What We Can Really Learn From Ancient Roman Concrete
The secret to why concrete structures built in the time of Ancient Rome are still standing may have finally been fully discovered. It turns out that the Romans really knew what they were doing when they built with concrete, in contrast to modern man whose concrete structures rarely last longer than 100 years.
Some of the concrete structures in Ancient Rome are not only still standing but, if anything, are probably even stronger than ever. By contrast, the same types of structures built in modern times often only last several decades. Bridges are frequently removed and rebuilt after only 50 years, and roadways are constantly in need of repair. Buildings may last longer, but they often reach a time for teardown and replacement that is not just dictated by the desire to construct a more modern building.
According to Marie Jackson, a University of Utah geologist, part of the reason for this difference concerns the nature of the concrete used. Back in Ancient Roman times, the concrete mixture included lime and sea water as a starter base, which the builders then mixed with volcanic rock (that era’s aggregate). They did this in part because that kind of rock was widely available at the time but also because they had observed naturally occurring deposits of tuff – igneous rock that contains fragments of bedrock, tephra and volcanic ash. The Romans copied what Mother Nature had carefully laid out in front of them.
When conventional Portland cement is cured, there is a hydration reaction that produces two very different by-products. One is calcium silicate hydrate (CSH), a substance that forms the glue that binds the aggregates together. A second is calcium hydroxide (CH), which, unfortunately, works in opposition to the CSH and actively helps undermine the strength of the Csh-aggregate bonds. This is part of why modern concrete is intentionally designed to be as inert as possible, because, otherwise, the presence of the CH would tend to prematurely tear apart the concrete.
The materials the Ancient Romans selected for their concrete mixture included the natural pumice pozzolan, a compound present in the volcanic materials there that “switches on” what is today referred to as a “pozzolanic reaction” when mixed with the hydrated concrete paste. That reaction ends up converting a significant amount of the useless CH by-product into more of the CSH. The pozzolanic reaction, therefore, effectively makes the concrete stronger even from the first day it is poured.
As Jackson looked further into comparing the old Roman structures to modern ones, she began noticing other differences. One important one (beyond the pozzolanic reaction process) was the presence of extensive mineral intergrowths that exist between the volcanic aggregates and the ancient concrete mortar. Those intergrowths keep the natural cracks that occur in any concrete over time from widening in the Romans’ version. In modern Portland cement structures, there are no such intergrowths to hold things together.
The last discovery made by Jackson was a big surprise and is perhaps the real secret to the longevity of the older concrete. Jackson and her team were given a chance to evaluate drill cores of concrete gathered from Ancient Roman harbors. Within those cores was a very rare mineral, aluminous tobermorite (Al-tobermorite). Not only does it show up very rarely in nature but it is also extremely difficult to synthesize, especially at the relatively low natural temperatures present there.
After (literally) digging further – and with the help of exotic examination tools like microdiffraction and microfluorescence provided by the Lawrence Berkeley National Laboratory – Jackson’s team saw that both Al-tobermorite and phillipsite, a similar mineral, had formed in the pumice particle and micropores within the cementing matrix. Their specific crystalline shapes tend to hold aggregates tight over time.
This research defined the raw materials present in the concrete mixture, but there was still one missing piece of the puzzle: how the deposits could grow over time. What the team figured out, after even more study, is that the regular soaking of the marine concrete deposits with sea water caused the normally-quite-corrosive briny water mixture to penetrate through the unique concrete structure. As each new splash of water made it through, some of the volcanic ash present dissolved. The resulting slurry then provided a base for new minerals to grow and then bond with the aggregates and already-existing concrete.
The result was a concrete mixture that, over time, not only healed itself of minor cracks but also became stronger with each succeeding wave – provided, of course, that the waves involved were not too intense.
In the end, the combination of the presence of volcanic materials in the aggregate, the volcanic ash, the resulting pozzolanic reaction, the presence of Al-tobermorite and phillipsite in the end product and then the constant washing by sea water produced a concrete that did more than just survive over time. It thrived.
The Ancient Roman solution also did one other thing that puts it far ahead of conventional Portland cement: Its creation produced a lot less carbon dioxide.
In contrast to the relatively low temperature and naturally occurring pozzolanic chemical reaction mentioned above, Portland cement is made by heating limestone to over 2,000°F. This not only requires a great deal of fossil fuel energy (just to heat the limestone) but the reason for heating the limestone is in part to bake the embedded CO2 out of the naturally occurring compound built into the tiny marine organ- ism structures that helped form the limestone in the first place. The combination of both ends up releasing a great deal of CO2 into the atmosphere.
The total amount of CO2 emitted currently in the process of making Portland cement works out to be about a pound of CO2 created for every pound of Portland cement manufactured. And there are billions of tons of Portland cement manufactured throughout the world every year.
