Snow-melting Agent Research Articles

Multi-Scale Study on the Effect of Snowmelt Salt on the Interface Adhesion of Rubberized Asphalt–Steel Slag

To explore the effect of snowmelt agent on the adhesion of the rubberized asphalt–steel slag interface, the adhesion of the rubberized asphalt–steel slag interface under different concentrations of snowmelt agent was studied. The macroscopic fracture characteristics of the steel slag-rubberized asphalt mixture under different concentrations of snowmelt salt were studied. The surface energy of steel slag and rubberized asphalt after the action of different concentrations of snowmelt salt was tested at the microscopic scale, and then their adhesion was calculated. It was used to study the microscopic surface interaction under the action of snowmelt agents. At the molecular scale, the interface models of rubberized asphalt–NaCl solution–Ca3SiO5 were constructed, and the interaction between steel slag and asphalt under different concentrations of snowmelt agent was studied. The results show the following: when the concentration of snowmelt agent is 8%–12%, the fracture of the rubberized asphalt–steel slag mixture is more inclined to brittle fracture, and the failure speed is faster; the adhesion of steel slag-rubberized asphalt is weakened under the action of the snowmelt agent, but it can still maintain good adhesion; before the concentration of snowmelt agent reached saturation, the adhesion property of steel slag-rubberized asphalt decreases with the increase of snowmelt agent concentration; when the concentration of snowmelt agent reached saturation, NaCl precipitates and adheres to the molecular surface of steel slag, which enhances the interaction between steel slag and rubberized asphalt; the inflection point with salt concentration is related to the solvent precipitated from the solution.

Pollution Characteristics and Sources of Ambient Air Dustfall in Urban Area of Beijing

Since 2016, the Ministry of Ecology and Environment and the Beijing Municipal Government have adjusted the minimum concentration limit for ambient air dustfall several times, indicating that they attach great importance to dustfall. To grasp the pollution characteristics and sources of dustfall, in this work, the filtration method was used to determine the insoluble dustfall and water-soluble dustfall in the urban area of Beijing. From our analysis, the influence of the meteorological parameters on dustfall was found, and the chemical components of dustfall were determined. The positive matrix factorization (PMF) model was also utilized to analyze the sources of dustfall. The results indicated that the average amount of dustfall in 2021–2022 was 4.4 t·(km2·30 d)−1, and the proportion of insoluble dustfall deposition was 82.4%. Dustfall was positively correlated with the average wind speed and temperature and negatively correlated with the relative humidity and rain precipitation. The impact of the meteorological parameters on insoluble dustfall and water-soluble dustfall was the opposite. The average proportions of crustal material, ions, organic matter, element carbon, trace elements, and unknown components were 48%, 16%, 14%, 1.4%, 0.20%, and 20%, respectively. The proportions of the crustal material and ions were the highest in spring (57%) and summer (37%). The contribution rates of fugitive dust source, secondary inorganic source, mobile source, coal combustion source, snow melting agent source, and other sources were 42.4%, 19.3%, 8.3%, 3.0%, 2.7%, and 24.3%, respectively. This study supported dustfall pollution control by analysing the pollutant characteristics and sources of dustfall from the standpoint of total chemical components. In order to better control dustfall pollution, control measures and evaluation standards for fugitive dust pollution should be formulated.

Relationship between Microstructure and Macroscopic Properties of Asphalt under Different Concentrations of Snow Melting Agent

Relationship between Microstructure and Macroscopic Properties of Asphalt under Different Concentrations of Snow Melting Agent

Interfacial bonding property and microscopic damage mechanism of bitumen-aggregate in salt-freeze-thawing environment

