Frost Cycles Research Articles

Characterization and damage of the historic brick masonry of the Zákupy castle stables

Abstract A chemical-mineralogical analysis and mechanical tests of historical bricks were carried out as part of the construction-technical survey. The objective was to identify the causes of significant masonry decay. The ruined agricultural yard is a national cultural monument. Conservators believe that the historical importance exceeds that of the neighbouring castle. Stables were designed in 1650 by prominent Italian builders Giulio Broggio and Giovanni Domenico Orsi. The building has not been maintained since the conclusion of World War I. After removal from the masonry, the analyzed samples of bricks reached a very high, almost total degree of water saturation - 87-94%. Some bricks are heavily contaminated with nitrates and sulfates, infrared spectrometry analysis showed that calcium nitrate tetrahydrate is the most abundant of the nitrates. The determined average values of physical properties (bulk weight 1764 kg/m3, capillary absorption 13.6% by weight and open porosity 24% by volume) from samples under atmospheric pressure are comparable to the values of masonry bricks produced today. The results of the tests on the bricks from the Zákupy Castle stables construction demonstrate the high manufacturing quality of the masonry elements utilized. Based on the results of the analyses, it can be assumed that three degradation factors contribute to the observed damage to the bricks: high wetting of the masonry (almost total saturation of pores with water), which is most likely long-term lasting, frost cycles - repeated freezing and thawing of water in the bricks during the winter months, and repeated crystallization of water-soluble salts present in pores near the surface.

Frost Damage Mitigation in Flowers and Fruitlets of Peach and Almond from the Application of a Multi-Attribute Approach Biostimulant.

To prevent frost damage in fruit trees, growers employ passive and active methods, and one of these second methods is the use of biostimulant compounds against abiotic stress. In this study, two trials were conducted to evaluate the effectiveness of a multi-attribute approach biostimulant-containing α-tocopherol, boron, and glycols, in peach ('UFO-4' cultivar) and almond ('Vairo' cultivar) trees. In a first trial, one-year-old shoots with flowers were collected after 24 h, 48 h, and 96 h of the biostimulant applications. Two different application rates of the product (1000 and 2000 cc ha-1) were tested and compared to an untreated control. In a second trial, one-year-old shoots with fruitlets were collected after 24 h of the biostimulant applications. In this case, only an application rate (2000 cc ha-1) was tested. In the two trials, the collected one-year-old shoots were subjected to different frost temperatures using a controlled environment chamber. The damage level was assessed by a morphological analysis of the flowers and fruitlets 96 h after each frost cycle simulation. The lethal temperatures (LT10, LT50, and LT90) of each treatment were calculated by probit analysis. The product applied 24 h and 48 h before the frost simulations significantly decreased the LT10 and LT50 in 1.5 °C in peach flowers, and 2.5 °C in almond flowers (a temperature reduction of 50% and 75%, respectively). These results were more consistent when the application volume was 2000 cc ha-1, instead of 1000 cc ha-1. Significant differences between treated and non-treated fruitlets were observed only in almond fruitlets, with LT10 and LT50 being 0.5 °C lower in treated fruitlets (20% reduction). In conclusion, the multi-attribute approach biostimulant applied 24 or 48 h before the frost reduced the mortality of peach and almond flowers, but its effectiveness to protect fruitlets after bloom was inconsistent.

Subarctic winter warming promotes soil microbial resilience to freeze-thaw cycles and enhances the microbial carbon use efficiency.

Climate change is predicted to cause milder winters and thus exacerbate soil freeze-thaw perturbations in the subarctic, recasting the environmental challenges that soil microorganisms need to endure. Historical exposure to environmental stressors can facilitate the microbial resilience to new cycles of that same stress. However, whether and how such microbial memory or stress legacy can modulate microbial responses to cycles of frost remains untested. Here, we conducted an insitu field experiment in a subarctic birch forest, where winter warming resulted in a substantial increase in the number and intensity of freeze-thaw events. After one season of winter warming, which raised mean surface and soil (-8 cm) temperatures by 2.9 and 1.4°C, respectively, we investigated whether the insitu warming-induced increase in frost cycles improved soil microbial resilience to an experimental freeze-thaw perturbation. We found that the resilience of microbial growth was enhanced in the winter warmed soil, which was associated with community differences across treatments. We also found that winter warming enhanced the resilience of bacteria more than fungi. In contrast, the respiration response to freeze-thaw was not affected by a legacy of winter warming. This translated into an enhanced microbial carbon-use efficiency in the winter warming treatments, which could promote the stabilization of soil carbon during such perturbations. Together, these findings highlight the importance of climate history in shaping current and future dynamics of soil microbial functioning to perturbations associated with climate change, with important implications for understanding the potential consequences on microbial-mediated biogeochemical cycles.

