Method and apparatus for creating a preferential breakage plane within cured columns

A frangibility device for creating a preferred breakage plane within ground improvement elements, comprising:

• a cutting member comprising a thin planar geometric plate formed with a single cement slicing wing, the cutting member having a straight radial slit extending along a first radius from a point offset from a geometric center of said cutting member to its periphery, and said planar geometric plate bent downward along a second radius perpendicular to said first radius to form the single cement slicing wing as an inclined sector of said planar geometric plate that is inclined progressively downward and outward along said slit for advancing the cutting member through uncured cementitious material of said ground improvement element;
• an elongate strut attached to the center of the cutting member;
• and
• a handle removably attachable to the strut for turning the cutting member and screw-advancement and slicing through an uncured column of cementitious material to a desired depth;
• whereby, after curing, said column of cementitious material can be easily broken along a plane immediately below the cutting member and an upper section removed with said elongate strut and cutting member.