Efficacy and mechanism of graphene oxide modified silane emulsions on waterproof performance of foamed concrete

As a lightweight construction material, foamed concrete has garnered considerable attention due to a variety of advantages. However, the high-water absorption increases the burden on the structure and accelerates freeze-thaw damage, and thus reduce the durability of foamed concrete. Herein, two kinds of waterproofing materials based on isobutyl triethoxysilane (IBTS) emulsion and graphene oxide/silane (GO/IBTS) composite emulsion were synthesized and used for foamed concrete by facile coating and soaking method. The results show that the soaked specimens exhibit excellent waterproof performance and the water absorption is almost 0%. By contrast, an internal waterproof layer is occurred in the coated specimens, and the water absorption rates of foamed concrete coated with IBTS emulsion and GO/IBTS emulsion are reduced by 75% and 82%, respectively. The waterproofing mechanism of the silane emulsion were analyzed by scanning electron microscope (SEM), energy dispersive spectrometer (EDS), flourier transform infrared (FT-IR), x-ray fluorescence analysis (XRF) and x-ray diffraction (XRD). The results demonstrate that the foamed concrete shows a rough surface topography and low surface energy after IBTS treatment, which resulted in a superhydrophobic surface. While the surface of foamed concrete became rougher with the admixture of GO, which further enhanced the waterproof performance of foamed concrete.