PSI - Issue 66

Jonathan Duarte Oliveira et al. / Procedia Structural Integrity 66 (2024) 313–319 Author name / Structural Integrity Procedia 00 (2025) 000 – 000

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The mixture here employed complies with the Brazilian IPT-EPUSP mix design method (Helene and Terzian, 1992), where the ingredients of the mixture are dosed in order to achieve a design porosity of 25%, corresponding to that used in Pereira da Costa et al. (2021). More precisely, for each m 3 of mixture, 367.93 kg of cement, 1471.73 kg of aggregate and 97.13 kg of water are employed (that is, the design density is equal to 1936.79 kg/m³). The design mass is obtained by multiplying the volume of the mold for the above density, corresponding to a mass of 6.54 kg for a cubic specimen with sizes of 150x150x150 mm. 2.2. Specimen casting and compaction To obtain the above design mass, the following procedure, proposed by Pereira da Costa et al. (2021), is employed. Firstly, the mold is put on a digital balance (maximum capacity of 150 kg and precision of 50 g) and its tare is measured. Then, the mold is filled with the mixture, which is compacted with a roller made of concrete, having a diameter of 30 cm and a length of 35 cm and with a weight of 57.4 kg. The compaction is made in one layer to simulate the in situ compacting technique used for pavements. Finally, the mold is weighed to check if the actual mass is equal to the design one. In the case of the actual mass is less or greater than the design one, material is added or removed and compacted again up to the design value is reached, with a tolerance of 50g. The specimens are placed in a wet chamber with controlled temperature (23ºC) and relative humidity (99%). The samples are demolded after 72 hours and cured in the above wet chamber for 28 days. 2.3. Physical properties The hardened density and porosity of the investigated material are measured according to the ASTM C1754 (2012) standard, at 21 days of curing. The average density is equal to 1870.97 ± 13.10 kg/m 3 , whereas the average porosity is equal to 27.11 ± 0.39%. With respect to the design values, a relative difference of -3.40% and 8.44% are registered, respectively. 2.4. Compressive strength The compressive tests are performed in accordance with the European EN 12390-3 (2003) standard. Firstly, a mechanical grinding machine is used to rectify the specimen ends. Then, the tests are performed by using an EMIC GR048 universal testing machine (Fig. 2(a)), equipped with a 200 kN load cell, under displacement control at a rate of 0.1 mm/min.

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Fig. 2. (a) Set-up configuration, (b) compression failure, and (c) crack path analysis by GOM (GOM GmbH, 2019).