How to Do Repairs on Mortar

Put on protective goggles and work gloves.

Locate the weakened area of the wall and fit the end of a chisel into the grooves of mortar at a 45 degree angle. Strike the end of the chisel with a rubber mallet to remove, approximately, a 1-inch-deep section of the old mortar material. If the mortar is still weak and crumbling, continue chiseling further until all of the weak mortar is removed.

Sweep a wire brush through the joints to remove the mortar chippings.

Position a wheelbarrow next to the work site. Pour pre-mixed mortar powder into the wheelbarrow.

Slowly incorporate water into the powder in the ratio described on the mortar's packaging. Stir with a shovel until the mortar has a uniform consistency.

Scoop the fresh mortar with a pointed trowel and pack it into the cleared joints to a 1/4-inch thickness. Wait 15 minutes between each application and build up the mortar joints 1/4 inch at a time until you reach a suitable level. Mortar will dry within 48 hours of application.