2013 Session: 737

• Benefits Achieved from Florida's Accelerated Pavement Testing Program
  Abstract: The need for faster and more practical evaluation methods under closely simulated in-service conditions prompted the Florida Department of Transportation (FDOT) to initiate an accelerated pavement testing (APT) program in 2000. APT allows monitoring of a pavement system’s performance and response to accumulation of damage within a much shorter time period, typically within weeks instead of years. The primary objective of FDOT’s APT program is to continuously improve the performance of Florida’s pavements. As such, implementation and technology transfer of research findings are of primary importance. The APT program has become a critical component of FDOT’s pavement research program. The success of the program can be attributed to the careful selection of research projects that address vital issues and prolong the life of Florida’s roadways. Engineers have successfully used the APT program to gain insight into new pavement technology and design methods that laboratory testing alone could not provide. Most important is the impact the APT program has had on pavement construction and design practices. APT research has led to the revision of FDOT’s Flexible Pavement Design Manual and construction specifications and has provided critical information to policy makers. While specific tangible benefits cannot be always directly determined for each project, it is clear that significant savings can be directly attributed to the implementation of APT research. For example, it is estimated that over $4 million is saved each year as a result of APT research and implementation of polymer modified asphalt binders and fine-graded asphalt mixtures.
  Authors: Greene, James; Choubane, Bouzid; Jackson, N. Mike
  Authors: Greene, James; Choubane, Bouzid; Jackson, N. Mike
  Year: 2013
  Document Type: Paper
  Subject: Design; Pavements
  Session: 737
  Paper Number: 13-0961
• Effect of Moisture Content on Pavement Behavior in a Heavy-Vehicle Simulator Test
  Abstract: A flexible test road structure was built and tested in an Accelerated Pavement Test (APT) using a Heavy Vehicle Simulator (HVS), to investigate its performance behaviour for a validation in a mechanistic performance scheme. In the test more than one million load cycles were applied, but approximately half way through the test, water was introduced to the pavement structure. The structure was therefore analysed in “moist” and “wet” state, before and after raising the water level. The increased water level had a significant effect on the responses of the structure with decreased resilient modulus and increased rate of accumulation of permanent deformation. Numerical analyses have been carried out to simulate the pavement responses, with the material properties based on field and laboratory testing. The observed accumulation of permanent deformation of the unbound layers was modelled using work hardening material models based on the numerical analyses. Generally good agreement was established between the measurements and calculations.
  Authors: Saevarsdottir, Thorbjorg; Erlingsson, Sigurdur
  Year: 2013
  Document Type: Paper
  Subject: Design; Pavements
  Session: 737
  Paper Number: 13-1191
• Case Study for Evaluating Benefits of Pavement Research: Final Results
  Abstract: The purpose of this paper is to describe a retrospective evaluation of heavy duty pavement innovations that were developed through research for a major rehabilitation project in California. The paper examines the performance benefits of the innovations and analyses the economic benefits of the research that resulted from the implementation of innovative pavement designs innovations. Performance benefits are presented through a brief description of the rehabilitation project, background on development of a long Life Pavement Rehabilitation innovation, and design requirements that limited permanent deformation (rutting) within the first five years of service. Results from field measurements confirm the innovative pavements met this performance criterion. Economic benefits of the research which resulted from the development and implementation of the innovative pavements are presented. The paper is a follow-up publication on the subject and contains the latest and final results on the pilot study to quantify direct benefits stemming from APT testing. It incorporates cost-benefit analysis including agency with- and without road-user costs and study the influence of the discount rate in net present value calculations. As expected, road-user costs have a significant influence on the cost-benefit calculations especially in the case of a heavily congested freeway. Results from the cost-benefit analysis show positive cost savings and benefit-cost ratios. Results reported in this paper show clear performance benefits from the innovations, indicate positive economic benefits from the research that led to innovations.
  Authors: du Plessis, Louw; Nokes, William; Burmas, Nicholas; Holland, T. Joseph; Harvey, John
  Authors: du Plessis, Louw; Nokes, William; Burmas, Nicholas; Holland, T. Joseph; Harvey, John
  Year: 2013
  Document Type: Paper
  Subject: Design; Pavements
  Session: 737
  Paper Number: 13-2604
• Three-Dimensional Finite Element Modeling of Instrumented Airport Runway Pavement Responses
  Abstract: The objective of this paper is to analyze runway pavement responses under moving aircraft tire loading using a developed three-dimensional (3-D) finite element (FE) model. The instrumented runway at Cagliari-Elmas airport (Sardegna, Italy) was modeled in the analysis, which consists of a 350-mm asphalt layer, a 400-mm granular base layer, and subgrade. The FE model characterized the asphalt layer as a linear viscoelastic material, and two interface bonding conditions between asphalt layers (full bonding and partial debonding) were used in the analysis. The aircraft tire loading was simulated using a nontraditional loading assumption that represents the non-uniform distribution of tire contact stresses along contact length and width under five ribs of an aircraft tire. Analysis results show that traditional loading assumption that assumes uniform contact stresses at the tire-pavement interface underestimates the critical tensile and shear strains in the asphalt layer. In particular, the relatively high contact stresses at tire edge ribs under heavy aircraft loading cause significant shear stresses at the pavement near-surface. The pavement responses under various loading conditions (aircraft type, wheel load, and speed) were calculated, and the critical responses were identified. Good agreements were achieved when the calculated pavement responses (vertical pressure and horizontal strain) at various locations were compared to the measured responses from field instrumentation. The model results show that partial debonding between asphalt layers causes much greater tensile strains at the bottom of the whole asphalt layer.
  Authors: Wang, Hao; Al-Qadi, Imad L.; Portas, Silvia; Coni, Mauro
  Authors: Wang, Hao; Al-Qadi, Imad L.; Portas, Silvia; Coni, Mauro
  Year: 2013
  Document Type: Paper
  Subject: Design; Pavements
  Session: 737
  Paper Number: 13-2732
• Benefits Achieved from Florida's Accelerated Pavement Testing Program
  Authors: Greene, James
  Authors: Greene, James
  Year: 2013
  Document Type: Presentation
  Subject: Design; Pavements
  Session: 737
  Paper Number: 13-0961
• Case Study for Evaluating Benefits of Pavement Research: Final Results
  Authors: du Plessis, Louw
  Authors: du Plessis, Louw
  Year: 2013
  Document Type: Presentation
  Subject: Design; Pavements
  Session: 737
  Paper Number: 13-2604
• Three-Dimensional Finite Element Modeling of Instrumented Airport Runway Pavement Responses
  Authors: Wang, Hao
  Authors: Wang, Hao
  Year: 2013
  Document Type: Presentation
  Subject: Design; Pavements
  Session: 737
  Paper Number: 13-2732
• Effect of Moisture Content on Pavement Behavior in a Heavy-Vehicle Simulator Test
  Authors: Erlingsson, Sigurdur
  Authors: Erlingsson, Sigurdur
  Year: 2013
  Document Type: Presentation
  Subject: Design; Pavements
  Session: 737
  Paper Number: P13-7104