Decrease In Frost Resistance Research Articles

An experimental investigation on freeze-thaw resistance of fiber-reinforced red mud-slag based geopolymer

This study aims to investigate the influence of different fiber types, lengths, and contents on their performance in freeze-thaw environments. Indoor freeze-thaw tests were conducted to evaluate the flexural strength, compressive strength, and mass loss of fiber-reinforced geopolymer materials. Additionally, SEM and XRD analyses were performed to examine the internal structure of the geopolymer composites. The results demonstrated that the incorporation of different fibers significantly improved various properties, particularly the flexural strength of the specimens. With an increasing number of freeze-thaw cycles, surface cracks became more prominent in the geopolymer specimens, leading to a gradual decrease in frost resistance. However, the addition of an appropriate amount of fiber effectively enhanced frost resistance. Following freeze-thaw exposure, an increase in fiber content initially resulted in a decrease and subsequently an increase in relative flexural strength, compressive strength, and mass loss. Notably, studies revealed that polypropylene fibers with a length of 9 mm and a content of 0.9 % exhibited minimal mass and strength loss. SEM analysis indicated uniform distribution of fibers within the geopolymer matrix, contributing to improved flexural strength and enhanced frost resistance in fiber-reinforced structures. XRD results indicate that red mud-slag based geopolymers produce high-strength hydrated calcium (aluminosilicate) silicate and hematite phases, which enhances the mechanical properties and durability of the specimens. In conclusion, this study highlights that incorporating suitable fibers can enhance the durability and performance of red mud-slag based geopolymers under freeze-thaw conditions. The findings provide valuable insights for optimizing fiber type, length, and content to achieve superior mechanical properties and frost resistance in geopolymer composites.

Main features of the technological process of aging of bitumen obtained from the residues from Ukrainian crude oil processing

The effects of the technological process of aging of bitumen obtained from the residues from processing of Ukrainian crude oil on the bitumen’s operational characteristics, structural-group composition, and thermal stability have been studied. The aging of bitumen with a thickness of 2 mm has been conducted under laboratory conditions at a temperature of 1630C for 5 and 10 h. Two types of bitumen, oxidized bitumen BND 60/90 and distillation bitumen BD 130/200, have been examined. It has been found that the bitumen quality worsens due to the technological process of aging, e.g. the bitumen hardness and refractoriness increase whereas the elasticity and frost resistance decrease. It has also been shown that, because of the technological process of aging, the content of resins in the bitumen decreases, the content of asphaltenes increases, and the content of oil components does not change significantly. The structural type of the oxidized bitumen changes thereat from a "sol–gel" type to a "gel" type. For the distillation bitumen, the structural type does not change. The derivatographic analysis has revealed that the bitumen thermal stability increases due to the technological process of aging. The reason for this is a decrease in the content of paraffinic ingredients in the bitumen along with the bitumen structure compaction due to the aging.

Structure, Impermeability and Durability of Cement Concrete

The paper presents the main hypotheses of frost destruction of cement concrete. The influence of cyclic temperature changes and the effect of static and dynamic (shock) loads on concrete on changes in the structure and strength of concreteis considered. The paper provides results of comparative tests of frost resistance of concrete containing a porous additive and a plasticizer, which contribute to an increase in the density and impermeability of its structure. It has been shown experimentally that the introduction of air-entraining additives with an additional effect of hydrophobization is productive from the standpoint of ensuring frost resistance of concrete of relatively low classes (up to C30/37), compressive strength up to 50 MPa and water absorption by mass more than 4.0 %. It is advisable to increase the frost resistance of concrete with greater impermeability and strength by increasing these indicators, in particular, due to the maximum decrease in the initial water content and high-quality compaction. This conclusion is experimentally confirmed by the data presented in the paper, since the “mechanism” of frost destruction of cement concrete is multifactorial, and the growth of its density (impermeability) and strength provide a higher ability to resist “force” effects associated with repeated alternating deformations of concrete, as well as the action of external loads, accumulation of fatigue phenomena, hydrodynamics of liquid filtration under the influence of changing temperature fields, etc. A comparative assessment of concrete frost resistance has been carried out using standardized and patented techniques containing a porous (air-entraining) additive, as well as plasticizing and mineral additives of amorphous micro-silica, introduced into concrete in order to increase its density, impermeability and strength and on this basis – increasing frost resistance. Experimental data are presented, reflecting the relationship and patterns of decrease in frost resistance of concrete subjected to the simultaneous action of static (for compression – different levels from the corresponding indicator of concrete strength) and shock, concentratedly applied dynamic loads. The regularity of the relationship between the accelerated frost destruction of concrete and the action of mechanical loads that cause cracking in its structure has been confirmed.

