Partial-depth patching involves removing shallow localized areas of deteriorated or spalled PCC pavement and replacing it with a suitable patch material such as hi-flow, shrinkage-compensated cementitious mortar reinfroced with inorganic fibres.
This technique is used to repair PCC pavement distresses that are confined to the top few centimeters of the slab, such as joint and corner spalling.
Design/Technique
The partial depth-patching technique consists of the following steps:
Square off the area to be patched and mark off approximately 8 cm beyond the distressed area. Use a concrete saw to make a vertical cut a minimum of 5 cm deep around the marked area. Ensure cuts (both at the corners and along the edges) intersect to obtain a rectangular or square patch with vertical sides.
After cutting, break out the area with pneumatic drills or jackhammers down to sound concrete. After the unsound concrete is removed, blow out the hole with compressed air to remove residual material and dust.
Use a stiff broom or brush to apply a primer; if the material does not use it, use a large brush to dampen the surface (no standing water) with water before placing material.
Insert a thin strip of wood or polystirene slab for the new joint. Another alternative is to completely fill the new joint, and cuti t when the patch material is set.
Mix, place, and finish the concrete. If necessary, due for example to the depth of the patch, mix the mortar with the suggested aggregates to match the existing concrete as closely as possible. Ensure that you have estimated for enough aggregate/patching material, plus extra, before mixing begins. When finishing has been completed, broom finish to match adjacent areas.
Route out and clean the joint, finally filling the joint with the appropriate filler material.
Cure the patch with water or using some type of pigmented curing compound, if required (i.e. high temperature that could dry the concrete).
