Portland cement

Portland cement is the most common type of cement in general use around the world as a basic ingredient of concrete, mortar, stucco, and non-specialty grout. It was developed from other types of hydraulic lime in England in the early 19th century by Joseph Aspdin, and is usually made from limestone. It is a fine powder, produced by heating limestone and clay minerals in a kiln to form clinker, and then grinding the clinker with the addition of several percent (often around 5%) gypsum. Several types of Portland cement are available. The most common, historically called ordinary Portland cement (OPC), is grey, but white Portland cement is also available. The cement was so named by Joseph Aspdin, who obtained a patent for it in 1824, because, once hardened, it resembled the fine, pale limestone known as Portland stone, quarried from the windswept cliffs of the Isle of Portland in Dorset. Portland stone was prized for centuries in British architecture and used in iconic structures such as St Paul's Cathedral and the British Museum. His son William Aspdin is regarded as the inventor of "modern" Portland cement due to his developments in the 1840s. The low cost and widespread availability of the limestone, shales, and other naturally occurring materials used in Portland cement make it a relatively cheap building material. At 4.4 billion tons manufactured (in 2023), Portland cement ranks third in the list (by mass) of manufactured materials, outranked only by sand and gravel. These three are combined, with water, to make the most manufactured material, concrete. This is Portland cement's most common use.

History Portland cement was developed from natural cements made in Britain beginning in the middle of the 18th century. Its name is derived from its similarity to Portland stone, a type of building stone quarried on the Isle of Portland in Dorset, England. The development of modern Portland cement (sometimes called ordinary or normal Portland cement) began in 1756, when John Smeaton experimented with combinations of different limestones and additives, including trass and pozzolanas, intended for the construction of a lighthouse, now known as Smeaton's Tower. In the late 18th century, Roman cement was developed and patented in 1796 by James Parker. Roman cement quickly became popular, but was largely replaced by Portland cement in the 1850s. In 1811, James Frost produced a cement he called British cement. James Frost is reported to have erected a manufactory for making of an artificial cement in 1826. In 1811 Edgar Dobbs of Southwark patented a cement of the kind invented 7 years later by the French engineer Louis Vicat. Vicat's cement is an artificial hydraulic lime, and is considered the "principal forerunner" of Portland cement.

The name Portland cement is recorded in a directory published in 1823 being associated with a William Lockwood and possibly others. In his 1824 cement patent, Joseph Aspdin called his invention "Portland cement" because of its resemblance to Portland stone. Aspdin's cement was nothing like modern Portland cement, but a first step in the development of modern Portland cement, and has been called a "proto-Portland cement".

William Aspdin had left his father's company, to form his own cement manufactury. In the 1840s William, apparently accidentally, produced calcium silicates which are a middle step in the development of Portland cement. In 1843, he set up a manufacturing plant at Rotherhithe, southeast London, where he was soon making a cement that caused a sensation among users in London. In 1848, William further improved his cement. Then, in 1853, he moved to Germany, where he was involved in cement making. William made what could be called "meso-Portland cement" (a mix of Portland cement and hydraulic lime). Isaac Charles Johnson further refined the production of "meso-Portland cement" (middle stage of development), and claimed to be the real father of Portland cement. In 1859, John Grant of the Metropolitan Board of Works, set out requirements for cement to be used in the London sewer project. This became a specification for Portland cement. The next development in the manufacture of Portland cement was the introduction of the rotary kiln, patented by Frederick Ransome in 1885 (U.K.) and 1886 (U.S.); which allowed a stronger, more homogeneous mixture and a continuous manufacturing process. The Hoffmann "endless" kiln which was said to give "perfect control over combustion" was tested in 1860 and shown to produce a superior grade of cement. This cement was made at the Portland Cementfabrik Stern at Stettin, which was the first to use a Hoffmann kiln. The Association of German Cement Manufacturers issued a standard on Portland cement in 1878. Portland cement had been imported into the United States from England and Germany, and in the 1870s and 1880s, it was being produced by Eagle Portland cement near Kalamazoo, Michigan. In 1875, the first Portland cement was produced in the Coplay Cement Company Kilns under the direction of David O. Saylor in Coplay, Pennsylvania, United States. By the early 20th century, American-made Portland cement had displaced most of the imported Portland cement.

Composition ASTM C219 defines Portland cement as:

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