Freeze-thaw Research Articles

Enhancement of Mechanical Properties and Freeze–Thaw Durability of Recycled Aggregate Concrete using Aggregate Pretreatment

Enhancement of Mechanical Properties and Freeze–Thaw Durability of Recycled Aggregate Concrete using Aggregate Pretreatment

Residual textile reinforced mortar‐to‐concrete bond after exposure to harsh environments

AbstractTextile reinforced mortars (TRM) are materials whose mechanical behavior has been extensively investigated during the last few years. However, studies on the behavior of these materials after exposure to various aggressive environments are still limited and, hence, their performance during their entire service life remains to be determined. The present study contributes to the knowledge pool regarding the behavior of concrete specimens furnished with TRM overlays post their exposure to various harsh environments, specifically through the analysis of shear bond tests. More specifically, 120 concrete substrates were reinforced with one and two layers of carbon textile which were embedded into a high and a low strength cementitious mortar and exposed to various harsh environments (carbonation, chlorides, carbonation and chlorides, different number of freeze–thaw cycles). It was concluded that: (i) a reduction of more than 25% is possible regarding failure stress; (ii) the number of textile layers plays an important role in TRM‐concrete bond behavior; and (iii) the influence of mortar strength is limited.

Performance Research and Engineering Application of Fiber-Reinforced Lightweight Aggregate Concrete

Low strength and low impact toughness are two of the main issues affecting the use of lightweight aggregate concrete in harsh cold environments. In this study, the strength of concrete was improved by adding high-strength fibers to bear tensile stress and organize crack propagation. Four sets of comparative experiments were designed with freeze–thaw cycles of 0, 50, 100, and 150 to study the mechanical properties of fiber-reinforced lightweight aggregate concrete under freeze–thaw conditions. A detailed study was conducted on the effects of freeze–thaw on the compressive strength, flexural strength, impact toughness, and microstructure of concrete with different fiber contents (3, 6, and 9 kg/m3). The results show that for ordinary lightweight aggregate concrete, under the freeze–thaw cycle, the internal pore water of the concrete froze and generated expansion stress, resulting in tensile cracks inside the concrete. The cracks gradually accumulated and expanded, ultimately leading to cracking and damage of concrete structures. After 150 cycles, the strength loss rate exceeded 25%. When adding a reasonable amount of fiber (6 kg/m3), the fiber took on the tensile stress and hindered the development of internal cracks, significantly enhancing the splitting tensile strength, flexural strength, and impact toughness of lightweight aggregate concrete. And the failure pattern of concrete was significantly improved. At the beginning of the freeze–thaw cycle, the internal tensile stress was less than the fiber tensile strength and the fiber–matrix bonding strength, and the strength reduction rate of the concrete was slow. Relying on the friction absorption capacity between the fiber and the matrix, the fiber used its own deformation to resist the tensile stress. In the late stage of the freeze–thaw cycle, due to the destruction of the fiber–matrix transition zone structure, the bond strength decreased, the crack resistance and toughening effect decreased, and the strength of the concrete decreased rapidly. Moreover, the reduction in impact toughness was greater than the compressive strength and flexural strength under static load.

Research on the Geosynthetic-Encased Gravel Pile Composite Highway Foundation in Low-Temperature Stable Permafrost Regions

In low-temperature stable permafrost regions, both active and passive cooling measures are commonly employed to ensure the long-term stability of highway structures. However, despite adopting these measures, various types of structural issues caused by permafrost degradation remain prevalent in high-grade highways. This indicates that in addition to preventing permafrost melting, structural reinforcement of the foundation is still necessary. Based on the analysis of the long-term foundation temperature field and settlement using the finite element method, which was validated through an indoor top-down freeze–thaw cycle test, this paper explores, for the first time, the feasibility of applying geosynthetic-encased gravel pile composite highway foundations—previously commonly used for permafrost destruction—in low-temperature stable permafrost areas where permafrost protection is the primary principle. By analyzing the long-term temperature field, settlement behavior, and pile–soil stress ratios of permafrost foundations influenced by both the highway structure and composite foundation, it was found that when the pile diameter is 0.5 m, pile spacing is 2 m, and pile length is 11 m, the mean monthly ground temperature of the permafrost foundation will not be significantly affected. Therefore, the properly designed geosynthetic-encased gravel pile composite highway foundation can be adopted in low-temperature stable permafrost regions where permafrost protection, rather than destruction, is required.