The effect of negative air temperatures and humidity on the photosynthetic apparatus functioning in some species of Oleaceae family

The characteristics of the photosynthetic apparatus functioning in the leaves of some evergreen species of Oleaceae family depending on the cold periods` weather conditions on the southern coast of Crimea are presented in this work. It has been revealed that changes in PSII are species-specific. Low air humidity in combination with negative air temperature promotes a significant decrease in frost resistance in the studied Olea and Osmantus genotypes. However, in Olea europea genotypes, changes in the PSII parameters under the simulation of winter desiccation approximated sublethal limits. The photosynthetic apparatus in L. lucidum species was more sensitive to a decrease in air temperature under conditions of relatively high air humidity. The development of the stress state in this species was accompanied by an increase in energy losses in the process of energy transfer from light-harvesting complexes. With the onset of frosty weather, a significant decrease in the chlorophyll a/b ratio was noted in all the studied genotypes. After the stress pressure, Olea europea cultivars and Osmantus spp. showed an increase in chlorophyll amount, in contrast to L. lucidum, in which the ratio of photosynthetic pigments remained low.

Effects of rice husk ash on itself activity and concrete behavior at different preparation temperatures

Abstract This paper aims to investigate the effects of rice husk ash (RHA) on itself activity and its concrete performance at different preparation temperatures for which three temperatures of 650 °C, 800 °C, and 900 °C were considered. To find a reasonable particle size, the effect of the particle size of the RHA on the workability of concrete at various grinding times was studied. A series of experiments were carried out to study the characteristics of the RHA, including X-ray fluorescence, XRD, ESEM, and an activity test. The carbonation resistance and frost resistance of concrete incorporating RHA were also investigated, where 10 and 30 wt.-% of cement was considered. The results show that the surface area of the RHA first increases and then decreases with grinding time. When the RHA is ground for 30 min, its surface area is largest and the workability of its mixture is also best. The burning temperature has little effect on the amount of SiO2. Although the structure and activity of SiO2 in RHA change at different burning temperatures, the performance of concrete incorporating RHA is higher than that of control concrete without RHA. With the same content of RHA, both carbonization resistance and frost resistance decrease with an increasing burning temperature of RHA. At the same burning temperature, both carbonization resistance and frost resistance increase with an increasing amount of RHA. Among all types of mixtures, the mixture incorporating 30 % RHA burned at 650 °C (i. e., RHA650) yields the best performance.

Increase of Impact Strength and Frost Resistance of Concrete Hydrotechnical Piles at Deaeration of Concrete Mixture with Air-Entraining Admixtures

In the article the main technological factors of influence on frost resistance of concrete are given. It is proved, that the reduction of air content in concrete mixture with air-entraining admixtures during continuous vibration does not lead to a decrease in frost resistance of concrete with an increase in its strength. The completed researchers have shown that when the concrete mixture is deaerated, the number of micro-destructions under the impact effects on concrete is significantly reduced. The obtained data allowed to offer a method of manufacture of piles, submerged by impact effects, for severe climatic conditions. The main parameters that must be provided during the production of piles and their clogging for increased durability are indicated. Deaeration of concrete mixture with air-entraining additives and initial air content does not lead to decrease of subsequent frost resistance of concrete. The creation in concrete mixture of initial excess air content increases mobility of concrete mixture, and subsequent deaeration allows getting concrete of especially high frost resistance with increase of its tensile strength. Deaerated concrete allows to increase the level of multiple impact tensions without further reduction of durability. This method of obtaining high-frost-resistant concrete of increased impact tensile strength is expedient to use in manufacturing piles for sea hydraulic installations. The tensile strength of concrete piles (after deaeration) should be not less than 50 MPa.

Brick Debris Dust as an Ecological Filler and Its Effect on the Durability of Asphalt Mix.

