Protecting and preserving bridges

On 11 September 2024, dramatic images of the collapsed Carola Bridge in Dresden went around the world, causing surprise and horror, even among experts. The incident emphasised the urgency of regular inspections and maintenance: Bridges are essential connections that not only manage traffic flows, but also uphold economic and social infrastructure. Neglecting these structures leads to unpredictable risks and can have serious consequences. Several tens of thousands of the 130,000 or so bridges in Germany are now known to require urgent repairs.

Germany plans to allocate €9.3 billion to bridge renovations by 2030. Yet, as of 2021, only 12% of bridge surfaces on federal highways were in good or very good condition, according to the German Construction Industry Federation. Meanwhile, 47% were classified as "barely adequate" or worse. The Central Association of the German Construction Industry describes this as a "grim symbol of Germany's infrastructure". The weekly German newspaper DIE ZEIT headlined "In the Land of Crumbling Bridges", and national radio station Deutschlandfunk referred to the situation as "a monument to Germany's shortcomings". Germany is not alone in facing this issue: In the United Kingdom, 3,000 bridges are deemed "non-compliant with building standards" according to the British automotive services company RAC. In France, a 2019 survey revealed that 25,000 bridges were in a precarious condition. In Italy, many of the over 7,000 bridges exhibit critical defects, while in the United States, more than 60,000 bridges have structural deficiencies, with renovation costs currently estimated at $123 billion.

Bridges facing increasing load demands

The causes of this widespread issue are clear: Growing societal mobility, economic growth and, in the case of Germany, its central role as a Euro- pean transport hub have dramatically increased traffic in recent decades. Much of the existing infrastructure is no longer sufficient to meet 21st-century demands. Additional strain is placed on bridges by higher axle loads and harsher environmental impacts. Moreover, most of Germany's bridges were built in the 1960s, and wear and damage naturally increase as structures age.

For this reason, maintenance and protection are crucial—not only is refurbishment faster and more cost-effective than new construction, but it is also more environmentally friendly. MC-Bauchemie offers an extensive portfolio of proven product systems for concrete repair, surface protection, structural reinforcement, and waterproofing of bridge structures. These systems meet all technical and aesthetic requirements and adhere to stringent German and European standards such as ZTV-ING and EN 1504.

Efficient and sustainable concrete repair with Nafufill

For the protection and repair of prestressed concrete and reinforced concrete structures in bridge undersides, supports and abutments, polymer-modified, cement-bound RM (PCC II) or SRM/ SRC (SPCC) concrete replacement systems have been used for over 30 years. In addition to partial reprofiling, adding concrete cover has become increasingly important. Especially for bridge under- side components, overhead surfaces, or supports, products that can be applied via spray techniques are clearly advantageous. These include products from the long-established Nafufill range from MC, such as Nafufill KM 250 (suitable for wet-spraying) or Nafufill GST-HS (suitable for dry-spraying). For large component surfaces that need to be restored, dry-sprayed concrete re- placement Nafufill SC 08, as well as products from the Nafufill GTS series, are also available as silo products. This allows contractors to benefit from easy and safe handling while helping the client reduce costs.

Innovative injection systems for sealing and long-term protection

Innovative solutions for the protection, sealing and reinforcement of bridge structures made of prestressed concrete, reinforced concrete or masonry are provided by MC’s injection systems. Effective sealing injection measures can be per- formed on tensioned and compression-stressed components of reinforced and prestressed concrete using the low-viscosity and penetration-active polymer resin MC-Injekt 1264 compact. This achieves the injection goal even under the influence of dynamic load cycles and increased moisture within the component. Larger voids can be permanently reinforced for the enhancement and strengthening of concrete and natural stone with the mineral slurry Centricrete UF.

MC-Color sets standards in surface protection 

When it comes to surface protection for bridge structures, MC is a pioneer and has actively shaped the development of such systems. With MC-Color, MC has developed a modular surface protection programme that combines technical performance characteristics for protection, aesthetic design, graffiti protection, and crack bridging of concrete surfaces, with optimal application properties.

