GeneralQ Is there any specified finish for shotcrete?
There are several different finishes that are specified for shotcrete. One is a natural gun finish, which is the natural finish as sprayed (often used in slope protection). Another is a cut-down finish, which is cut-to-grade with the edge of a trowel or cutting rod (this finish is often flashed and sealed with a light gun finish to seal and texture the surface). Often in concrete repair, a trowel finish is specified where the shotcrete is cut down with the edge of a trowel or cutting rod to grade after the initial set of the material, and the surface is lightly flashed and toweled. Several different finishes can be achieved with shotcrete, but it should not be pushed or floated with the flat part of the trowel, as is done with poured concrete. It is important to wait for the initial set of the material and to use the edge of the trowel to cut the high points or shave the surface to achieve the grade or effect desired. Several excellent articles describing shotcrete finishes and finishing techniques are available as free downloads from the ASA website: shotcrete.org. One article, Technical Tip: Technical Tips on Shotcrete Finishes, written by Denis Beaupre, describes the different finishes that can be applied to shotcrete. Another article of interest would be Finishes for Retaining Walls by Marcus H. von der Hofen. Go the Publications section of the ASA website, click on “Click here to search the archive of Shotcrete Publications” and type “Shotcrete Finish” in the search window.