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Creation 41(1):19, January 2019

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Ancient Roman concrete

… just like natural rock



The ancient Romans used a type of concrete that is far more durable in seaside applications than our modern concrete. Modern cement in constant contact with the sea eventually weakens, and the steel reinforcing inside then rusts as salty water travels into cracks in the structure. It takes only a few decades for the concrete to begin crumbling away.1

However, Roman marine concrete actually cured into a very tough material identical to hard rock. Two millennia old Roman piers and breakwaters are still standing rock-solid today.

Natural processes

Scientists recently reported studying the ancient concrete to learn why it cured into such an enduring state. The Roman recipe of lime,2 volcanic ash, and rock aggregate, mixed together with seawater, produced a concrete that under the microscope looks like natural rock.3 The scientists found that the mineral microstructure had grown stronger because of a naturally occurring chemical reaction between the lime and the ash in the presence of seawater, forming strong bonds between crystals.

Their results reveal one of the ways in which natural sedimentary formations can lithify (harden) very rapidly into rock. Pliny the Elder, writing in ancient times, recognized the correlation between natural rock, and man-made concrete.4 He described the rock-like cement produced by volcanic ash:

“Who, indeed, cannot but be surprised at finding the most inferior constituent parts of it, known as “dust” only, on the hills about Puteoli, forming a barrier against the waves of the sea, becoming changed into stone the moment of its immersion, and increasing in hardness from day to day—more particularly when mixed with the cement of Cumæ? There is an earth too, of a similar nature found in the districts about Cyzicus; but there, it is not a dust, but a solid earth, which is cut away in blocks of all sizes, and which, after being immersed in the sea, is taken out transformed into stone. The same thing may be seen also, it is said, in the vicinity of Cassandrea; and at Cnidos, there is a spring of fresh water which has the property of causing earth to petrify within the space of eight months. Between Oropus and Aulis, every portion of the land upon which the sea encroaches becomes transformed into solid rock.”5

Volcanic ash is not a requirement, however, for producing sedimentary rock. For instance, many natural sandstone formations are composed only of sand grains cemented by lime minerals. Abundant volcanic ash was available only in some areas of the world during the formation of the local geology, but wherever present, the ash often resulted in a tougher rock.

Rapid sedimentation and hardening

During the global Flood of Noah’s day, God caused the sea to rise and cover the land of the whole earth. The Flood lasted a year and involved widespread tectonic movement, break-up of the earth’s crust, and erosion and sedimentation on a massive scale. Volcanism was intense in places, and abundant evidence for this can be seen in many geological formations throughout the world. Both water-borne sediments and volcanic ash falls accumulated in sedimentary basins across the earth.

There is also geological evidence that vast quantities of lime minerals were present during the Flood, likely dissolved in subterranean waters that rose to the surface of the earth. These rock-making ingredients combined with seawater to create a perfect recipe for rapid sedimentary rock formation. Roman marine concrete provides an insight into how the world’s Flood deposits quickly hardened into the enduring sedimentary landforms we see around us today.

References and notes

  1. University of Utah, New studies of ancient concrete could teach us to do as the Romans did, phys.org, 3 July 2017. Return to text.
  2. Also known as slaked or industrial lime, made up of predominantly oxides and hydroxides of calcium. Typically produced by crushing and burning limestone or chalk (which are mostly calcium carbonate), then adding water. Different from agricultural lime, which is crushed limestone. Return to text.
  3. Jackson, M.D. et al., Phillipsite and Al-Tobermorite mineral cements produced through low- temperature water-rock reactions in Roman marine concrete, American Mineralogist 102(7):1435–1450, 1 July 2017 | doi:10.2138/am-2017-5993CCBY. Return to text.
  4. This correlation is now becoming apparent to industry. The latest ‘geopolymer’ research results in new concrete formulas based on rock formation processes. All these natural processes are very rapid—no long ages needed. Return to text.
  5. Pliny the Elder, Naturalis Historia, Book 35, chapter 47, www.perseus.tufts.edu. Return to text.

Helpful Resources

Flood By Design
by Michael J Oard
US $15.00
Soft Cover
Geology by Design
by Carl R Froede Jr
US $15.00
Soft Cover
How Noah's Flood Shaped Our Earth
by Michael J Oard, John K Reed
US $17.00
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Readers’ comments

Phillip C.
Very interesting. Do we not have any concrete recipes that come close to the hardness of the ancient Roman stuff? I'm guessing producing cheap concrete is more profitable in the long run than making anything like Roman concrete.
Jonathan Obrien
There's a lot of interest and activity in industry to come up with an affordable, marketable contemporary version of ancient Roman concrete. There's no reason it couldn't be made again today. It's simply a case of coming up with the right proportion and type of rock ingredients. Modern Portland cement-based concrete does have some definite advantages, for instance in high rise, multi-story buildings, with the internal steel reinforcing and rapid setting of the concrete giving an efficient means of construction that saves money.
Chris M.
Regarding rapid sedimentation and hardening, what do secular geologists say to events like Mt. St. Helens that showed layers of sediments can be laid in a matter of hours and not millions of years? How do they keep an evolutionary story line when we've actually see these geological events happen right in front of our eyes?
Jonathan Obrien
Geologists who believe in millions and billions of years of earth's history have made a faith commitment to the long ages worldview, which as an idea that had its beginnings among secularists who were motivated, as Charles Lyell put it, by the wish to "free science from Moses". They didn't want to believe in what the Bible clearly says. Today this now includes Christian geologists who don't believe the Bible's timeline for historical events in Genesis. It really helps to begin with the faith that the Bible is correct in what it states, and then from there to interpret the physical evidence in the rocks in the light of what the Bible clearly states. Geologists who see clear evidence of rapid geological processes and yet still believe that the earth is billions of years old simply, as it were, shrug their shoulders and say something like, "well, big deal, in this particular case the rocks and layers were produced in days, not millions of years ... but usually the process takes millions of years." They will believe what they want to believe, and then see the evidence for it.
Colin G.
In the 1960's, as a young teenager, while engaged in the sessions of the chemistry club at my local grammar school in Wimborne I was tasked with rediscovering/recreating the 'recipe' for ancient Roman concrete. The task was, from my perspective, a miserable failure resulting in several test tubes of hardened material and the eventual waste of said test tubes. I am very pleased to read in this article that science has progressed and identified the nature of Roman concrete. I am also pleased to note the findings that sedimentary rock can be hardened in the space of just a few years and not the 'millions of years' so often cited. Personally I long ago , in my late teens, espoused a young earth view based on a biblical time frame, creation week and world wide flood. Regards.

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