The preparatory class includes review of these best practices:
- Reading MPII. Adhesive anchors are manufactured and sold by a handful of companies. The overall usage and installation methods are generally similar, but each Manufacturer’s Printed Installation Instructions, or MPII, varies in the details. It is imperative that contractors follow those published details to ensure proper installation and performance of the adhesive anchor he or she is installing. “The installer needs to take their marching orders from the manufacturer’s instructions that come with the product they are installing,” says John Silva, director of codes and standards with Hilti North America. “It is very important that the installation procedures laid out in the instructions are followed so that the product’s bond values can be achieved.” For training purposes, the ACI certification class uses a generic MPII, created by the Concrete Anchor Manufacturers Association (CAMA) and its member companies as a composite of actual MPIIs currently in use. The certification class emphasizes a contractor’s ability to read and follow the directions in front of them.
- Hole cleaning. One of the most important steps a contractor can take to ensure an adhesive anchor’s rated bond strength is reached is properly cleaning the hole in which the anchor will be installed. “When you drill a hole in concrete, any fine dust or debris left over can affect the anchor bond, and if the dust is damp it could create a paste that could also affect bond,” says Mark Ziegler, P.E., vice president of technical services at Powers Fasteners, Inc. Each manufacturer offers specific hole cleaning instructions in its MPII, for both wet hole cleaning and dry hole cleaning. The ACI adhesive anchor installation program reviews the various hole-cleaning techniques and emphasizes the importance of following the specific directions for the anchor he or she is installing.
- Filling the hole. “One of the key things the ACI certification tests is technique,” Ziegler says. “Especially in the overhead position using the specific manufacturer’s equipment, anchor installation is very much a function of the installer. That’s where the hands-on training really shines.” The certification class reviews both piston plug systems and use of retaining caps with qualified two-part adhesive anchor products. Contractors will learn how to determine when the two-part product is properly mixed when dispensed through a mixing nozzle. It also emphasizes a bottom-up filling technique to ensure the entire hole is filled with adhesive following proper cleaning.
- Extreme temperatures. Manufacturers recommend contractors store adhesive anchor products within certain temperature ranges to prevent the product from getting too hot or too cold for good shelf life. On the job, if ambient temperatures are hot the adhesive components will become more fluid. “From a safety standpoint for the installer, this is especially important in overhead installations because the materials tend to drip more readily,” Silva says. “When you work with polymer materials you have to have proper protection – long sleeve shirts, hand protection and eye protection.” Furthermore, when base materials are also very warm, the adhesive anchor tends to set up much quicker and working time decreases. On the other end of the temperature scale, the opposite happens. Adhesive anchors will react to the cold and become less fluid and harder to work with. Cold temperatures will also cause the material to set up more slowly, and in extreme cold the reaction process can come to a halt. As such, some products are not suitable for cold temperatures. Each manufacturer offers guidance for how to deal with extreme temperatures and any restrictions should be stated clearly in the MPII. “In cases where there is any doubt, we want the contractor to contact us and let us walk them through the installation,” Silva adds.