Hi,
regarding clay in general, you must distinguish between different compositions in relation to its use as a building material. Maybe these distinctions will come back in America if this material were to become more generally used again. In England what is commonly used in relation to building is called, loam, (here called leem). This is a clay based material, containing aggregates for binding, (clay is the binder but a binder must necessarily have something to which to bind), strength and stability. Sometimes fillers are added for insulation, weight reduction, increased mass or structural advantage.

The only use for more or less pure clay, which is the inert remains of what was once organic material, in relation to building would be in the form of a sort of rammed earthen floor - unless you want to include baked tiles. Even these floors were traditionally stabilized. First of all, like Tim Beal writes there, by letting the natural clay stand under protection out doors for minimal 1 year - better three - to degrade imbedded organic material and break down it's inherent structure, and then further with the addition of horse urine and/or old beer, adding lime to increase hardness.

These floors can be adopted even for modern housing but in my opinion are better suited for barns, stalls, workshops. There is no better floor than this for a blacksmith's workshop, being fire and shock proof.

That said, there is this clay floor and there are composite clay, (in American terms), floors. That just means the material has been adapted to whatever particular conditions call for where it is used. And if I were to claim to be making a point at this point it would be that the uses of clay in making buildings are pretty limited. If I were to add anything practical that would be that a person can come to some conclusions about the ground under his or her feet with a simple test. Put some ground in a clear glass jar, let it settle, and it's possible to see its composition and their ratios to each other as the various components separate into layers .

Don Wagstaff