Albert Irénée Caquot (French pronunciation: [albɛʁ iʁene kako]; 1 July 1881 – 28 November 1976) was a French engineer. He was awarded the “Croix de Guerre 1914–1918 (France)” (a military honor) and received the Grand-croix of the Légion d’Honneur in 1951. In 1962, he was given the Wilhelm Exner Medal. He was a member of the French Academy of Sciences from 1934 until his death in 1976.

Early life

Albert was born to Paul Auguste Ondrine Caquot and his wife, Marie Irma (born Cousinard). The family owned a farm in Vouziers, a region called the Ardennes, close to the border with Belgium. His father taught him about new technologies by installing electricity and a telephone in their home as early as 1890. One year after finishing high school, at the age of eighteen, Albert was admitted to the Ecole Polytechnique in the year 1899. Six years later, he completed his studies and joined the Corps des Ponts et Chaussées, a group of engineers responsible for building roads and bridges.

Career

From 1905 to 1912, he worked as a project manager in Troyes (Aube) and was recognized for improving the city’s sewer system. These improvements helped protect the city from a major flood on the River Seine in 1910. In 1912, he joined a top structural engineering firm, where he used his special skills in designing structures.

Albert Caquot conducted research and quickly applied it to construction. His most important contributions include the following:

• Designing with reinforced concrete and other structural engineering methods. In 1930, he identified the intrinsic curve and explained why the elasticity theory was not enough for modern structure design.
• Geotechnics and foundation design. He introduced the corresponding states theorem (CST). In 1933, his work on the stability of loose and solid materials received praise from the French Academy of Sciences, where he became a lifetime member in 1934. In 1948, with Jean Kérisel, his son-in-law and student, he developed a theory important for understanding passive earth pressure, where soil and walls interact. This principle is widely used today in structures like retaining walls, tunnels, and foundation piles.
• Reviving the use of reinforced concrete in cable-stayed bridges, such as the Donzère-Mondragon Bridge (1952). He imagined building long bridges, even across the English Channel. In 1967, he designed a concept for a double-deck bridge with 810-meter spans and two 25-meter-wide decks for cars, trains, and Skytrain.

Throughout his life, Albert Caquot taught mechanical science at three of the most important French engineering schools in Paris: Écoles nationales supérieures des Mines, des Ponts et de l’Aéronautique.

During his career as a designer, he created over 300 bridges and facilities, several of which held world records at the time:
• The La Madeleine Bridge in Nantes (1928), a concrete cantilever bridge over the River Loire.
• The Lafayette Bridge in Paris (1928), a reinforced concrete truss bridge where compressed air vibrators were used for the first time.
• The new La Caille Bridge (1928) in the Alps, a 140-meter-span concrete arch bridge.
• The Louis Joubert dry dock (Normandie-Dock) in Saint-Nazaire (1929–1933).
• The La Girotte Dam (1944–1949).
• The Bollène lock on the Donzère-Mondragon Dam (1950), the world’s tallest lock.
• The Bildstock tunnel (1953–1955).
• The world’s largest tidal power plant on the River Rance in Brittany (1961–1966). In his eighties, he helped design an enclosure to protect the construction site from 12-meter-high ocean tides and strong currents.

Two major achievements made him famous internationally:
• The internal structure of the Christ the Redeemer statue in Rio de Janeiro, Brazil, on Corcovado Mountain (1931).
• The George V Bridge on the Clyde River in Glasgow, Scotland, where Scottish engineers asked for his help.

In his late eighties, he planned a large tidal power project in Mont St Michel Bay, Normandy.

Throughout his life, he worked in both structural and aeronautical engineering, influenced by the First and Second World Wars. His aeronautics work included designing the "Caquot dirigible" and creating fluid mechanics institutes at the French Aviation Ministry, which still exist today. Marcel Dassault, who worked with Albert Caquot early in his career, said he was one of the best engineers in aeronautics. Albert Caquot was visionary and led aeronautical innovations for forty years.

As early as 1901, he served in an airship unit of the French army. At the start of World War I, he was mobilized with the 40e Compagnie d’Aérostiers, using Drachen-type airships as a first lieutenant. He noticed that these balloon-like airships were ineffective in windy conditions.

In 1914, he designed a new airship with three air-filled lobes as stabilizers. He moved the inner air balloon from the rear to the underside of the nose. The Caquot airship could stay horizontal in 90 km/h winds. France produced "Caquot dirigibles" for Allied forces, including the English and U.S. armies, for three years. The U.S. also made nearly a thousand "Caquot R balloons" in 1918–1919. These balloons improved military observation and helped Allied forces win the war. In January 1918, Georges Clémenceau named him technical director of military aviation. In 1919, Albert Caquot proposed creating the French aeronautical museum (now called Musée de l’Air et de l’Espace in Le Bourget), the world’s oldest aeronautical museum.

In 1928, Albert Caquot became the first director of the new French Aviation Ministry. He focused on research, prototypes, and mass production, helping France become a leader in aeronautics.

Legacy

On July 2, 2001, France released a stamp valued at 4.5 French francs (0.69 euros) to honor Albert Caquot. The stamp was issued to mark the 120th anniversary of his birth and the 25th anniversary of his passing. Albert Caquot’s image appears on the stamp, surrounded by two of his inventions: the “Caquot dirigeable” (a type of airship) and the bridge of La Caille.

Since 1989, the Prix Albert Caquot has been given every year by the French Association of Civil and Structural Engineering.