SandBlast

 

Application:

Sandblast finish is typically applied to the precast shortly after initial concrete pour/curing by blasting high pressure grit against the precast surface. The application removes the outer cement paste, exposing the aggregates below. The exposing of aggregates is the primary control of the final color/texture appearance.

Finish Exposure

Sandblasting finish can be requested in light, medium and heavy exposure depths.  Deeper sandblasted depths will expose more of the concrete mix aggregates.  A medium depth is the most typical sandblast depth specified.  Lighter sandblast finishes can be difficult to replicate on large scale projects and heavy sandblast can result in a bruised aggregate appearance.

Pros:

Sandblasting is a dry finish applied post production which allows for portions of the precast to be protected during application and left undisturbed.  Sandblast finish can be used along with other finishes within a panel to create more interesting appearances.

Design Considerations:

Sandblasting can reveal defects (“bugholes”) previously covered by concrete surface paste due to the blasting application.  Precast surfaces more prone to bugholes (faces that are against side form during production and do not receive as much compaction for example) should be taken into consideration. Sandblast finish will typically lighten the appearance of the aggregates due to the blunt application.