Freeze-thaw Research Articles

Numerical simulation of the meso-mechanical properties of double cruciform fissures rocks after freeze–thaw cycles

Numerical simulation of the meso-mechanical properties of double cruciform fissures rocks after freeze–thaw cycles

Experimental investigation on freeze–thaw resistance of thermally activated recycled fine powder concrete

Recycled fine powder (RFP) is a new auxiliary cementitious material with potential activation. However, prior to its applications in concrete, its durability should be examined. This study focuses on RFP as the study subject. Through the freeze–thaw test of concrete, indexes such as the appearance change, mass and relative dynamic elastic modulus loss, microstructure, and pore and bubble structures are analyzed. The freeze–thaw model is used to predicate the service life of concrete under freeze–thaw cycles. The effect of a high RFP dosage on the freeze–thaw resistance of concrete before and after thermal activation is comprehensively examined. Results show that the appearance damage increases gradually when the RFP content is more than 15 %. For RFP dosages of 45 % and 60 %, thermally activated RFP concrete exhibits better freeze–thaw resistance than inactivated RFP concrete, and the maximum number of freeze–thaw cycles that thermally activated RFP can withstand is greater than that for inactivated RFP concrete. The mass loss and relative dynamic elastic modulus loss of thermally activated RFP concrete at 60 % dosage are lower than those of inactivated RFP concrete. Microscopic analysis shows that the most probable pore size, the proportion of harmful pores and more-harmful harmful pores of the thermally activation of RFP concrete is smaller than that of the inactivated RFP concrete when the dosages are 45 % and 60 %. Under the SEM image of dosage 60 %, the gels of the thermally activation of RFP concrete are more dense. These results indicate that the thermally activation of RFP tends to refine the pore structure and improve the pore distribution. Furthermore, the average radius and spacing of bubbles are smaller when the dosage of activated RFP is 60 %, thereby improving the freeze–thaw resistance of concrete. In this study, the freeze–thaw model used in this paper that can effectively describe the freeze-thaw change and predict the service life of RFP concrete. When the RFP dosage is 60 %, the lifespan of thermally activated RFP concrete is 2.4–3 times longer than that of inactivated RFP concrete, meeting the needs for structural designs in the central and southern regions of China for 50 years. The research results provide a theoretical basis for RFP resource utilization and the determination of the actual service life of RFP concrete.

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.

Laboratory mix preparation and investigation of mechanical behaviour of polyurethane-bound porous rubber pavement

With the rise in stormwater runoffs, permeable pavement like polyurethane-bound porous rubber pavement (PRP) offers a viable solution for urban stormwater management. Composed of stone and recycled crumb rubber aggregates bound by polyurethane, PRP features high air voids. This study explores PRP’s mechanical behaviour and freeze–thaw durability in cold climates, essential for sustainable urban infrastructure. We developed methods for sample preparation and air void assessment in PRP and conducted tests on compressive and indirect tensile strength, plus moisture-induced damage. Two scenarios were investigated: one examined four new mixes of varied compositions, and the other focused on mixes with different binders (aliphatic and aromatic). Our investigation reveals insights into PRP’s mechanical behaviour under colder climate conditions. The study shows that higher proportions of stone aggregates and binders enhance mechanical strength, while increased rubber content improves freeze–thaw durability. Furthermore, we found that different binders affect strength variations. The study concludes PRP is effective for low-traffic pavements in colder, freeze–thaw regions.

Preliminary safety and in vivo efficacy of Acmella oleracea extract‐loaded glycolipid emulsion serum—Effects on ocular irritation, dermal absorption, and facial skin biophysical and microrelief properties

