Forensic multi–analytical characterization of mid–20th century historic concrete: the Berlin Wall

Abstract

Thirty-six years after the fall of the Berlin Wall, its surviving concrete fragments remain powerful material witnesses of twentieth-century history and modern construction practices. Despite its global symbolic value, the concrete of the Berlin Wall has not previously been subjected to a systematic scientific investigation. The objective of this study is to provide a forensic, conservation-oriented characterization of selected Berlin Wall concrete elements preserved under the custody of the Berlin Wall Foundation. The scientific novelty of this work lies in presenting the first multi-analytical material study of Berlin Wall concrete, with a deliberate focus on binder composition, microstructure, and degradation processes; mechanical testing and reinforcement characterization are intentionally beyond the scope of this investigation. A complementary analytical methodology combining Raman spectroscopy, TGA–DSC, and FESEM–EDS is employed to assess material composition, state of conservation, and long-term alteration mechanisms. The results indicate a highly carbonated cementitious matrix dominated by calcium carbonate phases, while residual calcium silicate hydrate (C–S–H) and unhydrated clinker particles, particularly belite, remain detectable. Microstructural observations reveal a dense matrix with quartz- and calcite-rich aggregates and localized sulfate-enriched zones associated with prolonged environmental exposure. These findings provide a robust material basis for conservation strategies applied to modern concrete heritage and contribute to a deeper understanding of the Berlin Wall’s material history and preservation challenges.