In recent concrete research, a new type of coating has been developed: blends of polymers and nanoparticles. These coatings need to be thoroughly tested on different concrete mixtures, especially those with high amounts of supplementary cementitious materials (SCMs) to reduce the environmental impact, which is very important for the industry. This study used three vulnerable concrete mixtures to test the effectiveness of ethyl silicate and high-molecular-weight methyl methacrylate mixed with 2.5% and 5% halloysite and montmorillonite nano-clay.
The results from physical, thermal, and microstructural tests showed that concrete with a high water-to-binder ratio (0.6) and high SCM content (40% fly ash and 60% slag) is especially vulnerable under harsh conditions. Pure ethyl silicate or high-molecular-weight methyl methacrylate coatings did not adequately protect these concretes from physical salt attacks and salt-frost scaling. However, adding halloysite or montmorillonite nano-clay to these polymers provided better protection.
The ethyl silicate-based nanocomposites offered complete protection, improving up to 100% (with no or minimal surface scaling) against both types of damage, especially when using 2.5% halloysite nano-clay by mass. On the other hand, high-molecular-weight methyl methacrylate-based nano-clay composites were good at preventing physical salt attacks but did not offer enough protection against salt-frost scaling, as they started peeling off after 15 cycles.
Original: https://doi.org/10.3390/ma17051030