The standard grout bonded rock anchor consists of a plain or epoxy coated bar, grouted in an oversized drill hole.  Centralizers should be used to assure good grout cover (approx. 25mm) around the bar.  Where anchors will penetrate aggressive soils that are low in pH value (<5.5) and high in sulphate, additional corrosion protection may be desirable.  The degree of protection should be matched against the aggressivity of the environment and the expected life of the anchorage system.  Williams Multiple Corrosion Protection (MCP) systems offer increasing barriers against corrosion attack for confidence in permanent anchorage in all ground environments.  Williams protective outer end caps may also be used to seal the nut and washer from the environment when the outer end of the anchorage will not be encased in concrete.

• Grout fill inside sleeve after tensioning to    lock in pre-stress
• Unit is centered in drill hole by centralizers  and surrounded by grout
MCP III:
Three barriers around plain bar in free-stress zone, two barriers in bond zone, plus drill hole grout.
• Bar engulfed in pre-grouted poly corrugated tube in the bond anchorage zone and the free-stressing zone
• Smooth sleeve over the corrugated tube  in the free-stressing zone
• Unit is centered in drill hole by centralizer   and surrounded by grout
• Galvanized plate
• Protective end cap over nut and washer

MCP I:
Two barriers around plain bar in free-stress zone plus drill hole grout.
•       Plain or epoxy coated bar
•       Sleeve over bar in free-stressing zone
•       Grout fill inside sleeve after tensioning to lock in pre-stress
•       Unit is centered in drill hole grout with centralizers
MCP II:
Two barriers around plain bar full length plus drill hole grout.
•       Bar engulfed in pre-grouted poly corrugated tube in the bond anchorage zone
•       Smooth sleeve over bar in free-stressing zone