Durability and thermal insulation properties of glazed hollow bead concrete with nanoparticles in marine atmospheric environment

Abstract

Industrial and civil buildings in coastal areas have been in the marine atmosphere for a long time and are especially susceptible to the combined effects of carbonation and salt spray, which accelerate the deterioration of concrete durability and the reduction of thermal insulation performance. This paper focused on the effect of nano-SiO2 and nano-Al2O3 on the durability and thermal insulation of glazed hollow bead concrete (GC) under a salt spray carbonation environment, and analyzed the mechanism of nanoparticles on the improvement of durability and thermal insulation of GC by means of scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and X-ray diffraction (XRD) microscopic tests. The results showed that both nano-SiO2 and nano-Al2O3 incorporation could improve the durability and thermal insulation of GC to a certain extent. The optimal amount of both nanoparticles was 2 %, and nano-SiO2 had a stronger beneficial effect than nano-Al2O3. In comparison to GC, the free Cl− content in the surface layer of GCNS20 and GCNA20 after 56 cycles was decreased by 33.33 % and 27.22 %, respectively. Furthermore, the carbonation depths of GCNS20 and GCNA20 were decreased by 42.83 % and 36.38 %, respectively. The thermal conductivity of GCNS20 and GCNA20 decreased by 24.86 % and 17.34 %, respectively, while the thermal diffusion coefficients were reduced by 33.22 % and 23.73 %, respectively. The incorporation of nanoparticles effectively reduced the microcracks and pores in GC, improved its internal structure, and reduced the possibility of thermal bridge formation. In addition, the incorporation of nanoparticles significantly reduced the production of erosion products such as CaCO3 and Friedel's salt in GC.