How Is Portland Cement Plaster Applied?

Troweling

• The correct tool for applying mortar is the masonry trowel. This is a small spade-shaped tool that you use to scoop up the mortar to place it on the working surface. After dumping the mortar, use the trowel to spread it around until the desired area is covered.

Mortaring Between Rows

• To lay building materials such as bricks, stones or cement blocks, spread the mortar 1 inch thick to begin with. Place the blocks or stones on top of the mortar and tap them into it with the trowel or the hammer. Keep tapping until they compress the mortar down to a width of 3/8 inch. Scrape away the excess mortar that was squeezed out from under them.

Mortaring Between Blocks

• Fill the joints between the blocks or stones with 3/8 inch of mortar as well. This will give the wall a regular look. Use a level as you go, to make sure that each block is set levelly. This may require adjusting the mortar underneath the block. This adjustment can change the gap between the block and the one next to it, so be sure to check that none of the mortar there has fallen or been squeezed out.

Time

• Place the building blocks onto their mortar bed as quickly as possible. The mortar starts drying as soon as it is mixed, and the longer it dries, the stiffer it becomes. It can be difficult or even impossible to position the blocks in stiff mortar. As a general rule, apply all of the mortar and have all the blocks in place within 2 ½ hours of mixing the mortar. Even then, you may need to periodically add more water while you are laying blocks, to keep it workable enough.

Spills

• As you apply the mortar and set the blocks, pay attention to the mortar you have already applied. If it spills or leaks out of the joints and is not noticed, then it may harden in place along the face of the wall. This may ruin the look that you were going for. To remove spilled hardened mortar, scrub it with a stiff wire brush.