Bags or mattresses should be placed only on a stable slope. While a stacked bag revetment can
be placed on a steeper slope than a mattress, it should not exceed 1 vertical on 1.5 horizontal. A stacked
bag revetment should be at least two bags thick, preferably with the outside layer concrete-filled and the
interior bags sandfilled. When sand is used as filler material, the bag or mat fabric, and its seams, must
be resistant to ultraviolet light. Figure 56 shows a nonstabilized bag after six months of exposure.
Where vandalism or water-borne debris are likely, only concrete-filled units should be used.
Some form of toe protection should be provided, or the toe should be buried well below the
anticipated scour depth. Also, an adequate filter system, such as a properly installed and sized filter
cloth, should be installed.
Some types of bags and mats which have been used in the past are described below.
Burlap Bags. Burlap bags are recommended only when filled with concrete because of rapid
deterioration in the shoreline environment and the ease with which they can be torn.
Sand Pillows. Sand Pillows are ultraviolet-resistant bags made from a woven acrylic fabric.
They weigh approximately 100 pounds when filled. Because of their resistance to sunlight, they are
suitable for sand-filling in some areas.
Dura Bags. Dura Bags are large (4 x 12 x 1.7 feet), and must be filled in place using a pumped
sand-slurry or concrete. Their large size makes them more resistant to movement under wave attack.
Fabricated of ultraviolet-resistant material, they can be used in installations exposed to sunlight.
Fabriform Nylon Mat. The mat is designed to be filled with a highly fluid, lean-cement mixture.
The exterior cloth envelope serves primarily as a form until the grout hardens. Fabriform is a patented
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