Basic masonry repairs include:
- Filling in dings in floors and driveways
- Replacing a block or brick
- Repointing mortar
To patch concrete first remove all loose material from the old concrete. Use a vacuum cleaner. Then scrub away any oil or grease with hot water and trisodium phosphate (TSP). Use a stiff brush. Protect your hands with rubber gloves.
After the concrete is clean, wet it. Fill in the patch. The best mix for patching concrete is one part Portland cement to three parts fine, clean sand. Add concrete glue to help feather out the edges of your patch and secure it to the old concrete. Leave a wet rag or gunny sack over the patch for a couple days.
Replace a broken or missing concrete block with the same mix. Chisel the old mortar away. Soak the new block in water for five minutes and wet the blocks around the hole. Trowel in mortar on all sides and set in the new block. You may have to take some mortar out little by little to make the block fit. Keep nudging the block with your trowel handle or a piece of wood. Don’t use a hammer.
Once the block is in place and aligned, tool the joint to match the rest of the wall. If the other joints are tuckpointed (grooved) make the new joint match. Wipe up any mortar spilled on the face of the block before it hardens.
Use a finishing tool to finish mortar joints after the mortar begins to harden.
When you replace a brick or block, trowel in mortar around the opening. Nudge the block in place with the handle of a trowel or a piece of wood.
To patch concrete, clean and wet the area. Fill in the area and feather the edges so the patch will stick.
Replacing a fired (red) brick is the same as a concrete block. But be very careful to match the color or your replacement will stand out.
Try not to spill mortar over the face of the brick. If you do, you can remove the stain with acid and a stiff brush. BE CAREFUL WHEN WORKING WITH ACID. Always add the acid to water.
Adding water to acid can cause an explosion. Protect yourself with goggles and rubber gloves. Wear old clothing. Muriatic acid will remove clothes, eyes, and skin faster than it will remove the mortar stain.
Repointing is putting new mortar into joints when the old mortar is falling out. First clean out the crumbling mortar. You can make a tool for this by nailing through a block of wood until the point of the nail extends 1/2 inch. Slide this point along the joints and you won’t dig too deep. Then wet the bricks and flush out loose mortar with a good strong hose jet.
Mix no more mortar than you can use in one hour. If you are repointing a whole wall or chimney, use any color mortar. However, if you are patching only a section, take care to match the color of the old mortar. Don’t work with mortar when the temperature is below freezing.
You can make a tool to remove old mortar by driving a nail through a block of wood until it extends about 1/2 inch.