PSI - Issue 74

Lucyna Domagała et al. / Procedia Structural Integrity 74 (2025) 17 – 24 Lucyna Domagała / Structural Integrity Procedia 00 (2025) 000–000

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Table 2. Compositions of fine-aggregate concretes.

Concrete designation

Aggregate type

Cement (c) kg/m 3

Water (w) kg/m 3

Oven dry aggregate kg/m 3

Foaming admixture kg/m 3

S P

Polystyrene

303 267 245 279 310

246 216 198 225 251 302

230 107 223 431 781

0.8 0.7 0.6 0.7 0.8 0.0

Perlite

G C V R

Expanded glass Expanded clay Sintered fly ash

Natural sand (ref.) 372

1536

2.2. Specimens and testing methods When designing all the mixtures, a constant volume fraction of aggregate and cement paste was initially assumed, amounting to approximately 60% and 40%, respectively. However, due to the different grain size of the aggregates used, the concretes produced were finally characterized by a slightly different volume fraction of cement paste and aggregate. Additionally, in the case of perlite aggregate, it crumbled during mixing of the components in the mixer. As a result, the grain size of this aggregate in the concrete was finer than the initial one. From each of the fine-aggregate concrete mixtures, three beams of dimensions 40 × 40 × 160 mm were formed, intended for bending strength tests according to EN 196-1 (2016). According to this standard, compressive strength tests are carried out on six halves of the beams previously subjected to bending. Due to the small size of the beams and the use of fine-aggregate concretes for the production of thin-walled elements, density, water absorption and thermal conductivity tests were carried out on three slab elements of dimensions 300 × 300 × 30 mm, in accordance with the principles of EN 12390-7 (2019), PN 91/B-06263 (1991) and EN 12667 (2001) / ASTM C518-91 (2017), respectively. Both the beams and the slab elements were formed in a single layer and then compacted on a vibrating table. The strength tests of the hardened composites were carried out after 28 days of curing in standard conditions corresponding to the requirements of EN 196-1 (2016). The slab specimens, on the other hand, after 28 days of curing in laboratory air conditions (T = 20 o C, RH = 50 %) were subjected to thermal conductivity tests in their natural moisture condition, and then dried to a constant mass and their thermal conductivity coefficient in the dry condition was tested again. Fig. 2 shows examples of moulded beam and slab specimens used in the tests. a b

Fig. 2. Moulding test specimens: (a) slabs 300 × 300 × 30 mm; (b) beams 40 × 40 × 160 mm.