The Mechanistic-Empirical Pavement Design Guide requires that the resilient modulus of the subgrade be used to design the pavement thickness for both asphalt concrete and PCC concrete pavements. Due to the complexity of the test, test results have been inconsistent. For example, data to date has shown that: o Two different laboratories testing split samples of the same soil or aggregate layer get widely different results. o Two technicians on the same equipment would also get widely different results. o Repeated tests on the same sample by one technician on the same equipment would not always produce consistent results. The resilient modulus of a soil or unbound aggregate material is the recoverable stress/strain relationship of the soil. The greater the resilient modulus of the soils is, the "stiffer" the soil will be, and the greater the strength will be for supporting transmitted wheel loads. This parameter is considered to be the best indicator of a subgrade&039;s strength since the test replicates the dynamics of moving wheel loads. You can obtain a detailed guide for Determining Design Resilient Modulus Values for Unbound Materials which was developed through the LTPP Program. For copies of the CD-ROM, contact the study manager or email your request to LTPPINFO.gov. This guide is in CD-ROM format and contains three major components: an interactive tutorial, a technology transfer module, and supplemental materials. The interactive tutorial covers Resilient Modulus (MR) startup and quality control test procedures for unbound materials. The technology transfer module contains overview presentations and videos that were developed in partnership with the Minnesota Department of Transportation (DOT). The supplemental materials section contains LTPP protocols, FHWA research reports, and many other supporting documents. The CD-ROM is designed for highway administrators, engineers, laboratory managers, and technicians to help them understand MR and addresses key questions that they might have about the test procedures. Videos featured on the CD-ROM include: o Laboratory Resilient Modulus Testing: Is This the Right Time?--Intended for administrators and engineers, this 8-minute video explains MR and its uses. The video also describes developments that have made MR testing more consistent and easier to adopt. o Laboratory Resilient Modulus Testing: Startup and Quality Control Procedure--This 15-minute video for laboratory managers and technicians begins with a detailed definition of MR. It then explains the procedure developed under the LTPP program to ensure that a laboratory is arranged properly to conduct the MR test procedure and collect accurate test results that are comparable, regardless of where or when they were obtained. o Laboratory Resilient Modulus Testing: Sample Preparation and Test Procedure--This 13-minute video for managers and technicians describes each step in the MR test procedure, including how to prepare soil and aggregate samples.

This pooled fund study has three primary goals: 1. To reduce the variability currently associated with resilient modulus testing of unbound materials. 2. To conduct a precision and bias study of the test procedure. 3. Provide assistance to states to properly equip and setup a laboratory for successful MR testing.

Approximate amount of funding requested per State is $40,000.