Concrete Armor Units in Rivers

Concrete armor units can be used in place of riprap in rivers for channel revetment; structures including spurs, groins and weirs; and for prevention of local scour. The units have primarily been used in ocean applications where the complex shape increases the stability of the unit. The limited information available on river installations indicates that increases in stability resulting from shape are insignificant when units are placed on the bed of a channel, while some increase is noted when units are placed on a slope. The implications of porosity, stability and placement of concrete armor units with respect to river designs are presented. An equation for designing concrete armor units for local scour prevention is included. Riprap equations are recommended for designing channel revetment, spurs, groins, and weirs until further research is available on concrete armor units in a river system.