Use of lightweight ECS as a fill material to control approach embankment settlements

A research study was conducted to evaluate the use of light weight aggregate (LWA) material produced from the manufacturing of expanded clay and shale (ECS) for potential use as a roadway approach embankment material. The use of such LWAs is expected to reduce stresses on subgrade foundation, which in turn could lead to less or no approach settlements. The test site was constructed on the south end of a new bridge overpass on State Highway 360 in Arlington, Texas and a control section was constructed on the north end of the same bridge. In the control section, a low plastic borrow soil (normal fill) was used as an embankment fill material. This paper presents both laboratory and field evaluations of the utilization of both ECS material and conventional borrow soil as embankments fill material. Shear strength and consolidation tests were performed to evaluate strength and compressibility characteristics. The embankment section was instrumented with vertical inclinometers to monitor the fill movements due to field loading conditions. Pavement surface profiling of both ends of the bridge was also performed at regular time intervals. Numerical simulations of test sections were also attempted. Based on the data obtained from experimental, field monitoring and numerical studies, it can be mentioned that the utilization of ECS LWAs are efficient in minimizing the bridge approach embankment settlements and reduced bump problems at the entry and departure of the bridges. © 2010 ASCE