According to the Mine Faculty at the University of Arizona, cement is manufactured primarily from suitable limestone and shale rocks. Arizona had two dry-process cement plants in 1969, namely the Arizona Portland Cement Company plant in Pima County, near Tucson, and the American Cement Corporation plant at Clarkdale, in Yavapai County (52-53). The use of cementing materials goes back to the ancient Egyptians and Romans, but the invention of modern portland cement is usually attributed to …
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showed last 75 words of 1309 total
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