Mollinary stone bridge sustainably rehabilitated

• Name

  Careful restoration of Croatian cultural heritage asset

• Country

  Croatia, 2024

• Fields of Expertise

  Bridge

• Categories

• Products

  Oxal VP I T flow
  MC-RockMortar L
  Nafuflex High Performance
  MC-Injekt 1264 compact

Halfway between Zagreb and Rijeka in central Croatia lies the town of Ogulin on the river Dobra. A stone bridge from 1874 crosses the river here, named after the Austro-Hungarian officer and writer Anton Mollinary. The bridge with its five round arches is 72 m long and around 7.5 m wide. It is part of the Rudolfina Road, which connects Ogulin with the town of Novi Vinodolski, and counts among Croatia’s heritage-protected structures.

Old stone bridge in need of immediate rehabilitation

The Mollinary Bridge had not been repaired for a number of decades. The adverse weather conditions in the mountainous region had led to a massive deterioration of the structure over the years. The bridge had large cavities and cracks, and the reinforced concrete deck slab was so badly damaged that immediate repairs were necessary. The district council responsible involved MC Croatia in the project from the initial planning stage through to execution. MC not only supplied the necessary products, but also provided expert support to the contractor, VACON d.o.o. from Karlovac, in all phases of the project.

 

In April 2023, work began on sealing the parts of the bridge in contact with water using the injection resin MC-Injekt 1264 Compact. This easily injectable, low-viscosity duromer resin exhibits a high penetration effect when force-filling cracks, joints and cavities, is optimally compatible with moisture, and cures quickly and safely even under dynamic stress.

 

Maintaining stability and authentic appearance

The bridge abutments and stone piers were then carefully repaired and restored. In order to maintain stability, all cavities and cracks in the masonry were filled with the mineral suspension Oxal VP I T Flow. This highly flowable grouting and injection slurry from MC is physically matched to natural stone masonry.

 

To preserve the authentic appearance of the bridge, each joint between the stone blocks of the façade was carefully cleaned and prepared for repointing with the highly sulphate-resistant, microsilica-modified MC-RockMortar L mortar. It is resistant to temperature, freeze/thaw cycling and de-icing salt, has excellent substrate adhesion and is available in various colours. It was applied with great precision to achieve a uniform joint pattern that harmonises visually with the patina of the natural stone and at the same time provides lasting protection for the structure. Before asphalting, the bridge deck was finally sealed with Nafuflex High Performance, a polymer-modified bitumen thick coating.

Despite the particular challenge posed by the wintery conditions in the often very cold mountainous region, where snow and fog prevail and the weather is unpredictable, the repair of the Mollinary Bridge was successfully completed in just under three months.