AbstractObjectiveSubstantial efforts have been progressively devoted to developing innovative, safe, and effective topical anti‐aging products that not only improve the appearance of aged skin but also prioritize environmental sustainability and the responsible use of natural resources. Thus, the current study targeted to evaluate novel, natural emulsion/serum comprising new glycolipid emulsifier (lauryl glucoside/myristyl glucoside/polyglyceryl‐6 laurate) and Acmella oleracea plant extract as a model active.MethodsThe developed serum was assessed concerning its stability (freeze–thaw test, accelerated study), safety (in vitro screening of eye irritation potential, dermal absorption study) and efficacy (randomized, active/reference‐controlled, half‐face, in vivo study). Changes in skin biophysical properties, microrelief, roughness, texture, surface, and volume parameters were assessed in the periocular and perioral areas of human volunteers after 2 weeks of product application, utilizing several bioengineering and topography techniques.ResultsThe stability study demonstrated favourable stability profile of the developed serum, with practically unaffected stability‐indicating parameters (apparent viscosity, yield, flow point, storage and loss moduli, loss factor, pH, electrical conductivity) during freeze–thaw cycling and after 3 months of storage at 45°C. The hen's egg test on the chorioallantoic membrane of fertilized chicken eggs confirmed the absence of ocular irritation potential of investigated serum; no effects of haemorrhage, lysis or coagulation were occurred. Skin permeation study using diffusion cells revealed no permeation of spilanthol from the tested A. oleracea extract‐loaded serum through the pig ear skin into the receptor medium, thus suggesting no absorption into systemic circulation. In vivo efficacy study corroborated beneficial effects of evaluated serum on the condition/appearance of facial skin, at both periocular and perioral areas—significant (p &lt; 0.05) increase in skin hydration (10%–40%) and smoothness (~15%); significant (p &lt; 0.05) decrease in roughness (20%–30%), scaliness (~30%), and wrinkles (~15%)—implying more hydrated, smoother, visibly milder skin.ConclusionThe present findings confirmed the stability, preliminary safety (no ocular irritation, no dermal absorption, and good skin tolerability), and efficacy (improved skin hydration and microrelief) of the A. oleracea extract‐loaded, glycolipid‐based serum, supporting its potential as a safe and effective topical anti‐aging product.

Freeze-thaw durability of clayey soils stabilized by alkaline-activated kaolin and recycled cement kiln dust

Weak soils pose significant challenges for civil engineering projects, particularly in cold regions. Stabilizing such soils with additives is a common practice to enhance their geotechnical properties. This research aimed to evaluate the durability of clayey soils stabilized by alkaline-activated kaolin at 10, 25, and 50%, along with 10% recycled cement kiln dust (CKD). The stabilization process involved curing the soils at different temperatures (40, 60, and 80°C) for varying durations (1, 7, 14, and 28 days). The stabilized soils underwent 5, 10, and 20 freeze-thaw (F-T) cycles to evaluate their durability. The results indicated F-T cycling led to a reduction in the unconfined compressive strength (UCS) of unstabilized soils, with a more pronounced impact as the number of cycles increased. However, this adverse effect was mitigated by additive stabilization. The improvement in UCS in stabilized soils was directly linked to the additive content, curing duration, and temperature. Both additives demonstrated superior resistance to F-T cycles, with CKD outperforming kaolin. These findings provide guidelines for utilizing kaolin and CKD for earthwork applications in cold regions with economic and sustainability advantages.

Use of Wheat Fiber and Nanobentonite to Stabilize Clay Subgrades

Since clayey soils naturally present low mechanical strength, they pose direct challenges for engineering applications. Finding appropriate soil stabilizers to address the challenges posed by clayey soils is crucial for ensuring that the soil meets the necessary geotechnical requirements and fulfills economic and environmental issues. To this end, this research uses several stabilizers and techniques in clayey soils to improve their suitability for construction. The main objective of this study is to assess the use of wheat fiber and nanobentonite (NB) in soil stabilization, estimate their behavior in practices, outline their obstacles and potential for soil improvement, and consider their ecological and financial effects. This research also evaluates the behavior of the soil by incorporating NB (0.4, 0.8, and 1.2%) as a stabilizing agent. For this purpose, the randomly dispersed wheat fibers as a reinforcing agent at different dosages and lengths (0.3, 0.6, 0.9%, and 5, 10, and 15 mm) were combined to the soil matrix. The soil was characterized by conducting compaction, unconfined compressive strength (UCS), direct shear (DS), California bearing ratio (CBR), indirect tensile strength (ITS), freezing-thawing (F-T) tests, and microstructural analysis. The data were used to assess the effect of wheat fiber and NB on the soil’s geotechnical properties. The results revealed that incorporating 0.8% NB into the soil led to the best enhancement in compressive strength. This improvement is attributed to the dehydration and formation of a viscous-like film between the soil particles. In addition, 0.6% fibers with a length of 15mm increased the interaction and bonding forces between the particles of soil, resulting in a maximum increase in compressive strength. Combining fibers and NB improved the shear strength, tensile strength, and bearing capacity. Besides, the stabilized soil exhibited superior resistance to freezing-thawing cycles compared to the unreinforced clay. Overall, the results indicate that using wheat fibers and NB is a cost-effective and eco-friendly solution for stabilizing clay subgrades.