Performance Improvement of Microchannel Heat Exchangers with Modified Louver Fins under Frosting Conditions

Microchannel heat exchangers (MCHX) are increasingly being used in refrigeration and heat pumps due to their superior thermal-hydraulic properties. However, when the MCHX surface temperature drops below the freezing point, frost will accumulate on the fin surface, which significantly affects the heat transfer performance. In this study, a modified MCHX with extended windward fins was developed to improve the frosting performance. The thermal-hydraulic performance of the modified MCHX and conventional MCHX were compared and evaluated under frosting conditions. Results show that the extended fins on the windward side capture a large amount of frost and delay the rapid blockage of air flow passage by frost. The modified MCHX structure makes the frost more evenly distributed. During the 60 min frosting cycle, the total heat transfer capacity and the mass of the accumulated frost of the modified MCHX are 9.6–49.7% and 10.3–46.9% higher than the conventional MCHX, respectively. Furthermore, the modified MCHX has greater potential to improve the thermal-hydraulic performance under the condition of more uneven frost layer distribution. The purpose of this work is to provide useful guidance for the optimal design of MCHX under frosting conditions.

The effects of 3D printing on frost resistance of concrete

3DCP is becoming more common in the construction industry nowadays, however, the aspects of durability of printed concrete are not well-studied yet. This paper focuses on determining how frost-thaw cycles affect printed concrete samples, compared to cast samples of the same concrete mix and whether the conventional concrete frost resistance tests can be applied for 3D printed concrete samples. Two different concrete mixes were both printed and cast – first one was a ready-made mix provided by a dry concrete mix manufacturer and was used for reference, whereas the other mix was prepared at the lab. First, 7 and 28-day compressive and flexural strength as well as density were determined to establish the difference between mechanical and material properties of both printed and cast concrete samples that were intended to be used for frost resistance testing according to standard CEN 12390-9. Next, both printed and cast samples of both mixes were subject to a total of 56 freeze-thaw cycles while submerged in NaCl solution, allowing to determine mass loss of each sample after N frost cycles. To conclude, the obtained results enable the authors to evaluate how 3D printing affects concrete resistance to frost/thaw cycles compared to conventionally cast concrete as well as the possible causes for this. Further research is needed to improve both the design mix of concrete as well as the printing and testing methodology of frost resistance of 3D printed concrete which would possibly lead to its increased use in exposed outdoor structures in northern regions.

Multi‐stage evolution of frost‐induced microtextures on the surface of quartz grains—An experimental study

AbstractCoarse sand‐sized (0.5–1.0 mm) grains of vein quartz were subjected to frost‐induced stress under controlled laboratory conditions. A total of 1,000 freeze–thaw (FT) cycles, simulated under different (low, high) water mineralization conditions in the temperature range from −5°C up to +10°C, were used to test effects on collected samples. Scanning electron microscopic (SEM) microtextural analysis of grain surfaces was performed at 0 (start) and after 50, 100, 300, 700, and 1,000 FT cycles. The results indicate that variable frost‐induced microtextural imprints encountered on quartz grain surfaces prior to and following analysis depend largely on the mineralization (dissolved solute content) of water involved in the weathering process. The higher the water mineralization, the greater the intensity of mechanical weathering. Two predominant outcomes in the course of these micro‐scale frost weathering tests have been identified: a physical (mechanical) aspect manifested by the occurrence of conchoidal fractures and breakage block microtextures dominating up to 300 FT cycles, and a chemical aspect resulting in the occurrence of precipitation crusts and obliteration of grain microrelief. Moreover, three additional stages of microtexture development may be distinguished with the evolution of frost‐induced microrelief on the surface of quartz grains: (i) initial cracks of large‐sized conchoidal fractures, (ii) increasing frost cycles yielding additional small‐sized conchoidal fractures, and (iii) advanced breakage blocks. Frost‐induced exposure of fresh, unweathered grain surfaces leads to refreshing of the grain surface.

