Concrete from the Roman Empire to Today

Concrete is everywhere in Oklahoma and across the globe. From urban roads to rural oil drills, from major public works to your own house’s foundation, concrete is everywhere you go. While you might already appreciate the usefulness of concrete, when you look at the substance, you probably don’t give much thought to where it comes from. Concrete is actually an ancient substance dating back to the Roman Empire. In fact, parts of the Coliseum and the dome of the Pantheon are built of concrete. The very word “concrete” comes from the Latin word concretus, which means “condensed” or “compact.” After fall of the Empire, the technology passed into obscurity and was not re-integrated into building techniques until the 18th century. Since that time, however, the process for making concrete has been refined and perfected; making it sturdier and more attractive, and causing it to be one of the most widely used materials in the world. In fact, across the world, concrete is used more than steel, wood, aluminum, and plastics combined.

Concrete is made using a combination of aggregates and paste. Modern concrete in Oklahoma and elsewhere has an aggregate that is composed of a variety of materials, including sand, gravel, crushed stone, and, sometimes, even oyster shells and ash from coal-fueled plants. The paste in all modern concrete is cement, which contains such substances as clay, limestone, and gypsum, among others. Sometimes supplementary cementitious materials like power-plant ash and slag are added to the cement. Other times, admixtures are added. These substances give certain properties to the cement, such as changing the color or shrinkage rate. The proportion of materials must be carefully determined, or the concrete will be useless. All of these substances are crushed, mixed, burned, and ground before being mixed with water. At this point, the mixture dries through the process of hydration.

Once the proper ingredients have been assembled, concrete in Oklahoma is either put into a bag or a mixer. Bags of concrete are geared for smaller projects. Individuals then mix these bags with water as needed. Larger projects, however, will likely need a concrete mixer, especially since multiple bags of concrete can get quite expensive. Most companies choose to mix the concrete at the plant and then transfer it to the site in a rotating drum. Some companies, however, choose to mix it on site. At the site, there will be frames, in which the concrete will be poured. Usually these frames are made of wood, though reinforced concrete will require rods or mesh frames. Concrete is poured into these frames, smoothed over, and moistened before it dries. It is extremely important to keep the surface moist, since concrete shrinks as it dries, and keeping it moistened allows it to shrink evenly.

The history of concrete is much longer than you might think and the process of making it more complicated and specific than it would seem. With your newfound knowledge of the history and production process, you will never be able to see concrete in Oklahoma in quite the same way.

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