The Ajanta and Ellora caves are some of the most famous examples of monastic architecture in India. These structures were carved out of the side of a mountain more than 1,500 years ago and are home to some of the most impressive paintings and sculptures from that period.
Caves at these locations were constructed using locally available materials, including timber and red ochre. But the Ellora cave builders went a step ahead by using hemp as a building material. Yes, you heard that right – Hemp is a building material that was used centuries ago.
In this article, we will deep dive into the uses of Hemp in the field of construction and how the Ellora caves are still preserved with the use of the hemp plant, whereas the Ajanta cave builders missed out on this.
Ellora Caves: Saved by the Hemp
The Rashtrakuta dynasty and Yadavs carved 34 stone caves between the 6th to 11th centuries in north-west Aurangabad, Maharashtra – today known as the Ellora Caves. Over time, Ellora Caves have been recognized as an iconic example of Indian rock-cut architecture. Recent studies by Indian archaeologists have revealed an interesting tradition of the Buddhist monks who prayed in these caves. They mixed “hemp” with the plaster that coated the painted walls and ceilings, along with some clay and lime, to preserve the structure from degrading.
However, what compelled them to use Hemp as a building material?
The ancient Indian technicians likely were the first in the world to use hempcrete technology – mixing Hemp with Clay and Lime.
Recent studies have shown that hemp is more resilient and sustainable than other vegetal fibers commonly discovered in earthen plaster. Hemp fibers are natural insecticides and pesticides and are also excellent heat conductors that make them retain heat very efficiently. In addition to being rodent and fungi-resistant, hemp also provides weed control. Not only are they waterproof, but these materials can also control moisture and regulate humidity indoors. They’re non-toxic and fire resistant, plus their insulating properties allow them to absorb 90% of the natural sound.
Hemp has a significant advantage over other vegetal fibers, in that it absorbs more carbon dioxide from the atmosphere than it produces during its life cycle which can help to reverse the impact of global warming. Research has found that 1000 kg of hemp can absorb about 1500 kg of carbon dioxide.
The builders and inhabitants of Ellora Caves in the 6th century recognized all of these qualities of hemp.
Researchers believe, Hempcrete, a concrete-like substance produced from hemp fibers, would have provided the Buddhist monks and other priests with a healthy, pleasant, and aesthetically pleasing environment to pray and meditate.
It thermo-regulates, maintains temperature conditions stable, acoustic is dabbed, hence makes the energy of the area conducive for meditation.
Hempcrete was not only used by the ancient Indians in Ellora cave paintings, but also in Daulatabad fort, which is 15 km south of Ellora caves and can be dated back to the 13th century.
Was it only Hemp, or were there others?
The use of vegetal fibers in Indian Mud/Lime Plaster varied from site to site, it was not that it was just hemp that was used, and this depended on the availability of resources in the vicinity.
For example, jute fibers were used as an additive in lime plaster works at Hampi, Bidar fort whereas rice husk was used as an organic additive in Ajanta, Pitalkhora, Karle Caves, and Bhaja rock-cut cave paintings.
To all of you enthusiastic readers, have you noticed that we’ve only discussed the Ellora Caves and not the Ajanta Caves?
That is because the cave paintings of Ajanta, another UNESCO World Heritage site about 100 kilometers from the Ellora Caves, do not contain any depiction of Hemp in the earthen plaster.
Due to this, over time, the plaster of the Ajanta caves has been significantly damaged by insects, mainly silverfish that eat organic material like rice husks. They made holes in the soft plaster which caused it to loosen and fall off eventually.
According to researchers, at least 25% of the Ajanta artwork has been destroyed by insect activity. However, owing to the use of the hempcrete technology, no insect activity was noticed in the cave paintings of Ellora, and the priceless cave paintings were preserved from insect devastation.
Pretty sure that the Ellorians would have pinged the Ajantians regarding their discovery of this wonder plant and its uses, but they probably left the Ellorians message unread.
Is Hempcrete Stronger Than Concrete?
Hempcrete has a compressive strength of around 1/20 and only 15% density that of concrete. So, no, hempcrete is not stronger than concrete and hence must be used with the support of a load-bearing structural system of another material. However, the good news is because of the low density, hempcrete is resistant to cracking under movement, which makes it perfect for areas prone to earthquakes.
Fast Forwarding to the Recent Present
Back in 1990, people in Europe started to see the potential of hemp as a construction material. Because it can regulate humidity and absorb carbon dioxide, it was found especially useful in places with extremely cold weather.
People often prefer spending more time indoors, in countries with cold climates where the temperature frequently drops below zero degrees centigrade.
They also burn firewood or use room heaters, which then increase the concentration of carbon dioxide inside, and keeping the windows shut due to the chilly weather outside, doesn’t really help in this situation. Staying in such enclosed environments for long periods would be quite unhealthy and uncomfortable.
Incorporating Hemp into clay / lime / cement plaster during the plastering process will result in a room that is free of carbon dioxide and moisture, creating a pure and healthy atmosphere. Also as it has extreme heat retention properties, it can help to keep the room cool or hot, reducing the electricity consumption for air conditioning or heating.
The United States built its first hempcrete house in 2011, but the media’s attention was focused more on its narcotic qualities than on the construction’s innovative benefits.
The world’s primary producers of Industrial hemp now are France, Canada, and China. Many other countries, including India, continue to be fearful of its black market use and misuse due to its psychoactive effects.
However, what they fail to realize is that hemp does not have any psychotropic effects. You might be interested to know whether or not “Does Hemp get you high?“
Bottom Line for Hemp used in Ellora Caves
Hemp is an incredibly useful plant that is widely misunderstood and hated in the present day due to the public’s perception of its mind-altering properties. This hatred has spread all over the world, leading to millions of dollars being spent in exterminating this valuable crop.
This has led to people underestimating hemp’s usefulness and abandoned it due to social and cultural beliefs. But it’s about time we start stressing on the fact that we need to increase industrial hemp production in all countries due to its multiple environmental benefits.
Click here to read a comprehensive guide on Hempcrete.
Here are few articles published on same topic:
- Times of India: Hemp shielding Ellora caves from decay for 1,500 years
- The Better India: Lime, Clay & A Curious Third Ingredient – What Preserved the Ellora Caves for 1500 Years?
- Homegrown: Scientists Say That Cannabis Helped Preserve Ellora Caves From Decay For 1500 Years
Do you have a story about how cannabis has helped preserve something important to you? Share it in the comments below!