Atmosphere and frost cycle revealed by Pluto's dark side

Atmosphere and frost cycle revealed by Pluto's dark side

The Behavior of Cement-Bonded Particleboard with Modified Composition under Static Load Stress.

This article presents research on the behavior of cement-bonded particleboards under mechanical stress caused by the static load. The composition of the boards was modified using alternative raw materials–dust (DU) forming during the processing of cement-fibre boards and particle mixture (PM) generated in the production of cement-bonded particleboards. The particleboards (1-year-old) were subjected to an adverse environment (100 to 250 frost cycles). Mechanical parameters were tested, and the development of defects during static load of the boards by bending was analyzed using acoustic emission. Particleboards with modified compositions are slightly more resistant to adverse environments. The results of the acoustic emission showed the different types of defects occurring under stress by bending. Standard-composition particleboards showed defects located mainly under the cylindrical stress-test head. The modified boards showed larger location distribution of the occurring defects that were also concentrated further away from the cylindrical stress head. The energy during the occurrence of defects was higher in the modified boards in the location of weight application than in the reference boards.

Using patterned surface wettability to enhance air-side heat transfer through frozen water droplet vortex generators-part I: Experimental study

• Frozen water droplets can serve as vortex generators (VGs) to increase air-side heat transfer. • The VGs are formed via the naturally-occurring processes of condensation and freezing. • Patterned surface wettability encourages coalescence in predetermined locations. • A circular moat helps concentrate water inside a circular region prior to freezing. • The average height of the frozen droplets after the third defrost cycle was 1.25–3.20 mm. • The VG height is greater than the boundary layer thickness in the entrance region. In this study, a novel technique for deploying hemispherical vortex generators (VGs) on a refrigerator evaporator for air-side heat transfer enhancement is investigated. The dome VGs are formed via the naturally-occurring processes of condensation and freezing. By using patterned surface wettability to collect condensate and encourage coalescence in predetermined locations, it was found that large frozen droplets could be formed in various configurations on the fin surface, which in turn could then serve as VGs during the early frost growth period. These findings were examined experimentally here using a flat hydrophobic-coated aluminum plate (Part I) and were then simulated numerically in a follow-up study (Part II). Various geometries of staggered circles were studied to test the efficacy of the idea. The circular regions had an inner diameter of 3.175 mm (0.125 in) and were surrounded by a microchannel “moat” to promote the coalescence and trapping of condensate into a single droplet inside the circle. Surface testing was performed inside an environmental chamber via a one-hour condensation period ( T w ∼1°C) followed by three one-hour frost growth periods with ten minutes of defrosting in between. The following experimental conditions were used during testing: RH=60–80%, T air = 20°C–24°C, and T w = −3°C to –12°C. By varying the microchannel width (∼100–500 µm) and the wettability of the inner area, large frozen droplets were formed which remained visible for 40–60 min during the third frost cycle. The average diameter and height of the frozen droplets at the end of the third cycle were 3.20–3.90 mm and 1.25–3.20 mm, respectively.

Rain on snow induced urban floods in cold maritime climate: Risk, indicators and trends

AbstractUrban floods pose a societal and economical risk. This study evaluated the risk and hydro‐meteorological conditions that cause pluvial flooding in coastal cities in a cold climate. Twenty years of insurance claims data and up to 97 years of meteorological data were analysed for Reykjavík, Iceland (64.15°N; <100 m above sea level). One third of the city's wastewater collection system is combined, and pipe grades vary from 0.5% to 10%. Results highlight semi‐intensive rain (<7 mm/h; ≤3 year return period) in conjunction with snow and frozen ground as the main cause for urban flood risk in a climate which undergoes frequent snow and frost cycles (avg. 13 and 19 per season, respectively). Floods in winter were more common, more severe and affected a greater number of neighbourhoods than during summer. High runoff volumes together with debris remobilized with high winds challenged the capacity of wastewater systems regardless of their age or type (combined vs. separate). The two key determinants for the number of insurance claims were antecedent frost depth and total precipitation volume per event. Two pluvial regimes were particularly problematic: long duration (13–25 h), late peaking rain on snow (RoS), where snowmelt enhanced the runoff intensity, elongated and connected independent rainfall into a singular, more voluminous (20–76 mm) event; shorter duration (7–9 h), more intensive precipitation that evolved from snow to rain. Closely timed RoS and cooling were believed to trigger frost formation. A positive trend was detected in the average seasonal snow depth and volume of rain and snowmelt during RoS events. More emphasis, therefore, needs to be placed on designing and operating urban drainage infrastructure with regard to RoS co‐acting with frozen ground. Furthermore, more detailed, routine monitoring of snow and soil conditions is important to predict RoS flood events.

