One monofilament woven polypropylene fabric in which carbon black was 

 incorporated in the filament during the extrusion process retained satis- 

 factory strength properties after 11 years of exposure (no cover material) 

 in a coastal environment (Soil Testing Services, 1980). 



As yet, no standard test has been developed to measure the length of 

 time fabric, either untreated or treated, may be exposed to UV hefore 

 harmful degradation takes place. ASTM Subcommittee D-18. 19/D-13.61 is 

 currently attempting to develop such a test method. As stated above, there 

 are numerous design reasons for UV stabilizers being necessary in geotextiles 

 for coastal structures, especially in the absence of a method for determining 

 fabric life. 



(2) Fire . The melting point varies with the polymer used in the 

 to 260° Celsius (274° to 500° Fahrenheit). If fire gener- 

 ates heat beyond the fabric melting point, it will alter the geotextile 

 filter's piping and permeability performance. Some polymers will burn 

 (support combustion), while others only melt. 



(3) Ice . Ice formation within the structure of thick nonwoven 

 fabrics will enlarge the pore openings. Depending on the polymer and 

 fabric construction, some recovery (of unknown extent) may take place. The 

 soil retention capability will be reduced. 



(4) Kinetic Energy , Kinetic energy, in the form of direct wave 

 attack on unarmored geotextiles may cause rupture. Wave energy transmitted 

 by armor stone may damage covered geotextiles, if requirements described in 

 Tables 37 and 38 are not met. 



(5) Abrasion . Abrasion can tear fibers, weakening the fabric as 

 mentioned earlier. Fabric can be abraded by overlying material during con- 

 struction and storms, and by waterborne debris if the cover is removed. 



(6) Vandalism . If the fabric is not protected by a cover of earth 

 or armor it can be damaged by vandalism. 



308 



