Performance of plain and nano-modified coatings applied to a concrete bridge deck in cold regions

Surface treatments applied to new or existing concrete elements provide effective protection against intrusive media, helping to reduce maintenance and repair costs. However, technical data are scarce on documenting the field performance of concrete surface treatments in cold regions with aggressive conditions, particularly for emerging nano-modified coatings. To address this gap, a field study was conducted to evaluate the efficacy of different plain and nanocomposites as surface treatments on 34-year-old concrete bridge deck sections in Winnipeg, Manitoba, Canada. The study compared neat resins (silane, methyl methacrylate, and ethyl silicate) and nano-based coatings (nano-silica 50 % solution, silane with nano-clay, and silane with nano-silica at 2.5 % and 5 % by mass) on cores extracted from cracked and uncracked concrete prepared with two surface preparation methods. The experiments compared the initial performance (transport properties and microstructural features) of coated concrete to its performance after one year under service conditions. The results indicate that coatings play a significant role in providing protection against intrusive media and reducing maintenance efforts and costs. Among the coatings tested, silane and methyl methacrylate offered the least improvement in concrete protection with time in cold regions. The 50 % nano-silica solution provided moderate performance, whereas ethyl silicate and silane nanocomposites demonstrated superior performance in reducing transport properties regardless of the surface preparation methods. Given the improvement in long-term durability and cost, silane nanocomposites with a 2.5 % loading ratio may be a viable treatment method for concrete flatwork in cold regions. • Coatings on shot-blasted and power-washed bridge deck concrete performed similarly. • Silane and methyl methacrylate coated concrete decreased efficacy after one year. • The uneven distribution of nano-silica 50 % coating gave intermediate performance. • Ethyl silicate and silane nanocomposites delivered superior performance. • Silane with nano-clay or nano-silica at 2.5 % wt. were cost-effective alternatives.