PSI - Issue 79

Agnieszka Chowaniec-Michalak et al. / Procedia Structural Integrity 79 (2026) 198–205

204

Table 1. Comparison of results converted to impact energy

Sample ID

Drop height for Type II [cm]

Energy [J]

Drop height for Type II [cm]

Energy [J]

REF

(none)

–

20

3.9 9.3 9.8

G1-12 G1-36 G1-60 G2-12 G2-36 G2-60

62.5 75.0 80.0 60.0 72.5 72.5

6.1 7.4 7.8 5.9 7.1 7.1

47.5 50.0 60.0 50.0 75.0 75.0

11.8

9.8

14.7 14.7

For type I damage corresponding to the first visible cracking of the coating, the samples containing the fine granite powder (G1) reached energy values from approximately 6.1 J (G1-12) to 7.8 J (G1-60), indicating stable load transfer under relatively low impact energy. The presence of fine particles helped distribute stresses more evenly within the resin matrix, limiting local stress concentrations. For type II damage, generated at higher impact energies (9.3–14.7 J), the coatings with the larger-particle fraction (G2) performed better. This may be related to the ability of larger particles to dissipate impact energy more effectively within the coating structure. The comparison of results therefore suggests that different particle sizes may contribute to different resistance behaviors: fine particles (G1) appear to stabilize the coating under micro-damage conditions, while larger particles (G2) may help to limit crack propagation at the macroscopic level, improving resistance to more extensive failure. Converting the results to impact energy using (1) facilitates the comparison of tests with different weight masses; however, it does not fully represent the real dynamics of impact. For the same energy, the velocity and momentum of the weight differ, affecting the force–time profile and the failure mechanism of the coating. Therefore, energy should be treated as a comparative indicator, while standardized results should be reported and interpreted in the original metric of drop height. Due to the use of steel plates as the substrate, the obtained results do not reflect the actual impact resistance under service conditions, where the epoxy coating interacts with a concrete or cementitious substrate. Differences in stiffness and load transfer behavior may lead to different critical values. Nevertheless, the adopted method enables relative comparison of different epoxy resin modifications and provides a basis for developing potential impact resistance classes for epoxy flooring systems. 4. Conclusions Analysis of the impact resistance results of epoxy coatings modified with granite powders led to the following conclusions:  The use of granite powders in epoxy coatings allows for a reduction in the amount of epoxy resin and hardener without compromising mechanical resistance, aligning with the principles of the circular economy.  All modified coatings exhibited higher impact resistance compared to the reference sample, confirming the beneficial effect of mineral fillers.  The fine powder fraction (G1) improved resistance to localized, point-type damage (Type I), while the larger particle fraction (G2) more effectively limited crack propagation and extensive failure (Type II).  Converting the results to impact energy enables comparison between mixtures tested with different load masses, however, it represents a simplified model of dynamic loading and does not fully reflect the coating’s actual behavior under impact.  The use of steel plates as the substrate does not reproduce real service conditions, but it allows for relative comparison of different resin modifications and may provide a basis for developing impact resistance classes for epoxy flooring systems.