Hey guys, this is a rock taken from an 800 year old temple in India, and it has some strange properties. When dropped in water, it doesn’t sink like normal rocks, it floats. There are some rocks which naturally float in water, like Pumice but this rock you see here, is not a natural formation. In fact this is not a rock, it is a brick, made by heating a mixture of mud and other materials to a 1000 degree Celsius, and was made into a lightweight block.
During my recent exploration I met 2 guys, Dinesh who is an architect and Arvind who researches ancient sites. They explained that we use the same technology today, these blocks are called ACC or AAC blocks. AAC stands for Autoclaved Aerated Concrete – and is made by injecting foam into concrete which makes the block lightweight. These blocks when dropped in water, also float just like the ancient brick we saw. If we look at the Wikipedia page, it shows that AAC was invented in mid-1920s, just 100 years ago. However, we can see that this technology was in use 800 years ago in India.
Now, we don’t know what the ancient builders used to make the bricks float, and I could not get a sample of this brick to examine the ingredients. Since we don’t know how it was created, let’s move on to Why these bricks were created. I mean, what could possibly be the use of creating such lightweight bricks in Ancient India. This brick was taken from a temple called Ramappa temple, so I decided to go to the temple and find out why these light weight bricks were used.
You can see that this is a fabulous temple, the bottom portion is made of sandstone, which stands to a height of more than 25 feet, but there is a huge tower on top which is completely made of these floating bricks. It has now been covered with plaster of Paris by the archeology department. Why did ancient builders decide to create and use lightweight bricks for the tower? Why do we use AAC blocks today? Modern Engineers recommend the use of lightweight blocks in buildings to make them earthquake proof.
Structures built with heavy materials become rigid and are less flexible when earthquake occurs. When an earthquake happens, the building can sway horizontally or vertically and if the building is too rigid, it will start cracking and begin to collapse. On the other hand, light weight blocks like these floating Bricks, have these holes and are half the weight of regular bricks – these can make the structure more flexible to ground movement. If we make a building with these floating bricks, the building will swing and sway along with the ground, and will not collapse. This is exactly why, these floating bricks were used on the tower, to make it earthquake proof.
Now, all this sounds great in theory, but can this temple really withstand an earthquake? Let’s go inside and you will be surprised. As soon as you enter, you realize that this temple was affected by a massive earthquake. Look at these sandstone blocks, they have been twisted out of place and are not at the same level at all. This is the center of the temple, look at the floor. These rectangular rocks at the base, have popped up and are protruding on all sides. These blocks are called plinth beams and have been dislodged by an earthquake and the pillars have sunk to about 14 inches inside the ground. The original pillars would have stood 14 inches taller.
Remember, I showed you the exterior of the temple a few minutes ago, and at that time I guarantee you that you would have not guessed that this temple was affected by a massive earthquake. This earthquake occurred on April 1st 1843 and destroyed all the houses around the temple, but the temple which was already 600 years old at that time, was able to withstand the earthquake.
Now we can understand, why the ancient builders created these floating bricks, their earthquake proofing technology was not just a theory, it is a fact.
Right next to the main temple, there is a miniature model of the temple and this tower is also made of floating bricks. In the last century, many people have stolen these floating rocks from the smaller tower, which is why it looks like this now.
You may wonder why the bottom portion of the temple, which is made of sandstone did not collapse. The bottom structure is designed with an extremely wide base. The plinth beams were not rigidly connected, but were given gaps, so they could pop out and save the structure, when earthquake occurs. But most importantly, ancient builders employed a technique called Sandbox Technology. What is Sandbox Technology? The ancient builders dug a trench which is more than 10 feet deep, and filled it with a strange mixture. Initial analysis shows that this mixture consists of powdered granite, Non-centrifugal cane sugar, sand and another unique compound which has still not been identified. The temple was erected on top of this mixture, and the mixture acts as a cushion, and absorbs the vibrations of earthquakes, minimizing damage to the temple.