Rip-rap is used as protection for culverts, stream banks, drainage channels, slopes and other areas subject to erosion by water. In most instances, a geotextile should be placed beneath the rip-rap to maintain separation between the rip-rap and the underlying soils. In particular, it is necessary to utilize a geotextile within stream channels or around culverts to avoid scour and the migration of soils from the subgrade into the rip-rap.
- Avoid Scour
- Limit Migration of Fines Into Rip-Rap
When choosing a geotextile for a rip-rap application, the engineer is faced with a wide variety of products. Therefore, the geotextile's functions and properties must be carefully matched with the demands of the project.
To assure the proper geotextile is chosen, the percentage of soil fines and the amount of water it must pass is very important. The geotextile must also have the strength to handle the loads imposed during installation and throughout the project's service life. Ideally, it will distribute the load in all directions.
The rock weight and angularity also play a roll. In addition, the height at which it is dropped during installation must be considered. It is equally important that the installer take care during installation to avoid damaging the geotextile.
The two most popular geotextiles used in rip-rap applications are a woven monofilament and an 8 oz nonwoven. Numerous DOT'S specify an 8 oz nonwoven for rip-rap applications and woven monofilaments see wide use along many ocean shorelines in the US. Organizations such as AASHTO & FHWA specify a 6oz nonwoven for less aggressive installations.
Please click on the links below to visit our woven monofilament, medium-weight nonwoven product sections for more information and data sheets.