Atomic Bomb Dome Preservation Project I

In Fy1965, at the request of the City of Hiroshima, the Architecture Department in the Engineering School of Hiroshima University conducted a building survey of the Atomic Bomb Dome. Based on the conclusions of this survey, the City researched ways to preserve the Atomic Bomb Dome and work started in Fy1967.

Sealing and Repairing Cracks

Countless cracks covering the Atomic Bomb Dome indicated that there may be areas of damage within the walls themselves. Therefore, filling and sealing these cracks and detaching surface materials was a crucial aspect of preservation work, which was achieved through the use of an epoxy resin sealant.   

This repair work entailed inserting pipes into the walls, through which sealant was injected. We used two techniques vis-à-vis the insertion of pipes: a) inserting pipes into cracks and detaching surface materials, and b) inserting perforated pipes into cracks at diagonals from both sides, alternating in direction. By injecting sealant through perforated pipes, we expected that it would reach hollows and crevices deep inside the walls, and that the pipes would provide support similar to that of steel rods.
Larger cracks were filled and repaired with epoxy mortar and epoxy resin. Any pipes that were protruding from the wall were cut and sealed with a filling agent.

In addition, we injected resin into areas where finishing mortar was detaching from the surface of walls. After sealing cracks, we set injection pipes against the walls and, after the sealant had cured, injected epoxy resin.
 

We embedded U-shaped reinforced steel bars which crossed over the cracks and, on areas on the lower floors, steel flat bars that span large structural cracks to provide reinforcement.

Reinforcing Steel Frame

The Atomic Bomb Dome is structurally weak against external horizontal forces due to its high walls, limited horizontal bracing for floor boards (etc), and various other reasons. As such, a reinforcing steel frame was installed to increase the building’s horizontal rigidity (against typhoons and earthquakes). Only the bare minimum of steel framing was installed so that, as far as possible, it would not be visible from the outside.

Straightening Walls, Restoring Girders, and Repairing Brickwork

Tilting walls that were at risk of collapse were returned to their original positions and girders that had fallen to the ground were put back in place. Furthermore, to support the straightened walls and to prevent the collapse of mullions and other features, areas of brickwork were repaired.

Painting

Existing steel and the newly installed reinforcing steel frames were painted primarily to prevent the exposed steel from rusting.

Waterproofing

Waterproofing work was undertaken on the roof of the former storehouse area, the tops of walls, and on window sills. After cleaning the roof, it was first coated with mortar screed, followed by a coating of resin, a coating of covering mortar, and finished with finishing mortar. After cleaning wall heads and window sills, they were coated with epoxy resin and finished with cement mortar, which was applied at an incline. 

Inquiries regarding this page

Park Development Division, Greenery Promotion Department, Urban Development Bureau
Tel: 082-504-2393 // Fax: 082-504-2391
Email: park@city.hiroshima.lg.jp