Evaluation of Point Load Test Effectiveness in Estimation of Long-Term Durability of Some Chinese Limestone Rocks Due to Frost Action

In spite of point load method has been frequently used for assessment of the decay state of stones under weathering agents, its method in estimation of long-term durability of natural rocks remains limited. This study aims to assess the point load method efficiency in evaluation of long-term durability of limestone types due to frost action. For this reason, the frost process up to 100 cycles was applied on different limestone types which quarried from mine in China and the ultrasound properties including compressional wave velocity (Vp) and spatial attenuation (αs) were determined before and after frost cycles and then their variation rates were obtained. The variation rates of Vp and αs including ΔVp and Δαs, respectively, were taken into consideration as a function of the decay state of stones and as indicators of the frost durability action. The results indicated that there are a strong correlations between point load index values (σp) and ΔVp and Δαs with R2 of 0.79 and 0.82, respectively. It was found that the point load method is an effective tool for evaluating the long-term durability of rocks and can be used for a fast and on-field assessment of long-term durability of stones especially at different mine faces. Therefore, it can facilitate the choosing of a highly durable stones for different outdoor applications. Further, the point load index values can be used to make a new classification of rock strength depending on their durability.

Predicting Unconfined Compressive Strength Decrease of Carbonate Building Materials against Frost Attack Using Nondestructive Physical Tests

Carbonate building materials and engineering constructions are exposed to severe seasonal environmental fluctuations and result in a full or partial disintegration, especially in cold regions, and employment of nondestructive methods for evaluating the durability of building materials subject to frost weathering is gaining great significance. This research aims to obtain reliable relationships between unconfined compressive strength decrease and nondestructive parameters variations of limestone types under frost conditions and provide useful information regarding their durability in order to ensure the long-term viability or sustainability of these materials used for constructions against frost conditions. In this study, five important types of Chinese limestone used as construction materials were subjected to 50 frost cycles. Unconfined compressive strength, compressional wave velocity and spatial attenuation, and porosity were obtained at the end of every 10 cycles. As a result of progression in frost cycles, the increase and decrease rates were determined at the end of every 10 cycles, and the relationships between them were obtained to predict the loss ratios of unconfined compressive strength (RDσc). Results indicated that at the end of 40th cycles, there was a high correlation between RDσc and spatial attenuation loss with an R2 of 0.8584. Furthermore, there was also a strong relationship between RDσc and compressional wave velocity decrease after the end of 20th and 50th cycles with an R2 of 0.9089 and 0.9025, respectively. Therefore, these relations are reliable to provide useful information for durability and viability of studied samples under frost conditions and support the use of the ultrasonic measurements. It can also be successfully used for pre-estimation of unconfined compressive strength loss of studied limestone types against frost weathering without any tests.

Modelling of early winter snow density using fully polarimetric C-band SAR data in the Indian Himalayas

The seasonal snow cover contributes significantly to the water resource in the Indian Himalayas, and snow density is one of the vital parameters in the determination of the hydrological potential of snow. The application of conventional methods for snow density retrieval using fully polarimetric SAR data is constrained by the properties of snow primarily due to the melt and frost cycles, as compared to fresh dry snow. The surface component of backscatter is significant in case of melt and frost. In the conventional decomposition based methods, the surface component is not considered for the inversion of permittivity, as proposed in this study. In this paper, we also propose a methodology for the estimation of snow density using bi-temporal fully polarimetric C-band RADARSAT-2 synthetic aperture radar (SAR) data. We utilize the relation between the differential modified Mueller matrix components, the attenuation constants, and the Fresnel transmission coefficients. The permittivity of snow is derived using the inversion of the Fresnel transmission coefficients which is used to determine the snow density using a state of the art empirical relation. The snow density estimates from the proposed method are compared with other methods based on coherency matrix decomposition and evaluated against in-situ measurements collected during a field campaign carried out in Dhundi in the state of Himachal Pradesh in India. The snow density estimates using the proposed method are observed to correlate with the in-situ measurements and were also found to be better than the decomposition based methods.

