JAPAN-APSARA Safeguarding Angkor

Outline of the Conservation

The Northern Library forms a pair with the Southern Library, with the two libraries standing on opposite sides of the grand causeway extending from the west grand gate to the central complex. The Northern Library has been partially restored by EFEO and ASI in the past. In our conservation project, we carried out the following tasks.

1) Reconstruction of the side chamber and porch roofs

Among the 800 or so fragments scattered around the building, we identified the original positions of about 450 fragments and repaired 310 elements that we judged were reusable for reconstructing the roofs. In regard to parts with missing original elements, we created about 190 new sandstone elements in cases where those elements were necessary for reconstructing collapsed elements and their shapes could be confirmed from remaining traces.

2) Repair of the pillars and beams of the side chambers and porches

We repaired ten pillars and twelve beams by supplying new sandstone or by applying reinforcements. In cases where the original elements could not be reused and were made of reinforced concrete, we created new elements using sandstone.

3) Prevention of leaks in the roof and consolidation of deteriorated walls of the main chamber

4) Dismantling and reinforcement of the porch platform

Characteristics of Conservation Techniques

1) Repair of elements

As part of the task of repairing elements in this project, we supplied new sandstone elements to damaged parts that were structurally important. This was to ensure effective load transmission. Additionally, for the repair of porch pillars, we embedded stainless steel ribs and inserted new sandstone supplements in vertically-cracked pillars.

2) Creation of a project record database
All records of this project, including various diagrams, photographic records, and records of the repair of elements, were basically converted to HTML format digital files. Reports were compiled in a manner that would ultimately allow them to be accessed form a database.

3) Positional adjustment of the reconstruction part
The entire building of the Northern Library is sunken a maximum of 25 cm at the center, so a full dismantling work was deemed necessary to completely return the collapsed part to its original position. However, since the consolidation settlement of the platform was stable in its present condition, we preferred to maintain this state of stability. Therefore, in this project, we adopted a restoration method which consisted of partial dismantlement and positional adjustment using lead plates and lime mortar to raise the reconstruction part.

4) Surface finishing of the engravings on new elements
Methods for finishing new elements differ according to each restoration team. JSA’s policy is to finish elements so that "there is no conspicuous difference between the original and new elements," but at the same time "the original and new elements can be clearly distinguished." To this end, we applied engravings so that the elements resembled the engraved finish of the original elements, and then used a bush hammer and chisel to roughen the surface and produce a soft finish.