When constructing a floor, concrete contractors often unroll a sheet of plastic vapor retarder over the subbase and cover it with a blotter layer of compacted granular fill before placing concrete on the fill. But how effectively do vapor retarders resist punctures during construction operations?

Using ACI 302-96 recommendations as a guide, we developed a test program in which we placed plastic sheets of different thicknesses on subbases and under fills composed of compacted rounded (natural) or angular (crushed) aggregates. When we removed the compacted fill and examined the sheets for punctures, we found out which thicknesses performed best.