The birth of modern cement
Joseph Aspdin’s patent of 1824 for Portland cement (so called due to its resemblance when hardened to Portland Stone ), is often considered as a landmark in the history of cement production. Although, in reality, Aspdin’s cement was closer to an hydraulic lime than a modern cement. Further developments by William Aspdin and later by Isaac Johnson in the 1850s, with changes in the proportioning of clay and limestone and the introduction of higher calcining temperatures, led to the production of cements very similar to those of today. At the start of the 20th century, cement manufacture changed from a batch process (using small ‘Beehive’ kilns) into a more continuous process utilising rotary kilns.
Improvements in the understanding of the chemistry of cement and in quality control have produced a high quality modern cement, whose properties can be fine tuned to optimise performance in different environments. Today’s Portland cement is often blended with other materials, such as limestone, fly ash or blast-furnace slag.