Microscopic Stereological Methods to Characterize Orientation of Nonwoven Geotextile Fibers

Abstract

Procedures for quantifying the orientation of fibers composing nonwoven geotextiles are presented. These procedures are based upon measurements made at the microscopic scale. Methods for experimentally determining the orientation of fibers within a nonwoven geotextile are presented. The experimental methods require the geotextile to be impregnated with a fluid that will eventually harden and preserve the original geometry of the fibers. Procedures vary from using fluids that use wax to procedures that incorporate fluids that eventually become very hard. Both thick sections and thin microtome sections (5 μm) can be used as the cross section from which orientation of the fibers is determined stereologically. Orientations for the fibers are represented by combining the concepts of probability and three-dimensional orientation tensors. Three-dimensional orientations of the fibers are modelled using second-order and fourth-order orientation tensors. All the necessary parameters can be determined from stereological measurements on three mutually perpendicular planes and are determined from the results of digitizing microscopic cross sections of the geotextile.