Atomic Bomb Dome Preservation Project Ⅱ

Twenty years after the first preservation project, a preservation survey was conducted which revealed deterioration of construction materials, including concrete and bricks, as well as materials used for repair work during Project I.

As a result, repair work that focused primarily on deterioration prevention to ensure that the Atomic Bomb Dome would be preserved for years to come was undertaken in Fy1989.

U-Cut Resin Injection

We repaired cracks that had appeared in the mortar of bricked areas of the walls by cutting U-shaped grooves along the cracks which were then cleaned and coated with a primer. Then, we used a caulking gun to fill the grooves with an epoxy sealer which was smoothed out into a flat surface with a spatula.

Resin Injection Combined with Anchor Pins

We repaired areas of detaching finishing mortar through a combined approach using anchor pins and epoxy resin injections that involved drilling alternating holes for setting anchor pins into the wall and for injecting epoxy resin.

Holes for the anchor pins were drilled through to the brick wall beneath the surface of the finishing mortar, which was then set in place by inserting anchor pins. After drilling holes for epoxy resin, we inserted injection pipes through which the resin was injected behind the finishing mortar.

Resin Injection Combined with Pipe Insertion

To fill gaps in brick walls and above lintels, we drilled holes that passed through the gap, inserted perforated pipes, and sealed entry points with a putty-like epoxy resin. We then injected epoxy resin with a hand-pump from the bottom of the pipe until the resin started to come out the perforated holes. After resin injections were completed, protruding pipes were cut and covered with putty so they were less noticeable.

Sealing Mortar Joints

To repair mortar joints, we first chipped away areas of deteriorating mortar, cleaned the cavities, and taped off the surrounding bricks with masking tape. After coating cavities with a primer and allowing it to dry, we used a caulking gun to fill them with epoxy sealer. Before the sealer hardened, we smoothed the surface with a spatula and removed the masking tape.

Painting

After scraping, cleaning, and preparing the surfaces of the original steel domed roof truss, spiral staircase, and the reinforcing steel installed during Preservation Project I, we coated them with an anticorrosive paint.

Permeable Water Absorption Inhibitor

We coated the entirety of the Atomic Bomb Dome with a transparent permeable water absorption inhibitor.

Replacing Original Steel

Sixteen largely corroded foundation plates at the bases of the steel dome’s columns were replaced with atmospheric corrosion resistant steel.

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