Propagating ice front induces gas bursts and ultrasonic acoustic emissions from freezing xylem.

Ice formation and propagation in the xylem of plants is a complex process. During freezing of xylem sap, gases dissolved in liquid sap are forced out of the ice lattice due to their low solubility in ice, and supersaturation of xylem sap as well as low water potential (Ѱ) are induced at the ice-liquid interface. Supersaturation of gases near the ice front may lead to bubble formation and potentially to cavitation and/or to burst of gases driven out from the branch. In this study, we investigated the origin and dynamics of freezing-related gas bursts and ultrasonic acoustic emissions (AEs), which are suggested to indicate cavitation. Picea abies (L.) H. Karst. and Salix caprea L. branch segments were exposed to frost cycles in a temperature test chamber, and CO2 efflux (indicating gas bursts) and AEs were recorded. On freezing, two-thirds of the observed gas bursts originated from the xylem and only one-third from the bark. Simultaneously with gas bursts, AEs were detected. Branch Ѱ affected both gas bursts and AEs, with high gas burst in saturated and dry samples but relevant AEs only in the latter. Repeated frost cycles led to decreasing gas burst volumes and AE activity. Experiments revealed that the expanding ice front in freezing xylem was responsible for observed gas bursts and AEs, and that branch Ѱ influenced both processes. Results also indicated that gas bursts and cavitation are independently induced by ice formation, though both may be relevant for bubble dynamics during freezing.

Solar Strategies for net-zero energy housing in Canadian North

The North imports most of its energy for fuel and cost of fuel is much higher than the national average, consequently, cost for space heating relying on fuel is very high. The North has an abundance of solar energy available. With the growing concerns on climate change, the region desires to be less dependent on fossil fuels. Significant energy savings for little added cost in housing could be achieved by building high performing envelope systems and integrating solar design strategies. The objective of this paper is to investigate the potential of integrating solar design strategies in improving energy efficiency of housing suitable for the Canadian Northern climates through modelling by optimizing passive solar design and optimal use of thermal and electrical energy from Building Integrated Photovoltaic/Thermal system (BIPV/T) to achieve net-zero energy housing. A reference home with typical construction built in Northern region is modelled using EnergyPlus. The key solar design strategies and building envelope parameters are optimized to minimize energy consumption and maximize the energy production for the reference home. The parameters investigated include thermal resistance of building envelope components, window-wall ratios, thermal mass, night window shutters, shading schedules, and ventilation rates. The optimal use of thermal energy produced by BIPV/T system by integration with Heat Recovery Ventilation (HRV) and air-source Heat Pump (ASHP) is evaluated. Modelling results show that 43% energy saving can be achieved by optimizing the passive solar design and overheating can be eliminated by proper solar shading and natural ventilation. The integration of BIVP/T with HRV can reduce the frost cycle by 10.4%. These preliminary findings demonstrate the potential of integrating solar design strategies to reduce energy consumption and develop net-zero energy housing for the Canadian North.

Freezing in-sight: the effect of frost cycles on use-wear and residues on flint tools

Alterations caused by post-depositional processes have long hampered functional analysis of stone tools, and several attempts have been made to understand their effect on the visibility and identification of use-related traces and residues. Alterations can be caused by a broad range of phenomena that involve both mechanical and chemical processes. In this article, we present the results of an experimental study focused on the reproduction of alterations caused by repeated freeze–thaw cycles, which are among the crucial processes that many prehistoric artefacts have been subjected to after their deposition. Thanks to the use of a climate chamber, we succeeded in reproducing alteration polish comparable to what is frequently observed on prehistoric stone tools, in particular those dating to the Palaeolithic and Mesolithic periods. The results open new possibilities for exploring the effect of post-depositional processes on the preservation of use traces and residues and demonstrate that alterations can also contribute to the understanding of site formation processes.

