“Foundation” Of Cement

What if I told you that cement is a powder chemically composed of calcium, silicon, aluminum and iron, amongst other minerals, that, when mixed with water forms a paste that binds and hardens to form a concrete structure? While interesting, the composition is not what makes cement fascinating. Now, what if I told you that a close variation of the same man-made powder was used to build pyramids in ancient Egypt? The history behind the creation of cement is what makes the material so intriguing.

Early civilizations including Assyria and Babylon used clay to bind stones together for building structures. While Egypt and Greece experimented with materials like limestone and gypsum to create cement, Rome was the first civilization to maneuver the chemical properties of its input materials in order to make cement exhibit different properties according to its application. Developing a composition that built long-lasting structures, Rome is attributed with the creation of industry-wide used cement. Interestingly, most of the structures in the Roman forum, including the famous Coliseum, Roman baths and Basilica of Constantine, were built from concrete. Pozzolanic cement, named after a village near Vesuvius called Pozzuoli, was founded in Rome. This cement was found to be set under water and used to construct harbors. Marcus Vitruvius Pollio, a famous Roman architect who wrote 10 books about cement, wrote in the second volume, “There is also a kind of powder from which natural causes produces astonishing results. This substance, when mixed with lime and rubble, not only lends strength to buildings of other kinds, but even when piers are constructed of it in the sea, they set hard under water” (Vitruvius, “The Ten Books of Architecture,” Dover Publications, 1960.) about pozzolana.

John Smeaton, through experiments, discovered that limestone mixed with a large amount of clay to create cement hardens under water. He used this to rebuild Eddystone Lighthouse, which stood for 126 years. Following this, many men experimented with cement. It was a bricklayer and mason, Joseph Aspidin, who, in 1824, created and patented the composition of Portland cement. It was created by pulverizing a set proportion of limestone and clay, burning it into a clinker and grounding it. In 1845, Isaac Johnson pulverized the mixture at much higher temperatures, making the first modern cement. The higher temperature allows for clinkering, making the materials more reactive. Modern-day Portland cement is made with a fixed proportion of calcium, silicon, iron and aluminum.

The cement industry hit India in 1904 when South India Industrial Ltd. set up a small cement factory in Madras. Soon after, in 1914, Indian Cement Company Ltd. started manufacturing artificial Portland cement in Porbundar, Gujarat. Because producing cement within the country was significantly cheaper than importing it from Britain (due to cheaper labor and availability raw material, amongst other reasons), the cement industry in India flourished. Now, India is the second largest producer of cement in the world, second only to China.

 

–  Tanvi Jindal

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