Ancient builders created structures that are still standing today, yet most modern structures quickly show signs of deterioration. Experts have been studying materials hoping to copy the endurance of ancient buildings. Many of them have turned to Roman and Mayan architecture for inspiration.
Self-Healing Concrete
Starting in 200 B.C., the ancient builders of the Roman Empire were constructing impressive concrete structures that have stood the test of time. Even in harbors where seawater greatly affects the composition of the structures, the concrete can be found the way it was when it was poured 2,000 years ago, according to archaeologist John Oleson from the University of Victoria in Canada.
Most modern concrete begins with Portland cement mixed with water to create a chemically reactive substance. The process used by ancient Romans in making concrete is almost similar. They mixed materials such as burnt limestone and volcanic sand with water and gravel to create chemical reactions that would hold everything together.
Scientists believe that some Roman concrete is still standing due to the ancient materials' ability to repair themselves. In a recent study, civil and environmental engineer Admir Masic from the Massachusetts Institute of Technology suggested that this self-healing ability comes from chunks of lime studded throughout the material instead of being mixed in evenly.
Experts analyzed concrete samples from the ancient Privernum and discovered that the Romans were not mixing their materials well enough. When cracks form, water seeps into the concrete and activates the leftover pockets of lime. This sparks up new chemical reactions that can fill in the damaged areas.
Geologist Marie Jackson from the University of Utah has a different proposal. Her research suggests that the endurance of ancient Roman structures is due to the specific volcanic materials that they use. Volcanic rocks are gathered by builders and are mixed into their concrete. Being a naturally active material, the volcanic rock changes over time as it interacts with the element, sealing the cracks that develop over time.
Secret Mayan Recipe
At a Maya site in Honduras, intricate sculptures and temples remain intact even after 1,000 years of exposure to a hot, humid environment. In an investigation by Carlos Rodriguez-Navarro and his colleagues, the secret to their longevity lies in the trees that sprout among them.
Ancient Mayan masons used extracts from chukum and jiote trees mixed with lime. When researchers tested this recipe, they found that the resulting plaster is durable against physical and chemical damage. Bits of organic material from the tree juice were also incorporated into the molecular structure of the plaster, mimicking the sturdy natural structures such as seashells and sea urchin spines.
Materials scientist Cecilia Pesce from the University of Sheffield believes ancient builders might have just gotten lucky. They probably toss about anything into their mixtures as long as it is cheap and available. It is like a natural selection process where the ones that did not work out have long since collapsed.
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