC tests for asphalt pavements include: asphalt content, mixture properties of laboratory samples, density, …, etc. Results of these tests are used to ensure that the constructed pavements comply to specifications. However, quality of compliance to specifications and quality performance are two different things and are not always directly related to each other. The ultimate goal of QC is to have high quality of performance. However, efforts are made to achieve this goal by using laboratory based specifications, which are empirically related to field performance.
Current specifications are based on standard conditions which can be easily controlled in the laboratory but never exist in the field. Also, laboratory tests are run on samples representing individual layers (such as surface, base, etc.). In real life, a pavement structure performs as one unit and failure in one layer could happen because of another layer. Therefore, a performance-based specification that describes how a pavement must perform under the actual field conditions should be considered.
A study is underway in the Dubai Municipality (DM), U.A.E., to develop a procedure in which the falling weight deflectometer (FWD) is used to evaluate the in situ structural capacity of new pavements. FWD testing is conducted on each layer before constructing the next layer. Comparisons between the FWD test results and target deflection values are made to evaluate the construction quality of layers, as well as to identify weak spots. In this paper, the outline of this procedure is presented. Also, the results of a pilot study conducted to evaluate the procedure are presented.
Head, PMS Unit - Dubai Municipality, Dubai,
Director, Dubai Municipality,