Most of the industry does not endorse the use of polymer-modified additive in shotcrete. Please refer to ACI RAP Bulletin 12 and ACI 506R for further information and insight from the American Concrete Institute (ACI) at www.concrete.org. Shotcrete applied by competent contractors to properly prepared surfaces exhibits excellent bond characteristics to the substrate. Additionally, a good shotcrete mixture that is properly applied will yield a durability equal to or superior to cast concrete. There are many examples discussed in various articles of Shotcrete magazine at www.shotcrete.org/archivesearch/ArchiveSearch.asp.