Experimental investigation of frost induced damage of cement mortar

Questions connected to influence of frost degradation on microstructure and physical properties of water saturated cement mortars and their resistance to cyclic water freezing are the objectives of research. The main aim of the investigation is to analyze the ice-induced deterioration of cement mortars with different water/cement ratios (w/c=0.50 and 0.40) in a accelerated durability tests. The changes of pore size distribution and water absorption coefficient are investigated by means of mercury intrusion porosimetry and capillary absorption test. Additionally, the analysis of the impact of drying temperature (40°C, 60°C, 80°C and 105°C) on the microstructure is introduced.The performed tests enabled to estimate that the destruction of the cement matrix and the range of observed changes depend on the initial pore size distribution and their volume in the cement matrix. It is also established that the increase of transport properties is correlated with the change of pore size distribution. The obtained results allow to conclude a decrease of content of small pores (up to 150nm) and increase of larger pores for mortar with w/c=0.50. Application of superplasticizer, which resulting in reduction of water to cement ratio up to 0.40, allows to obtained resistant to 150 frost cycles cement mortar.

Influence of CNT Addition to the Frost Resistance of Concrete

Frost resistance of concrete is one of the main durability parameter of Central European climatic conditions. Nanoparticles are the most worldwide examining in materials science. In Brno University of Technology has been interested in nanoparticles for years. First steps were dedicated in identification of nanoparticles (CNT), their dosage and dispersion. After solving before mentioned steps the CNT implementation to concrete could happened. In article was experimentally verify influence of CNT addition to concrete frost resistance after 100 frost cycles. Per results it could be said that addition small dosage of CNT increased frost resistance of concrete.

Distribution of pines in the Iberian Peninsula agrees with species differences in foliage frost tolerance, not with vulnerability to freezing-induced xylem embolism.

Drought and frosts are major determinants of plant functioning and distribution. Both stresses can cause xylem embolism and foliage damage. The objective of this study was to analyse if the distribution of six common pine species along latitudinal and altitudinal gradients in Europe is related to their interspecific differences in frost tolerance and to the physiological mechanisms underlying species-specific frost tolerance. We also evaluate if frost tolerance depends on plant water status. We studied survival to a range of freezing temperatures in 2-year-old plants and assessed the percentage loss of hydraulic conductivity (PLC) due xylem embolism formation and foliage damage determined by needle electrolyte leakage (EL) after a single frost cycle to -15 °C and over a range of predawn water potential (ψpd) values. Species experiencing cold winters in their range (Pinus nigra J.F. Arnold, Pinus sylvestris L. and Pinus uncinata Raymond ex A. DC.) had the highest frost survival rates and lowest needle EL and soluble sugar (SS) concentration. In contrast, the pines inhabiting mild or cool winter locations (especially Pinus halepensis Mill. and Pinus pinea L. and, to a lesser extent, Pinus pinaster Ait.) had the lowest frost survival and highest needle EL and SS values. Freezing-induced PLC was very low and differences among species were not related to frost damage. Reduction in ψpd decreased leaf frost damage in P. pinea and P. sylvestris, increased it in P. uncinata and had a neutral effect on the rest of the species. This study demonstrates that freezing temperatures are a major environmental driver for pine distribution and suggests that interspecific differences in leaf frost sensitivity rather than vulnerability to freezing-induced embolism or SS explain pine juvenile frost survival.

Steel reinforcement corrosion in concrete under combined actions: The role of freeze-thaw cycles, chloride ingress, and surface impregnation

In most durability design codes, service life of reinforced concrete structures is estimated after selection of one single and dominant deteriorating process. However, the predicted service life is frequently not reached in practice. One reason is the fact that each dominant deteriorating process is usually accompanied by other aggravating processes. In this contribution, the influence of freeze-thaw damage on chloride penetration into concrete, and consequently on steel reinforcement corrosion have been investigated. It was concluded that chloride penetration into concrete can be accelerated considerably by freeze-thaw cycles. The increasing of chloride diffusion coefficient can be described by a linear function of frost cycles. Under the combined actions of frost attack and chloride exposures, the propagation of steel corrosion was accelerated tremendously. During the penetration process, separation of the dissolved chloride ions from water occurs due to the filtering effect of the nano-structures and the adsorption of chloride ions to the capillary pores. Water on the front run much deeper than chloride ions. Chloride ingress can be reduced significantly; and thus, the initiation of steel corrosion can be postponed greatly by water repellent surface impregnation even after 100 freeze-thaw cycles.