As in ancient China or the Roman Empire, many of the Mayan temples and buildings are still standing thousands of years after their construction. But how have they managed to withstand the passage of time and the harsh tropical climate? Well, it seems, copying nature.
Recent research has discovered that builders in ancient China used sticky rice lime mortars and that the Romans, great masters of engineering and construction, mixed lime with volcanic ash from Vesuvius to make highly durable concrete.
They all did the same thing: adding heat, water, and natural ingredients to limestone to produce exceptionally durable lime mortars for use in structures that have survived millennia.
In the case of the Mayan empire, some hypotheses said that they manufactured a mortar like Roman cement, and others, that the Mayans used the bark of some plants to obtain a material of extraordinary resistance.
Today, a study directed by Carlos Rodríguez Navarro, professor of the Department of Mineralogy and Petrology of the Spanish University of Granada (UGR), shows that the lime-based binding material developed by the Mayans to build temples and bas-reliefs in Mesoamerica (Yucatán, Guatemala, Honduras and El Salvador) contained sap of two endemic plants of the continent: the chukum and the jiote.
To carry out the study, the team collected samples of lime plaster and stucco from the ancient Mayan archaeological site of Copán (Honduras), from between 540 and 850 BC. C., and analyzed their properties.
For the analysis, the team used high-resolution techniques such as transmission electron microscopy (TEM) and high-resolution X-ray diffraction using synchrotron radiation.
“We identified remains of this type of organic compound in the stucco, we replicated it in the laboratory and obtained a material with the same characteristics and the same physicomechanical properties as the ancient Mayan mortars, and we demonstrated that the Mayans used this technology to manufacture the binding material. of their constructions”, explains Rodríguez Navarro to EFE.
The process is simple: “By submerging the chukum and jiote barks in water, they release a substance rich in polysaccharides.”
This juice, when mixed with the lime and sand to make the mortar, “provides the mixture with extraordinary physicomechanical and chemical properties, which allow it to withstand mechanical forces in a spectacular way and make it very resistant to the chemical dissolution of the rainwater, for example”, adds the researcher.
And it is that this organic juice, together with calcium carbonate, transforms the mixture “into an extraordinarily resistant material similar to biominerals such as calcite or calcium carbonate that we find in the shells of a mussel -for example-, which are much more resistant than the same material created by inorganic precipitation, that is, when there is no living being that generates that calcium carbonate”, he points out.
That was the secret of the Mayans: to imitate nature to artificially generate a material with improved properties and extraordinarily resistant -such as the shell of a mollusk or the spine of a sea urchin, which is called biomimetics, a technology that develops new materials copying nature.
The finding could be useful for heritage conservation and the creation of sustainable building materials.
“In many restorations of historical monuments or buildings, it has been seen that the use of current materials and cements is not compatible with ancient structures, but this material could be an alternative for the artistic repair of monuments. The possibilities are enormous”, concludes the researcher.