Water–Rock Interaction and Freeze–Thaw Cycles as Drivers of Acid Rock Drainage Generation by a Rock Glacier in the European Alps

Water–Rock Interaction and Freeze–Thaw Cycles as Drivers of Acid Rock Drainage Generation by a Rock Glacier in the European Alps

Comparative Analysis of Sewage Sludge Characteristics After Natural Deposition, Accelerated Aging, and Composting

This study investigated treatment methods for urban wastewater sludge, specifically examining natural drying over five years, accelerated freeze–thaw–drying cycles, and composting with and without a zeolite additive. The findings reveal that composting effectively stabilized the sludge while retaining essential nutrients crucial for agriculture. Notably, with the addition of 2% zeolite by total mass, approximately 40% of the total nitrogen was preserved. Adequate aeration during composting maintained acceptable levels of phosphorus compounds, with the phosphorus content expressed as P2O5 showing significant retention compared with the natural drying methods. Composting also demonstrated a substantial reduction in petroleum hydrocarbon concentrations, which decreased from 30 mg/kg to 3 mg/kg, thereby showcasing its potential for processing contaminated sludge. The inclusion of zeolite enhanced the nitrogen retention by an additional 10–20% compared with the composting without zeolite, aligning with previous studies on its effectiveness. While composting and thermal treatments, like accelerated freeze–thaw cycles, influenced the physical properties of the sludge—such as reducing the moisture content and altering the volatile substance concentrations—they did not significantly affect the heavy metal levels. Natural drying over five years resulted in reduced metal quantities, which possibly reflected changes in the wastewater characteristics over time. Given that the heavy metal concentrations remained largely unchanged, additional treatment methods are recommended when the initial sludge contains high levels of these contaminants to ensure the safe use of the final product as fertilizer. This study underscored the significant role of biochemical and microbiological processes during composting and natural drying in transforming sludge properties. Future research should focus on establishing upper contamination thresholds and exploring microbiological safety measures to enhance the viability of sludge reuse in agriculture, balancing nutrient preservation with environmental safety.

Effect of nano‐SiO2 dispersion on the mechanical properties and frost resistance of modified cement paste

AbstractThe dispersion of nano‐SiO2 (NS) in cement plays a critical role in enhancing the properties of cementitious materials. In this study, the combination of ultrasonic dispersion and polycarboxylic acid water reducing agent (PCE) was used to significantly improve the dispersion of NS. The effects of ultrasonic dispersion time, NS content, and PCE content on dispersion quality were investigated, alongside their impact on mechanical properties, electrical resistivity, and frost resistance. The results demonstrated that this synergistic method optimized the dispersion of NS, leading to superior mechanical properties and frost resistance. With an ultrasonic dispersion time of 40 min, NS content of 1.0 wt.%, and PCE content of 0.75 wt.%, the cement paste achieved its optimal performance. Compared to non‐dispersed samples, compressive strength increased by 33.7%. After 75 freeze–thaw cycles, the mass loss was 2%, the relative dynamic elastic modulus was 99.15%, and the strength loss was 13.74%.

Research on mechanical properties and pore structure evolution process of steam cured high strength concrete under freeze thaw cycles.

With the widespread use of high-strength concrete structures (HC), the impact of pore structure on their performance has become a current research focus. The mechanism by which different curing conditions and freeze-thaw cycles influence the evolution of pore structure remains unclear. Therefore, this study systematically investigated the frost resistance of high-strength concrete under different curing conditions, measured the mass loss rate, compressive strength, and relative dynamic elastic modulus of concrete under freeze-thaw cycles. Utilizing low-field nuclear magnetic resonance (NMR) technology, this study analyzed the evolution of pore structure in HC under freeze-thaw cycles. Additionally, the fractal dimension was used to evaluate the change of concrete internal pore structure, so as to reflect the influence of pore structure on the mechanical properties of concrete subjected to freeze-thaw cycles, and then evaluated the freeze-thaw damage of HC. The experimental results indicated that the steam curing regimes led to an increase in the porosity of HC, thereby influencing its frost resistance. Steam-cured high-strength concrete (SMHC) exhibited a higher degradation rate under freeze-thaw cycles, resulting in a greater level of deterioration compared to standard curing high-strength concrete (SDHC), even under the same number of freeze-thaw cycles.

