Over the past few years MSE walls have gained in popularity as the premier embankment design for bridges and overpasses. Two key components of this type of design is a stable base for construction and drainage in order to eliminate moisture, which can contribute to corrosion, since most of these structures have a minimum 75-year design life.

In the early 80’s Levy initially utilized an open-graded Air Cooled Blast Furnace Slag for one of these structures in Northwest Indiana. The primary advantages of using ACBF are its light weight (an ASTM 57 gradation has a unit weight of 80 pounds per cubic foot, which is typically 20% lighter than most natural materials), which reduces loading in poor soil conditions and drainability as a result of the ASTM 57 gradation.

One of the hurdles we needed to overcome was the existing testing protocol. The procedures being used were initially designed for soils (-#10 mesh) and were potentially not representative of an open-graded aggregate, which could contain less than 4% passing the #10.

Levy’s Research and Development group participated in the development of new testing procedures, which measure the materials physical properties in an “As Used” condition. These procedures are currently being used and specified by several agencies, which has led to the expanded utilization (over 400,000 tons) of open-graded material for MSE Walls in the Midwest.