It consists of three product lines: MC-Color Proof, MC-Color Flair and MC-Color Flex. In each of these three product lines, the variants pure (“standard”), pro (“professional”) and vision (“high-end”) offer alternatives for varying requirements of concrete surfaces. Depending on the location, function and future exposure to environmental factors such as UV radiation, temperature fluctuations, moisture, exhaust gases, de-icing salts and biological growth, the MC-Color product line can be relied on to provide a suitable solution.

MC-Color Flex combines optimal protection with aesthetics

In combination with the fine mortars from the Nafufill product family, the MC-Color systems have been tested and approved according to Europe- an and national regulations. The surfaces treated with Nafufill can be overcoated within a few hours. The protective coating also acts as a curing agent, reducing work steps, drastically shortening processing time and helping to save costs. A current project where MC-Color Flex is used as concrete protection against harmful environmental influences such as salts, chlorides and carbonation is the longest pier in India, the Mumbai Trans Harbour Link, which opened on 12 January 2024 (see MC aktiv 1/2024). In fact, MC-Color Flex has already become the standard for infrastructure and civil engineering protection in India. During the construction of the Alexandra Road Bridge in Dublin’s port, MC-Color Flex not only met the high demands for the structure's protection but also those pertaining to its aesthetic appeal (see MC aktiv 2/2022): MC-Color Flex pro gave the bridge a unique design.

Comprehensive protection for bridge decks 

When repairing bridge decks, the properties of concrete replacement systems must meet the strictest performance requirements, as must the surface protection systems. After all, bridge decks are particularly exposed to freeze-thaw cycling and salt attack, which can damage the entire bridge structure over time. To prevent this, MC- DUR product family OS F (OS 11) systems are recommended to ensure a coating with enhanced dynamic crack-bridging ability, even in spray or splash areas exposed to de-icing salts.

This also applies to walkable and drivable sur- faces. In the OS F(a) system, the epoxy resin primer MC-DUR 1320 VK forms the basis for a highly elastic, crack-bridging intermediate layer based on polyurethane with MC-DUR 2211 MB, followed by a durable, viscoplastic wear layer with MC-DUR 2210, which is filled and scattered with quartz sand. The final layer consists of a particularly resistant epoxy resin seal with MC-DUR 1322. For special requirements, MC has expanded the application range of its floor coating system MC-DUR TopSpeed to include a high-performance coating: The highly flexibilized roller coating MC-DUR TopSpeed flex, based on MC’s Kinetic- Boost® technology, combines easy application and rapid curing, largely independent of moisture and temperature influences, with excellent crack-bridging properties.

Duisburg (see MC aktiv 2/2024). Furthermore, MBC-VT 116 has ensured the reliable sealing of the deck slab over 27,000 m² in the first section of the new Leverkusen Rhine Bridge, a critical traffic point on the A1, which is crossed daily by over 100,000 vehicles (see also cover photo and photo on pages 8-9).

Special resins for sealing deck slabs

The special resin MC-DUR LF 680 is a proven solution for sealing and scratch filling that com- plies with relevant German technical codes of practice when installed under a sealing layer of polymer bitumen sheeting. It can be applied on fresh concrete (≥ 5 days old), even at low temperatures (≥ 2 °C) and cures very quickly, even under moisture influence.

MC-DUR LF 680 has a reworking time of one hour at 20 °C and 50% relative humidity, or approximately two and a half hours at 2 °C. MC-DUR LF 680 therefore enables early application of the waterproofing membrane even in the autumn and winter months and ensures excellent adhesion to the substrate – without the risk of carbamate formation, a separating layer that can result from reaction with moisture in the air when using conventional products.

In less extreme weather conditions, the epoxy resin MBC-VT 116 can also be used. Recently, it demonstrated its strengths, including in the repair of four motorway bridges on the A42 in

Short supply routes and global availability

The backlog of investment in bridge structures is increasingly becoming a global problem. Therefore, fast and sustainable solutions are needed. MC offers not only proven, technically high-quality product systems that meet the highest demands, ensuring safety and cost-efficiency, but also their optimal worldwide availability.

With 15 production sites across four continents, short and fast delivery routes are guaranteed. After all, MC's innovative product systems for bridge repair and long-term maintenance hold a special place worldwide. And the facts speak for themselves: Demand is high, and every repair is not only significantly faster and cheaper than a new build, but also much more climate-friendly.