The following photos are from a wall where there are some areas of poor consolidation. The areas in questions were saw cut to apppx 1/4” depth and the loose material was chipped out. The surface profile after this type of removal leaves a fractured, rough substrate ideal to receive a patching mortar. The repair material selected is US SPEC Quickset. Prior to placing the material the area will be saturated with water. Due to cold temperatures, cold weather procedures were discussed. Heating the substrate, mixing water and the repair material itself will help speed up the set in colder weather. After placing, a insulated blanket can be placed over the repair area. Tenting and heating the area is also on option. (There is still some dust in a few of the photos that needs to be removed prior to patching).
Quickset