L'Invention du beton arme: Hennebique, 1890-1914 (review)

L'Invention du béton armé: Hennebique, 1890-1914. By Gwenaël Delhumeau. Paris: Editions Norma/Institut français d'architecture, 1999. Pp. 344.

The rapid acceptance of reinforced concrete as a construction material between 1890 and 1914 is one of the most striking developments in the history of building technology. What makes this pioneering era so interesting is that concrete structures spread worldwide and yet, as S. B. Hamilton notes, the material was "deeply mysterious in its basis of design." Not only was there little reliable information regarding its use, but it was sold mainly in the form of proprietary systems, and patentees resisted revealing their calculations. Despite the uncertainties, however, investors took the plunge, and within a short period reinforced concrete structures went up around the globe. And some collapsed, too.

One of the most important pioneer firms was that of François Hennebique. In L'Invention du béton armé, Gwenaël Delhumeau discusses the rise of this firm and the reasons for its success. It achieved prominence quickly: in 1892, the year it was founded, it made studies for seventy-one projects, of which six were executed; seven years later, following steady annual growth, it completed more than twenty-seven hundred studies, of which more than twelve hundred were executed. The question Delhumeau addresses is this: How did a self-educated builder manage so successfully to sell his new and unproven product and build an international business?

Delhumeau's book is organized topically. In the first chapter, he discusses Hennebique's technology—a combination of metal and mortar or concrete—along with his patents, the best known of which was a system for floor construction consisting of metal stirrups around reinforcing bars. Chapter 2 treats the organization of the firm, which took the form of a central office that, with regional branches, handled project design and oversight and local contractors whom Hennebique recruited and licensed to do the actual construction. In the central office—first in Brussels, after 1898 in Paris—Hennebique's staff of engineers and draftsmen (and, for a time, architects) produced drawings and calculations; here, too, Hennebique trained agents and licensees to build according to his methods.

Right from the start, Hennebique sought out large projects that would give him maximum exposure. Publicity was an important part of the firm's commercial strategy. It published a company organ, Le Béton armé, intended for agents and contractors but also aimed at influencing potential clients. There were technical articles and information on projects and tests of structures, the latter illustrated with the ever popular photos of concrete floors loaded with a mountain of cement sacks. Delhumeau's last two chapters deal with Hennebique's relations with architects, with competitors, and with regulation. In answer to the central question—why did investors accept reinforced concrete?—he suggests that is was due to its real advantages: reinforced concrete was an economical solution to many problems, one of the most serious of which was the protection of buildings from fire. Many of Hennebique's early customers had owned buildings that burned down, or they planned to put up structures, like textile or flour mills, that housed hazardous operations. Their need for noncombustible buildings induced them to take a chance and Hennebique was ready and able to convince many of them to select his system.

In his research, Delhumeau has drawn on the archive of the Hennebique firm, at the Institut Français d'Architecture in Paris. This remarkable collection includes roughly eighty thousand project files, sixty-five hundred photographs, and other materials dating from the founding of the firm until it closed in 1967. Because he helped process this collection, Delhumeau was uniquely placed to learn details about the firm. But this immersion may also account for the narrow focus of the book, which only incidentally addresses the context in which the firm developed. Even though the organization sometimes seems random...