Freeze–Thaw Durability and Shrinkage of Calcium Sulfoaluminate Cement Concrete with Internal Curing

Freeze–Thaw Durability and Shrinkage of Calcium Sulfoaluminate Cement Concrete with Internal Curing

Strength Deterioration Mechanism of Interface between Soil–Rock Mixture and Concrete with Different Degrees of Roughness under Freeze–Thaw Cycles

Strength Deterioration Mechanism of Interface between Soil–Rock Mixture and Concrete with Different Degrees of Roughness under Freeze–Thaw Cycles

Relationship between soil structure and hydrological properties of the active layer in the permafrost region of the Qinghai–Tibet Plateau based on fractal theory

Soil structure and hydrological properties influence ecosystem stability and hydrological cycles. Fractal theory has been widely used in the quantitative analysis of soil particle-size distribution (PSD), aggregate and pore distribution, and evaluation of soil degradation, desertification, and wind erosion. However, the complex relationships between soil physiochemical properties and soil hydrological processes based on fractal theory have not been thoroughly investigated. This study focused on the correlation among soil structure, physicochemical properties, and hydrological properties in the active layers of various soil types and vegetation coverages in the permafrost region of the Qinghai–Tibet Plateau (QTP) using the principles of fractal theory. The results showed that the fractal dimension of soil PSD (DPSD) in the active layer of the QTP was predominantly within the range of 2.13–2.70, which is notably smaller than the fractal dimension of the soil water retention curve (DWRC: 2.72–2.93). With decreased vegetation coverage, the alpine soil particles exhibit gradual fineness, increasing the DPSD. Soil physicochemical properties were affected by the interactions among internal factors and the external environment, such as geographical locations, slope orientations, vegetation coverages, and soil freeze–thaw cycles. The results of correlation analysis indicated that the fractal dimension of PSD and the soil water retention curve (WRC) were significantly correlated with soil textural, physicochemical, and hydraulic properties, particularly in clay, silt, and very fine sand content. Finally, a fractal model of WRC in the permafrost region was established based on DPSD and WRC parameters of the Gardner and van Genuchten models. The study provides an improved perspective for revealing the transport process and influencing mechanism of soil water and salt in the active layer of the QTP and a more accurate prediction of soil physiochemical and hydrological properties for climate warming and wetting.

Study on the physical mechanical properties and freeze-thaw resistance of energy storage concrete with artificial phase change aggregate

As the main material for major infrastructure in cold regions, the mechanical properties and freeze-thaw resistance of concrete have become key scientific issues affecting the safety and normal operation and maintenance of infrastructure in cold regions. Energy storage concrete with phase change materials (PCM) has high thermal storage performance, which is beneficial to improving the frost resistance of concrete. In our preliminary research work, the artificial phase change aggregate (APCA) containing PCM with high latent heat, good mechanical properties and frost resistance were made and tested. The APCA was added to the concrete and replaced with natural coarse aggregate in different proportions, resulting in several energy storage concrete schemes with different APCA contents. The water absorption characteristics, microstructure and pore characteristics of energy storage concrete with different APCA contents were tested and analyzed through negative pressure saturation test, SEM and MIP. The effects of APCA replacement on the composition, mechanical properties, failure morphology characteristics and frost resistance durability of energy storage concrete at various ages were analyzed through XRD test, strength test and freeze-thaw cycle test. The results showed that replacing natural coarse aggregates with APCA changed the pore characteristics of concrete, reduced its saturation water absorption rate, but did not change the composition of hydration products at various ages of concrete. Replacing with an appropriate amount of APCA in concrete is beneficial for reducing the total porosity, the number of more-harmful pores and harmful pores. APCA reduce the compressive strength and splitting tensile strength of energy storage concrete at various ages. The early splitting strength of energy storage concrete increases rapidly, while the later growth is relatively slow. APCA are beneficial for suppressing the expansion of pores and cracks under freeze-thaw action of concrete. APCA is helpful to improve the freeze–thaw resistance of the energy storage concrete. After 100 freeze-thaw cycles, their strength is still 96% of the 28 day strength, and their compressive strength is about 35 MPa. This study provides a reliable experimental and theoretical basis for improving the freezing resistance of concrete in cold area.

