Rehabilitation of Dujmovača Tunnel: Innovations in Waterproofing Enhancements

The Dujmovača Tunnel (M604), a vital part of the Split suburban railway line in Croatia, has undergone a comprehensive rehabilitation aimed at upgrading its structural integrity and waterproofing systems. As Split continues to grow as the second-largest city in Croatia, the need for reliable transportation infrastructure has led to the enhancement of this critical tunnel beneath the city center.

In late 2025, rehabilitation efforts were complemented by the use of PENETRON ADMIX, a crystalline waterproofing admixture specifically designed to enhance the durability and performance of shotcrete layers used in the tunnel lining. This innovative product was incorporated into the project to combat water seepage and bolster the long-term structural stability of the tunnel, which is an essential transport route for residents and visitors alike.

The Role of PENETRON ADMIX

One of the key benefits of PENETRON ADMIX is its ability to provide waterproofing performance that rivals two layers of conventional sprayed waterproofing membrane systems while simplifying the installation process. Applied as a slurry, the admixture self-seals cracks, reducing permeability and potentially saving significant time during project execution. This is critical in construction projects where deadlines are often tight, particularly when mitigating water intrusion issues.

During the drainage and waterproofing upgrade, the project initially proposed a dimpled membrane system to effectively channel water flows into drainage outlets. However, unexpected challenges arose when the specified composite drainage material became unavailable, leading to tests indicating insufficient shotcrete adhesion.

Managing Director of Penetron Hellas, Theodor Mentzikofakis, notes that these challenges illuminated the necessity for enhanced mechanical resistance and waterproofing capabilities. As a result, a redesigned approach was implemented, merging reinforcement mesh with additional layers of waterproofed shotcrete. This strategic alteration aimed to create a static arch effect, reinforcing the tunnel’s mechanical resilience.

Advantages of Revised Techniques

The new technical proposal introduced a systematic enhancement which integrated two extra waterproofed shotcrete layers—one measuring 8 cm and an additional 10 cm on untreated surfaces. This combination not only improved the mechanical properties of the tunnel but also significantly advanced the waterproofing effectiveness.

By applying PENETRON ADMIX, the construction team could increase the layer thickness, transitioning from a traditional 3 cm + 3 cm + 4 cm application to a more efficient 3 cm + 8 cm format. This adjustment yielded substantial time savings, removing approximately 60 days from the waterproofing schedule, which is crucial, especially given the limited daily work window of 6½ hours.

Testing and Results

Post-rehabilitation testing revealed a dramatic decrease in water penetration depth, with results showing an 83% reduction after just ten cycles of performance evaluation. This improvement exemplified the effectiveness of PENETRON ADMIX in enhancing the waterproofing capacities of shotcrete. Moreover, this advanced waterproofing solution has proven to be a more cost-efficient alternative to traditional PVC sheet membranes and sprayed waterproofing systems, without compromising the tunnel's mechanical strength.

Conclusion

The rehabilitation of the Dujmovača Tunnel showcases cutting-edge innovations in construction materials aimed at enhancing longevity and performance. With the assistance of PENETRON's products and the strategic alterations in construction methods, this project not only meets the immediate needs for an upgraded transport corridor but also contributes to the overall infrastructure resilience in Split, addressing both present-day and future challenges.

For additional insights into the Penetron waterproofing solutions utilized in this project, interested parties can visit Penetron's official website or follow them on their social media platforms. Such advancements reaffirm the importance of integrating modern materials and techniques into construction projects for sustained operational success and safety.