A METHODOLOGY FOR THE EVALUATION OF GEOTEXTILE PORE OPENING SIZES UNDER CONFINING PRESSURE

This paper presents a methodology used to evaluate the pore opening si zes of a needle-punched, nonwoven polyester geotextile under pressure, using a permeameter subject to vibration. Particles passing through t he geotextiles were collected and analysed to establish a particle siz e distribution curve. Preliminary results obtained under no confining pressure compare well with a standard test method based on hydrodynami c sieving. Confining pressures up to 25 kPa appeared to exert some inf luence on the pore opening size of relatively thin geotextiles. Howeve r, for pressures greater than 25 kPa, the variation of geotextile pore opening size is small. The tests results and microscopic observations suggest that needle-punching during the geotextile manufacturing proc ess has a significant influence on the geotextile pore structure. Rega rdless of the limited amount of data available, the methodology descri bed may provide a useful tool for the study of geotextile pore opening sizes under confining pressure.