VICAT Louis

Published on 4 February 2008

 

1786-1861

His ambition was to be a poet ... and now everyone in the world uses the artificial concrete he developed which "keeps its strength under water" that he invented in 1817, thereby opening the way for the industrialzation of hydraulic binders .In Le curé de campagne Balzac praised him as "the man responsible for the only progress that has been made in the science of building" Since 1889, he is featured with the 71 other famous scientists and engineers - including Cauchy, Belgrand, Fresnel and de Prony - whose names Eiffel inscribed on the large frieze above the first floor on the Southern side of his tower.

 

It all began in the Lot Département after a period of involvement in the construction of the Périgueux - Brive road, when, in 1812, he was put in charge of building the bridge at Souillac. He spanned the Dordogne, whose flow varies enormously and which is subject to violent flooding which frequently disturbs the riverbed, with a bridge consisting of 7 low arches each with a 22 metre span.

During the ten years it took to build the bridge - due to slow funding - Vicat attempted to find a new material that hardened rapidly under water to replace slow-setting mortar, which was the mixture of hydrated lime and anvil dross recommended at the time by the Conseil général des Ponts et Chaussées.

Along with others at the same time he was attempting to discover the secret of the famous Roman "cement" that hardened under water and retained its strength in water for centuries, as can be seen in many surviving structures such as the Pont du Gard. On the basis of experiments on lime conducted in England by Wyalls, Parker and Smeaton, in Sweden by Bagge and in France by Chaptal, he analyzed the properties of the constituents of the natural hydraulic binders he found in the caves near Souillac and, in advance of his contemporaries, managed to synthesize the binders by varying the proportions of the constituents. Artificial cement, which was known at the time as "grey gold" was discovered in 1817. Vicat developed a theoretical explanation for hydraulic behaviour in order to lay to rest any doubts and presented in in the same year to the Academy of Sciences, receiving warm praise from de Prony, Gay-Lussac and Girard.

 

In 1818, at the request of the Conseil général des Ponts et chaussées, he published his famous Recherches expérimentales sur les chaux de construction, les bétons et les mortiers ordinaires in which he described in simple but precise terms the manufacture of hydraulic lime whose qualities exceed those of the natural lime produced by chance by heating a finely ground mix of accurately proportioned limestone and clay. He also invented the "Vicat needle" for the determination of setting times. He received many distinctions as a result of his product’s rapidity of manufacture and the savings it generated.