As I write this post I hear and feel the wump, wump, wump of the contractors sledge hammer coming down on our concrete front porch. We could put it off no longer. Subsiding soil in the front of the house has dropped the soil from below the concrete stoop to the point where it was hanging on to the foundation by friction rather than by concretion. The stoop was beginning to succumb to the pull of gravity and it had to be torn out.

The eastern plains of Colorado right up to the foothills are covered by expansive soil. Bentonite and other clays swell, contract, and generally heave with moisture cycling. When you combine this with ignorant and shabby construction practices, you set into motion future remediation.

Measure it with a micrometer, mark it with chalk, cut it with a torch, beat to fit, paint to match, inspect it with a microscope.

There are scattered reports of amelioration of this expansive property by amending the soil with several % of lime.  Excessive additon of lime has the effect of enhancing the swelling, so care must be taken. I am unaware of anyone practicing this kind of art. Addition of lime (CaO and/or the hydrate)will make the soil alkaline, so some planning will have to go into the decision to amend soil for expansive properties.

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