NCHRP 20-50(9) [Completed]
LTPP Data Analysis: Feasibility of Using FWD Deflection Data to Characterize Pavement Construction Quality
| Project Data
||Richard N. Stubstad|
Background: Use of the falling weight deflectometer (FWD) has become an integral part of the process for structural evaluation of pavements in recent years. In addition, there is a potential for using FWD data to characterize pavement construction quality. For example, FWD deflection data obtained shortly after constructing each pavement layer may reveal variations in deflections and shape of deflection basins along a project or among projects that can be caused by differences in the properties of pavement layers resulting from construction variability. Therefore, procedures that take into account the effects of loading schemes, deflection measurement locations, deflection basin parameters, and other related factors could be used to analyze deflection data and to characterize construction quality. However, the feasibility of developing such procedures has not been established.
Research is needed to evaluate the feasibility of developing methods to characterize pavement construction quality based on FWD deflection data. If proven feasible, the research will encourage further validation and implementation by highway agencies and lead to effective means for characterizing construction quality that can be used to enforce pavement quality specifications. The data available from the Long Term Pavement Performance (LTPP) studies are expected to aid in such an evaluation.
Objective: The objective of this research is to evaluate, based on the data available from the LTPP studies, the feasibility of developing procedures to characterize construction quality of new and reconstructed flexible and rigid pavements based on FWD deflection data and, if feasible, recommend such procedures. The research shall use the data available in the LTPP Information Management System (IMS) database classified as "Level E" and, if needed, be supplemented with relevant data from other sources.
Tasks: Accomplishment of this objective will require at least the following tasks.
Phase I: (1) Collect and review literature related to the use of FWD data to assess pavement construction quality of flexible and rigid pavements. From the data elements available in the LTPP database, identify the elements needed to conduct this research and determine the extent of availability for each. Acquire the needed data and develop a database that includes the data proposed for use in the project. (2) Based on the information and data obtained in Task 1, propose revisions to the work plan for using the data available from Specific Pavement Studies (SPS) to evaluate the feasibility of developing procedures to characterize construction quality of flexible and rigid pavements based on FWD deflection data. The plan shall consider the data available from the experiments dealing with structural factors for flexible pavements (SPS-1), structural factors for rigid pavements (SPS-2), and environmental effects in the absence of heavy loads (SPS-8) and clearly describe what the research team can realistically achieve with the available data. (3) Prepare and submit an interim report that documents the research performed in Tasks 1 and 2. Following review of the interim report by the NCHRP, the research team will be required to make a presentation to the project panel. Work on Phase II of the project will not begin until the interim report is approved and the Phase II work plan is authorized by the NCHRP.
Phase II: (4) Execute the plan approved in Task 3. Recommend procedures that can be used for assessing pavement construction quality based on FWD deflection data, and develop a plan for future studies to validate these recommendations. (5) Submit a final report that documents the entire research effort.
The revised final report was submitted after additions and revisions to address panel comments.
The revised final report is available as NCHRP Web Document 52