The most extensive use of prefabricated asphalt panels has been in 

 lining and waterproofing all types of water storage reservoirs, including 

 domestic water reservoirs, sewage lagoons, industrial waste-treatment 

 reservoirs, evaporation ponds, and reflecting pools. They are also used 

 for lining canals and ditches, and for bank protection. Prefabricated 

 asphalt panels have been used underneath riprap or rock reveted embankments 

 to prevent leaching of sand and earth through the rock revetment usually 

 caused by action of waves and tides. The development of geotechnical 

 fabrics has largely replaced the use of asphalt panels in recent years. 

 Asphalt panels have the advantage of providing a relatively thin watertight 

 barrier that can be used as a surface lining. In addition, they do not 

 require heavy machinery to install. They are useful for relining reservoirs 

 where the concrete lining has cracked badly and where leaking has been 

 excessive. Prefabricated asphalt panel linings are also used as an element 

 of composite lining structures, most frequently serving as the watertight 

 surface of a built-up lining. 



(6) Miscellaneous. 



(a) Sand Asphalt . Sand asphalt is a mixture of sand, with or 

 without added mineral filler, and asphalt cement. Mineral filler added to 

 the mix permits a higher asphalt content and makes it possible to obtain a 

 denser, tougher, and more stable mix. 



Sand asphalt has been used alone for linings, as base courses for other 

 linings, for revetments, and for groins, although not in the coastal zone. 

 The largest use of sand asphalt for hydraulics purposes in the United 

 States probably has been for bank paving along the Mississippi River by the 

 U.S. Army Corps of Engineers. The Netherlands has made extensive use of 

 sand asphalt in the construction of seawall revetments. Typically, the base 

 thicknesses range up to 0.20 meter (8 inches) and are usually capped with 

 a layer of asphalt concrete. 



Local sand deposits generally can be used, as gradation is not par- 

 ticularly critical. The asphalt cement should be AC-20 (or equivalent AR- 

 or penetration grade) or a higher viscosity grade. A typical mix would have 

 an asphalt content of about 6 percent. If about 5 percent mineral filler is 

 added, the asphalt content would probably be around 8 percent. Sand asphalt 

 mixes for linings are not as watertight as specially designed hydraulic 

 asphalt concrete. 



(b) Asphalt Prime Treatments. Priming the soil surface of a 

 hydraulic structure with asphalt is often done to seal it temporarily or to 

 reduce seepage until such time as waterborne sediments in the impounded 

 water settle and plug the soil pores. Asphalt primers have also been 

 applied to sloped embankments before placing a sprayed-asphalt membrane. 

 The purpose, in this case, is to anchor the membrane to the slope. Primes 

 have also been used for much the same purpose as prime treatments of roadway 

 surfaces prior to paving operations, that is, to plug up voids and to provide 

 a more stable surface on which to place asphalt construction. Prime treat- 

 ments are neither watertight nor permanent. They are most applicable to 

 silty sand soils that are quite permeable. 



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