Brick debris is one of the main construction wastes obtained from demolition of buildings. However, this material can be successfully used in the recycling process. The purpose of the study was to determine the brick dust addition effect on asphalt surface service life. An asphalt concrete reference mix was designed for bonding layer and prepared using a Marshall compacting device. In addition, three mixes with combined lime-brick filler were prepared as well as one mix containing only brick filler. The samples were tested for their volumetric properties—density, bulk density, air void content, resistance to water and frost and stiffness modulus with varying test temperatures. It was found that 25% of brick dust addition to the filler did not considerably change the properties of the tested samples, while in the case of 50% filler the replacement stiffness and frost resistance decrease; however, the minimum required value is maintained. It can be concluded that the lime filler can be replaced with up to 50% of brick dust without a negative impact on the properties of asphalt mix. The proposed solution fits into the idea of sustainable development indicating a way of brick debris management.

Chemical Composition of Ceramic Tile Glazes

We have carried out laser emission and x-ray fluorescence spectral analysis of glaze before and after its application to ceramic tile produced by Keramin JSC (Belarus). We have studied the internal microstructure of the ceramic samples. It was established that on the surface and within the bulk interior of all the samples, there are micropores of sizes ranging from a few micrometers to tens of micrometers and microcracks as long as several hundred micrometers. The presence of micropores on the surface of the ceramic tile leads to an increase in the water absorption level and a decrease in frost resistance. It was found that a decrease in the surface tension of ceramic tile coatings is promoted by substitution of sodium by potassium, silica by boric anhydride, magnesium and barium by calcium, CaO by sodium oxide, and SiO2 by chromium oxide. We carried out a comparative analysis of the chemical composition of glaze samples using S4 Pioneer and ElvaX x-ray fluorescence spectrometers and also an LIBS laser emission analyzer.

Relationships between modified methylene blue value of microfines in manufactured sand and concrete properties

To better understand and assess the effect of microfines on concrete properties, the synergetic effect of methylene blue value and content of microfines on properties of low and high strength concrete was studied and then the relationships between the index of modified methylene blue value (MMBV) and concrete properties were investigated. The results show that relationships between MMBV and fresh and hardened properties of concrete can be fully established, and the correlation between MMBV and C60 concrete property is higher than the correlation between MMBV and C30 concrete. With the increase of MMBV, concrete workability and frost resistance decrease while drying shrinkage decreases; however, compressive strength and chloride-ion penetration resistance of C30 concrete have not been negatively affected whereas those of C60 concrete are significantly deteriorated when MMBV exceeds 100. To make use of microfines without remarkably damaging concrete quality, it is suggested that MMBV of microfines in MS used in C30 and C60 concrete be no more than 100.

Critically reduced frost resistance of Picea abies during sprouting could be linked to cytological changes

Frost resistance of sprouting Picea abies shoots is insufficient for survival of naturally occurring late frosts. The cellular changes during sprouting appeared to be responsible for frost damage as frost events that damaged sprouting shoots did not damage older needles and stems. Whilst resting buds showed initial frost damage at -15.0 degrees C, 20 days later, current year's growth was damaged at -5.6 degrees C. The decrease in frost resistance in sprouting shoots of P. abies was accompanied by a significant reduction of the cellular solute concentration, indicated by much less negative Psi(oSAT) values (increase from -2.8 to -1.2 MPa). psi(oSAT) decreased again after the final cell volume was reached and cell wall thickening began. After bud break, ice nucleation temperature increased from -4.7 degrees C to -1.5 degrees C. This increase was probably caused by the loss of bud scales, the onset of expansion growth of the central cylinder and the development of vascular tissue permitting the spread of ice from the stem into the growing needles. The onset of mesophyll cell wall thickening coincided with the lowest frost resistances. Cell wall thickening caused an increase in the modulus of elasticity, epsilon, indicating a decrease in tissue elasticity and after that frost resistance increased again. Metabolic and cytological changes that evidently leave little leeway for frost hardening are responsible for the low frost resistance in current year's growth of P. abies. This low frost resistance will be significant in the future as the risk of frost damage due to earlier bud break is anticipated to even further increase.

RESEARCHES REGARDING FROST RESISTANCE AND BELATED SPRING FROST RESISTANCE OF SOME APRICOT TREE VARIETIES IN S D TIMISOARA CONDITIONS, UNDER CUTTINGS IN GREEN INFLUENCE

Trees spring passing from the rest period to intense biological activity brings trees frost resistance decrease. In case of the apricot tree, specie with short biological rest period, return frosts are very harmful after the un-tempering period, but especially spring belated frosts. Belated spring frosts catch trees in the phase with flowers or fruits barely formed, phase of maximum sensibility, which has an effect over yield diminution through fruits loss or fruits quality depreciation.