Deicing salt or snow-melting agent has a corrosive effect on the pavement, which reduces the durability of asphalt pavement. The interfacial bonding properties of bitumen-aggregate is one of the main factors affecting the durability of asphalt mixture. To evaluate the interfacial bonding properties of bitumen-aggregate and reveal the damage mechanism under salt-freeze-thaw coupling effect, the bitumen-aggregate samples with the same film thickness were formed by controlling the applied load. The corrosion of deicing salt on bitumen-aggregate and bitumen film samples was simulated by freeze-thaw cycles in 1 %, 3 % and 5 % NaCl solution. The pull-off test of SBS modified bitumen-aggregate after salt-freeze-thaw cycles was conducted. The Fourier transform infrared spectrometer (FTIR) test was carried out to qualitatively and quantitatively analyze the impact of salt-freeze-thaw coupling effect on bitumen functional groups. The surface morphology of bitumen samples treated in salt-freeze-thawing environment was also scanned by atomic force microscopy (AFM) in tapping mode. The results illustrate that the pull-off strength of bitumen-aggregate decreases sharply first and then the decrease rate slows down with the rise of salt-freeze-thaw coupling cycles. The carbonyl index and sulfoxide index of SBS modified bitumen increases, and the butadiene index decreases after freeze-thaw cycles in NaCl solution. The environment of salt erosion and freeze-thaw cycle accelerates the deterioration of SBS modifier and reduces the distinction of various phases in bitumen binder. Then the Ra and Rq of SBS modified bitumen decreases significantly in salt-freeze-thawing environment. The decrease of butadiene index and root mean square roughness leads to the weakening of adsorption between SBS modified bitumen and aggregate, which is the main reason for the damage of interfacial bonding performance of bitumen-aggregate. In summary, the salt-freeze-thawing environment damages the bonding performance of bitumen-aggregate. The damage law and deterioration mechanism of bonding properties of bitumen-aggregate presented in this paper provides some references for the optimal design of asphalt mixture in salt-freeze-thawing environment.

Study on the Effect and Mechanism of Different Snowmelt Agents on Asphalt

Abstract This article explores the effects of different types of snow-melting agents on the high-temperature performance, low-temperature performance, rheological properties, and creep properties of asphalt in order to better understand the mechanism of different types of snow-melting agents on asphalt. Chlorine salt snow-melting agent solution, nonchlorine salt snow-melting agent solution, and mixed snow-melting agent solution were prepared, respectively, and the erosion of asphalt was carried out by periodic immersion test method. Then, through the penetration test, ductility test, softening point test, dynamic shear rheological test, and multi-stress recovery creep test, the effects of different types of snow-melting agents on the high-temperature performance, low-temperature performance, rheological properties, and creep properties of asphalt were investigated. Finally, the mechanism of action of different types of snow-melting agents on asphalt was analyzed by scanning electron microscopy, infrared spectroscopy, and differential scanning calorimetry. The results show that the chloride snow-melting agent has the greatest influence on the high-temperature performance, low-temperature performance, rheological properties, and creep properties of asphalt, followed by the mixed snow-melting agent, and the nonchloride snow-melting agent has the least influence on the high-temperature performance, low-temperature performance, rheological properties, and creep properties of asphalt. From the macroscopic experiment, microscopic experiment, and mechanism analysis of this article, it is suggested that nonchlorine salt snow-melting agent should be used in snow removal on snowy road surface.

Retracted: Application of TOPSIS Method Combined with Grey Relational Degree in the Selection of Snow-Melting Agent Use Plan

Retracted: Application of TOPSIS Method Combined with Grey Relational Degree in the Selection of Snow-Melting Agent Use Plan

Preparation of temperature-sensitive slow-release snowmelt agent by UV-irradiation grafting method

To achieve temperature-control or intelligent-release objectives, a slow-release salt-storage snowmelt agent (TSSA) microcapsule was prepared by UV-irradiation grafting method. Combined with swelling and contraction properties of a temperature-sensitive hydrogel, the TSSA exhibited a temperature sensitive slow-release function, excellent permeability and release difference at about 25°C. Conductivity test of its asphalt concrete sample mixed with TSSA (named AC-TSSA) showed that, by adding 4 wt% TSSA equal volume replacement of mineral powders, the conductivity of the soaking solution of AC-TSSA decreased by 56.1% after soaking for 10 days. After 10 days soaking of AC-TSSA, the increase rate of conductivity was stabled at 0.09 mS·cm−1·h−1. The high temperature stability and water stability of AC-TSSA with 5 wt% TSSA equal volume replacement of mineral powders showed that the dynamic stability and residual strength ratio increased by 1.3% and 1.1%, respectively. Accordingly, the utilization rate of snowmelt agent is expected to be significantly improved.