The effect of freeze‒thaw cycles on the physicochemical stability and nutritional composition of camel milk

The effect of freeze‒thaw cycles on the physicochemical stability and nutritional composition of camel milk

Mechanical Properties of Subgrade Soil Reinforced with Basalt Fiber and Cement under Freeze–Thaw Cycles

Mechanical Properties of Subgrade Soil Reinforced with Basalt Fiber and Cement under Freeze–Thaw Cycles

MRNA stability after multiple freeze thaw cycles

mRNA stability after multiple freeze thaw cycles

Improved chronological constraints for Holocene rock glacier activity in the Ben Ohau Range, Southern Alps/New Zealand

Schmidt-hammer exposure-age dating (SHD) was applied to selected rock glaciers in the south central Ben Ohau Range, Southern Alps, New Zealand, to expand the available regional data set following a previous pilot study. Additional SHD-sampling was conducted on high-altitudinal moraines at two locations with published cosmogenic 10Be surface-exposure ages and utilised to establish a new regional SHD-age calibration equation. SHD-age estimates available for a total of eight rock glaciers and based on &gt;16,000 sampled boulders were analysed in a chronological, morphodynamic, and palaeoclimatic context. SHD-age estimates for initiation of rock glacier formation indicated by the age of their respective frontal ridges spread between 12.1 ± 1.6 and 7.2 ± 0.8 ka with a cluster of four individual features between 9.3 and 8.6 ka. Activity at some rock glaciers commenced immediately after local deglaciation and all are considerably older than previously anticipated. Successive transverse ridges dated on the rock glaciers reveal a clear general trend of increasing age with increasing distance from the rooting zone. This reflects conveyor-like transport of boulders in predominantly stable position on the surface. The SHD-age estimates of the ridges themselves are interpreted as morphological evidence for phases of strong morphodynamic activity connected to cold periods and increased debris supply by climate-driven frost weathering. All investigated rock glaciers show a climax of such activity during the Early Holocene. After c. 7.0 ka such phases became less frequent and subsequently rare during the Late-Holocene. These newly obtained chronological constraints for rock glacier activity are discussed in the context of related palaeoclimatic conditions and their potential to complement the hitherto limited regional palaeoclimatic records for the Early Holocene based on glacial activity.

Experimental Study on Deformation and Damage Evolution of Cracked Red Sandstone Under Freeze–Thaw Cycles

Cracked rock masses in cold regions are subjected to freeze–thaw cycles over extended periods, resulting in freeze–thaw deformation. The combined effects of freeze–thaw cycling and the depth of cracks significantly influence the stability and durability of underground rock engineering in these regions. In some cold regions with minimal annual rainfall, rock masses are unable to absorb external water during freeze–thaw cycles. As freeze–thaw deformation progresses, the rock transitions naturally from a saturated state to an unsaturated state. To investigate the deformation damage mechanisms and evolution patterns of saturated red sandstone with initial non-penetrating cracks of varying depths (20 mm, 30 mm, 40 mm) under freeze–thaw cycling conditions without external water replenishment and with naturally varying saturation levels, relevant freeze–thaw cycle experiments and strain monitoring were conducted. The results indicate that cracked red sandstone experiences residual strain in each freeze–thaw cycle, which gradually accumulates, leading to irreversible freeze–thaw damage deformation. The cumulative residual strain of the rock specimen after 45 freeze–thaw cycles was 40.69 times greater than the residual strain from the first cycle. Additionally, the freeze–thaw strain characteristic values exhibited a clear correlation with crack depth. These findings provide experimental methods and data references for analyzing the deformation and failure mechanisms of cracked rock induced by freeze–thaw damage in cold regions.