Regulation of frost resistance during cold de-acclimation and re-acclimation in oilseed rape. A possible role of PSII redox state.

A possible role of photosynthetic apparatus during cold de-acclimation was studied in oilseed rape (Brassica napus var. oleifera). Plants of spring (Star) and winter (Górczañski) cultivars were cold acclimated at + 5 degrees C, and de-acclimated during 4 weeks at combinations of + 12 and + 20 degrees C operating in the light or/and dark, with a 12-h photoperiod. Evidence is presented that the photosynthetic apparatus may be involved in temperature perception during de-acclimation. De-acclimation was faster under a 20/12 degrees C (day/night) treatment than under the reverse 12/20 degrees C (day/night). De-acclimation rate was constant when the day temperature was constant, irrespective of the night temperature both under cold day temperature regimes (12/20, 12/12 degrees C (day/night) and warm-day treatments (20/12, 20/20 degrees C (day/night). The fast decrease in frost resistance observed under warm-day de-acclimation was always accompanied by an acceleration of elongation growth. In the spring cultivar, elongation growth increased starting from the second week of de-acclimation, regardless of temperature conditions. Once elongation growth had commenced during de-acclimation, it continued throughout the period necessary for re-acclimation to low temperature. Re-acclimation to the initial freezing tolerance level was only possible when plant elongation was reduced. In addition re-acclimation of the photosynthetic apparatus to low temperature was impossible in fast growing plants. A possible relationship between PSII, growth rate and frost resistance during cold acclimation and de-acclimation is discussed.

Cycloheximide induced decrease in frost resistance of winter wheat is mediated by inhibition of adaptive rearrangement of the cell and chloroplast structure

Cycloheximide in the concentration inhibiting protein synthesis and frost resistance of plants proved to prevent formation of cell and chloroplast structures specific for the plants adapted to frost. Important role of structural rearrangement of the cells during hardening preventing intracellular ice nucleation is proposed.

Winter hardening and glutathione status in the bilberry (Vaccinium myrtillus) in response to trace gases (CO2, O3) and nitrogen fertilization

Bilberry plants (Vaccinium myrtillus L.) at a field site in northern Finland (65°N) were subjected to nitrogen fertilization [6.5 mmol m−2 NH4NO3× Ca(OH)2] at the beginning of 3 growing seasons in late May and to trace gas fumigation (CO2 and O3) for 5 months (May–September) in 1993–1995 in order to investigate frost resistance and glutathione concentrations during the winter hardening period, and to assess the correlation between these variables. Harvesting was performed twice in the autumn of both 1994 and 1995, and the two‐year data for each harvest were pooled. The frost resistance of the bilberry stems increased by about 10°C during the hardening period between the two harvests. Nitrogen fertilization increased the frost resistance towards late autumn. The fumigation treatments had no marked effect on it. The combination of elevated CO2 and nitrogen fertilization induced a decrease in frost resistance. Increases in total glutathione concentrations and the proportion of reduced glutathione (GSH) in the stems were evident during hardening. Nitrogen fertilization positively affected the total glutathione concentration and the proportion of GSH at the beginning of the hardening period but the effect disappeared during the hardening process. Trace gas fumigation as such had no marked effect on glutathione concentration. Increases in glutathione concentrations during hardening did not correlate with frost resistance, possibly due to different timing of the appearence of the response to fertilization treatment, i.e., glutathione responded in the beginning of hardening while frost resistance at the end. The lack of correlation with frost resistance, and especially the different responses to nitrogen fertilization, may reflect the indirect role of glutathione in the development of winter hardening, as a transport and storage form of reduced nitrogen and sulphur. In conclusion, winter hardening and glutathione status in the bilberry seems to be sensitive to nitrogen fertilization, and not affected by elevated CO2 and O3.

