You may wonder why we don't use Roman concrete today if that is the case; well, one of the reasons as to why is because, although it gets stronger over time and withstands erosion from water, when this cement is still young and has not had time to develop its strength from seawater, it likely does not have the ...
Cons of Roman Concrete
A significant setback on Roman concrete is that it takes longer to set and cure, which can be problematic for construction projects. Due to the unavailability of materials around the world like volcanic ash, producing Roman concrete is difficult.
But how did their construction materials help keep colossal buildings like the Pantheon (which has the world's largest unreinforced dome) and the Colosseum standing for more than 2,000 years? Roman concrete, in many cases, has proven to be longer-lasting than its modern equivalent, which can deteriorate within decades.
It was a formidable tool of Roman engineering know-how. Yet, for all its advantages, concrete had one major defect: it was unsightly. Once the wooden formwork was removed, it showed an ugly surface. In the beginning, its use was mainly restricted to substructures where noone would see it.
Because both minerals take centuries to strengthen concrete, modern scientists are still working on recreating a modern version of Roman cement.
As it turns out, not only is Roman concrete more durable than what we can make today, but it actually gets stronger over time.
Why is Roman concrete more durable than modern concrete? Modern concrete is porous and degrades in contact with seawater. Seawater can seep into its pores, and when dried out the salts crystalize. The crystallization pressure of the salts produces stresses that can result in cracks and spalls.
Its strength was sometimes enhanced by the incorporation of pozzolanic ash where available (particularly in the Bay of Naples). The addition of ash prevented cracks from spreading. Recent research has shown that the incorporation of lime clasts allowed the concrete to self-repair cracks.
The research team found the ancient Romans made their concrete with quicklime, which is lime in its pure state, rather than the more typical slaked lime, and that this gave it "self-healing" properties.
During the Middle Ages, concrete technology crept backward. After the fall of the Roman Empire in 476 AD, the technique for making pozzolan cement was lost until the discovery of manuscripts describing it was found in 1414.
When tested, StarCrete had a compressive strength of 72 Megapascals (MPa), which is over twice as strong as the 32 MPa seen in ordinary concrete. Starcrete made from moon dust was even stronger at over 91 MPa.
Here's what you should know about Roman concrete, the strongest concrete on Earth. What is Roman concrete? Roman concrete, or opus caementicium, was developed over 2,000 years ago. It was used in a variety of structures, many of which still survive today.
For many years, researchers have assumed that the key to the ancient concrete's durability was based on one ingredient: pozzolanic material such as volcanic ash from the area of Pozzuoli, on the Bay of Naples.
It turns out the ancient Romans had the perfect recipe for water-resistant concrete. The material, called opus caementicium by the Romans, is made from a hydraulic cement, meaning it can set underwater or in wet conditions.
Roman Concrete didn't exactly follow a formula, and they don't appear to have done any controlled testing of how the material performed. That means the strength of a block of “Roman Concrete” was really up to a die roll, and ultimately wasn't as reliable as a modern approach.
Materials, Methods and Innovations
because it was more durable. Also, its off-white color made it an acceptable substitute for marble.
Unfortunately, the recipe for self-healing concrete was lost throughout the ages, and it is unclear when exactly its use as a building material waned. Scientists such as Masic have been studying samples of Roman concrete and cement to understand why this material is so strong.
Lime clasts and concrete's durability
Additional analysis of the concrete showed that the lime clasts formed at extreme temperatures expected from the use of quicklime, and "hot mixing" was key to the concrete's durable nature.
The Pantheon Dome is one of the most famous structures built from Ancient Roman concrete that can be seen in-person today. The dome was completed around 127 CE, during the reign of Emperor Hadrian.
Incredible facts about Roman concrete
Reinforced concrete (reinforced with steel rebar) did not exist. As a result, buildings lasted longer as they did not suffer from steel corrosion. Pozzolana (derived from volcanic dust) made the concrete more resistant to saltwater than our modern-day concrete.
Scientists develop a 'cosmic concrete' that is twice as strong as regular concrete. Summary: Scientists have created a new material, dubbed 'StarCrete' which is made from extra-terrestrial dust, potato starch, and a pinch of salt and could be used to build homes on Mars.
This analysis suggests that the materials undergo a rare chemical reaction. The concrete is made of quicklime, or calcium oxide, and volcanic ash. When seawater gets into its cracks, it causes a chemical reaction that actually strengthens the concrete.
One of the first forms of concrete used that still exists today can be found in the Pyramids at Giza, Egypt, which were built around 3,000 BC.
Technically, concrete never stops curing. In fact, concrete gets stronger and stronger as time goes on. But, as far as we're concerned, to reach a practical strength, most industrial concrete mixes have a 28 day curing period.
Despite their empire falling more than 1,500 years ago, the Roman recipe for concrete remains stronger than anything around today. And it's all thanks to seawater. Roman concrete combined volcanic ash, lime, volcanic rock and seawater.