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Pompeii Construction Site Confirms Romans Used Hot-Mixed, Self-Healing Concrete

Researchers link quicklime blended with volcanic ash to lime clasts that mend cracks through chemical reactions.

Overview

  • A Nature Communications study led by MIT’s Admir Masic with the Pompeii excavation team analyzes in-situ materials and walls preserved by the 79 CE eruption.
  • Excavators found unfinished rooms with premixed dry piles containing intact quicklime fragments, volcanic ash and aggregates, plus weights and measuring tools consistent with controlled ratios.
  • Microscopy, spectroscopy, and isotope data reveal hot-mixing signatures, including fractured lime clasts and calcium-rich reaction rims that grew into ash particles.
  • The authors call this the clearest archaeological support to date for hot mixing and self-healing behavior, while noting the absence of direct procedural records from antiquity.
  • Findings challenge readings of Vitruvius’s slaked-lime account and are being positioned to inform more durable, lower-maintenance modern concretes, with Masic’s startup DMAT pursuing applications.