The use of hemp in construction is an ancient technology that was lost almost 1500 years ago and revived thanks to historical research.
Everything new is a well-forgotten old, or "that awkward moment" when it turns out that the knowledge of the ancient builders was one and a half thousand years ahead of modern know-how.
Indian scientists studied the composition of the plaster covering the walls of one of the cave temples of Ellora to find out the secret of the amazing preservation of the ancient frescoes.
Ellora is a famous temple complex of the 5th - 9th centuries in the Indian state of Maharashtra, a grandiose monument from the UNESCO World Heritage List, a real miracle of architecture - 34 temples and monasteries were carved by ancient architects in the thickness of basalt rocks.
In addition to their historical and architectural value, the temples of Ellora have become a symbol of the religious harmony of their time: in the southern part of the complex there are 12 Buddhist temples, in the central part - 17 Hindu ones, in the north of the complex - five Jain temples.
All temples are numbered in accordance with the proposed chronology of construction. Buddhist temple number 12, or Tin Tal (translated as “three-tiered”) was chosen for the study. Tin Tal, like the entire Buddhist part of the complex, was built between the 5th and 7th centuries.
One of the authors of the study, archaeochemist Manajer Rajdeo Singh (Manager Rajdeo Singh), has long been engaged in the conservation and restoration of such monuments. He drew attention to the better, in comparison with the others, the preservation of the frescoes in the temple No. 12. A sample of plaster taken for analysis showed an unexpected result: plant fibers, namely hemp, were found in the mixture for wall decoration.
Professor of botany Milind M. Sardesai joined the research. The ancient plaster was studied by all methods available to modern science: scanned with a scanning electron microscope, examined under a stereomicroscope, carried out infrared and Fourier spectroscopy …
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All the results indicated that ancient Indian plasterers added 10% of hemp stem fibers to the classic mixture of clay and lime, and that it was hemp that gave the usual coating almost supernatural properties. This mixture has protected Tin Tal temple murals from destruction for over 1,500 years.
The botany professor was entrusted with further research. Milind Sardesai collected cannabis samples in Jalna district near Aurangabad and on the outskirts of Delhi. “The analysis showed a complete correspondence of modern samples to the hemp that was found in the composition of the ancient finishing material.
We did not find any differences. A sample from Ellora's cave temple contains 10% hemp, Cannabis Sativa, mixed with sand or clay. This explains, among other things, the absence of traces of insect activity in Ellora,”The Times of India quoted Singh's conclusion.
Singh mentioned insects for a reason. He worked for a long time in Ajanta - this is a complex of cave temples neighboring and similar to Ellora, another architectural masterpiece from the UNESCO World Heritage List, but more ancient. The temples of Ajanta were created in the 2nd century; hemp was not used for wall decoration. Bottom line - “In Ajanta, insects damaged at least 25% of the murals,” Singh said.
However, the property of hemp to scare away harmful insects is far from the only "superpower" of this plant. “Hemp fibers are stronger and more durable than other plant fibers.
In addition, the plant gums contained in hemp, due to their plasticity and stickiness, could act as an effective binder, improving the quality of the mixture of clay and lime,”Sardesai told Discovery News.
According to scientists, “hemp plaster is not only a natural insecticide and pesticide, it perfectly retains heat, is moisture resistant and is able to regulate the level of humidity, is non-toxic, fireproof, and also has sound insulation properties (it can absorb up to 90% of natural noise).
In other words, the ancient builders created a very calm, healthy, comfortable and aesthetically pleasing environment for the Buddhist monks of Ellora. And all these properties of cannabis, scientists emphasize, were known to the builders and inhabitants of Ellora back in the 6th century AD.
Paradox: these days this technology is called innovative, as is the building material itself - hempkrit (from the English hemp - hemp and concrete - concrete, cement). The unique properties of cannabis became known to modern builders thanks to one of such historical studies conducted several years ago not in India, but in France.
French scientists have found traces of hemp in the building materials of the same era, which include the Buddhist temples of Ellora, VI century AD. Since then, this simple and effective technology seems to have been forgotten for a millennium and a half, and it only began to revive in recent years.
European studies have shown that hempkrite is able to maintain its unique properties for 600-800 years. Indian scholars especially noted, with pride in their ancient compatriots, that the "Hempkrit" used in the temples of Ellora had already served twice as long.
But this is despite the extremely unfavorable weather conditions - folds of basalt rock, in which the temples were cut, let in a lot of water, the level of humidity inside the temples is quite high and rises in the rainy season.
“Ellora is clear proof that only 10% of hemp fiber blended with clay and lime can maintain and protect walls from damage for 1,500 years,” Singh said.
In Russia, the unique properties of hemp have been known for a long time. The famous hemp, which for centuries has been one of the main items of Russian export, is hemp fibers.
The strength and resistance of hemp to salt water has been appreciated by sailors for centuries - ropes are still made from hemp. But the technology of using hemp in construction has either been lost or has not been sufficiently studied by archaeologists and historians.
In modern conditions, an additional "wow factor" of hempcrit is its ability to absorb carbon dioxide and release oxygen. In combination with the already listed properties of hemp, this makes hempkrit a truly unique building material - environmentally friendly, cheap to manufacture and easy to process.
In 2011, the first Hempkrite house was built in the United States - but, unfortunately, media attention was focused on the exotic material, and not on its unique properties.
The spread of hempkrit around the planet is hindered, as you might guess, by restrictive laws prohibiting the cultivation of the hemp needed to make it. Indian scientists regret this in their research.
The variety of hemp used in Ellora is the cannabis hemp (Cannabis Sativa). Nowadays, its variety has been bred, industrial hemp, which does not have psychotropic properties.
The main producers of industrial hemp are France, Canada and China, but many other countries, including India, continue to fear the criminal activity and abuse traditionally associated with the cultivation of this tainted plant.