Job Reports

Technical description:

The office block at the corner of Amalias street and Xenofontos street, in Athens, has been registered as a listed building by ministerial decisions no. 2702/184/21 January 1987 (Gov. Gazette Issue 63D / 12 February 1987) and no. 59746/5423/7 May 1976 (Gov. Gazette 672Β / 1976), issued by the Ministry for the Environment, Physical Planning and Public Works and the Ministry of Culture, respectively. It is a corner three-storey building with a basement and a courtyard area, the registration of which as a scheduled site has been revoked by ministerial decision no. 1482/12 March 1987 issued by the Ministry of Culture.

The building has suffered extensive damages as a result of the earthquake of 7 September 1999, and additional damages due to the works carried out in the area for the construction of the traversing Athens Metro underground tunnel.

According to the static design prepared, the main structure will be fully restored and its aptitude will be enhanced by constructing a foundation beam (foundation-stone shackle) plus sealing the masonry’s cracks and strengthening its bearing capacity by the use of grouts added to a system of horizontal and vertical shock absorbers (CINTEC method).

Description of the CINTEC method
The stonework is repaired and the building’s breached walls are stabilised (restored) through the placement of a grid of shock absorbers cased in fabric coated pipes filled with grout of inorganic materials. This method is based on the principle of continuous transfer of loads inside the masonry, by placing special shock absorbers and injecting grout of controlled inflowing volume and pressure.

The repair elements consist of steel bars at an appropriate length coated in a tubular fabric casing. They are placed in holes drilled across the length and the height of the wall and moulded with grout of controlled volume and pressure. Penetration is carried out using a rotary diamond crown system, without oscillations, while the machinery is placed on suitable racks for horizontal, vertical or angled penetrations. Small drillings are carried out using heavy-duty hydraulic equipment in combination with dust absorption. The procedure calls for dry penetration, to avoid harming the surface decoration.

Intervention works at the building’s main structure engender a need for protecting, repairing and restoring all building and decorative elements. This necessitated an architectural design addressing restoration requirements with respect to all individual building elements subjected to interventions. In addition, the design provided for restoration works on the ceiling painting and plasterwork decorations.

According to the project’s schedule, the following building works will be carried out in parallel and in coordination, either prior or subsequent to the reinforcement works designated by the static design:

• Protection of the building, its users, the workers and the environment.

• Excavations followed by removal of the dug out materials, and backfills.

• Repair of the damaged elements (walls, floorboards, floors, aperture casements, decorations).

• Finishing of the repaired elements.

In more detail, the works to be carried out in succession involve:

• Installation of scaffolds at the length of all frontages (facing the streets and the courtyard) coated by a special protective net or burlap.

• Protective sheltering (by polyethylene and chipboard sheets) of all floors and aperture casements in the areas where works on the main structure will be carried out.

• Protective covering of all decorative paintings and sculptures.

• Extremely careful cutting or dismantlement of the basement’s marble floors in the armoured concrete shackle construction zones.

• Excavation followed by removal of dug out materials.

• Restoration of the floors to their previous state after completion of the reinforcement works.

• Identification and preparation of the locations suitable for placing the wall reinforcement grout injection tubes, so as to avoid damaging the decoration or the electromechanical installations.

• Repair of the damages to the walls’ inside and outside faces after completion of the jet grouting (coatings and colourings with the full primer required).

• Preparation of the areas where holes are drilled for placing the system of metal shock absorbers (CINTEC method), i.e. removal of roof tiles, etc., and then repair and finishing works for their restoration to their previous state (replacement of the roof tiles, waterproofing, coating and finishing with colourings).

• Restoration of any damages to aperture casements and immovable furniture.

• Restoration of the affected decorative paintings and sculptures according to pertinent artwork conservation specifications.

• Removal of the protective coatings and the scaffolds.