Influence of Phosphorus Incorporation on the Crystallization Behavior and Electrochemical Properties of Portland Cement

The growing demand for sustainable construction materials has sparked interest in innovative cementitious components that improve performance while mitigating environmental impact. This study explores the influence of red phosphorus (P) on the crystallization dynamics and electrochemical stability of Portland cement. Specifically, we investigate how varying phosphorus concentrations (0–10%) affect phase evolution and structural integrity. A comprehensive suite of analytical techniques, including field emission scanning electron microscopy (FE-SEM), energy-dispersive spectroscopy (EDS), electron probe microanalysis (EPMA), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS), was employed to characterize crystallization behavior. Additionally, open circuit potential (OCP), potentiodynamic polarization tests, and electrochemical impedance spectroscopy (EIS) were utilized to evaluate electrochemical properties. Quantitative defect analysis showed that the number of pores increased from 150 ± 22 to 420 ± 22 ea/mm2, the crack width increased from 0.10 ± 0.01 to 1.40 ± 0.60 μm, and the crack length increased from 1.20 ± 0.20 to 4.20 ± 1.21 μm. In addition, OCP shifted from −0.16 ± 0.01 to −0.27 ± 0.03 V, Icorr increased from 2 × 10−7 ± 1 × 10−8 to 8 × 10−7 ± 3 × 10−8 A/cm2, and Rp decreased from 10.5 ± 0.4 to 6.0 ± 0.2 kΩ with increasing P composition, indicating deterioration of the microstructural and electrochemical stability of the cement matrix. These findings provide quantitative guidance for controlling phosphorus utilization in cement formulations.