Laboratory Evaluation Of HMA Mixes Manufactured With Pg64-28nv And Pg64-28pm Polymer-modified Asphalt Binders

The purpose of this study was to evaluate and compare the mechanical properties of asphalt mixtures manufactured with PG64-28PM to those manufactured with PG64-28NV. Additionally, a mechanistic-empirical analysis was conducted to evaluate the impact of the two polymer-modified HMA mixtures on predicted pavement performance

Review of Percent Within Limits for Dense Graded HMA

Nevada Department of Transportation (NDOT) has asked the University of Nevada, Reno to research and develop a Percent With Limits program. They find it difficult to enforce demerits when pavement sections are measured to be out of tolerance. For example, if a pavement section is found to have poor compaction or unacceptable asphalt binder content, they are supposed to suspend the construction. However, they may allow construction to proceed if those same sections pass other parameters. This ambiguity has caused confusion among the contractors and it may have allowed inadequate pavement sections be left in place without penalty. In addition, NDOT currently evaluates pavement sections based on single test points or an average of the test points. There is no consideration for the variability or consistency of the measured parameters, as long as they are within the upper and lower specification limits. A literature review covering 11 states was performed in order to present to NDOT how other states utilize PWL. They include Arizona, California, Colorado, Idaho, Kansas, Michigan, New Mexico, New York State, Utah, Vermont, and Washington State. These states employ the PWL methodology and details of their methods were evaluated. This report provides information such as lot and sublot sizes, parameters used for testing, frequency of testing, upper and lower specification limits, pay factor calculations, and how the pay adjustment was conducted. Pavement performance relies heavily on how well it was constructed. By utilizing a PWL system, contractors are provided an incentive to produce higher quality roads by building them closer to the target values and with less variability. PWL allows the agency to estimate the quality of the constructed pavement and issue bonuses or penalties based on the justified results of the PWL analysis

Develop a PWL System for Dense Graded Hot Mix Asphalt Construction, Including Pay Factors

This research project developed a PWL system that the Nevada DOT can effectively implement on the construction of dense graded HMA mixtures. The PWL system includes pay factors that are based on pavement performance indicators such as rutting and cracking. In addition, the developed PWL System is incorporated into a user-oriented software that is capable of analyzing the relevant data, establishing the PWL values, and applying the appropriate pay adjustments. The research was completed over three phases: Phase I – Review of Existing PWL Specification Systems: this phase reviewed several PWL specification systems for HMA construction. Based on the findings of the review, the research team recommended the general framework of the PWL system to be developed in Phase II. Phase II – Develop the PWL Specification System: this phase developed the PWL system. The developed system uses several materials and mixtures properties to identify the PWLs for all sublots and lots of HMA mixtures. Weight factors are identified for each of the materials and mixtures properties leading to the development of a single PWL for each lot within a construction project. Phase III – Implement the Specifications: this phase will implement the developed PWL system on several NDOT projects and uses the data from these projects to fine tune the syste