Your browser is no longer supported

For the best possible experience using our website we recommend you upgrade to the newest version of your browser.

Your browser appears to have cookies disabled. For the best experience of Construction News, please enable cookies in your browser.

Welcome to the Construction News site. As we have relaunched, you will have to sign in once now and agree for us to use cookies, so you won't need to log in each time you visit our site.
Learn more

HAC returns to prove its mettle.High Alumina Cement (HAC), also known as 'fondu concrete', was invented in 1908 in the laboratories of French cement manufacturer Pavin de Lafarge.

It started crossing the Channel in bulk in the 1960s when the frantic pace of construction in those booming days made its rapid hardening and early strength seem like the answer to contractors' dreams.Soon Lafarge was selling 30,000 tonnes a year and two thirds of this were going into pre-stressed concrete beams.In 1973 disaster struck. Pre-stressed beams in three different buildings collapsed. HAC was taken off the market with its failure blamed on a process known as conversion.However, Lafarge was convinced that the product itself was not at fault, only the way it was used. So the company started a long-term research programme to prove its worth.Now the company is relaunching HAC on the results of its research and independent tests carried out by the Building Research Establishment, the Royal School of Mines and Imperial College.This has shown that the product goes through a two-stage process of crystallisation which gives high early strength. Then the natural conversion process reduces this strength to more normal levels. A further strength increase comes with time.A company spokesman said: 'It is a highly technical product for use under controlled conditions which, for the right applications, gives contractors advantages they can achieve in no other way.' These include resistance to extremes in temperature, thermal cycling, abrasion and acid.Lafarge is concentrating on road construction, runway repairs, tunnelling, pipelines, foundations and marine applications. But no-one is suggesting it is used in concrete beams.