漢城百濟의 ‘烝土築城’에 대한 硏究

Abstract

It has been generally accepted that "Jeungto Chukseong(Building a fortress by boiling soil)" described in King Gaero Section of Baekje History in Samguk Sagi(A history of three kingdoms) indicates construction of earthen fortress using a method called Panchuk(Placing earth between boards and hardening it). However, there is a record that Tongman Fortress in Jeokyeonha, Shaanxi, China, is also built using "Jeungto Chukseong" like the fortress in Hanseong Baekje. But it is found that the fortress was built using lime. Therefore, it is possible that for the "Jeungto Chukseong" indicated in Samguk Sagi, lime was used. To use unslaked lime safely, a process of making it to slaked lime is needed. In this process, unslaked lime reacts to water and generates a lot of stream and heat. And it is thought that this process is expressed as building a fortress by boiling soil. To obtain lime, limestone or shell needs to be heated to over 900°C for a long time. When the limestone is heated and carbon dioxide is removed, it changes to calcium oxide(unslaked lime), a material with new property. When the calcium oxide reacts to water, it becomes calcium hydroxide and when it combines with carbon dioxide in the ground, it changes to calcium carbonate, which is hard like stone and waterproof. Using chemical change to make new material for construction means significant development of civil engineering technology at the time. In China, lime began to be used in the Zhou Dynasty. At the time, lime was made by burning shells and it was applied to walls mostly. After the Han Dynasty, construction technology using stones and bricks developed and lime began to be used as mortar that binds bricks and stones. Mixing lime, sand, and loess to strengthen the foundation or build a strong structure started in the Southern and Northern Dynasties. "Jeungto Chukseong" using the mixture of lime, sand and loess was first used for Tongman Fortress, the capital of Daeha, in 424. In Korea, lime was first used in Goguryeo for wall application or mortar. But the use of lime for the construction of fortress began during King Gaero of Baekje as indicated in the expression "Jeungto Chukseong" in Samguk Sagi. Lime used in the earth for the fortress found during the excavation of Mongchon Earthen Fortress in 1984 proves this. It is estimated that the mixture of lime, sand, and loess might be used for Pungnap Earthen Fortress, but it is not clear whether lime was actually used since the components of the fortress was not analyzed even though the cross section of the wall was examined during its excavation. To decide if Mongchon Earthen Fortress and Pungnap Earthen Fortress were built during King Gaero, analysis of components of each fortress needs to be carried out. Lime has been widely used as construction material from ancient times. And lime does not exist in nature and it is produced through chemical change. It is caustic material that requires caution in production and handling. Therefore, production of lime and expansion of its use need to be seen in a new way in terms of the development of civil engineering technology.