The geotechnical needs of DOTs and other agencies responsible for roads and bridges are vast. Issues include: Culvert repair Soil stabilization Void filling Concrete slab lifting Sinkhole remediation Slope control Slough control in tunneling
Protecting concrete usually means shielding it from the elements of nature or from harsh manmade chemicals. But it’s not just concrete that needs such protection. Corrugated metal pipe, steel surfaces, material hoppers, rail cars and masonry all can come in contact with corrosive or abrasive materials or harsh conditions.
This document covers the processes of surface preparation, priming and installation of a protective epoxy coating system.
Problem: Heavy use, aggressive chemicals or exposure to elements can wear away the concrete surface.
Application of a protective epoxy coating can extend the life of the surface.
Surface preparation is considered to be the most important step of any resinous protective coating application. Improper surface preparation could turn what seems to be a simple process into a lengthy, difficult repair. Please refer to Prime Practices “Surface Preparation” for complete details on preparing the surface.
Store material overnight to precondition to 70 to 80 degrees F (21 to 26 C) prior to use. Pre-mix each component prior to combining. “B” component contains pigments, fillers and other chemicals that settle over time. Failure to properly pre-mix will result in uncured or improperly cured material or color variances in the cured material.
Only mix the amount of material you can use within the stated pot life. Use a slow speed mix drill and mixing paddle. Avoid introduction of air into the mixed material by controlling the speed of the drill and keeping the mixing paddle at the bottom of the pail. Scrape the sides and bottom of the pail during mixing.
Note: Large batches of epoxy will set up faster than smaller ones. Only mix the amount of material you can use in the given pot life of your coating system.
Fill pock holes, divots or other surface imperfections with a fast cure patching mortar such as Prime Resins Floor Fix for horizontal surfaces, or Prime Gel 2000, 2100 or 2500 Quick Bond for either vertical or horizontal surfaces. Protective coating systems are only as sound as the concrete they are applied to. All unsound concrete should be repaired or replaced prior to protective coating applications. Be sure to allow cementitious repair mortars to fully cure prior to applying coating.
Priming the surface:
Use Hydrolock (water-based primer sealer) prior to installing coating system. Mixing preparation and procedures apply. Apply primer at a rate of 200 – 300 square feet per gallon (18.58 – 27.87 sq. meters per gallon). Primer will appear white or milky immediately after placement. Avoid allowing primer to pond in low areas when applying to horizontal surfaces. Primer is considered dry and ready to coat as soon as it turns clear (1 to 3 hours), do not wait longer than 24 hours to apply coating system.
Apply coating system
Follow all previously mentioned material preparation and mixing procedures. Protect adjacent structures by applying tape along the edges of the intended area to be coated along with any penetrations. Use a cut-in brush to coat edges prior to rolling complete area. Use a 1/4” – 1/2” mohair roller cover and notched squeegee to apply epoxy coating system at a rate of 80 square feet (7.4 sq. meters) per gallon (20 mils). Two coats are recommended. Allow 1 to 3 hours for first coat to initially set then apply second coat. The first coat must be tack free and firm enough to walk on without leaving footprints. Do not wait longer than 24 hours prior to installing a second coat. Any air bubbles that form in the coating can be removed by back rolling with a tined (spiked) roller before the coating is tack free. Use spiked shoes to minimize damage when walking on uncured coatings.
For a non-slip surface:
Do a small test area first to determine proper aggregate size.
Broadcast aluminum oxide or oven dried sand aggregate into the first coat while it is still tacky. It is recommended to use the size aggregate appropriate for the profile required, use smooth or non-angular (few sharp edges) aggregate or follow manufacturers recommendations. After initial cure, sweep or blow off excess aggregate and apply second coat.
Aluminum oxide or suitable oven dried sand aggregate
Prime Practices “Surface Preparation”