Native Backfill Materials for Mechanically Stabilized Earth Walls

Mechanically stabilized earth walls are an attractive alternative to conventional reinforced concrete retaining walls. The economy of these walls for non-critical applications might be improved by using alternative backfills consisting of on-site soils or quarried materials for the reinforced zone. The results of this study indicate that use of alternative backfill soils is feasible for non-critical wall applications. Soils for use with metallic reinforcement should be well graded with a maximum size of 3 inches and have less than 20 percent fines with a plasticity index less than 6. Backfill for polymer-reinforced walls should be well graded with a maximum size of 3/4 inch and less than 30 percent fines with a plasticity index less than 9. Use of wall systems such as geosynthetic reinforced modular block walls should be considered when using alternative backfills. The primary benefit of using alternative soils is in material procurement. Additional costs might be incurred for quality control testing and material placement; however there is presently insufficient data to provide quantitative estimates of these costs.