15 March 2001
5.11. Sealing Patch/Slab Interface. An inportant procedure in placement of partial-depth
repairs is sealing the patch/slab interface. The patch/slab interface is sealed with a one-to-one
cement grout. This grout will form a moisture barrier over the interface and impede delamination
of the patch (delamination of the patch can occur if water at the interface freezes during the
winter). A joint sealant may also be used.
5.12. Curing. Proper curing of partial-depth repairs is very important due to the large surface of
small patches compared to the volume of patch material, as well as the fact that concrete gains
bond strength much slower than it gains compressive strength. This relationship is conducive to
quick moisture loss and is different from most other concrete applications. Proper curing
generally employs the application of curing compound at the time bleed water has evaporated
from the surface. Because curing is critical for partial-depth patches, the first 24 hours should be
wet cured with burlap or a similar material. The balance of the 7-day curing period may be with
liquid membrane compounds. In general, the procedures used for curing full-depth repairs can
be considered for partial-depth repairs.
In hot or dry climates, the patches should be cured for 14 days with a double mat of saturated
burlap covered with polyethylene sheeting, over which plywood or lumber is placed. The
covering should be removed and the burlap resaturated daily and the covering replaced.
5.13. Joint Resealing. Resealing the repair joint is extremely important, because it will help
prevent moisture and incompressibles from causing further damage. It is important that the new
transverse and longitudinal joints constructed within the patch area be formed or sawed to
provide the proper joint seal reservoir, and match surrounding joints. The joint faces must be
clean and dry for good sealant performance. Resealing of joints should be done in accordance
with the recommendations outlined in AFM 88-6, Chapter 7, and the Concrete Joint and Crack
Repair Field Manual.