We have been hauling home and cleaning up loads of salvaged brick for free. They would make really cool raised wicking bed planters. However, portland cement mortar is really expensive. Are there cheaper and more natural alternatives? Lime was the only one I found, and it is more expensive then portland cement here.
Would it be really crazy to mix up a batch of stabilized adobe mix (clay, straw, small amount of cement) and use that as mortar?
Besides the environmental footprint of the OPC (ordinary portland cements) industry being something not to support...I can say that earth and lime based mortar actually have (and still do) present as one of the most durable methods humans have come up with to help fill voids (not glue together) in masonry and wood. OPC...in its current form...has only been around for about 150 years or less. Natural cements (only a few manufactures left in North America) are similar to lime, but are mainly employed by Historical Restoration Artisan like myself to use in preserving vintage masonry fabric. Plus, it is very expensive.
Will earth mortars wash away? Depends on the application, the mix, matrix blend, and environment. About the only time I will use a modern OPC (as I just did today) is in a "critical structural bearing repair" that require "instant" load bearing requirements...and/or...some water features. This is a very narrow, well defined, and technical application, which does not happen that often.
If you employed a solid "herring bone" pattern with lime and/or earth mortars, the results will last a very long time in my experience. Each application is different, depending on goals and requirements of the project.
One thing that is not very often discussed is the lithification of your below ground earthen mortar. This, for those that aren't married to a geologist, is the process of stone building through mineralization. This is a natural process that reinforces subsoil masonry that is not vapor retarded : .
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