The construction process consisting in ramming local raw earth in wooden formworks has been used since Antiquity. In the Mediterranean region, the scientific community recognizes the invention of this massive earth construction process (opus formarium) by the Phoenicians who founded the colony of Carthage, in 814 B.C., on the famous hills of Byrsa (actual site of Tunis). This does not preclude this building process having been imagined elsewhere, by other cultures and in other times, or transferred (Latin America, United States, Australia). But, on this question, no exhaustive balance has been made. At Carthage, though the local construction way has been recognized as very eclectic, mixing several materials (notably stone and earth) filling a construction system in masoned pillars (opus africanum), pisé was commonly used until the destruction of the city by the Romans, as it has been clearly shown with the archaeological report on the excavations undertaken during the 1970’s by Serge Lancel and Jean-Paul Thuillier (1982). The Mediterranean and North-African substratum of the pisé culture was laid down and, without any doubt, influenced the Roman earthen construction practices that are then described in Varron’s writings (De Res Rusticae, I, 14, 40) and those of the Spanish Columelle (De Re Rustica, X, 1, 2 et XI, 3, 2), during the 1st Century A.C., and then in Palladius’ writings during the 5th Century (Opus Agriculturae, I, 34). This cultural substratum will be reappropriated by numerous Iberian authors who are bearing
of G.C. Goiffon, the “Journal de Physique” (1772) and the “Cours Complet d’Agriculture” (1786) of the French Abbot Rozier in which the Lyonese architect François Boulard (at the request of the Abbot) offers a more methodical description of the technique (quality of the soil, tools and construction process). With his famous “Cahiers d’école d’architecture rurale” (1790 et 1791), François Cointeraux will take place in this long line of generalist, technical and economical essays on pisé that will become fully recognized with the “Traité théorique et pratique de l’Art de Bâtir” of Jean-Baptiste Rondelet (1840) describing the pisé construction method traditionally used in the region of Lyon and Dauphiné. So, it is on this ancient Mediterranean substratum, then modern and European (translations of François Cointeraux), that the technical pattern of the traditional pisé, was passing through centuries and was at the same time transferred to far away continents and countries, but without any fundamental questioning nor innovation, just accepting some regional or local variations. The Industrial Revolution of the 19th Century initiated a declining process of the traditional pisé technique that was lately confirmed in France with the extermination of carpenters (traditionally in charge of building in pisé) who were mobilized for timbering the trenches during the First World War and many of them were killed. This declining process came to an end in the 1950’s. Today, pisé mainly exists in developing regions where the building culture is still alive and where the intensive manpower is cheap. Even if there was a revival of pisé in France (P. Dufournet, 1950), and in Australia (G.F. Middleton, 1953), it is only during the 1970’s that we can observe a rebirthing of pisé construction resulting of the two successive energy crises (1973 and 1979). A process of new experimentations and innovation closely associating technique and economy, contributes to the development of new types of “climbing” formworks and then new techniques for prefabricating pisé blocks in situ (N. Meunier, 1987), or pier walls (M. Rauch, 2001). All these innovations were directed at lowering the executing costs in regions where the intensive manpower for building in pisé is very expensive. Today, contractors wishing to go on building in pisé, in industrialized countries, are facing an economical handicap of the technique and also a limited market, despite new arguments in favor of pisé being promoted. If economical arguments, more than ever before, are still very influent, energetic considerations seem to supplant them with the paradigm of sustainable development. The thermal properties of the material (mass, inertia) and the comfort control (hydrous transfer) are much more valorized. Therefore, we observe new trends in favor of the use of pisé in
outer or inner envelope, or skin and, more ahead, in the direction of new techniques for building in massive earth from the use of poured earthen concrete as soon as the rheology (the pouring of the material) will be better controlled. Outside the regions of the world where the traditional pisé is still used and viable, the hybridization of the materials and building systems is taking the lead and stimulates the development of research and development (R&D) programs (see the “Grands Ateliers”, in Villefontaine, France, and enterprises that are taking out patents), as much more contemporaneous architectural achievements are showing (U.S.A, Australia, South Korea, …). So, with the promised development of the new “clay” concretes, new technical, economical, construction and architectural perspectives are opened. In counterpart, this inevitable evolution could act for the disappearance of the “old pisé” at the advantage of a true “new pisé” to which François Cointeraux, also inventor of the compressed block, was already dreaming.