Learn to mix mortar and make wall slipforms

By using slipforms, even a novice can build a strong, freestanding wall. We'll show you the ropes to making slipforms and mixing mortar so that you can take your masonry skills to the next level.

Learn to mix mortar and make wall slipforms

Mix mortar properly

Mortar eliminates much of the shaping and shimming needed in dry-wall construction. However, it doesn't glue the stones together. Portland cement, the active ingredient in mortar, cures as hard as stone. In a semi-liquid state, it automatically provides a perfect cushion for rocks as they're laid, filling in the smallest gaps. Here's how to start mixing:

  • Proportions for the dry ingredients of mortar are measured by volume. Make a bottomless box or deep frame with a capacity of approximately 0.03 cubic metres (1 cubic foot) for preparing the correct ­proportions.
  • Use 1 centimetre (1/2 inch) plywood or 2.5 centimetre (1 inch) lumber for the sides. Use 5 x 7.5-centimetre (2 x 3-inch) boards for handles. For extra strength, join with screws rather than nails.
  • To mix, place the box in a mixing trough, fill it with the ingredient, and lift it up. Each filling equals one unit of a particular ingredient.
  • To mix concrete by hand, first wet the mixing trough. Spread ingredients in layers over three-quarters of the bottom, then pour water into the remaining area. To mix, use a mason's hoe to pull sections of dry material forward into the water. Blend until the mixture holds its shape when you make a depression.
  • To use a power mixer, blend the dry ingredients and then add water for a workable mix.

Construct a wall slipform

  • Make forms 45 centimetres (18 inches) deep and approximately 2.5 metres (8 feet) long. Plan walls to be even multiples of these dimensions so that your slip forms can be used in efficient combinations.
  • Cast walls a minimum of 35 centimetres (14 inches) thick.
  • For face boards, use 2.5 x 5-centimetre (1 x 2-inch) boards or sheets of 1 centimetre (1/2 inch) plywood . Nail the face boards to 5 x 10 centimetre (2 x 4-inch) braces.
  • Leave gaps of about 1 centimetre (1.2 inch) between face boards (or drill holes) so that tie-wire loops can be threaded through to hold the sides together.
  • Bore holes in the end, top, and bottom braces to bolt forms together end-to-end and in vertical layers.
  • Apply oil to slipforms for easy removal and to prevent mortar from sticking.

It may seem complicated, but you can save a lot of money and become a better handyman by mixing your own mortar and learning how to construct and use wall slipforms. If you take your time and follow these instructions carefully, soon your achievements will be set in stone.

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