The object is a building that currently has 4 above‑ground levels plus a basement. The cause was the result of a global reconstruction that included adding a floor with redevelopment. A second adjacent building was planned to be erected after the reconstruction. The reconstruction of the building and the upper block involved an increase in loads estimated at approximately 30%. The customer’s request to preserve the original shape and style of the existing structure led to the decision to build an additional floor “inside the existing” one. For this purpose, 4 new T‑shaped foundation beams were built, on which new internal columns rested, and floor slabs were added up to the roof. As soon as the construction of the load‑bearing structure was completed and the foundation soil was sufficiently loaded by the new internal structure, Uretek came to help by injecting geopolymers into the foundation soils beneath the foundation beams. According to the project manager from the technical side, the ability to inject polymers at several levels in depth gave a great guarantee of the result, both in terms of increasing the bearing capacity of the soil and in terms of resistance to future settlement. In fact, in this project there was a great need to keep settlement to a minimum, given the future possibility of uneven settlement problems. Thus, these problems were eliminated. After the projects were implemented, tests were carried out that gave excellent results.

Tasks

• The building, which was to be strengthened and re‑prestressed, had no sagging, but due to the increased load, it was necessary to adjust the bearing capacity of the soil under the new foundation beams. In addition, due to the excavation work that would be carried out next to the building for the construction of a new building, it was necessary to stabilise the soil for the excavation work in order to limit landslides.
• After the reconstruction was completed, the project further included the construction of a second adjacent building, starting from the basement. To act quickly and without causing excessive vibration that could be caused by construction work in the stress zone of the adjacent building, the construction management decided to stabilise the soil before the excavation stages by injecting Uretek materials.

Technology applied:
To achieve the set goals, Uretek, using its patented deep injection technology, chose a method of binding the loosened soil and limiting landslides. Special geopolymers, when injected into the soil, rapidly expand due to a chemical reaction and develop high swelling pressure. Two phases were carried out: Phase No. 1 – surface compaction: injections were made into the foundation‑soil contact zone to improve the geomechanical properties of the soil and fill macroscopic voids. Phase No. 2 – deep consolidation: injections were carried out at 2 additional depth levels in the soil volume most subject to loads. All Uretek work did not interrupt parallel construction work by other contractors.

The work was constantly monitored using a laser level system sensitive to 1 mm movements, as well as by geodetic survey engineers. Special tests carried out before and after the project implementation showed a significant improvement in soil density parameters. Cooperation with Uretek did not end at the stage of completing the injection work. It ended with a final stage of technical cooperation to verify the results of how the second, newly erected building was put into operation. The project made it possible to strengthen the soil to a depth of up to 3 m from the foundation support level. In total, 28 cubic metres of soil were strengthened under 4 foundation beams, and about 15 linear metres of the excavation front were also strengthened. The total injection time was 3 working days.