Wall Rock is defined as well graded rock with less than 10% fines. Many quarries refer to it as drain or sewer rock because it has no fine grained material in its makeup which allows water to pass easily through it.
all Rock is very
important to any segmental retaining wall (SRW) no matter how tall. Some
people might claim that the primary function of Wall Rock in an Segmental Retaining Wall (SRW) is to
promote drainage but that is not true.
|Incidental Water Drainage|
Wall Rock’s primary function in an SRW is to aid in the compaction in and around the facing. Its second primary function ties directly to the first and is to aid in connection between the facing units and the geogrid layers. Its other, less primary, function is to allow incidental water that may get into the wall structure to drain freely down to the drain pipe at the bottom of the wall facing and route the water out of the wall, keeping the facing dry.
So please do not refer to this material as drain rock because now you know drainage is not its primary function.