Portland cement was invented in 1824.
Used as a building material for millenia, cement is an amalgam of powdered inorganic compounds including silica, limestone, gypsum and clay. When combined with water, a chemical reaction commences and the material solidifies and hardens. Various names for various types of cement depend on the types of inorganic materials used. Portland cement gets its name from a quarry in Portland, England, where the cement was first produced. Portland cement can be used alone, or amended with additional powders and aggregates that alter the stiffness, strength and drying time.
Ancient Origins
As far back as 3000 B.C., ancient builders developed cementitious products to hold together building materials, such as bricks and wood. The Egyptians used sun-baked mud fortified with straw, the Greeks developed lime mortars and the Babylonians used the sticky bitumen oozing from their lands. It wasn't until the 4th century B.C., when the Romans developed an incredibly durable pozzolana cement mixed from the dust of Mount Vesuvius, that humans constructed buildings made entirely from cement. The Romans engineered baths, roads, bridges, aqueducts and the magnificient structures such as the Pantheon and Colisseum from their simple cements. The knowledge of cement craft faded during the Middle Ages but was rediscovered during the 16th and 17th centuries when demand for durable, permanent building materials rose.
The Invention
A young bricklayer from Leeds, England, developed Portland Cement. Joseph Aspdin was the son of a bricklayer, experimenting with various combinations of finely ground limestone, argillaceous clay or shale and sand or iron ore. Aspdin patented his product in 1824. He named it Portland cement, as the hardened cement resembled the prized limestones quarried on the Isle of Portland, England. The first commercial application of Portland Cement occurred in 1828, when engineer I. K. Brunel used the product to fill a breach in the Thames Tunnel
Manufacture
Portland cement is a mixture of calcium oxide, silica, alumina and iron, obtained from ground limestone, clay, sand and iron ore or furnace slag. Portland cement mixtures contain a high ratio of ground limestone, lending the mixture great strength and a stone-like beauty. The contents are finely ground into a powder and baked in a kiln to temperatures reaching 2,900 F. Gypsum is added to the mix and the contents are finely ground again. During the heating process, the mixture undergoes chemical change, reconstituted into new compounds that react with water in a crystallization process called hydration. After the addition of water, the cement transforms into a solid state within a few hours and continues to strengthen as the concrete cures.
Uses
Portland cement is a very versatile building material. Masons combine the cement with aggregrates such as gravel to expand the volume of the mix, prevent excessive shrinkage and reinforce the material. Mixed with sand, Portland cement becomes a highly sticky mortar suitable for parging and binding masonry rock and other solid materials together. Portland cement is one of the most common cement building materials today, due to its use as a general purpose material as a cement and for its suitability as a binding and strengthening ingredient for concrete building purposes.
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