Borobudur Temple is the largest Buddhist temple in the world. The temple, which was built about 12 centuries ago, is a proof of the achievement of building technology in the past. In fact, Borobudur temple was able to be built with many levels. But until now, many still wonder how the ancient people were able to build temple buildings and glue the stones between them. In fact, the temples that existed since ancient times were not built with cement, but with effective reinforcement methods.
According to the Indonesian Ministry of Education and Culture, the Borobudur temple is a man-made structure made of volcanic stone formed by natural processes. These are then processed into blocks with an average size of 25 x 35 x 45 cm. The shape of the building itself is a stepped building, which is a development from the prehistoric period.
Borobudur temple, which is built on a hill at an altitude of about 270 m above sea level, is divided into 3 parts and 9 levels. The temple, which is currently about 12 centuries old, is able to survive because it uses a grafting technique on its rocks. According to the Ministry of Public Works and Housing of the Republic of Indonesia, the technique used in the Borobudur temple is like a jigsaw puzzle that allows rocks to be carved with certain techniques so that they can be connected and locked together.
The construction of this temple involved the use of stone blocks consisting of outer stones and filler stones, which were arranged in stages and joined together without the use of adhesives to form the building as seen today. In the arrangement of the outer stones and filler stones, there are various types of joints that represent past technology to increase the stability of the building.
The types of joints include bird's tail, tactic, lidar groove, and purus and hole. The types of joints used in the construction of this temple certainly take into consideration the compressive force and shear risk.
On the other hand, the foundation of Borobudur temple uses a direct foundation system, where the stone layer under the walls is laid on the hill soil at a depth of 3-6 layers of stone, while the stone layer under the floor is laid at a depth of 12-16 layers of stone. The Borobudur temple also has an open drainage system that allows rainwater to fall directly onto the floor surface. This rainwater is then channeled to the courtyard through the fountain (gorgoyle) located on each level, and finally discharged to the hillside through the channels around the temple courtyard.
However, this drainage channel was built during the restoration process of Candi Borobudur in 1975. This drainage channel was built to overcome rainwater seeping into the temple and the land on the hill where Candi Borobudur stands. The drainage system starts from holes in the temple and ends at wells that collect water at the foot of the hill. These pipes are used to quickly drain rainwater from the temple. By reducing the amount of water entering the hill on which the temple stands, the erosion rate of the hill is reduced, making the land more stable for the temple. Although the drainage channel was not built during the construction of the Borobudur temple in ancient times, the construction of this drainage channel is important because rainwater seepage can damage the temple structure.