Selecting Reinforced Fill Materials for MSE Retaining Walls

This paper describes research being performed under National Cooperative Highway Research Project (NCHRP) HR 24-22. The objective of the project is to develop selection guidelines, soil parameters, testing methods, and construction specifications that will allow the use of a wider range of reinforced fill materials within the reinforced zone of mechanically stabilized earth (MSE) walls than is currently practiced. The results of a literature search on the use and performance of different soil types for reinforced fill in MSE walls is reported. State transportation agency and private industry responses to a "survey of the current practice" for MSE backfill are discussed. New guidelines for MSE backfill are recommended, and economic incentive to relax current MSE wall reinforced fill specifications is presented. Numerical analyses used in the design of MSE walls are described. A full-scale field test will be conducted in Phase II to establish properties for "high fines" reinforced fill and associated design controls that give acceptable performance, and details are described.