Prediction of freeze–thaw and thermal shock weathering on natural stones through deep learning-based algorithms

Prediction of freeze–thaw and thermal shock weathering on natural stones through deep learning-based algorithms

The Effect of the Construction of a Tillage Layer on the Infiltration of Snowmelt Water into Freeze–Thaw Soil in Cold Regions

The snow melting and runoff process in the black soil area of Northeast China has led to soil quality degradation in farmland, posing a threat to sustainable agricultural development. To investigate the regulatory effect of tillage layer construction on the infiltration characteristics of snowmelt water, a typical black soil in Northeast China was selected as the research object. Based on field experiments, four protective tillage treatments (CK: control treatment; SB: sub-soiling treatment; BC: biochar regulation treatment; SB + BC: sub-soiling tillage and biochar composite treatment) were set up, and the evolution of soil physical structure, soil thawing rate, snow melting infiltration characteristics, and the feedback effect of frozen layer evolution on snowmelt infiltration were analyzed. The research results indicate that sub-soiling and the application of biochar effectively regulate soil aggregate particle size and increase soil total porosity. Among them, at the 0–10 cm soil layer, the soil mean weight diameter (MWD) values under SB, BC, and SB + BC treatment conditions increased by 6.25%, 16.67%, and 19.35%, respectively, compared to the CK treatment. Sub-soiling increases the frequency of energy exchange between the soil and the environment, while biochar enhances soil heat storage performance and accelerates the melting rate of frozen soil layers. Therefore, under the SB + BC treatment conditions, the maximum soil freezing rate increased by 21.92%, 5.67%, and 25.12% compared to the CK, SB, and BC treatments, respectively. In addition, sub-soiling and biochar treatment effectively improved the penetration performance of snowmelt water into frozen soil layers, significantly enhancing the soil’s ability to store snowmelt water. Overall, it can be concluded that biochar regulation has a good improvement effect on the infiltration capacity of surface soil snowmelt water. Sub-soiling can enhance the overall snowmelt water holding capacity, and the synergistic effect of biochar and deep tillage is the best. These research results have important guiding significance for the rational construction of a protective tillage system model and the improvement of the utilization efficiency of snowmelt water resources in black soil areas.

Hydrophobic treatments and their application with internal wall insulation

Hydrophobic (or water repellent) treatments have been proposed to mitigate moisture risks associated with internal wall insulation when applied to solid masonry walls. This can reduce risks associated with moisture accumulation within the structure such as mould growth or the deterioration of joist ends and other embedded timber. Where treatments perform well there is a net reduction of moisture content and risk. However, such treatments slow down drying processes, and therefore may result in a net increase in moisture if the treatment is bypassed by, for example, cracks. Some treatments may lead to damage to external masonry surfaces in some situations. Freeze–thaw and salt crystallisation are the two main causes. Hygrothermal simulations may give some indication of risks but techniques to assess the risk of surface damage are either simplistic, impractical outside of the research environment or both. This paper reviews the current field of assessing and predicting the risk of surface damage associated with surface treatments.

