PSI - Issue 79

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

200

2. Materials and Methods 2.1. Epoxy system A commercial two-component epoxy system was used (component A – epoxy resin, component B – hardener), prepared in a constant weight ratio of A:B = 100:50 parts by mass. 2.2. Characteristics of waste granite powders Two types of granite powders differing in particle size distribution were used, designated as G1 and G2, as shown in Fig. 1, where G1 represents the fine dust fraction and G2 a fine sand–like fraction. The finer powder, G1, contains most particles in the 25–40 µm range, with approximately 73% of the mass consisting of particles below 40 µm, and complete sieving ending at 250 µm. The G2 powder contains a significant proportion of particles in the 100–500 µm range, with only about 12% of the mass below 100 µm and complete sieving occurring at 1000 µm. The difference in particle size distribution allows for the assessment of the effect of filler particle size on the impact resistance of epoxy coatings.

100%

96% 98% 100%

96%

a

b

0% 3% 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% Percentage by mass (%)

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% Percentage by mass (%)

88%

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Total value

73%

58%

18%

12%

8%

0% 0% 0% 0% 0%0% 1%98%

0

2

5 10 25 40 50 63

100250

Sieve size (µm) 0 2 5 10 25 40 50 63 100 250 500 1000

Sieve size (µm)

Fig. 1. Particle size distribution of waste granite powders: (a) G1; (b) G2.

2.3. Sample preparation Seven mixtures differing in the type and amount of granite powder were prepared for testing. The reference mixture (REF) consisted of pure epoxy resin with hardener, mixed in a weight ratio of 100:50. The remaining mixtures contained granite powders G1 or G2 in amounts of 12, 36, and 60 parts by weight per 100 parts of resin (with the ratio maintained at 100:50:x). The designations of the mixtures were as follows: The prepared mixtures were applied onto steel plates with dimensions of 10 × 10 cm and a thickness of 1.03 ± 0.01 mm. After curing, coatings with an average thickness of 2.38 ± 0.16 mm were obtained. The samples were left under laboratory conditions until fully cured before performing the impact resistance tests. To minimize the influence of substrate heterogeneity, steel plates were used as the coating substrate instead of a cementitious or concrete substrate. In actual flooring systems, an impact may strike either the cement matrix or an aggregate grain (fine or coarse), which would lead to significant variability in the results. The use of uniform steel plates made it possible to achieve greater repeatability and comparability of the results.  G1-12, G1-36, G1-60 – mixture with G1 powder,  G2-12, G2-36, G2-60 – mixture with G2 powder.