PENNTROWEL Epoxy Underlayment is a three-component, 100% solids, epoxy grouting compound. The components are mixed together and used to smooth, repair, or slope concrete slabs. The installed underlayment exhibits excellent physical properties and adhesion. PENNTROWEL Epoxy Underlayment can be applied in a variety of thicknesses. When resurfacing exceeds two inches, up to 25% coarse silica sand (1/8 - 1/4) may be added. Coarse sand or other aggregates must be dry and free of salt and other contaminants. Consult Corrosion Engineering specification CES-232 for complete installation details.