Evaluation of SMA-13 Asphalt Mixture Reinforced by Different Types of Fiber Additives

This research aims at systematically evaluating the properties of SMA-13 asphalt mixture reinforced by several fiber additives including flocculent lignin fiber (FLF), granular lignin fiber (GLF), chopped basalt fiber (CBF), and flocculent basalt fiber (FBF). Firstly, the thermal stability, moisture absorption, and oil absorption property of these fiber additives were analyzed. Secondly, the property of SMA-13 reinforced using four types of single fibers and two kinds of composite fibers (FLF + CBF and FLF + FBF) was comprehensively analyzed. Specifically, the high-temperature performance was evaluated using the uniaxial penetration test and the rutting test, the medium-temperature anticracking property was evaluated using the IDEAL-CT test, the low-temperature property was analyzed using the beam bending test, and the water stability was studied by the freeze–thaw splitting test. Thirdly, the dynamic mechanical response of different-fibers-modified SMA-13 was evaluated using the uniaxial compression dynamic modulus test. Finally, correlation analysis between the results of dynamic modulus and the high-, medium-, and low-temperature mechanical performance was carried out. The research results reveal that the stability of CBF and FBF under thermal action is better than that of GLF and FLF, and FBF shows the best thermal stability. The oil absorption property of FLF is better than that of GLF, followed by FBF and CBF. The comprehensive mechanical properties of CBF- and FBF-reinforced SMA-13 are better than those of FLF- and GLF-modified SMA-13. CBF can better reinforce the mechanical property of SMA-13 under low and medium temperature, while FBF can better reinforce the performance of SMA-13 at high temperature. FLF/CBF- and FLF/FBF-composite-modified SMA-13 show better high-temperature mechanical performance than that of the single-fiber-reinforced mixture, and FLF has some negative impact on the properties of FLF/FBF-composite-modified SMA-13 at low temperature. Fibers have no significant influence on the water stability of the mixtures. Meanwhile, the linear correlation between the mechanical performance of all the fiber-reinforced SMA-13 and the dynamic modulus result is good.

Mechanical, Durability, and Microstructure Characterization of Pervious Concrete Incorporating Polypropylene Fibers and Fly Ash/Silica Fume

Pervious concrete, because of its high porosity, is a suitable material for reducing the effects of water precipitations and is primarily utilized in road pavements. In this study, the effects of binder-to-aggregate (B/A) ratios, as well as mineral admixtures with and without polypropylene fibers (PPFs) (0.2% by volume), including fly ash (FA) or silica fume (SF) (10% by substitution of cement), on the mechanical properties and durability of pervious concrete were experimentally observed. The experimental campaign included the following tests: permeability, porosity, compressive strength, splitting tensile strength, and flexural strength tests. The durability performance was evaluated by observing freeze–thaw cycles and abrasion resistance after 28 d curing. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), thermal analysis (TGA-DTA), and scanning electron microscopy (SEM) combined with energy dispersive spectroscopy (EDS) were employed to investigate the phase composition and microstructure. The results revealed that, for an assigned B/A ratio identified as optimal, the incorporation of mineral admixtures and fibers mutually compensated for their respective negative effects, resulting in the effective enhancement of both mechanical/microstructural characteristics and durability properties. In general, pervious concrete developed with fly ash or silica fume achieved higher compressive strength (>35 MPA) and permeability of 4 mm/s, whereas the binary combination of fly ash or silica fume with 0.2% PPFs yielded a flexural strength greater than 6 MPA and a permeability of 6 mm/s. Silica fume-based pervious concrete exhibited excellent performance in terms of freeze–thaw (F-T) cycling and abrasion resistance, followed by fiber-reinforced pervious concrete, except fly ash-based pervious concrete. Microstructural analysis showed that the inclusion of fly ash or silica fume reduced the harmful capillary pores and refined the pore enlargement caused by PPFs in the cement interface matrix through micro-filling and a pozzolanic reaction, leading to improved mechanical and durability characteristics of pervious concrete.

