Best Practices for Longitudinal Joint Construction and Compaction

US Transportation Collection2018PDFTech ReportPutman, Bradley J.Kim, Eric Mu-YoungClemson University. Department of Civil EngineeringSouth Carolina Department of Transportation. Office of Materials and ResearchUnited States. Department of Transportation. Federal Highway AdministrationSouth Carolina. Department of TransportationSouth CarolinaUnited StatesAsphalt pavementsBest practicesConstructionField testsLaboratory testsLongitudinal jointsPavingFHWA-SC-18-06SPR 728Final reportJoints are the weakest area of an asphalt pavement and longitudinal joint cracking occurs for a number of reasons that lead to low density, low indirect tensile strength, and high permeability at the joint. The purpose of this study was to evaluate the different joint construction techniques used in South Carolina and perform comprehensive testing and analysis to compare the effects of multiple variables on the quality and performance of the longitudinal joints. Nine asphalt resurfacing projects were selected for sampling to make observations, conduct field testing, and cut cores from the joint and interior portion of the pavement for lab testing. The selected asphalt pavement projects consisted of three different surface type mixes (surface type A, B, and C), two longitudinal joint construction techniques (safety edge and butt joint), and one rolling pattern (hot overlap). Like other research studies, the laboratory performance of longitudinal joint was significantly worse than interior portions of the mat with respect to density, permeability, and/or indirect tensile strength (ITS). The compacted asphalt pavement density shared a direct and indirect relationship with ITS and permeability, respectively. The safety edge did not significantly improve the quality or performance of longitudinal joint. Through statistical analysis, surface mix type and depth of the compacted asphalt pavement were found to influence the performance of the joint in laboratory testing. Field testing, on the other hand, generally did not yield significant differences between the pavement interior and joint edge with respect to in-situ density or infiltration. The results of this study informed the development of a set of best practice guidelines for longitudinal joint construction along with recommendations for further assessment prior to developing new specifications for joint construction.140