Application of Electron Paramagnetic Resonance for Evaluating and Improving the Mechanical Performance of Cement-Based Materials

Cement-based materials play a vital role in modern construction, where mechanical performance and durability are of primary importance. This study investigates the microstructural and mechanical properties of Portland cement-based systems using electron paramagnetic resonance (EPR) spectroscopy in combination with compressive strength tests. The results indicate that an increase in the specific surface area of cement particles leads to a higher concentration of spin centers, which influences hydration processes and strength development. The addition of activated Portland cement in the range of 5–15 wt.% resulted in an improvement in compressive strength of up to 15%. However, a further increase beyond this range caused a reduction in strength, which may be attributed to decreased material density and less efficient particle packing. High-strength and rapid-hardening cements exhibited higher concentrations of spin centers and improved mechanical performance. These findings confirm that EPR analysis is a useful tool for evaluating the relationship between microstructural characteristics and the mechanical behavior of cement-based materials.