St Mark’s Basilica is an architectural masterpiece and a landmark of Venice. In recent years, however, it has been repeatedly threatened by flooding. A glass barrier system will protect St Mark’s Basilica against future damage caused by high waters and flooding. Standing approximately 1.2 m tall, the glass barriers were permanently and securely anchored into the floor with the fischer FIS EM Plus injection mortar combined with fischer FIS A anchor rods.
St Mark’s Basilica in Venice (Basilica di San Marco) is one of the city’s main attractions and one of the most spectacular cathedrals in all of Italy. Hundreds of thousands of visitors come to see the cathedral on St Mark’s Square (Piazza San Marco) every year. For centuries, St Mark’s Basilica has been the public and religious hub of Venice. It is dedicated to Saint Mark the Evangelist and was founded in 828, however its current architecture originated in the 11th century. St Mark’s Basilica combines Byzantine architecture with other styles, such as subsequent Venetian Gothic modifications. It serves as a testament to the power of the Republic of Venice (La Serenissima), an economic and maritime power that existed from the 7th/8th century until 1797. Since 1807, St Mark’s Basilica has been the cathedral church of the Patriarchate of Venice. From fine marble pillars to the many gold leaf mosaics that gave the cathedral its name, the Golden Basilica, there are many artistic treasures to be found. It contains one of the world’s largest continuous mosaics over a surface of more than 8000 m². But St Mark’s Basilica finds itself repeatedly threatened by flooding. Discreet glass barriers will now preserve the historic landmark for future generations.
During the night of 13 November 2019, the water rose to 1.87 m above sea level in Venice. This was the highest recorded level since the devastating flood of 1966, which reached levels of 1.94 m. The seawater flooded the crypt of the Basilica, resulting in structural issues and damaging the floor mosaics and masonry. The effects of efflorescence on the bricks, limestone and marble inside the Basilica are serious, as the salts that make up the building materials are broken down by the moisture and penetrate the structure. This leaves unsightly stains on the surface once the water evaporates. Once evaporated and dried out, the salts crystallise, which increases their volume. This means that the limestone and marble typically found in Venetian architecture are severely impaired by the effects of the seawater. Deep efflorescence deposits cause flaking, cracks and spalling in the cavities and cracks of the stone.
The glass barrier surrounding St Mark’s Basilica consists of thermal pre-stressed multi-layered glass connected to an AISI 316 stainless steel structure. Approximately 150 metres of glass fully surround the Basilica at a right angle. Particularly transparent panels were chosen for the glass barriers so that the colours of the white marble facade of St Mark’s Basilica would remain unaffected, ensuring an uninterrupted view of the cathedral from St Mark’s Square despite the barrier. fischer’s FIS EM Plus injection mortar was used together with FIS A anchor rods to secure the stainless steel tracks to the concrete foundation. The chemical fixing system guarantees lasting and secure anchorages in concrete and post-installed rebar connections according to the European Technical Assessments (ETAs) and an ICC approval for the USA and countries in the Far East. According to the ETA, it has a service life of 100 years and, according to the Stuttgart engineering office IEA, a service life of 120 years. The injection mortar has been approved for seismic applications in performance categories C1 and C2 (ETA) or categories A to F in accordance with the ICC-ESR. It is also a safe choice for water-filled drill holes and in the event of fire (fire resistance class R240). Its ICC approval additionally includes underwater installation.
With a height of 1.20 m, the balustrade will protect the Basilica against flooding up to a level of 2 m above sea level. The protective barrier will therefore keep this historical landmark dry while preserving it for future generations.
