The tower of the historic fortress complex in Gradačac is a landmark of the city. Age-related settlement and inhomogeneous subsoil conditions had led to deformations that threatened structural stability. The aim of the project was therefore to specifically improve the load-   bearing capacity of the ground without affecting the historic structure. The soil stabilisation measures were implemented by the construction company Neimari d.o.o. in close coordination with MC-Bauchemie in Bosnia and Herzegovina. From the outset, technical requirements and heritage conservation specifications were given equal priority. 

Minimally invasive method with maximum precision 

The particular challenge lay in the sensitive existing conditions: the working space beneath the foundation slab was extremely limited, ruling out conventional methods. At the same time, the subsoil consisted of heterogeneous, partially loosely compacted layers that had caused uneven settlement. What was required was a minimally invasive method with the highest precision, controlled material distribution, and rapid effectiveness, one that would provide lasting stabilisation while meeting the tight project schedule. 

MC-Montan Injekt FN for subsoil consolidation 

The injection system MC-Montan Injekt FN was used, an environmentally friendly, low-viscosity polyurethane-based duromer resin for rock, foundation soil and civil engineering structures. Thanks to its high flowability, the material penetrates even the finest pores and cavities. Once cured, it forms a homogeneous structure that sustainably consolidates the subsoil and significantly improves its mechanical properties.

The technical approach was precisely tailored to local conditions. MC-Bauchemie trained the executing personnel in injection techniques to ensure proper implementation. After drilling beneath the foundation slab, injection lances were installed in a defined grid. Injection was carried out to a depth of up to three meters at uniform intervals of 80 cm and a controlled pressure of six bar. A specially matched 2K pump ensured precise dosing and uniform mixing, allowing the material to be introduced exactly into critical soil zones.