|■Tokyo National Research Institute for Cultural Properties
||■Center for Conservation Science
|■Department of Art Research, Archives and Information Systems
||■Japan Center for International Cooperation in Conservation
|■Department of Intangible Cultural Heritage
Behavior measurement by the staff of the Department of Archaeology
Hearing survey with restoration experts
As part of the above-mentioned project commissioned by the Agency for Cultural Affairs (re-commissioned by the Nara National Research Institute for Cultural Properties), we dispatched experts to Myanmar for the fourth time in 2017. Two staff members from the Institute conducted structural behavior monitoring and a survey on traditional building techniques and production systems (from November 25th through December 3rd), while an outside expert tested brick materials (from December 9th through December 12th).
In the structural behavior monitoring checked for the fourth time, no progress was found in deformation of the three monitored historical brick buildings in Bagan in particular. However, many of the resin crack gauges installed on the external surfaces of the buildings had come off due to bird and animal attacks, so they were replaced by metal disks. We also trained the local staff of the Department of Archaeology to facilitate voluntary measurements.
Through the hearing survey with local experts who have engaged in restoration of cultural heritage for many years, we exchanged opinions on the details of traditional building techniques and production technologies surveyed in this project while confirming how to produce mortar used in past times and the materials in detail. Since we obtained all materials required for reproduction of this old mortar based on the collected information, we will analyze the mortar sampled from the structures built in the Bagan era in the past survey to compare with the reproduced mortar. We also contacted bricklayers to ask how the restoration work is implemented and their awareness of traditional building techniques and production technologies.
At the material testing carried out in a facility of Yangon Technological University in Yangon City, we implemented bending, shearing, and compression strength tests with the prisms (four-layered brick specimens) and mortar specimens produced in the previous visit (September).
We would like to continually accumulate useful data for better conservation and restoration of the cultural heritage structures in the Bagan area through such surveys.
Crack Gauge Damaged by Squirrels and Installation of Crack Disk
Performance by Local Bricklayer
Manufacture of Brick Specimens
As part of the above-mentioned project commissioned by the Agency for Cultural Affairs (re-commissioned by the Nara National Research Institute for Cultural Properties), we conducted the third on-site survey for 2017 (from September 17th through October 2nd) by dispatching six members, including three outside experts. This time we conducted structural behavior monitoring, surveys on traditional building and production techniques, material experiments, and so forth.
In the structural behavior monitoring checked for the third time, no progress was found in deformation of the three monitored buildings in particular. However, part of the crack gauge had come off due to damage by birds or animals, and therefore, continual monitoring could not be performed at some of the measuring points. Therefore, we took measures according to the on-site situation by covering crack gauges or switching to crack disks.
The heritage building has various values: not only its appearance but also the techniques used for its construction. Regrettably, in the conventional restoration work in Bagan, people were scarcely aware of the conservation or reproduction of original techniques. And also scarce studies on such techniques are precious few. Thus, for this survey, we checked the bricklaying techniques in 20 buildings together with experts in building structure and conservation/repair. We also collected information on production techniques of traditional buildings through interviews and demonstrations with local bricklayers involved in repair.
As part of our technical assistance, we delivered lectures at the Bagan Branch of the Department of Archaeology and National Museums, the Ministry of Religious Affairs and Culture in Myanmar for its 13 staff members, including the Deputy Director of the Bagan Branch, on September 20th. The three lectures were given in an omnibus manner: “Seismic damage of masonry cultural heritage in Asian countries” (Masahiko TOMODA, Head of the Conservation Design Section of the Tokyo National Research Institute for Cultural Properties); “Surveys for Structural Analysis of Brick Cultural Heritage Buildings and Their Cases” (Professor Mikio KOSHIHARA, the University of Tokyo); and ”Conservation and Repair Work for Former Winery Facilities of Chateau Kamiya” (Yasuo NAKAUCHI, Adviser, the Japanese Association for Conservation of Architectural Monuments). The audience showed much interest in reinforcement materials and techniques in particular.
On the other hand, in Yangon, we conducted compressive strength tests for single bricks (14 pieces) from September 23rd through October 1st in cooperation with the Myanmar Engineering Society (MES) and Yangon Technological University (Y1TU). In addition, we manufactured prisms (four-layered brick specimens) using three types of mortar that differed in materials and mix proportions based on the information obtained from the production technique survey in Bagan (nine in each type), cylindrical mortar specimens (three in each type), and square mortar specimens (three in each type). We are planning to conduct strength tests for these specimens about two months later.
We hope to accumulate more data useful for conservation and repair of the cultural heritage buildings in the Bagan area through such surveys and experiments.
Process of shaping the collected brick samples
Installation of targets for deformation monitoring
The 6.8-magnitude earthquake that struck Chauk on August 24, 2016 caused considerable damage to the Bagan Archaeological Zone in Myanmar, mostly to the brick buildings constructed between the 11th and 13th centuries. The Tokyo National Research Institute for Cultural Properties rushed eight experts from various fields related to the conservation and restoration of historical buildings on two successive missions: the first in September 2016 and the second in October through November of the same year. The missions identified the state of the damage in the cultural heritage and studied its causes and mechanisms. The findings from these missions were published in March 2017 as the Report on the Project “Study on the Earthquake Damage in the Bagan Archaeological Zone, Myanmar.”
In this fiscal year, we are undertaking the above-mentioned technical assistance project (subcontracted by the Nara National Research Institute for Cultural Properties) as part of the “Networking Core Centers for International Cooperation on Conservation of Cultural Heritage Project” commissioned by the Agency for Cultural Affairs, with the aim of providing information and technical advice to help improve the quality of the restoration work currently conducted by local authorities, while continuing to examine the appropriate measures to conserve and restore the damaged cultural heritage buildings. As the first field study for this project, we dispatched a group of three experts to the heritage site from May 17 to 25, 2017, during which the group collected brick samples to use for tests, including for material composition or mechanical strength testing, and also started the monitoring of structural behavior.
By taking into account the types of buildings, year of construction, parts where bricks were used, dimensions of structural members, and other factors, the group collected a total of 24 pieces of damaged structural members as brick samples from the six buildings affected by the earthquake. The collected samples were shaped at the site into a form suitable for tests. In addition, to conduct material testing in Myanmar, they consulted with representatives from the Myanmar Engineering Society (MES) and visited its testing facility.
As for the monitoring of structural behavior, the group installed crack gauges and targets for deformation monitoring on the three buildings (two temples and one pagoda) where typical crack and deformation patterns had been found during the study conducted in the previous fiscal year, and then measured their initial values. By continuously monitoring the progress of damage and deformation, we expect to be able to accumulate data over time that will be useful not only for assessing risk levels, but also for developing maintenance plans for the conservation and restoration of the cultural heritage buildings.