Q: What is Rapid Set® DOT Repair Mix?
A: Rapid Set® DOT Repair Mix is a blend of high-performance Rapid Set® Hydraulic Cement with an ASTM concrete grade sand, air entrainment and a high range water reducer. This product can be mixed neat or extended up to 100% with a concrete grade course aggregate. It provides rapid strength gain, high durability and low/no shrinkage for horizontal concrete repairs. Simply mix with water and it will achieve structural strength in excess of 3000 psi in one hour.
Q: What are the advantages of using Rapid Set DOT Repair Mix?
A: Rapid Set DOT Repair Mix can be mixed neat or extended 100% with a course aggregate. This allows the user flexibility to repair thin to thick horizontal applications with one product by simply choosing to use neat or extending with an aggregate. This product is a structural concrete providing 3000 psi in one hour, 5000 psi in 3 hours. To meet the environment demands of exterior road and bridge placements, Rapid Set DOT Repair Mix is air entrained. This product, when mixed with the recommended amount of water (3 to 5 quarts per bag), yields a very workable mix.
Q: Is it a modified portland cement product?
A: No. The high-performance properties come from the Rapid Set Cement in the mix.
Q: Is a bonding agent necessary?
A: Bonding agents are not required. Proper surface preparation is the main component in achieving a good bond. Many specifications call for a slurry coat (brush coat) of the product to be applied as a bonding medium. If this method is used make sure not to allow the slurry coat to dry. If bonding agents are specified, they should be used as a supplement to a good surface preparation, not as a substitute.
Q: Can I blend other bagged products with Rapid Set® DOT Repair Mix?
A: Blending with other products may give unpredictable results and is not recommended. The use of Rapid Set approved additives and various colors are acceptable.
Q: How thick can I apply Rapid Set DOT Repair Mix?
A: ½” to 6” neat and up to 24” extended with course aggregates.
Q: How do I mix it?
A: Just add water to use as a grout or thin repair. If extending with a course aggregate, mix in aggregates last. The use of a mechanical mixer such as a mortar mixer or a drill mounted mixer (egg beater type) is recommended. To maximize working time, organize work so that all people and equipment are in place before mixing.
Q: How do I extend the set time, especially during hot weather?
A: Use Rapid Set® SET Control® admixture. 1 to 3 packets can be incorporated with the mix water to extend the set times. Strength is not affected.
Q: How do I place and finish it?
A: Fill to full depth and proceed horizontally. Do NOT place in layers that allow setting to occur between lifts. Use traditional finishing tools and methods. Rapid Set DOT Repair Mix is fast setting and does not bleed water so apply your final finish immediately after placing. Cover and wet cure for an hour.
Q: How do I cure Rapid Set DOT Repair Mix?
A: Water curing Rapid Set DOT Repair Mix installations is recommended. The objective of water curing is to maintain a wet surface until the material has gained moderate tensile strength. Begin water curing as soon as the surface has lost its moist sheen and continue for a minimum of one hour.
As an alternative to water curing, curing compounds that meet ASTM C-309 Type II Class B may be used. Apply these curing compounds in accordance with the manufacture’s recommendations.
Q: Can I use it in wet applications?
A: Yes. Rapid Set DOT Repair Mix is made with Rapid Set Cement, pure hydraulic cement. Hydraulic cement hardens underwater and in wet conditions.
Q: Does temperature affect Rapid Set DOT Repair Mix?
A: Cold temperatures will slow down the setting time as will hot temperatures accelerate the set times. Rapid Set hydraulic cement generates a great deal of heat in its hydration process. This begins within the first 15 to 30 minutes after mixing. Adjusting the temperature of the concrete mix with regards to the temperatures of the existing concrete and ambient conditions will help in achieving the stated set time. Covering the area (blankets in cold and plastic in hot) will assist in allowing Rapid Set DOT Repair Mix to be placed in extreme conditions (32° F to 100° F) and develop strength as stated by the manufacturer.