Selecting and specifying products for repair
Each DOT is confronted with different environmental conditions. In Florida chloride penetration is a big problem. Freeze-thaw issues and salt applications in northern states cause repair problems. And intense heat in the Southwest can influence product applications. Repair specifications are different throughout the country.
Every manufacturer of products used for bridge repairs wants to be on approved DOT lists. Roger Pratt, the business manager of the concrete repair division for MAPEI, says each DOT has its own product qualifications, so companies like MAPEI must conform to the regulations of each. Andrew Fulkerson, MAPEI’s technical services manager, says MAPEI sends each DOT the product test results related to its work. The company often sends actual products to DOTs so they can verify test results.
DOT specifications are usually generic, stating the type of material required. But they often list product names meeting their requirements for the application. Manufacturers work hard to be listed. The generic types of products used for bridge repairs include the following:
- Sealers and penetrants. These include Silane water repellents, corrosion inhibitors, sealers and coatings, and “healers” — low viscosity resins that fill and seal cracks.
- Grouts. Low shrinkage materials used to set anchor bolts, rebar, and plates.
- Repair cements. Prepackaged products for horizontal, overhead, or vertical applications and repairs.
- Corrosion inhibitors. Galvanic anode products attached to steel reinforcement to protect against corrosion.
- Carbon fiber reinforcement. Reinforcement material secured to the outside of concrete elements with resins to increase structural strength.
- Rebar. Epoxy coated and stainless steel reinforcement.
- Structural crack mending materials. Epoxy and other fluid resins which can be injected into cracks to effect structural repair.
- Joint sealants. Flexible products which prevent water intrusion even when there is structural movement.
- Fast setting concrete. Concrete which can be placed on decks and opened to traffic use within short spaces of time.
- Shotcrete. Either wet or dry concrete used in a shotcrete process to repair structures.
- Bonding agents. Polymers and resins that structurally bond repair materials to bridge concrete.
Both DOT and the manufacturers of products work to develop better bridge repair products, sometimes together. Mike McCloskey, a parking and restoration specialist for BASF, says his company constantly does research and development work for new products — bringing them to DOT with the hopes they will be included in specifications. And Fulkerson says sometimes BASF develops products for an individual DOT.
The process of selecting and specifying products, as well as new product development, is handled differently by DOTs. But Dale Mizer, construction products manager for Euclid Chemical, says DOTs influence each other, so getting approved in specifications by one DOT can lead to approval by others.
Daubenberger says MnDOT is constantly funding and participating in research to discover new products and technologies that work better, working in cooperation with universities and other agencies in research efforts.
Juntunen says the Michigan DOT is also experimenting with performance specifications; telling bidders how the installation should perform over time, giving contractors some latitude with regard to how work is performed but also increasing their responsibility.
Contractor requirements for this work
DeHaven says not all DOT work happens through public lettings. Sometimes a DOT has the expertise in house to install work, and sometimes small contracts are sent directly to contractors — especially those requiring fast repairs.