Title: Effects of Gamma-Ray Irradiation on Hardened Cement Mortar
Author(s): Yuliia Khmurovska, Petr Štemberk, Svyatoslav Sikorin, Jiří Němeček, Daria Jóźwiak-Niedźwiedzka, Magdaléna Doleželová, Yuliya Kaladkevich, Eryk Pavalanski and Viktar Fatseyeu
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Keywords: cement mortar, drying, experiment, gamma‑ray, nanoindentation, porosity, X‑ray diffraction
The effect of gamma‑ray irradiation on cement mortar properties is investigated in this study in order to understand the mechanism behind the strength and stiffness reduction, which may be significant according to the available
researches. 60Co irradiation facility with the generating dose rate of 0.1–10 Gy/s and the total activity of 4.4·1015 Bq (120 kCi) was used to perform the irradiation, so that the total observed dose of the irradiated samples reached the
values ranging from 12.0 to 15.0 MGy. An identical set of control samples was placed in the same laboratory condi‑ tions away from gamma radiation. The results of nanoindentation, X‑ray diffraction analysis and mercury intrusion porosimetry of the irradiated and the control samples are shown and explained in detail in this study. The nanoinden‑ tation creep compliance and the nanoindentation elastic modulus of the irradiated and the control samples do not show any significant difference. The mineral composition obtained using the X‑ray diffraction analysis of the irradiated and the control samples is also similar. The pore structure rearrangement and microcrack occurrence, which were evidenced by the mercury intrusion porosimetry and scanning electron microscopy, led to the porosity increase and may be attributed to the significant decrease of compressive strength.