Contrast that with the manufacturing process of the Ancient Roman marine concrete. In that process, the pozzolanic reaction actually consumes some of its waste products as it cures. It is also “manufactured” without the 2,000°F fossil-fuel-powered kilns needed for Portland cement. It is therefore far “greener” and far less damaging to the environment, with an estimated total carbon footprint that’s less than one-tenth that of its modern counterpart. And this only takes into consideration the initial manufacturing process. When you consider longevity, the carbon savings are vastly more.
Now that the Ancient Roman concrete recipe has been rediscovered, the next step for Jackson’s team is to see if there is a way to reinvent it for modern times and actually convince people to use it. That could result in major value for the construction industry – and beyond.
What the researchers have not thoroughly explored is just how the Romans came to develop such technology. Was it really developed by accident, just from using materials readily available to them, or was the knowledge handed down to them from an even earlier civilization?
While mainstream archaeologists disagree, the ancient Egyptians had their own methods for producing long-lasting concrete, and some of the stones in the great pyramids were cast concrete, not stone blocks.
The story of how those pyramids were built is wellknown to many brought up in Western countries. Supposedly there were great stone quarries in existence at a distance from the construction site. From there, large stone blocks were cut out, using the tools of the time – supposedly tools made of copper, a common enough but soft metal. Thousands of laborers – who invested sweat and blood and often died in the process – were involved in every build. That part has been explained – and even fantasized – in children’s books and in movies like The Ten Commandments. It is part of our common mythology about this once-great ancient civilization.
Strangely, though, for a people who documented almost every aspect of their lives so well, this pyramid-building thing, which must have consumed a great amount of time and many people to manage, was somehow never documented in the Egyptians’ hieroglyphs. All that cutting of stones, moving them to the assembly site and lifting them up with ramps resulted in no images at all. And there are also no signs of the housing where the workers would have lived – nor are there any traces of the tools they supposedly used to carve out the stones.
As in any scientific field, it took some strong creative thinkers to consider another option. One of the more radical of these thinkers was Joseph Davidovits, a French materials scientist. His answer to the puzzle, put forth in the mid-1980s, was that the reason there was no great housing tracts, no trace of the tools and no illustrations or telling of the construction process suggested above was that it all never happened. Instead, Davidovits hypothesized that the Egyptians created the blocks used to build the pyramids with concrete poured on-site into wooden molds.
The concrete he imagined has some significant similarities to what the Ancient Romans used at their breakwaters and marine areas, at least in how it was formed. Davidovits guessed that the mixture was composed of clay, water, lime and crushed limestone mixed with a water slurry to form an alkaline substance. He further considered – and the brilliant simplicity of the concept is what makes it even more logical – that the blocks were built and assembled in place and as they cured and solidified, they would press against one another and settle precisely into place. It was a far simpler idea than having to ensure the precision of cutting each individual block to exact requirements. The joints between the blocks would also naturally form from the pressing together of the edges of the blocks.
Further evidence has backed up the concept of blocks being formed in place – or nearly in place.
Michel Barsoum, a professor of materials science and engineering at Drexel University in Philadelphia, and Gilles Hug of the National Center for Scientific Research in France decided to investigate Davidovits’ theories using a microscope, X-rays and chemical analysis of bits of stone from the pyramids. They discovered that a small but significant percentage of the blocks on the higher portions of the pyramids were indeed cast from concrete.
Barsoum’s team further discovered that while Davidovits was on the right track, there was one key difference in the Egyptian concrete. Electron-microscope analysis showed that instead of ordinary clay, the mix- ture featured Diatomaceous earth as the “clay” component. Its combination of being a soft sedimentary rock with embedded fossilized remains of algae made it a far more active combination during the curing process. Also, like the ever-restructuring and hardening nature of the seaside Roman concrete, this type of material tended to resettle, restructure and strengthen – rather than weaken – over time.
As for the building process for the overall pyramid, based on a combination of what the team had actually seen of the real building blocks and their own theories, Barsoum and company thought it could be logical that some cut stone blocks might have been used near the base, as a foundation of sorts. Then, as the construction continued to move farther up to the top and it became more challenging to lift the stones to the higher levels (even with complex ramps), the construction process shifted to a higher percentage of poured concrete.
The team analyzed this with considerable scientific rigor, with photographic study, chemical analysis and modern microscopic and structural materials analysis to back up their studies. Their results pointed to pyramids where their lower sections were likely formed from cut rock and the higher sections made from geopolymer blocks that had been formed in place – or nearly in place.
One piece of evidence Barsoum’s group found that supports this theory came from an examination of some of the pyramids’ building blocks that archaeologists have referred to as “backing blocks.” These were never intended to be seen by anyone and yet had precise features that appeared to many like they had been precisely cut. Why they would have been precisely cut when that would have required more work is a puzzle, with the far more logical explanation being that they were simply cast in place and the forms were precise because of having been molded in place.
