The American Society for Testing and Materials, or ASTM, No. 57 stone is often used as sub base fill material below road surfaces and buildings. It is a fragmented stone with angular edges and is regularly utilized as a drainage layer when used with geotextile fabric. Although the material is touted by many as "self-compacting," excess voids left from zero compactive effort in locations with little confinement may not eliminate the possibility of future settlement. What happens when the environment above the No. 57 stone causes it to settle?
[Editor] Read on for the answer to this interesting question in the case of settlement of a structure at the University of North Carolina at Chapel Hill. The contributed article by Katherine Witt describes how URETEK Mid-Atlantic used their high-density polyurethane resin to stabilize the No. 57 stone beneath a settled foundation as well as lift the surrounding slab back into place. [/Editor]