Anonymous; Vitruvius (1st century BCE) wrote about the materials in his treatise On Architecture
Plate 022
c. 200 BCE onward
Roman Italy
No photograph is shown for this exhibition. The museum displays an image only where it can show the object honestly.
About this date
Roman builders used lime mortar earlier. Large-scale concrete made with volcanic ash is generally dated to the 2nd century BCE. The Pantheon dome was completed in the 120s CE.
About credit
The recipe developed within Roman building practice. Vitruvius described materials and methods but did not invent them.
Chapter II
The world before
Life before Roman Concrete
Large buildings were made of cut stone blocks or fired brick, which limited the shapes and spans achievable.
II
The human achievement
How it came about
Roman builders mixed lime with volcanic ash (pozzolana) and aggregate. The mixture set by chemical reaction, even in water. Used with brick facing, it formed the Pantheon’s dome, whose span of about 43 metres remained the largest unreinforced concrete dome for many centuries.
III
Understanding the invention
How it works
Roman Concrete, explained in two steps.
01
Step 01 of 02
Ash that reacts
Volcanic ash reacts with lime and water to form a hard, durable binder, which is why Roman marine concrete lasted.
Ash that reacts
Lighter at the top
IV
The transformation
What changed for humanity
Architecture
Vaults and domes created large interior spaces such as baths and the Pantheon.
Infrastructure
Harbours, bridges and aqueducts could be built more quickly and cheaply.
Concrete could be poured into any shape, so builders no longer depended on cut stone. It made large interior spaces, harbours and aqueducts possible.
V
Before and after
Life before and after Roman Concrete
Before
Timber beams or small stone arches.
After
A concrete vault spanning wide spaces.
On larger screens, drag the divider (or use the arrow keys) to give more room to the world before or after.
VI
Its legacy
What came after
MHI 022
Roman Concrete
Beyond the collection
Modern concrete
Portland cement, patented in 1824, revived the material in modern form.
Beyond the collection
Skyscrapers
Reinforced concrete allowed tall buildings.
VII
Human stories
The people and the moments
Why it lasted
Researchers studying Roman harbour concrete have found that seawater helped form new minerals over time. The details of the original recipes are still being studied.
Where accounts differ, this museum follows the documented record and says so.
