High-Performance Wall Coating for the Silvertown Tunnel in London
On 7 April 2025, London celebrated a major milestone in urban infrastructure with the official opening of the Silvertown Tunnel. The 1.4-km twin-bore tunnel, which has been constructed at a cost of roughly 2.2 billion British pounds, connects Silvertown in East London with the Greenwich Peninsula, providing a long-awaited solution to the congestion that has plagued the Blackwall Tunnel for decades.
After completion of the structural work in September 2023, the client Riverlinx evaluated various tunnel coating systems for the Silvertown Tunnel. The choice fell on MC-Color T 21, a high-performance tunnel coating from MC-Bauchemie
Credit/Quelle: Riverlinx CJV
MC-Color T 21
Originally approved in 2018, construction of the tunnel began in March 2021. In September 2023, following the completion of tunnelling works, Riverlinx, the consortium responsible for delivering the tunnel, approached MC-Bauchemie to explore coating options that could meet their stringent demands for reflectivity, cleanability, fire-behaviour and long-term performance. MC-Color T 21 – then a newly launched high-performance tunnel coating from MC-Bauchemie – was selected to fulfil these requirements. MC-Bauchemie supported the project throughout with technical support, product sampling and on-site application guidance, deploying trained applicators and technical teams from both Germany and its UK subsidiary.
Silvertown Tunnel: Over 22 000 m² of Coating Area
For the entire 22 400 m² of application area, MC-Color T 21 was used in white for the main tunnel coating as well as in green and orange to clearly mark safety passages and exits. The coating work commenced in December 2023 and was completed within just one month, concluding in January 2024. The high-performance tunnel coating required no special substrate preparation beyond standard high-pressure water jetting to remove dust. Application followed standard procedure: one coat of MC-Color Primer followed by two coats of MC-Color T 21, all applied using airless spraying.
Application and Material Properties
Before applying the MC-Color T 21 coating, the substrate is prepared in the usual manner using high-pressure water jetting
Credit/Quelle: MC-Bauchemie
Easy application of the single-component coating with a paint roller. In the Silvertown Tunnel, MC-Color T 21 in white was applied as the main coating using an airless spray method
Credit/Quelle: MC-Bauchemie
From a practical standpoint, the product’s single-component formulation ensures ease of application, eliminating mixing errors and allowing unlimited working time. Compared to conventional resin coatings, MC-Color T 21 cures independently of ambient humidity and condensation during the curing phase, allowing for consistent results even under challenging site conditions. Coupled with a touch-dry and overcoating time of just one hour and a full curing time of one day, the system helps to meet tight construction schedules and deliver projects on time. Its fast-curing properties and ease of use ensured seamless application and smooth progress, despite concurrent traffic and equipment activity inside the tunnel.
Hight Light Reflectance Value and Durability
MC-Color T 21 was specifically engineered to meet the needs of next generation tunnel infrastructure. Its high light reflectance value (LRV) ≥ 70% not only enhances visibility within the tunnel but also exceeds the requirements of the British Standard BS 5489-2:2016, which mandates a minimum wall reflectance of 60%. This improved brightness contributes directly to road safety by reducing blinding due to sudden changes in light levels and increasing reaction times, while also enabling more energy-efficient lighting systems. On-site reflectivity and luminescence measurements, conducted by an independent third party in April 2024, confirmed that MC-Color T 21 met the prescribed reflectivity threshold under BS 5489-2:2016.
3D Microstructure Ensures Durability and Water Vapour Permeability
MC-Color T 21 incorporates an advanced 3D crosslinking technology, forming a dense three-dimensional microstructure within the coating matrix. In this system, acrylate elements are densely cross-linked in a similar manner to reaction resin systems. This intensive internal network significantly strengthens the macromolecular cohesion of the coating film, making it far more robust than traditional dispersion paints and standard concrete protection coatings. The resistance to cleaning and abrasion is comparable to that of two-component reaction resins, making the coating ideal for high-demand infrastructure environments such as tunnels.
For the entire 22 400 m² of application area, MC-Color T 21 was used in white for the main tunnel coating as well as in green and orange to clearly mark safety passages and exits
Credit/Quelle: Riverlinx CJV
Another key advantage of MC-Color T 21 is its high water vapour diffusion capability. While traditional epoxy and polyurethane resins tend to trap residual moisture, which can lead to blistering or delamination, MC-Color T 21 allows moisture from the substrate to escape. This property reduces the risk of blisters and detachment, thereby significantly extending the coating’s service life. – which is a crucial factor in tunnel maintenance, where coating renewal usually requires partial tunnel closures – resulting in considerable logistical challenges and high costs.
UV-Resistance and Fire-Safety
The UV-resistant formulation of the MC-Color T 21 coating prevents yellowing and fading, even under exposure to tunnel lighting and sunlight at entrance and exit zones. Its smooth, dense finish repels dirt and allows for effortless cleaning with jet washing. Critically, the product is classified as non-flammable according to A2-s1-d0 for fire behaviour, placing it in the best-in-class category among conventional tunnel coatings and further enhancing tunnel safety. These properties were essential requirements for Riverlinx in selecting a coating that could maintain both functionality and appearance over many years with minimal maintenance effort.
