MORTAR

Mortar is a material used in masonry field to fill the gaps between blocks in construction and bind the blocks together -- these can be stone, brick, breezeblocks (cinder blocks) etc. It is a mixture of sand, a powdered adhesive and water that is applied as a paste and then dries hard. The earliest known mortar was used by the ancient Egyptians, and was made from gypsum. This form was essentially a mixture of plaster and sand, and was quite soft. Lime mortar, using quicklime, CaO, was discovered about 4000 BC, about the time the great Egyptian pyramids were built.

Mixing mortar to the right consistency is only the first step. Depending on the temperature or humidity, mortar can begin drying out in as little as 15 minutes. Keep mortar out of direct sunlight when possible. If the mortar begins to dry out, add a small amount of water and begin to remix it. If the temperature drops below 40F, wait for a warmer time to work with the mortar. Low temperatures can alter the strength of the mortar.