Ancient Indus Valley engineers developed self-healing mortar for their public bathhouses
Engineers in the Indus Valley city of Mohenjo-daro utilized a self-healing gypsum mortar to create watertight public baths and advanced sewage systems in 2600 BC.
The Great Bath of Mohenjo-daro, constructed around 2600 BC, utilized a sophisticated waterproofing technique that rivaled 19th-century European engineering. The 12-meter-long pool was lined with a layer of bitumen and a specialized mortar composed of lime, gypsum, and sand. This mixture was engineered to be self-healing; when micro-cracks formed, the infiltration of water triggered a crystallization process that naturally resealed the gaps, maintaining a watertight seal against two atmospheres of pressure.
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