PSI - Issue 73

Loran Nermend et al. / Procedia Structural Integrity 73 (2025) 130–137 Author name / Structural Integrity Procedia 00 (2025) 000–000

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deterioration in mechanical performance. As reported by Cicione et al. (2021), delamination of printed sample can occur as a result of heat exposure. Zhou et al. (2025) reported that depending on the heating regime and particle orientation during interlayer strength testing, the interlayer bond strength can be diminished by 73.9 % at 400°C, 83.1 % at 600 °C and 90 % at 800 °C. However, it is worth noting that in this study, after exposure to 450°C , cast specimens were not affected by temperature, while in the case of printed specimens a 14% loss was reported for BGS250 specimens. On the contrary, the highest loss of compressive strength after exposure to 600°C was found for the Control (print) specimen. In all cases reported, residual compressive strength varied from 0.47 to 0.63, and no clear difference between printed and cast specimens was observed. This could be attributed to the compressive strength testing methodology used for printed specimens, in which the load is applied perpendicular to the print direction. As a result, the influence of interlayer bonding is reduced. Based on Kodur (2014) and Eurocode 2 (EC2) data, the residual relative compressive strength of normal strength concrete containing siliceous aggregate after exposure to 600°C is equal to 0.45, while for calcareous aggregate, it is equal to 0.6. Therefore, reported data for 3DPC seem to align with a typical EC2 curve. In the case of dynamic elastic modulus (Figure 5, bottom row) substantial losses in specimens were found both after exposure to 450 °C and 600 °C, which are also following the reduction factors presented in EC2. Marginal differences between types of specimen (cast vs print) were found. Based on the data presented, no substantial differences between types of material were found; therefore, it can be concluded that the replacement of cement with radiation shielding admixtures has marginal effects on the elevated temperature performance of 3DPC. In the case of the dynamic elastic modulus (Figure 3, bottom row), significant reductions were observed in the specimens after exposure to both 450 °C and 600 °C . These reductions align with the reduction factors specified in EC2. Only marginal differences were found between the specimen types (cast vs printed). Furthermore, based on the presented data, no substantial differences were observed between mixes. Therefore, it can be concluded that replacing cement with radiation-shielding admixtures has a minimal impact on the elevated-temperature performance of 3D printed concrete (3DPC).

Table 2. Compressive strength and standard deviation (SD) values [MPa] of cast and printed specimens.

Sample designation

Oven-dry sample

450 °C

600°C

F c

SD

F c

SD

F c

SD

C - cast

97.2 59.6

5.87 2.63 7.08 3.75 4.74 3.90

104.0

1.734

62.1 28.1 59.5 30.0 60.2 35.6

3.78 5.09 3.41 2.19 5.49 4.14

C - printed

54.8

4.44 4.09 7.51 2.61 2.62

BG250 - cast

104.3

102.9

BG250 - printed BGS250 - cast BGS250 - printed

56.2

52.6

102.3

106.2

58.7

50.4