[Greenbuilding] Crushing Clay

[natural building]

On 2011-08-06, at 10:36 PM, JOHN SALMEN wrote:

> I probably missed something in this thread but why are we crushing dry clay?

John, perhaps you found the answer to this question in my other posts, but in case you didn't... it is for the construction of a rammed earth foundation stem wall for my workshop in Victoria, BC.

Moisture content in RE is critical in order to obtain adequate compressive strength when OPC is not being added. The clay needs to be crushed as much as is possible / practical in order to allow the water to penetrate to all of the particles and thereby activate the ionic bond. Since a lump of clay that is 2 mm in diameter will contain at least 1000 individual particles of clay, the smaller you can crush it, the better.

Too little water and you haven't 'activated all the clay particles, too much and you will introduce excessive shrinkage. Both of these weaken the final product, particularly when we are only talking about 2 - 3 MPa compressive strengths.

Regards,

Steve Satow

www.naturalbuildingsite.net
naturalbuilding at shaw.ca

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