Materia e forma: il ritorno della terra cruda nel progetto contemporaneo. Tecniche, sperimentazione progettuale e valore culturale nell’innovazione tecnologica del costruire in terra battuta

The essay examines the transformation of the rammed earth technique (taipa or pisé) from an ancestral building practice into a sustainable and innovative solution for twenty-first-century architecture. Rammed earth is an ancient construction technique based on the compaction of raw earth within formworks, widespread across many civilizations and regions (Asia, North Africa, the Mediterranean basin, and the Americas). In Portugal, it found broad application in the southern regions such as Alentejo and Algarve, characterized by clayey soils and dry climates. This architectural heritage possesses not only material value but also an intangible dimension, connected to traditional know-how and collective, participatory building processes that have now almost completely disappeared. Traditional taipa constructions in the Alentejo Litoral were simple, with low heights, small spaces, and gently sloping roofs. However, during the twentieth century, with the spread of industrial materials such as concrete, taipa was progressively marginalized (in Portugal beginning in the 1950s). This abandonment was driven by a cultural and value crisis that associated earth with ideas of backwardness and poverty—a prejudice that modern architects had to overcome. Contemporary Renaissance and Technological Innovation Since the 1990s, there has been a renewed interest in earthen architecture, no longer limited to preservation but aimed at its valorization as an identity resource and a factor of competitive differentiation. Taipa is now seen as an intrinsically sustainable solution, aligned with contemporary environmental and cultural challenges. This rediscovery has been driven by technological innovation, which allows overcoming the historical limitations of the artisanal technique. The evolution of taipa is based on three main vectors: Prefabrication and Industrialization: The development of prefabrication in controlled environments makes it possible to produce standardized or customized rammed-earth elements with high precision and quality. This approach integrates taipa into contemporary production flows, making it compatible with digital tools such as BIM and parametric design (mass customization), and freeing it from its exclusive association with rural or marginal architecture. Automation and Robotics: The introduction of robotics and automation is transforming the construction process. Robotic systems allow precise mechanical compaction and the creation of complex “free-form” geometries impossible with traditional formworks. Moreover, automation enables targeted control of the mixture and stratification, generating chromatic and tactile effects directly on the wall surface, turning it into an expressive and narrative element. Hybrid Systems: Taipa is increasingly being integrated with other materials (such as concrete for foundations and lintels, or tensioned steel) to improve structural strength and durability—especially in seismic contexts—while maintaining physical-chemical compatibility and breathability. Examples such as the Prestressed Earth Furnace Tower in Switzerland demonstrate the feasibility of post-compressing earthen walls. The current evolution of taipa is not merely an update of an ancient technique but a systemic reformulation of the construction process that combines sustainability, technology, and architectural language. Taipa thus emerges as a cultivated material and a key component for ecological transition, offering solutions for an architecture that enhances territorial identity and bridges constructive memory with the most advanced technological possibilities.