Influence of HCl on the Mechanical Characteristics of Red Mud Based Geopolymer

Acid corrosion can make serious damage to building materials. Therefore, investigating the durability of building materials in acidic environments is of significant engineering significance. In this study, a corrosion test was conducted on red mud based geopolymer (RMBG) within a simulated HCl environment. The primary objectives of this investigation were to analyze the morphological changes, stress-strain behavior, and compressive strength of RMBG at various stages of erosion. Additionally, this study aimed to assess the pore characteristics of RMBG when subjected to a HCl environment at different erosion durations. Mercury intrusion porosimetry (MIP) testing technology was employed for the characterization of these pore properties. The shifts in macro characteristics observed in RMBG are elucidated from a microscopic level. The results underscore the notable resistance of RMBG to HCl corrosion. Even after 112 d of exposure to HCl erosion, the compressive strength remains at over fifty percent of its initial value. However, the sample surface begins to show roughening after 28 d of erosion. Subsequently, the appearance of cracks becomes more pronounced at the 56 d mark and intensifies with prolonged erosion. This transformation is attributed to concurrent acid corrosion reactions and geological polymerization reactions occurring in the HCl environment. At each stage of erosion, the relative intensity of these two reactions varies. Notably, the pore volume and pore size distribution of RMBG exhibit only subtle changes in the HCl environment. However, there is a discernible shift in the transformation of initially harmless pores into less harmful ones over time.