Mixing Natural Hydraulic Lime Mortar
How To Mix Natural Hydraulic Lime
The Cement Mixer Method:
This method is ideal when large amounts of mortar are required on a dependable basis. The only down-side to using 'Batch' or 'Drum' mixers is that they typically cause the mortar to 'ball-up', which will create additional labour, and the mortar will then have to be squished. This is caused by the paddles within the mixer itself. However, the following steps will help to reduce this problem.
Before mixing the mortar, it is important to measure out the Lime and Sand by volume, using a bucket. Measuring the materials with a shovel will not suffice, because the volume of each load will differ. Each mix should be as consistent as possible.
1. It is important to start with a dry and empty mixer. In order for the lime and sand to thoroughly mix together, they need to blend without the addition of water.
2. Measure out the chosen sand to lime ratio — this will depend on the grade of Natural Hydraulic Lime being used and its intended application.
3. Add the sand to the mixer.
4. Add the lime to the mixer.
5. Start the mixer and allow the materials to mix dry for at least several minutes.
6. Stop the mixer and let the materials settle for 5-10 minutes.
7. Start the mixer again and begin adding small amounts of water until the desired consistency is obtained. When pouring water into the mixer, allow it to mix for a minute or so before adding more. Adding too much water will only weaken the final mixture, making it unstable. Introduce just enough water for the chemical processes to take place, so that the lime and sand properly bond. A mix which resembles a hardy pizza dough is ideal.
8. Once an optimal mixture of sand to lime to water is obtained, allow it to continue mixing for 10-20 minutes.
9. Stop the mixer and let the mortar settle before applying it.
If you would like to see some of our completed Masonry and Stonework projects which used Natural Hydraulic Lime Mortar, please visit our Gallery and Current Projects pages. We are currently in the process of reconstructing 17th-Century Limestone Stonework, involving Church features at the Norfolk Heritage Lodge in Saanich, B.C., Canada.
Lennox Masonry of Victoria, B.C., specializes in Traditional Stonework, Heritage Restoration, Historical Masonry, and creative Masonry Projects. If you are interested in obtaining a unique work of art in the medium of stone and masonry, please Contact us today.