PSI - Issue 68

Zoi S. Metaxa et al. / Procedia Structural Integrity 68 (2025) 184–189 Z.S. Metaxa et al. / Structural Integrity Procedia 00 (2025) 000–000

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2.2. Density measurements The method used to determine the density of the mortar samples followed the guidelines outlined in EN 1015–10. The mass of each mortar prism was measured using an accurate digital scale. The specimens were oven-dried at a consistent temperature of approximately 60 °C until two successive weight measurements, taken 2 hours apart, showed no significant variation. Once the drying process was complete, the average mass of the prisms for each mix was calculated. The density was then determined by dividing the mass of the specimen by its volume. 2.3. Thermal conductivity measurements Thermal conductivity measurements were performed using the heat flow meter method, following ISO 8302 and EN12667. The tests involved placing cuboid specimens between heated plates to measure the material's capacity to resist heat transfer. The primary goal was to evaluate the insulating potential of the XPS-modified mortars as the XPS content increased. 3. Results and discussion The results were analyzed in terms of flexural strength, density, and thermal conductivity, with an emphasis on how varying percentages of XPS replacement influence these properties. Table 1 presents the average values and standard deviations for flexural strength, density, and thermal conductivity across different XPS content levels (0 vol.% to 100 vol.%). As XPS content increases, the flexural strength shows a gradual decline, from 7.32 MPa at 0 vol.% XPS to 5.42 MPa at 100 vol.% XPS, indicating a reduction in mechanical performance. Similarly, the density decreases from 2115.65 kg/m³ at 0 vol.% XPS to 1482.40 kg/m³ at 100 vol.%, confirming the lightweight nature of XPS composites. On the other hand, thermal conductivity improves with increasing XPS content, reducing from 1.170 W/mK to 0.610 W/mK, demonstrating enhanced thermal insulation properties. Table 1. Summary of flexural strength, density, and thermal conductivity (λ) for XPS-modified mortar mixtures in average values and respective standard deviation (St. Dev.) out of at least three specimens per different investigated case.

Density [kg/m 3 ]

Flexural strength [MPa]

Thermal conductivity [W/mK]

Mix Code

Average

St. Dev.

Average St. Dev.

Average

St. Dev.

0 vol.% 10 vol.% 20 vol.% 30 vol.% 40 vol.% 50 vol.% 60 vol.% 70 vol.% 80 vol.% 90 vol.% 100 vol.%

7.32 7.28 7.25 7.13 7.06 6.95 6.84 6.60 6.34 6.10 5.42

0.42 0.17 0.37 0.37 0.38 0.23 0.08 0.13 0.13 0.24 0.15

2115.65 2104.60 2062.76 2049.01 2004.80 1945.84 1850.64 1763.59 1693.73 1601.97 1482.40

26.01

1.170 1.093 1.121 1.109 0.992 1.030 0.970 0.928 0.822 0.724 0.610

0.090 0.202 0.088 0.126 0.173 0.159 0.039 0.155 0.053 0.044 0.021

7.53 3.54

12.03 11.30 12.35 10.49 33.53 20.36

3.17 6.07

3.1. Mechanical performance The flexural strength evolution of XPS-modified mortars at 3, 7, and 28 days is depicted in Fig. 1a. It is observed that, the overall trend of mechanical strength development is similar across all mixtures, indicating that the presence of XPS does not significantly alter the pattern of mechanical strength increase over time. Although the absolute values vary with XPS content, the mechanical strength increase with curing days remains almost constant for all investigated