Impact of Sample Storage Time and Temperature on the Stability of Respiratory Viruses and Enteric Viruses in Wastewater

Wastewater-based surveillance (WBS) has been widely used to track SARS-CoV-2 as well as many other viruses in communities during the COVID pandemic and post-pandemic. However, it is still not clear how temperature and storage time would influence the stability of viruses in wastewater. In this study, we assessed the stability of SARS-CoV-2, pepper mild mottle virus (PMMoV), influenza viruses A (IAV) and B (IBV), respiratory syncytial virus (RSV), and enteric viruses in raw wastewater stored at room temperature, 4 °C, and −20 °C for 3 and 6 days. SARS-CoV-2, PMMoV, IAV, and enteric viruses were found to be stable up to 6 days after storing at room temperature or 4 °C. SARS-CoV-2 and RSV were more susceptible to freeze–thaw cycles compared to PMMoV and enteric viruses, which were relatively stable for up to 6 days stored at −20 °C. Low detection of IBV in wastewater made it difficult to evaluate the impact. Based on our findings, we conclude that short-term storage or transportation of wastewater samples within 6 days at ambient temperature or 4 °C is acceptable for the majority of these viruses. Freezing samples at −20 °C for even short periods is not recommended for WBS of respiratory viruses. The data obtained from this study can provide guidance for quality assurance purposes from the operational aspects of wastewater surveillance.

An experimental study on the shear strength and shear fracture evolution of freeze–thaw granite containing rock bridges based on digital image correlation

An experimental study on the shear strength and shear fracture evolution of freeze–thaw granite containing rock bridges based on digital image correlation

Preparation of strong, tough and highly ion-conductive nanocellulose hydrogels based on freeze–thaw cycles: performance evaluation under different freezing temperatures

Abstract Rapid and effective preparation of hydrogels with excellent properties by cyclic freezing–thawing has remained an enormous challenge as hydrogels prepared using traditional freeze–thaw methods demonstrate poor, unstable and unalterable mechanical properties. In this study, an innovative method was introduced to develop a nanocellulose hydrogel with excellent properties via cyclic freezing–thawing and ionic cross-linking, and various methods were used to characterise the structure and properties of the hydrogel. The results showed that hydrogen and ester bonds existed in the soy hull nanocellulose–sodium alginate–calcium chloride (SHNC/SA/Ca2+) hydrogel and that the internal structure of the hydrogel changed from a lamellar to three-dimensional network structure owing to low temperature, increasing the cross-linking density of SHNC and SA and enhancing the mechanical strength of the hydrogel. Meanwhile, the SHNC/SA/Ca2+-4 hydrogel demonstrated excellent elongation (804 %), viscoelasticity (storage modulus = 89.6 kPa), mechanical strength (tensile strength = 0.59 MPa, compressive strength = 1.52 MPa), ionic conductivity (3.84 S/m), transparency (54 %), anti-ultraviolet properties and fatigue resistance. The simple preparation process, excellent performance and three-dimensional porous network structure of the nanocellulose hydrogel offer broad application prospects in many fields.

Rock coast geo model: process-response dynamics, resilience and vulnerability

Geology and geomorphology link starkly in coastal environments, exemplifying the importance of Fookes' geo model approach to understanding site dynamics. Cliffs, and the shore platforms that front them, are subject to both marine and subaerial processes. Throughout his work, Fookes emphasises the role of climate as a weathering agent, influencing material properties and requiring consideration in engineering projects. Comparatively, more is known about the operation of rock weathering processes on shore platforms than on cliffs. Yet, with changing climate, it is becoming apparent that winter salt and frost weathering, and summer salt and wetting-drying weathering contribute to more frequent occurrences of coastal rockfalls. Increasing storm activity and rising sea levels are enhancing marine and subaerial processes. Rock coasts are amongst the most rapidly eroding coastlines in Europe. New applications of technologies, including seismometers, Lidar and InSAR, provide a fuller understanding of rock coast process-response geo model behaviour and the resilience of rock coasts on engineering timescales. Communicating scientific understanding of rock coast dynamics to policy-makers, planners and the public remains a challenge. Assessments of hazard, risk, resilience and vulnerability of rock coasts associated with climate change provide useful communication tools. Databases such as the British Geological Survey GeoCoast geohazard data product, and EMODnet Geology (European Marine Observation and Data Network) coastal behaviour data products integrate and visualise available data and information to communicate situational awareness to a broad audience.