Evaluation of Non-nuclear Alternatives to Replace the Nuclear Density Gauge During Compaction Quality Control of Unbound Pavement Layers

摘要

Pavement performance is highly dependent on several factors that include: structural adequacy, material properties, traffic loading, and construction quality. The quality of subgrade or base/subbase compaction also significantly affects the performance of pavements; predominantly flexible pavements. In particular, the majority of the distresses in flexible pavements are mainly attributed to the compaction defect in these layers. In current practice, the compaction quality of these layers is usually quantified using the nuclear density gauge (NDG). However, several concerns arise due to the use of the NDG. This study was initiated with the aim of evaluating the sensitivity of the parameters measured using non-nuclear methods/devices to moisture content, compaction effort, testing time after compaction, and aggregate type. To fulfill this objective, a laboratory procedure for compacting large samples was developed. This procedure facilitated testing using three non-nuclear devices: Briaud compaction device (BCD), light weight falling deflectometer (LWD), and dynamic cone penetrometer (DCP). Four types of aggregates, two subgrade soils, one dense graded aggregate, and one recycled concrete aggregates, were selected to comprehensively cover a wide range of subgrade and base/subbase materials. Each device was evaluated for accuracy and repeatability. The sensitivity of the results measured from each device to moisture content, compaction effort applied, and testing time was also evaluated. Based on testing results, it was concluded that the DCP was most sensitive to detecting changes in the measured parameters. In addition, precision of the DCP was similar to other non-nuclear devices.