Brickwork is put together using a cement mortar. As cold weather hits the face of the brick wall, the mortar may be soaked in water, which freezes. This will cause the mortar to expand and crack and may break apart the brickwork. Repairing a brick wall requires that you break away the old mortar and refill it. This is called repointing. It may take you a few bricks to get the hang of pointing, so it might be a good idea to practice your pointing on brick walls that are not seen daily.
Cut into the cracked mortar using a 4-1/2-inch angle grinder blade. Turn on the blade and run it along the mortar, pushing the grinder until the head touches the wall.
Place a flat chisel into the cracked mortar and hit it with a hammer to break out the old mortar.
Place your mortar mix into a large plastic tub and mix in water slowly using a brick trowel. Mix until the mortar has a thick consistency, then allow it to sit for 10 minutes. Test the mortar consistency by scooping a small amount of mortar into your trowel. Turn the trowel upside down. The mortar should stick. If the mortar is too loose, add more of the mortar mixture. Add water if it is too thick.
Take a scoop of mortar into your trowel and place it next to the wall. Scoop the mortar into the crack using a pointing trowel. The pointing trowel is long and thin, allowing you to force the mortar into the crack. Fill the horizontal cracks first, then move to the vertical cracks.
Pound a 6d finishing nail into a 1/2-inch piece of scrap wood so that the nail is at the same depth as the old mortar in the wall.. Run the nail along the new mortar to even it out.