Synthesis and evaluation of self‐healing polyvinyl alcohol‐tannic acid membranes for skin bio‐applications

AbstractAutonomic self‐healing films have shown limited mechanical strength, hindering their application as biomaterials, particularly in skin bioengineering. To address this challenge, we developed polyvinyl alcohol (PVA)‐tannic acid (TA)‐based membranes with improved self‐healing properties and strong mechanical performance. Using a blade coating method and freeze–thaw cycles (−10°C for 1 h, followed by room temperature thawing), the synthesized membranes demonstrated a tensile strength of 8.8 MPa before healing and 7.6 MPa after healing, achieving an 88% healing efficiency. Membrane thickness showed a slight reduction from 465 to 432 μm posthealing. After 3000 bending cycles at a 1 cm radius, the membranes maintained flexibility with no significant changes in water vapor transmission rate (WVTR) (7.66 g/m2·day) or oxygen transmission rate (OTR) (0.13 cm3/m2·day·bar). These results underscore the membranes' suitability for dynamic skin environments, combining robust mechanical properties with excellent self‐healing capabilities. The PVA‐TA membranes present a promising solution for advanced skin bioengineering applications.

Effects of freeze–thaw on the detachment capacity of soils with different textures on the Loess Plateau, China

Soil detachment capacity (Dc) is a crucial indicator for quantifying erosion intensity. However, the combined actions of freeze–thaw and water flow complicate the erosion process, leaving the variation mechanism of Dc under this condition systematically unexplored. This study examined five loess soils from a seasonal freeze–thaw area. The mechanism driving changes in Dc was quantified through freeze–thaw simulation combined with flow scouring tests, and a Dc prediction model was established. The results revealed that the shear strength (τm), cohesion (Coh), and internal friction angle (φ) in silt loam were higher than in sandy loam. After freeze–thaw cycles (FTC), τm, Coh, and φ of the five loess soils decreased by 1.02–1.37, 1.07–9.15, and 0.92–1.05 times, respectively. As FTC increased, τm and Coh gradually stabilized, while φ showed minimal fluctuation, indicating that FTC had a cumulative effect on the deterioration of soil mechanical properties. During FTC, Dc in Wuzhong sandy loam was the largest, being 1.14–3.24 times greater than in other soils, suggesting a significant main effect of soil type on Dc variation, with a contribution rate of 19.27 %. Dc eventually stabilized with increasing, indicating a critical FTC of around 10 for its impact on Dc. Compared to unfrozen soils, Dc increased by 33.69 %–102.40 % under the combined effects of freeze–thaw and water flow, clarifying that FTC aggravated soil instability. Effective stream power was the optimum hydraulic parameter, contributing the most to Dc (45.94 %). FTC (6.41 %) and initial soil moisture content (8.59 %) were less influential, as FTC initially degraded soil properties, and then the combined action with water flow intensified soil damage, causing the role of freeze–thaw factors to be obscured by other variables. A Dc prediction model using a general flow intensity index estimated well Dc, with both R2 and NSE at 0.94. Model performance comparison emphasized the need for validation when extending the application range beyond development conditions. These findings provide new insights into the detachment mechanisms of different textured soils under compound freeze–thaw and hydrodynamic influence in freeze–thaw region.

Exploring dealkalization and Cr removal from red mud through freeze-thaw and acid washing: an experimental approach

Red mud (RM) is an industrial solid waste produced during the extraction of alumina from bauxite. The strong alkaline and heavy metal leaching issues are the primary factors limiting its utilization. This paper proposes a method for dealkalization and chromium (Cr) removal by repeated freeze and thaw to enhance the comprehensive utilization rate of RM. This study focused on the Bayer RM and investigated the effects of freeze-thaw (FT)-acid washing (AW) for dealkalization and Cr removal. The variables were the eluent concentration and FT cycles. The results showed that the synergistic action of FT-AW significantly improved the efficiency of dealkalization and Cr removal. After five FT cycles with 0.5 mol/L oxalic acid, the dealkalization and Cr removal rates reached 97.5% and 65.38%, respectively, 16.1% and 7.40% higher than those achieved at room temperature. The repeated FT disrupted the structure of the RM particles, leading to an increase in the pore space between the soil particles. This enables complete eluent contact and reaction with Cr and alkali, thereby enhancing the removal rate. The FT-AW process is suitable for practical engineering applications. It offers a novel method for RM dealkalization and Cr removal by using the FT alternation phenomena in seasonally frozen regions.

