PSI - Issue 64

Barbara Klemczak et al. / Procedia Structural Integrity 64 (2024) 1126–1133 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

1129

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Table 1. Basic properties of the applied MPCMs. Property

Chemical composition/value

Shell Core

Melamine-formaldehyde polymer shell

Paraffin based

Peak melting temperature, o C

24

Density, g/cm 3

0.78 184

Heat of fusion, J/g

Particle size (mean), μm

15-30

Table 2. The recipes for all tested foamed concretes. Component, kg/m 3 Density, kg/m 3 _MPCM content OPC MK

MPCM

HA

SP

ST

Water

Foam

350

207.0 197.1 187.0 295.5 281.5 266.0 413.7 394.2 372.2

34.0 32.3 31.0 48.4 46.1 44.0 67.8 64.6 61.0

-

4.8 4.6 4.3 6.9 6.6 6.2 9.6 9.2 8.7

1.2 1.2 1.1 1.7 1.6 1.6 2.4 2.3 2.2

7.0 6.6 6.3 9.9 9.5 9.0

96.4 91.8 87.2

56.0 57.0 59.0 51.0 52.0 53.0 43.0 44.0 45.0

350_10%MPCM 350_20%MPCM

16.5 23.6

500

-

137.6 131.0 124.0 192.6 183.5 173.3

500_10%MPCM 500_20%MPCM

23.6 50.1

700

-

13.9 13.2 12.5

700_10%MPCM 700_20%MPCM

33.0 70.2

For the investigation of FC's thermal properties, the focus was on thermal conductivity and specific heat. Thermal conductivity was evaluated using the Isomet 2114 thermal analyser (Applied Precision Ltd, 2011), employing a dynamic method that analyzes temperature response and heat flow impulses. The reported results represent averages obtained from six measurements conducted on samples measuring 100 mm x 100 mm x 100 mm ( Fig. 2 b ). Specific heat was assessed with the Netzsch HFM446 instrument, suitable for measuring specific heat capacity in low conductive materials (NETZSCH Geratebau GMBH). The method involves placing the sample between two heated plates at different temperatures while measuring heat flow with heat flux sensors covering both sides of the sample. The resulting temperature gradient creates a one-dimensional heat flow, measured by two calibrated heat flux sensors. The measurement concludes once steady-state conditions are reached. Considering practical applications, the study focused on ambient temperatures relevant to building materials, ranging from 0°C to 50°C during measurements. At this stage, measurements were carried out only on foamed concrete with a density of 500 kg/m 3 . The samples with the dimensions of 300 mm x 300 mm x 40 mm were used ( Fig.2 c ). The reliability of results was confirmed by low standard deviations — averaging 6.9% for mean compressive strengths of foamed concretes with and without MPCM addition, and not exceeding 5.6% for measured thermal properties.

Fig. 2. Exemplary produced samples: a) for compressive tests, b) for thermal conductivity, c) for specific heat tests