A second example was in the places where the blocks were irregularly shaped rather than all being precisely cut – something that occurred far more often than the Hollywood versions of all of this would have one believe. In those places, if the blocks had simply been cut to different sizes and fit together, not only would this have made the whole assembly process far more difficult but it would also have resulted in gaps between the blocks. Yet the structure did not have any gaps. Instead, the irregular blocks were precisely fit together, evidence that supports a “molded in place” concept where the blocks were pressed together and the seams between them naturally filled out.
A scientist who built further on both Davidovits’ and
Barsoum’s work was Linn Hobbs, a professor of materials science and engineering at the Massachusetts Institute of Technology. Hobbs and his students wanted to better understand what kinds of concrete mixtures might have been available to the construction leaders of the time. Using their understanding of what was naturally occurring and doing some reverse engineering of their own, they hit upon one critical new (actually, “old”) ingredient that was definitely available and used by the Egyptians of the time: natron salts.
These salts were readily available to the ancient Egyptians, formed naturally as salty lake beds evaporated. The natron salts had one other famous use: They were part of the mummification process. They also become alkaline when exposed to water, which, in turn, made them an excellent activation substance for the geopolymer reactions. The final mixture that Hobbs and his team ended up rediscovering was a geopolymer concrete of natron salts, crushed limestone, kaolinite and silica.
A logical next question is “Where did the Egyptians get their technique for making concrete that lasts thousands of years, along with all the other advanced technology that seems to have just appeared in a very short period of time?”
While much of the technology likely came from Sumer, where human civilization first arose, the Egyptians themselves may have left an answer to the big question of where their technology ultimately came from.
In the Temple of Horus, also known as the Temple of Edfu, hieroglyphs tell a fascinating story that provides important clues to our true history and helps explains many of the anomalies that archaeologists have tried to cover up.
Some of the inscriptions in the temple suggest that its lay-out was designed by a pre-dynastic group of people, known as the Shemsu Hor, the “Followers of Horus”. The text also tells the same story of an ancient advanced civilization as Plato’s story of Atlantis. Yet, mainstream Egyptologists have suppressed or ignored this vital information and presented a false narrative not supported by the evidence.
Could advanced concrete technology indeed been handed down by survivors of a highly advanced ancient civilization?
Suppression of Our Real History
Roman and Egyptian concrete are just one example of how our history has been lost or deliberate efforts made to keep it concealed. Our modern civilization suffers because of this loss of ancient knowledge, but it doesn't all have to be lost.
In addition to the Egyptians, the ancient Sumerians left behind a vast written record of their own civilization and the earliest human history on clay cylinders. This record is of immense importance, and translating and studying it should be a very high priority.
Yet of the more than 500,000 cylinders that have been discovered so far, only a tiny percentage have been translated and access to the cylinders remains restricted. Some of them that have been translated tell a fascinating story that could transform modern society – if only the information was more widely disseminated and accepted.
The books of the Bible’s Old Testament are predated by the Sumerian texts. But most Christians would rather believe their distorted comic book version instead of the original, more accurate and authentic record.
It is the same with the more modern New Testament. We now know that much of it was fabricated by the Romans to hijack early Christianity. We know this because we now have authentic texts used by the early Christians – the very texts the Romans sought to destroy because they contradicted the new Roman version of Christianity.
The texts were discovered in 1945 by two Egyptian brothers while they were digging for fertilizer around the Jabal al-ārif caves close to the Upper Egyptian town of Nag Hammadi. The texts consisted of 13 leather-bound papyrus codices buried in a large sealed clay jar. Being Muslim, the brothers’ mother burned some of the texts and they were lost forever. What wasn’t burned was sold or given to a Coptic priest for safe-keeping. Eventually the texts made their way to Cairo and were seized by the government. One book was sold outside the country and given to the famous psychologist Carl Jung.
Despite their importance, most of the texts were not translated until the 1970s. The first translation was published in 1977, but it was not until 1988 that the full translated texts were made widely available in English.
The Nag Hammadi library tells a much different and certainly more accurate story of Jesus and his time. One of the books claims to have been written by Jesus himself.
The texts include many of those that the Roman church banned and sought to destroy because they did not support the Roman version of Christianity, which was a system for social control – not the spiritual and intellectual liberation that the real Jesus taught.
Today, most people calling themselves Christians have still not heard of the Nag Hammadi library and when informed of it show no interest in reading the authentic new testament. They are happy to continue their devout belief in a mythology that was invented by the Roman government to undermine the teachings of Jesus.
As we reach the end of our modern carbon-fueled civilization, it is high time that we discover our true history and learn from it. It is time for us to build a new civilization based on intelligent and sustainable technology and adopt a new way of thinking about ourselves and our place in the world that is based on reality and not a mythology designed to keep us enslaved in a cycle of self-destruction.
Colosseum built by Romans in 72-80 AD from concrete. Photo by Kosala Bandara, CC