In this paper, the resistance to the freeze/thaw cycles for four groups of mortars (lime—LM, lime based—LBM, cement—CM, and aerated cement—ACM mortars) with different amount of mortar components within each group is quantified via a ratio of flexural/compressive strength after and before exposure to freeze/thaw cycles. Using a pore system obtained by three different methods (mercury intrusion porosimetry, X-ray micro-computed tomography analysis, and SEM (Scanning Electron Microscopy) analysis), an attempt was made to explain why some mortars achieved better resistance to freeze/thaw cycles than others. The mortars with lime as a binder in the composition (LM and LBM groups) did not survive the freezing and thawing regime, while no visible damage was recorded in samples of the CM and ACM group. It is concluded that the low initial value of the mechanical properties of the LM and LBM mortars, as well as the higher proportion of harmful pores (pores greater than 0.064 μm) compared to CM and ACM mortars are responsible for their poor durability. According the results of nanotomography, it is concluded that the most important factor influencing freeze/thaw resistance is pore connectivity—the higher the connectivity of the macropores, the higher the freeze/thaw resistance of the mortar. SEM analysis proved to be a very useful method for aerated cement mortars as it revealed the pore sizes that were not covered by mercury porosimetry and nanotomography.

This study examines the influence of raw material characteristics, methods of shaping and of parameters of firing process of clay bricks, on pore-size distribution and on resistance to freeze–thaw cycles (with particular emphasis on the retention time of the specimens at the maximum achieved temperature). Pore-size distribution was measured by mercury-intrusion porosimetry, while the resistance to freeze–thaw cycles was assessed by exposing the bricks to freeze–thaw cycles (HRN B.D8.011 standard) monitoring the appearance of surface changes, decrease of compressive strength as well as the Maage factor. A correlation was set up between the Maage factor and the ratio of the compressive strength before and after freezing as a quantitative indicator of bricks resistance to frost. By using this correlation for all the examined bricks, regardless of their raw material and shaping procedure, a low coefficient of correlation (R² = 0.26) was obtained. When processed separately, machine-made bricks had a significantly higher correlation coefficient value (R² = 0.60) than the hand-made bricks (R² = 0.28).

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.

Seven different concrete mixtures were prepared to estimate the possibility of using pervious concrete for light traffic urban areas. The total porosity, density, compressive strength, flexural strength, abrasion resistance, and traffic noise absorption capacity were tested for all the concrete specimens. The first mixtures corresponded to a standard dense concrete mixture (M1), while the other mixtures were pervious concrete mixtures involving two different types of aggregates (dolomite and steel slag) and different proportions of aggregate fractions. The total porosity, density, compressive strength, flexural strength, abrasion resistance, and traffic noise absorption capacity were tested in the case of all concrete specimens. The total porosity increased, whereas the compressive and flexural strength decreased simultaneously with an increase in the share of coarse aggregate fractions. The abrasion resistance and acoustic characteristics improved if only a fraction of the aggregate was used in pervious concrete preparation.

In this study, the influence of freeze/thaw cycles on the mechanical and thermal properties of bricks and mortar as building parts of masonry walls, as well as the influence on the masonry wall itself is investigated. At the material level, the influence of freeze and thaw cycles on the mechanical and thermal properties of masonry components (bricks and mortar) was investigated; at the construction level, the influence of freeze and thaw cycles on the mechanical and thermal properties of a masonry wall was studied. To study the influence of freezing on the energy demand characteristics of masonry buildings, in terms of energy conservation and greenhouse gas emission, a case study was investigated on a typical structure of a historical building located in Croatia, that had undergone a process of energy certification. The applied freeze/thaw regime negatively influenced the compressive strength and the thermal properties of bricks and mortar, as well as the mechanical and thermal properties of the wall. Considering the thermal properties of the material before and after its exposure to freeze/thaw cycles, we concluded that the annual energy consumption, the heating costs, and the CO₂ emission of a family house could increase up to 3.7% after frost action in the studied case.

The aim of this research is to analyse the reliability of the existing methods, and find new ones, for assessing brick resistance to freeze-thaw cycles. A series of bricks were tested against a range of properties; compressive strength ratios pre- to post-freezing and Maage’s factor, were calculated. Using a database created in this way, an analysis of existing classifiers was carried out and new ones were established based on which bricks could be classified into resistant and non-resistant to freeze-thaw cycles. The median pore radius, the ratio of compressive strengths pre- to post-freezing and the water desorption coefficient at 180-360 minutes proved to be good classifiers with a clearly specified cut-off for the distinction between resistant and non-resistant bricks with an acceptable risk of a wrong decision. The ratio of compressive strengths pre to post freezing and the water desorption coefficient at 180-360 minutes were described using the pore system in the brick.