DoItYourself.com notes there are many steps to using vermiculite to cure concrete, including measuring out the correct amount of concrete and vermiculite. The ratio may change due to the size of the project, but is typically three parts vermiculite to one part concrete.Continue Reading
Before beginning the project, check with the vermiculite company to ensure the product was mined from an area free of asbestos and is otherwise safe. This is necessary because vermiculite was made with asbestos until the early 1990s.
An optional step is to soak the vermiculite in water the night before the project. This may help prevent cracks from forming and makes the substance easier to mix.
Measure water carefully before beginning the project, and add it to a large container for mixing. Add the concrete, and then add vermiculite. Add vermiculite slowly, and add more water as necessary so the mixture maintains a mud-like consistency.
Pour the mixture into the mold and use a plastic sheet to cover the area after pouring. Because of the vermiculite, the mixture may take several days to set fully. During this process, do not be alarmed if the concrete looks weak and flaky; this is a natural part of the process, and it will harden after additional time setting.Learn more about Building Materials