Effects of freeze-thaw cycles and heat treatment on the odor-binding properties of myofibrillar protein to key fishy compounds

This study investigated the effects of different freeze-thaw (F-T) cycles and subsequent heat treatment on the odor-binding properties of myofibrillar protein (MP) in grass carp to four key fishy substances. The odor-binding ability of MP significantly decreased as freeze-thaw (F-T) cycles increased (p < 0.05). After heating, the odor-binding ability of MP further decreased. Freeze-thaw treatment induced the oxidative denaturation, decreased total sulfhydryl content and unfolded the α-helix in MP, which modified and re-buried the exposed odor-binding sites, reducing odor-binding ability. After heating, the oxidative damage and aggregation of MP induced by freeze-thaw cycles, along with thermal effects, synergistically accelerated the oxidative denaturation and formation of disordered structures of heated MP. Enhanced hydrophobic interactions led to a dominant aggregation effect, which reduced the binding sites and further decreased the odor-binding ability of heated MP, resulting in more release of odors.

Preparation, Characterization, and In Vivo Anti‐Fatigue Evaluation of Octacosanol Nanoemulsions

ABSTRACTOctacosanol (OCT) is a natural aliphatic alcohol with multiple activities, but the poor solubility limited its wide applications. In this study, OCT nanoemulsions were prepared by a low‐energy emulsification method. The particle size, polydispersity index, and Zeta potential of OCT nanoemulsions were 12.59 nm, 0.131, and −10.54 mV, respectively. OCT nanoemulsions could keep stable up to 180 days at 4°C with particle size ranging from 12.61 to 16.57 nm. In addition, OCT nanoemulsions could remain stable upon exposure to autoclaving, acid–base (pH 2–8), freeze–thaw, ultraviolet (UV) irradiation, and low concentrations of ions. The grid test time and exhaustive swimming time of the OCT nanoemulsions group increased by 70% and 40% compared with the exercise control group, indicating that OCT nanoemulsions could enhance the muscle strength and endurance performance of mice. Compared with the exercise control group, the muscle glycogen, liver glycogen, superoxide dismutase (SOD), and glutathione peroxidase (GSH‐Px) levels of the OCT nanoemulsions group increased by 97%, 45%, 62%, and 20%, while the blood lactic acid and lactate dehydrogenase levels of the OCT nanoemulsions group decreased by 33% and 22%, respectively, suggesting that OCT nanoemulsions had the anti‐fatigue effect. Hematoxylin and eosin staining showed that OCT nanoemulsions could repair muscle damages induced by excessive exercise. These findings could pave the way for the development of OCT nanoemulsions with high stability and anti‐fatigue potential.

Frost weathering in contemporary active-layer deposits—micro-scale records from Kaffiøyra Plain (NW Spitsbergen)

Frost weathering in contemporary active-layer deposits—micro-scale records from Kaffiøyra Plain (NW Spitsbergen)

Effect of anionic polyacrylamide amendment on the climatic durability of solidified waste rock fine

In order to improve the climatic durability of solidified waste rock fine (WRF), anionic polyacrylamide (APAM) was innovatively introduced to amend solidified WRF in this study. The effects of APAM content, freeze-thaw (F-T), and wet-dry (W-D) cycles on the mechanical behaviors of solidified WRF were explored. After that, zeta potential, fourier transform infrared (FTIR) spectroscopy, and scanning electron microscope (SEM) tests were initiated to understand the behavioral mechanisms of APAM. The results show that APAM can significantly improve the mechanical properties and durability of solidified WRF, and there exist a threshold content of APAM (0.3%~0.8% in this study), beyond which the strength will decrease. The microscopic test shows that the bridging effect and the filming effect induced by APAM are considered to be the two decisive factors affecting the mechanical behavior of S-WRF. On the one hand, the linear APAM long chain enables the cohesion between particles to be stronger through ion bridging, on the other hand, the long chains cross-link with each other to form a network interwoven inside the structure, thus playing a microfabric reinforcement role and enhancing the crack resistance of the solidified matrix. In addition, life cycle assessment (LCA) further confirmed the advantages of using industrial by-products combined with APAM to amend solidified-WRF. These results provide a theoretical basis for using APAM as trace additives to mitigate climatic durability-related issues.