Joseph Aspdin (25 December 1778 – 20 March 1855) was an English bricklayer, businessman, inventor, and stonemason. He obtained the patent for Portland cement on 21 October 1824.

Life

Joseph Aspdin, also called Aspden, was the oldest of six children born to Thomas Aspdin, a bricklayer who lived in the Hunslet district of Leeds, Yorkshire. He was baptized on Christmas Day, 1778. He worked in his father’s trade and married Mary Fotherby at Leeds Parish Church (the Parish Church of St. Peter at Leeds) on May 21, 1811.

By 1817, he started his own business in central Leeds. He likely tested ways to make cement in the following years, because on October 21, 1824, he was given the British Patent BP 5022, titled "An Improvement in the Mode of Producing an Artificial Stone." In this patent, he created the name "Portland cement," inspired by a type of stone called Portland stone, an oolitic limestone found on the Isle of Portland in Dorset, England.

Soon after, in 1825, Joseph partnered with a neighbor from Leeds named William Beverley to build a cement production plant in Kirkgate, Wakefield. Beverley remained in Leeds, but Joseph and his family moved to Wakefield, which was about nine miles away. Joseph received a second patent in 1825 for a method of making lime. The Kirkgate plant closed in 1838 when the Manchester and Leeds Railway Company bought the land, and the site was cleared. Joseph then moved his equipment to a new location nearby in Kirkgate.

At this time, Joseph’s eldest son, James, worked as an accountant in Leeds, while his younger son, William, managed the plant. However, in 1841, Joseph formed a partnership with James and posted a notice stating that William had left the business and that the company would not be responsible for his debts. The notice said, "I think it right to give notice that my late agent, William Aspdin, is not now in my employment, and that he is not authorized to receive any money, nor contract any debts on my behalf or on behalf of the new firm."

In 1843, William started his own cement plant in Rotherhithe, near London. There, he made a stronger type of cement using a new recipe, which became the first "modern" Portland cement. In 1844, Joseph retired and gave his share of the business to James. James moved the operation to a third site at Ings Road in 1848, and this plant remained active until 1900. Joseph Aspdin died on March 20, 1855, at his home in Wakefield.

Implications of the patent

Joseph Aspdin named the product Portland cement because hardened mortar made from it looked similar to “the best Portland stone.” At the time, Portland stone was the most respected building material in England. The patent does not describe the product known today as Portland cement. Instead, the product was intended for use in stuccos and architectural pre-cast moldings, which required a cement that hardened quickly but had low strength. It was fired at low temperatures (below 1250 °C) and did not contain alite (C₃S: 3CaO·SiO₂, tricalcium silicate).

The product was part of a group of materials called “artificial cements,” created to compete with James Parker’s Roman cement. It was similar to an earlier material developed by James Frost. The process used was called a “double burning” method: limestone was burned first, then slaked, mixed with clay, and burned again. This was a common practice when only hard limestone was available. Grinding technology at the time used flat millstones, and it was more cost-effective to burn and slake limestone than to grind it.

The limestone Aspdin used was Pennines Carboniferous limestone, which was used for paving roads and town streets. A key feature of the patent (and his earlier lime patent) was using “road sweepings” as a raw material. If road sweepings were unavailable, he used the limestone directly. Joseph Aspdin was prosecuted twice for removing entire paving blocks from local roads, showing that limestone supply was a major challenge before rail transport made it easier to bring in stone.

His son, William, improved the process by using a mix with more limestone, burning it at higher temperatures with more fuel, and grinding the previously discarded hard clinker material. This increased wear on grinding equipment. However, William did not patent his changes and sometimes claimed his father’s patent. In 1848, William moved to Northfleet, Kent, where soft chalk was abundant. Records suggest William had financial problems and questionable business practices, but he is credited with starting the “modern” Portland cement industry.