CENTENARY OF CEMENT

Southland Times, Issue 19393, 6 November 1924, Page 5

CENTENARY OF CEMENT

MEMORIAL TO INVENTOR. A LEEDS STONEMASON. PRESENT USES OF CONCRETE. A bronze memorial tablet to Joseph Aspdin, the inventor of Portland cement, was unveiled recently in the Leeds Town Hall. Aspdin, who was a Leeds stonemason, patented his invention in October, 1824. He mixed finely-powdered lime with clay, then subjected the mixture to a very high temperature, until the carbonic acid gas had been driven off, and he then ground up the calcined mass. He. found that the powder thus obtained, if water were added, set quickly, and that the cement, when dry, had the colour of Portland stone, after which he named it. The advantage of his process was that the cement could be made from any chalk or limestone and clay, provided that the substances were mixed in the proportions of about three to one and thoroughly burnt. Thus Portland cement rapidly superseded the older and far dearer cements made in a few places where the local limestones or clays were found to yield a useful binding material. Aspdin made an effort to keep his method as a trade secret by means which provoke a smile. But it was too useful a discovery to be retained within the 20ft wall of his factory, though the workmen were kept in ignorance of the patent mixture and though st angers were excluded. Several of Aspdin’s descendants were present at the ceremony, and they had with them the original parchment record- ’ ing the patent. Fifteen prominent cement manufacturers from various parts of the United States and Canada made a pilgrimage to Leeds to take part in the commemoration. Mr F. W. Kelly, President of the American Portland Cement Association, said the cement had contributed to the safety and convenience of the world in a thousand ways. He estimated that if masonry had been used in all the great structures of the past century, the additional cost would approximately have amounted to a quarter of the present national debt of Great Britain. 1316 usefulness of concrete was increasing, and it was calculated that in 1923 the world used 50,000,000 tons of Portland cement. Aspdin had done more literally to bind the world together than had all the diplomats of all times. America had led the way in developing the use of concrete, but other countries are now making rapid progress with similar development. Thousands of houses are now being built of concrete in Britain, and a lavish use of concrete is made in the construction of docks, harbours, railways buildings, bridges, roads, water supply dams and conduits, and ducts for electric wires. The British Exhibition at Wembley is ia iteelf a massive memorial to Aspdrn.