Foundations for Imperium: Investigating waterproof mortar technology in Roman Italy

Abstract

Water accessibility in the ancient Mediterranean reached its zenith during the Roman Empire, where at its height, Rome was supplied by eleven aqueducts that carried massive quantities of water for hundreds of kilometres to the city. This unprecedented scale of water manipulation was in part enabled by advancements made in waterproof mortar technology during the late Republic and Early Empire in Naples, Pompeii and Rome, where builders experimented with adding light-weight volcanic ash to create a new type of mortar. This improved mortar was water insoluble, highly durable and could set when submerged in water. These unique properties made it ideal for use as a lining in water infrastructure and quickly the raw materials and knowledge needed to produce this specialised technology were being traded outside Italy to the rest of the Empire. However, as traditional Mediterranean cultural systems transformed in Late Antiquity and urban populations dispersed, the complexity of Roman mortar made replicating it impractical, leading to its decline and eventual disappearance. Consequently, water accessibility diminished in Europe to the point that Roman standards would not return until the Industrial Revolution some 1100 years later. 

This presentation will explore the unique social, economic and political factors that drove the development and spread of Roman waterproof mortar technology from the 1st century B.C.E. – 4th century C.E. by analysing the results of optical microscopy and digital image analysis conducted on mortar samples collected from across the Bay of Naples, Rome and Pompeii. 

About the presenter 

Rory is a UQ graduate who completed his Honours degree in November of 2021. Since then, he has continued his research into Roman waterproof mortar technology and is currently in the application process for a Master of Philosophy through the school of Historical and Philosophical Inquiry.