How it began
Joseph Aspdin was a bricklayer from the Hunslet district of Leeds who had set up his own business in central Leeds by 1817. On 21 October 1824 he was granted British Patent 5022, titled An Improvement in the Mode of Producing an Artificial Stone. In it he coined the term Portland cement, because set mortar made from it resembled Portland stone, the most prestigious building stone in England at the time, quarried on the Isle of Portland in Dorset.
How it works
The patent describes calcining limestone, mixing it with a set quantity of clay and water until very fine, and drying the mixture in a pan. The dried material was broken into lumps and calcined in a furnace similar to a lime kiln until the carbonic acid was driven off. It was then ground, beaten or rolled to a fine powder. Mixed with enough water to reach the consistency of mortar, the powder could be used for stuccoing buildings, waterworks and cisterns.
How it spread
In 1825 Aspdin and a Leeds neighbor, William Beverley, set up a production plant at Kirkgate in Wakefield, about nine miles away, and Aspdin took out a second patent for making lime. Limestone supply was a difficulty before stone could come by rail, and Aspdin was twice prosecuted for digging up paving blocks from local roads. He retired in 1844 and died in Wakefield in 1855.
What lasted
The 1824 patent does not describe the product recognized as Portland cement today. It was a fast-setting, low-strength cement aimed at stuccos and pre-cast moldings. Aspdin's son William later used a mix with more limestone, burned it at a higher temperature and ground the hard clinker that had previously been discarded. That stronger product is described as the first modern Portland cement, and William is credited with launching the modern industry.
