PSI - Issue 74

Małgorzata Lenart et al. / Procedia Structural Integrity 74 (2025) 44 – 49 Małgorzata Lenart / Structural Integrity Procedia 00 (2025) 000–000

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with time, Neville (2012). Shrinkage also depends on the dimension of the concrete element, the greater the surface modulus of the element (e.i. the ratio of the area of the concrete element exposed to external influences to its volume) the greater the shrinkage, Lenart (2015). 4. Methods for determining shrinkage of cementitious composites Determining the amount of shrinkage has long been of interest to researchers. Therefore, there are many shrinkage testing methods, including: • Ring Test used in the method according to ASTM C1581, • Measurement gauge of hardened samples used in, among others: EN 12390-16 standard, the Amsler method (PN 84/B-06714/23), the Graff-Kaufman method (PN-84/B-06714/24), ASTM C157 and many others • Shrinkage gutter measurement – a method originally used in the OENORM B 3329 standard, it can measure volumetric changes from the time the material is placed in the gutter to the subsequent shrinkage from drying, • Bending drain test used to measure the dimensional stability of materials for floor screeds based on cement, among others, in accordance with EN 13892-9. This method can also determine the effect of temperature change on dimensional stability (effect of underfloor heating). • Measurement of early shrinkage changes by the shrinkage cone method or the Thin-Layer-Measurement System method used in devices manufactured by Schleibinger, • Measurement of chemical shrinkage by methods described, for example, in Holt (2001). In conclusion, it can be seen that there are many factors affecting the shrinkage of cementitious composites, moreover, different test methods, which have their advantages and disadvantages, determine different types of shrinkage depending on the measurement procedures used. Therefore, a system of shrinkage measuring gutters was used for this research because it measures the total shrinkage occurring in the tested cement composite to the greatest extent. In addition, the test results are recorded automatically, without human intervention, at a predetermined frequency, and these results are recorded directly in millimeters per meter of sample length. 5. Research The aim of the study was to determine the effect of a polymer additive dosed at two levels on the course of shrinkage deformation over the 90 days of the test. Shrinkage was determined in shrinkage gutters according to our own test procedure, based on the original one mentioned in Section 4. Additionally, the effect of the type of care on the course of the aforementioned shrinkage deformations was studied. Three variants of specimen care were used: A – no additional protection against drying out, which is equivalent to no care, B – care with a care preparation sprayed onto the samples, C – protection with a standard foil against drying out of the samples. 5.1. Materials and the test procedure Portland ash cement CEM II/B-V 32.5R, which meets the requirements of PN-EN 197-1, was used for the study. The content of silica fly ash in the cement was 21-35%, according to the manufacturer's declaration. This cement was selected for the study because, on the one hand, it has good technological parameters, is easily available and, above all, this cement has a lower carbon footprint than pure clinker Portland cement, hence it is pro-ecological, more “friendly” to the environment. For the tests, quartz sand with a grain size shown in Table 1 was used as a fine aggregate .

Table 1. Grain size of the sand used for testing .

Fraction

0-0.125

0.125-0.25

0.25-0.5

0.5-1.0

1.0-2.0

2.0-4.0

Amount [%]

2

16

44

22

11

5