Portland Cement: Rediscovery of Ancient Rome's Hydraulic Cement (HI-12)
Early Romans discovered that a mixture of burned lime and volcanic ash produced fine hydraulic cement -on that sets underwater. Many structures using this material as mortar and cement were constructed in the Roman Empire. During the Dark Ages this knowledge was lost.

In 1824, Joseph Aspdin in Leeds, England, rediscovered hydraulic cement. He named it "portland cement" because the hardened material resembled a building stone on the Isle of Portland.

Portland cement was first manufactured in the United States at Copley, Pa., in 1872. It was first produced in Indiana at South Bend in 1877, where marl and clay were first used successfully as ingredients. Today, controlled mixtures of limestone, shale, iron oxide and silica are burned in rotary kilns, and the resulting clinker, with gypsum and other additives, is ground into powder. Indiana's five portland cement plants are in Gary, Logansport, Greencastle, Mitchell and Speed.

Our Hoosier State Beneath Us: Historical