Netinger Grubeša Ivanka, Vračević Martina, Ducman Vilma, Marković Berislav, Szenti Imre, Kukovecz Ákos
Faculty of Civil Engineering and Architecture Osijek, Josip Juraj Strossmayer University of Osijek, Vladimira Preloga 3, 31000 Osijek, Croatia.
Institute IGH, Janka Rakuše 1, 10000 Zagreb, Croatia.
Materials (Basel). 2020 Aug 22;13(17):3717. doi: 10.3390/ma13173717.
This paper estimates the frost resistance of bricks using the ratio of compressive strength before freezing to compressive strength after freezing to describe the damage degree of bricks being exposed to freeze-thaw cycles. In an effort to find the ratio that clearly distinguishes resistant bricks from non-resistant bricks, the authors attempted to establish the correlation between the ratio and Maage factor as a recognized model for assessing brick resistance. To clarify the degree of damage of individual bricks, the pore size distribution has been investigated by means of mercury porosimetry. Additionally, micro computed X-ray tomography (micro-CT) has been employed to define the influence of the type of pores (open or closed) and their connectivity on the frost resistance of bricks. According to the results, it can be concluded that there is a good correlation between the Maage factor and the ratio of pre- to post-freeze-thaw cycle compressive strengths, and that the latter ratio strongly correlates with the percentage of large pores (≥3 mm) in the brick. If such a correlation could be confirmed in a larger sample, then the ratio of pre- to post-freeze-thaw cycle compressive strengths could be used as a new method for assessing brick resistance to freeze-thaw cycles and it would be possible to determine the minimum percentage of large pores required to ensure the overall resistance of brick to freeze-thaw conditions. The complexity of the problem is, however, evidenced by the fact that no clear connection between the type (open versus closed) or connectivity of pores and the frost resistance of bricks could be revealed by micro-CT.
本文通过冻融循环前抗压强度与冻融循环后抗压强度之比来估算砖的抗冻性，以此描述砖在冻融循环作用下的损伤程度。为了找到能清晰区分抗冻砖与非抗冻砖的比值，作者试图建立该比值与马格因子之间的相关性，马格因子是评估砖抗性的公认模型。为了阐明单块砖的损伤程度，采用压汞法研究了孔径分布。此外，还利用微计算机X射线断层扫描（micro-CT）来确定孔隙类型（开放或封闭）及其连通性对砖抗冻性的影响。根据结果可以得出，马格因子与冻融循环前后抗压强度之比之间存在良好的相关性，并且后者与砖中大于等于3毫米大孔隙的百分比密切相关。如果在更大的样本中能证实这种相关性，那么冻融循环前后抗压强度之比可作为评估砖抗冻融循环能力的新方法，并且有可能确定确保砖整体抗冻融条件所需的大孔隙最小百分比。然而，问题的复杂性体现在通过微计算机X射线断层扫描未发现孔隙类型（开放与封闭）或连通性与砖抗冻性之间存在明确联系这一事实上。
