Tornado Alley (PROG)

[Dale C]

When did their engineers forget how to make cement their own from locally acquired material.

http://www.buildeazy.com/newplans/eazylist/cement.html

Four essential elements are needed to make cement. They are Calcium, Silicon, Aluminum and Iron.

Calcium (which is the main ingredient) can be obtained from limestone, whereas silicon can be obtained from sand and/or clay. Aluminum and iron can be extracted from bauxite and iron ore, and only small amounts are needed. Lacking ore? there is the ever present auto junk yard with tons of iron and aluminum.