Ancient Roman Concrete 2K Years Old Roman concrete, aka concrete made 2,000 years ago by the ancient Romans has lasted amazingly well compared to modern concrete. Some data states that today's concrete starts to breakdown within 50 years. Actually, I have seen concrete for sidewalks start to flake off surface layers within 5 years. Yet, Rome’s famed Pantheon, which has the world’s largest unreinforced concrete dome dedicated in 128 AD is still intact. In the photograph on the left, I am standing next to concrete steps and the columns of a Roman Temple, now a Catholic Church in Assisi Italy. This structure was made over 2,000 years ago.
Now since some calculations say that manufacturing concrete today contributes 8% of carbon emissions world wide and our modern concrete can crumble within decades, especially when exposed to eroding environmental conditions, longer lasting concrete will help our environment by lowering carbon emissions.
So why does Roman concrete last thousands of years? The answer came this year in a 2023 study that used reverse engineering on samples of concrete made by the ancient Romans. A team of investigators from MIT and laboratories in Italy and Switzerland, discovered ancient concrete-manufacturing strategies that incorporated several key self-healing functionalities. One of several papers was published in the journal Science Advances.
First, everything previously assumed about ancient Roman concrete is wrong:
Under high-resolution with multi-scale imaging and chemical mapping techniques, researchers gained new insights into the potential functionality of "Lime Clasts" and the slaking process was not a contributing factor. Studying samples of ancient concrete, the small white particles were forms of calcium carbonate. Under spectroscopic examination it was determined they had been formed at extreme temperatures. This was the key to the super-durable nature of Roman concrete and the hot mixing produced compounds that would not otherwise form. Additionally, this increased temperature significantly reduces curing, setting and construction times.
Now since some calculations say that manufacturing concrete today contributes 8% of carbon emissions world wide and our modern concrete can crumble within decades, especially when exposed to eroding environmental conditions, longer lasting concrete will help our environment by lowering carbon emissions.
So why does Roman concrete last thousands of years? The answer came this year in a 2023 study that used reverse engineering on samples of concrete made by the ancient Romans. A team of investigators from MIT and laboratories in Italy and Switzerland, discovered ancient concrete-manufacturing strategies that incorporated several key self-healing functionalities. One of several papers was published in the journal Science Advances.
First, everything previously assumed about ancient Roman concrete is wrong:
- The one magic ingredient was pozzolanic material such as volcanic ash
- The various small particles in the concrete was due to poor mixing practices or just being sloppy
- The slaking process using water and lime to form a highly reactive paste material made the difference
Under high-resolution with multi-scale imaging and chemical mapping techniques, researchers gained new insights into the potential functionality of "Lime Clasts" and the slaking process was not a contributing factor. Studying samples of ancient concrete, the small white particles were forms of calcium carbonate. Under spectroscopic examination it was determined they had been formed at extreme temperatures. This was the key to the super-durable nature of Roman concrete and the hot mixing produced compounds that would not otherwise form. Additionally, this increased temperature significantly reduces curing, setting and construction times.
Rome's Trevi Fountain With Water via 2K Year Old Aqueduct Studies conducted show that the hot mixing process has the lime clasts develop brittle nanoparticulate architecture, thus creating the ability for self healing. If a crack started in the concrete, a reaction would start with water and create a calcium-saturated solution that would recrystallize as calcium carbonate filling the crack. This adds further strength to the concrete and heals cracks before they can spread. Recent examination of ancient Roman concrete samples exhibited calcite-filled cracks.
To test this mechanism, which was responsible for the durability of the Roman concrete, samples of hot-mixed concrete were made and then deliberately cracked. Water was sent through the cracks and within two weeks the cracks had completely healed. As a result of these successful tests, work is being done to commercialize this modified concrete material.
If commercializing is successful, this "old made anew" concrete material will help improve the durability of the 3D Printing of concrete homes for the poor, (see previous GTG blog post of this topic) save money in production and time, less concrete manufacturing due to this concrete having a longer lifespan, and help reduce greenhouse gas emissions.
Bill Lauto, at GoingTrueGreen.com
Environmental Scientist
International Sustainability and Energy Consultant
Contribute your comments!
To test this mechanism, which was responsible for the durability of the Roman concrete, samples of hot-mixed concrete were made and then deliberately cracked. Water was sent through the cracks and within two weeks the cracks had completely healed. As a result of these successful tests, work is being done to commercialize this modified concrete material.
If commercializing is successful, this "old made anew" concrete material will help improve the durability of the 3D Printing of concrete homes for the poor, (see previous GTG blog post of this topic) save money in production and time, less concrete manufacturing due to this concrete having a longer lifespan, and help reduce greenhouse gas emissions.
Bill Lauto, at GoingTrueGreen.com
Environmental Scientist
International Sustainability and Energy Consultant
Contribute your comments!
Research was done by Janille Maragh at MIT, Paolo Sabatini at DMAT in Italy, Michel Di Tommaso at the Instituto Meccanica dei Materiali in Switzerland, and James Weaver at the Wyss Institute for Biologically Inspired Engineering at Harvard University. The work was carried out with the assistance of the Archeological Museum of Priverno in Italy.
