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Mixing Mortar
The mix
A general-purpose mortar is six parts bricklayers sand, one part cement and one part lime (6:1:1).
A plasticiser can be added to make the mortar more workable and a waterproofing agent is added to mortar for brick fences to prevent damp.
Sand is normally sold by the cubic metre or tonne. One cubic metre of sand weighs roughly 1.5 tonnes.
Keeping the mortar at the right consistency is part of the art of laying bricks. The mortar holds the bricks in place and levels the courses. It should be soft and pliable and not too dry, a bit like toothpaste.
Mortar is good for one and a half hours (add a little water to keep it soft and workable) before it loses elasticity and should be thrown out.
You will need:
- Bricklayer's sand (70 per cent bush sand and 30 percent sharp sand), cement and lime, or pre-mixed mortar
- Plasticiser, waterproofing agent and oxides (optional)
- Wheelbarrow, plywood or concrete mixer
- Shovel
- Mortar board
- Trowel
- Jointer or raker
Here's how:
1. When mixing by hand, thoroughly mix the ingredients dry before adding water. The mortar should finish an even colour. In a concrete mixer, put the water in first, then the sand, the cement and finally the lime, topping up with water if needed.
2. Transfer the mixed mortar to a mortar board. Mortar boards are about one square metre and made of waterproof plywood or a light steel plate. Keep the mortar on the board soft and pliable by working it continually with the trowel.
3. Trowel the mortar off the board with a smooth wrist, elbow and shoulder movement.
4. Using the tip and edge of the trowel drop and move the mortar left, then right on the board to get an even consistency.
5. Using the back of the trowel, move the mortar back across the board to finish the mixing.
Mortar joint types
Different mortar joints are shaped while the mortar is wet:
Flush joint - cut flush with a trowel.
Round ironed joint - using a round iron jointer; used in restoration work on Federation houses.
Raked joint - using an adjustable raker up to 10mm deep; used in house construction.
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