Nebraska LTAP


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Nebraska Transportation Center, Report # SPR-1(10)P335


A Report on Research Sponsored By: Nebraska Department of Roads


Quality control (QC) and quality assurance (QA) are necessary to ensure fulfillment and compliance to specifications, guidelines, manuals, and programs which outline methods and requirements during construction. Density, an important part of quality control, can be used to evaluate the quality of Hot Mix Asphalt (HMA) and soil compaction. This study investigated new technologies used for QC and QA by comparing the Pavement Quality Indicator (PQI) model 301 with a nuclear gauge and core sample measurements for HMA. For soil QC and QA, non-nuclear technologies—the Electrical Density Gauge (EDG), the Moisture Density Indicator (MDI), and the Light Weight Deflectometer (LWD)—were also investigated against a nuclear gauge and traditional non-nuclear methods of measurement. Overall, the nuclear gauge shows higher accuracy and higher correlation with cores than the non-nuclear gauges tested in this study. A thorough investigation of calibration methods was also performed, both in the lab and on the field, to improve the accuracy of the PQI‘s results. Data analyses showed that the accuracies of the non-nuclear soil gauges are somewhat lower than that of the nuclear gauge. With an improved methodology to create soil models for the EDG and standardized ways to develop the LWD‘s target values, the EDG and LWD could have a similar or better accuracy than the nuclear gauge. With the EDG and the Soil Density Gauge (SDG), both recently ASTM approved, nonnuclear soil technology is the future. Furthermore, the non-nuclear gauges could be a better alternative to a nuclear gauge when the following benefits are considered: (1) economic savings; (2) faster data measurement (PQI); (3) elimination of intense federal regulations and safety concerns; (4) elimination of licensing and intense training.