 This is the most-used method since the materials are cheap and installation is simple.Injected concrete mixes can be used in many different rocks and grounds, and the concrete sheath protects the bar from corrosion.The concrete mixture is generally made up of water and cement in the ratio "W"/"C" = 0.40-0.45, producing a sufficiently fluid mixture to allow pumping into the hole, while at the same time, providing high mechanical strength when set.