Performance of geotextile separators five years after installation

During the reconstruction of a state highway in 1991, a full-scale test sec tion was established at a site with a history of poor pavement performance, most likely because of a soft silty clay subgrade, high ground-water table , and heavy logging truck traffic. Five different separator geotextiles and a soil-only control section were installed in each lane. Excavations were made in the test section 5 years after installation, and samples of geotext iles, subgrade, and base course materials were exhumed for visual observati on and laboratory testing. In addition, in situ soil tests were performed o n the exposed subgrade soils. This paper summarizes these observations and test results. Although some fines from the subgrade had migrated through th e geotextiles into the bottom of the base course, there was no evidence aft er 5 years of any adverse effect on the pavement itself. Minor geotextile d amage that apparently occurred during construction had little effect on the pavement performance. In all of the sections with geotextiles, the subgrad e soils were found to have consolidated significantly in comparison with th e soil-only sections. Overall, the geotextiles performed their intended fun ction well.