Date of Graduation

5-2012

Document Type

Thesis

Degree Name

Master of Science in Civil Engineering (MSCE)

Degree Level

Graduate

Department

Civil Engineering

Advisor

Richard Coffman

Committee Member

Norman D. Dennis

Second Committee Member

Brady R. Cox

Keywords

Applied sciences; Filtration; Geotextiles; Separation

Abstract

Field and laboratory tests were conducted on 18 full-scale, geosynthetic reinforced, roadway test sections located in Marked Tree, Arkansas. Base course, geosynthetic, and subgrade samples were collected, and pavement depth, in-situ density and in-situ hydraulic conductivity measurements were obtained during a geotechnical site investigation. The performance of sections containing geotextile products being used for separation and filtration (Carthage Mills FX-66, Mirafi 570, Propex 2006, Propex 2044, and Propex 4553) was investigated.

Moisture content, sieve analysis, Atterberg limits, modified proctor, specific gravity, and hydraulic conductivity tests were performed on the acquired soil samples. Transmissivity and permittivity testing was conducted on the geotextile samples. Performance of the flexible pavement system was monitored (annual inspections performed) by Arkansas State Highway and Transportation Department (AHTD) personnel.

The hydraulic conductivity values determined in field were validated using the empirically obtained Moulton (1980) equation and the effective particle size, porosity, and fines content obtained from the forensic analysis. The base course was identified to be non-freely draining (hydraulic conductivity<10,000 ft/day) based on the field hydraulic conductivity values. No differences were observed in the hydraulic conductivity measurements for the base course for sections containing or not containing geotextiles. The average permittivity of the geosynthetics installed in the ten-inch thick sections was lower than the permittivity of the geosynthetics installed in the six-inch thick sections. No correlation was observed between the average transmissivity values for the ten-inch thick and six-inch thick sections.

Excessive rutting was observed in six-inch thick sections containing the Carthage Mills FX-66 geotextile product. Also, more rutting, alligator cracking, and ponding was observed in the six-inch thick sections than the ten-inch thick sections, regardless of the presence of geosynthetics. Based on the results of this research, the wrong types of geotextile fabrics were originally installed at the Marked Tree Test Section. The geotextile fabrics, as installed at the base course/subgrade interface, did not improve the performance of the pavement system. It is recommended that geotextile design criteria be met prior to installation, and that the current geotextiles be day-lighted to provide enhanced drainage.

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