Interrelationships between ultrastructure, sugar levels, and frost hardiness of ray parenchyma cells during frost acclimation and deacclimation in poplar ( Populus × canadensis Moench ‹ robusta›) Wood

Summary Ray parenchyma cells of poplar wood ( Populus × canadensis Moench ‹ robusta ›) were studied for changes in ultrastructure and in the level of various sugars in fall, winter and spring in relation to freezing resistance as measured by LT 50 (temperature at which 50% of the cells are injured). Before acclimation (mid-October), frost hardiness is low (LT 50 −3 to −5 °C), sugar levels have not yet increased while the ray cell protoplast has already become dense in structure. This is due mainly to the elimination of large vacuoles, their replacement by small storage protein vacuoles, and the vast accumulation of storage material in general, i.e. in amyloplasts, protein bodies, and oleosomes. Frost acclimation started during leaf fall (end of October) concomitant with a sudden increase of total sugar content, consisting mainly of sucrose and its galactosides. An increase in these sugars is paralleled at the ultrastructural level by a prominent vesicular and cisternal ER-system originating in the cytoplasm. Full acclimation (LT 50 lower than −50 °C) is obtained within 3 weeks (mid-November) and coincides with maximum content of sucrose and its galactosides (reaching 300 µg mg −1 DW in ray cells) and with a prominent development of vesicular and cisternal ER. The evidence for the accumulation in this elaborated ER-system of these sugars is discussed and a proposal for its functional significance both as an intrinsic device for dehydrating the protoplast during frost hardening and for delivery of membrane material to the plasma membrane is made. Transient rises of winter temperature above freezing were paralleled by a noticeable decrease in frost resistance (LT 50 −40 to −30 °C), declining sugar levels, and by gradual diminution of the particular ER-vesicles in cytoplasm. In March, at temperatures of 5 to 10 °C, sugar content rapidly lowers concomitandy with complete vanishment of vesicles from the cells. A decrease in frost resistance, in contrast, begins later, e.g. in mid-April, suggesting the involvement in frost hardiness of non-sugar compounds at this stage.

Influence of soil substrate and ozone plus acid mist on the frost resistance of young Norway spruce

The needles of clonal Norway spruce grown in environmental chambers on two different soils (an acidic soil 1 and a calcareous soil 2) and exposed to two levels of ozone fumigation (a low level combined with neutral mist = control, and an elevated one combined with acid mist = treatment) were analyzed for their frost hardiness. No effect of ozone was observed on either the development of frost resistance during the hardening phase or on the decrease in frost resistance during the dehardening phase. The preliminary results of Brown et al. (1987) and Barnes and Davidson (1988), which indicated that ozone treatment predisposes plants to winter injury, could thus not be confirmed. Frost resistance was, however, distinctly influenced by the content of the mineral nutrients of the soils. The pronounced K + deficiency of the needles of the trees growing on the neutral soil (Alps) had less effect on the development of frost resistance than did the Ca ++ and Mg ++ deficiency of the needles of the trees grown on the acidic soil 1 (Bavarian Forest). The variability of frost resistance between the different clones on soil 1 was partly attributed to fluctuations in the mineral nutrient content of the needles, rather than to a genetic predisposition.

STUDY OF PINE STRAWBERRY FROST RESISTANCE BY ARTIFICIAL FREEZING METHOD

The study of the frost resistance was carried out in 2017–2019 on the basis of the Laboratory of Physiology of Fruit Plant Resistance, Russian Research Institute for Fruit Crop Breeding. Strawberry cultivars of different ecological and geographical origin (‘Kokinskaya Rannia’, ‘Rosinka’, ‘Solovushka’, ‘Tzaritza’, ‘Urozhaynaya TzGL’ – Russia; ‘Sara’ – Sweden; ‘Alba’, ‘Marmolada’ – Italy; ‘Korona’, ‘Sonata’ – Holland) were used as experimental material. The frosts resistance of strawberry varieties was studied in the laboratory conditions was used by artificial freezing. A model of strawberry plant selection was developed to determine the main components of winter hardiness. On the basis of preparation of plant samples for modeling of damaging factors of the winter period, storage conditions of experimental plants were developed. Plant hardening and modeling of damaging factors of the winter period were carried out with the additional modification for strawberries. As a result of the artificial freezing, the damage to the tissues of rhizome and apical buds of shoots of strawberry varieties of different ecological and geographical origin were evaluated in early winter period and during thaws in winter. It was determined that the decrease in the temperature to -15°C at the end of November did not cause irreversible damage to the strawberry varieties. The decrease in the temperature to -20°C in early December increased the damage to the studied strawberry varieties. During the winter it was determined that the strawberry response to the thaw increased by the end of the winter period. The decrease in frost resistance is primarily due to the resumption of growth processes under the influence of positive temperatures. As a result of determining the components of winter hardiness, the varieties Solovushaka, Tzaritza (Russia), Sara (Sweden) and Korona (Holland) showed the greatest potential of frost resistance.