Improvement on freeze-thaw durability of municipal solid waste incineration fly ash-based autoclaved wall blocks by triethoxy(octyl)silane/nano-Al2O3 and triethoxy(octyl)silane/graphene nanoplatelets coatings

The envelope structures hardly have the service life up to the design life in severe cold area. Polymer/nano-materials composite coatings are used to enhance the freeze-thaw durability of wall materials. Municipal solid waste incineration fly ash and fly ash were used to fabricate solid wastes-based autoclaved wall blocks (SW-AWBs) with hydrothermal synthesis method. Nano-Al 2 O 3 and graphene nanoplatelets were modified by the coupling agent and used to prepare composite coatings with triethoxy(octyl)silane. Effect of different coatings on the durability of SW-AWBs was compared and discussed. The results showed that the specimens surface changed from hydrophilic to hydrophobic after treated by composite coatings. Meanwhile, the capillary absorption coefficient of SW-AWBs decreased by 57.3%–78.8% and 92.4%–94.1% after treated by triethoxy(octyl)silane/nano-Al 2 O 3 and triethoxy(octyl)silane/graphene nanoplatelets coatings, respectively. Under 15 freeze-thaw cycles, the mass loss of SW-AWBs dropped by 61.9% and 69.4%, the strength loss reduced by 70.5% and 79.4% after treated by triethoxy(octyl)silane/nano-Al 2 O 3 and triethoxy(octyl)silane/graphene nanoplatelets coatings, respectively. Overall, triethoxy(octyl)silane/graphene nanoplatelets had a superior effect on improving the freeze-thaw durability of SW-AWBs than triethoxy(octyl)silane/nano-Al 2 O 3 .