Parging protects a cracking or aged concrete or cinder block foundation against the elements, and it also creates an attractive finish that is similar to stucco in appearance. To parge a concrete wall, you apply mortar to it so that the mortar covers imperfections such as cracks or the spaces between cinder blocks. You can use a "Type N" mortar mix, which is commonly available from do-it-yourself and building supplies stores, to parge concrete walls.
Scrub the concrete wall to be parged with a stiff brush saturated in concrete cleaner or TSP and water mixed according to package directions. Rinse the wall by spraying water on it with a garden hose.
Empty a bag of mortar mix into a wheelbarrow or mixing tub. Use a trowel, hoe or rake to create a depression in the middle of the mix.
Pour the amount of water recommended on the package into the depression and mix the water and mortar mix with a hoe, shovel or trowel.
Spray a light mist of water on the wall if it is no longer moist.
Wet the trowel by spraying it with water or dipping it in a pail or pan of clean water. Apply an even coat of mortar mix to the wall with the wet trowel, starting at one lower corner of the wall and working upward with enough pressure to force mortar into the porous concrete surface. Dip your trowel in water and smooth out the mix after you have coated about 2 or 3 square feet of wall and smooth out the mortar.
Repeat Step 5 until you have covered the entire wall. Apply a second, thinner coat over the first coat if you wish.
Clean your equipment with your garden hose at high pressure before the mortar dries. If it does dry, use a sharp instrument such as another trowel to chip the mortar off your tools and mixing vessel.