Grout-Filled Bags. The major advantage of grout-filled bags is that the units hold their shape after
the fabric deteriorates or is torn. Again, it is recommended that larger bags be used for breakwater
construction because the smaller ones are susceptible to displacement. In addition, larger bags reduce the
number of bag contact points where openings may develop.
Recommendations made for sand-filled bags apply to grout-filled bags, except that vandalism is
not a major concern.
Gabions. The same basic design considerations given for gabion revetments apply here. The wire
mesh should be PVC-coated, the baskets should be tightly packed, and a filter cloth should be used
beneath the structure to help control settlement. A gabion mat should be provided around the structure to
protect against scour. Tight packing of the stone is particularly important to avoid large distortion of the
baskets under wave action. A photograph of a gabion breakwater is shown in Figure 39.