Insight into pore size distribution and moisture migration behavior in aerogel cementitious composites using BET-MIP and LF-NMR methods

Abstract

The durability of cementitious composites is closely related to their internal pore distribution and moisture migration patterns. In this study, low-field nuclear magnetic resonance (LF-NMR), specific surface area and porosity test (BET) and mercury intrusion porosimetry (MIP) techniques were used to compare and analyze the effects of different SiO2 aerogel contents on the pore size distribution, pore water content distribution and internal water transport of Silica aerogel incorporated Cementitious composites (AICs). The results show that with the increase of aerogel content, the pore structure of AICs has changed, and the pore connectivity has been enhanced. Compared with AIC0, the porosity of AIC10 increased by 11.89%. BET-MIP combined characterization method and LF-NMR method showed consistency in analyzing the change trend of pore size distribution of AICs, showing a trend of increasing the proportion of macroporous pore volume, thereby accelerating the water transport rate and reducing the durability of the material. In addition, during the water absorption process, the water distribution inside the material is uneven, and the area with low water content shows a cold tone in the spatial imaging.