<p>Owing to the extremely poor engineering properties of calcareous sand, calcareous sand foundations easily cause serious consequences such as ground subsidence and pavement cracking of airport runways in the process of island and reef construction, which is a key scientific problem that urgently needs to be solved. As a new type of inorganic binder, polyurethane foam adhesive (PFA) can optimize and improve the engineering mechanical properties of calcareous sand, which is easily crushed, deformed and settled. Therefore, the one-dimensional compressive mechanical properties and microscopic pore size distribution characteristics of polymer-solidified calcareous sand were investigated in this study. On the basis of the one-dimensional compression test, the deformation characteristics of PFA-solidified calcareous sand were studied, and the influences of both the PFA content and the soil particle gradation factors were considered. The pore size distribution characteristics were then obtained via mercury intrusion porosimetry tests to reveal the microstructure features of calcareous sand stabilized with PFA and to analyze the pore size changes before and after consolidation. The results of this study can serve as a reference for calcareous sand foundation treatment technology.</p>