Field experimentation of bio-cementation using low-cost cementation media for preservation of slope surface

Microbial induced carbonate precipitation (MICP) is a promising bio-cementation method that involves ureolytic bacteria to improve the geotechnical properties of soil. The laboratory-scale studies carried out in the recent past showed that the MICP can be a potential alternative for slope surface preservation. However, the use of analytical-grade chemicals makes this method too expensive, limiting the applicability of the method especially when implicated at field-scale. The purpose of this research work was to assess the effectiveness of using inexpensive low-grade chemicals for the in-situ stabilization of slope surface. Two test plots were established at the project site (Hokkaido expressway slope, Japan) and subjected to MICP treatment via surficial spraying. One was treated using the cementation media formulated by low-grade chemicals (inclusive of fertilizer urea, snow-melting agent and beer-yeast), while the typical analytical-grade media was used to treat the other plot. After 20 days of treatment, the treated slope surfaces were evaluated by surface strength, CaCO3 content, scanning electron microscopy, energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD) analyses. The outcomes indicated that the surface was significantly improved by low-grade chemicals; a stiff surface layer was desirably formed to the depth of 5 – 10 cm with the surface strength and CaCO3 content in the ranges of 0.14 – 1.02 MPa and 0.56 – 3.7%, respectively. The results are compared and discussed, and the challenges in the use of low-grade chemicals are pointed out for the way forward. Cost analysis disclosed that the material cost of the cementation media was reduced by around thirty-seven-fold (by 97%) compared to the analytical-grade media. While demonstrating the potential use of low-grade chemicals, the field-scale experiment could contribute to narrow down the gap between the present-state and real-scale deployment of MICP technology.

Characteristics and Source Apportionment of Atmospheric Ion Deposition During Winter and Spring in the Core Area of Beijing

In recent years, the Ministry of Ecology and Environment and the Beijing Municipal Government have continuously strengthened the control indicators of dustfall. In order to grasp the characteristics and sources of ion deposition in dustfall, the filtration method and ion chromatography were used to determine the dustfall and ion deposition during winter and spring in the core area of Beijing, and the PMF model was carried out to analyze the sources of ion deposition. The results indicated:① the average values of ion deposition and its proportion in dustfall were 0.87 t·(km2·30 d)-1 and 14.2%, respectively. The dustfall and ion deposition on working days were 1.3 times and 0.7 times that on rest days, respectively. ② The coefficient of determination in the linear equations between ion deposition and precipitation, relative humidity, temperature, and average wind speed were 0.54, 0.16, 0.15, and 0.02, respectively. In addition, the coefficient of determination in the linear equations between ion deposition and PM2.5 concentration and dustfall were 0.26 and 0.17, respectively. Therefore, controlling the concentration of PM2.5 was crucial to treating ion deposition. ③ Anions and cations accounted for 61.6% and 38.4%, respectively, in the ion deposition, and SO42-, NO3-, and NH4+ accounted for 60.6% in total. The ratio of anion and cation charge deposition was 0.70, and the dustfall was alkaline. The ρ(NO3-)/ρ(SO42-) in the ion deposition was 0.66, which was higher than that of 15 years ago. ④ The contribution rates of secondary sources, fugitive dust sources, combustion sources, snow-melting agent sources, and other sources were 51.7%, 17.7%, 13.5%, 13.5%, and 3.6%, respectively.

High efficiency Al-based multicomponent composites for low-temperature hydrogen production and its hydrolysis mechanism

In this study, a series of multicomponent Al-based composites were prepared by mechanical ball milling of Al powder, low-melting-point metals (Ga, In, Sn), NaCl, g-C3N4 and carbon nanospheres. The composites were thoroughly analyzed using state-of-art characterization techniques with respect to morphologies, structures, chemical compositions, thermal, and electrochemical properties, etc. The hydrogen production performance of Al-based composites has been investigated under three low-temperature conditions, including deionized water (275.15 K), snow-melting agent aqueous solution (253.15–273.15 K), and aqueous electrolyte solutions (KOH, FeCl3, CaCl2, ethylene glycol) at 233.15 K. The best hydrogen production performance with a hydrogen yield of 1133 mL·gAl−1 at 275.15 K and 1095 mL·gAl−1 at 253.15 K was obtained. Especially, no induction time was observed in either condition. Even at 233.15 K in KOH solution, its reaction induction time was around 6 s and final hydrogen yield reached 1057 mL·gAl−1. The observed hydrogen production capabilities of composites have been analyzed and understood in depth, and a tentative multicomponent activation mechanism for low-temperature hydrogen production was proposed as well.

Experimental Study on the Influence of Snow-Melting Agents on Fiber-Reinforced Cemented Soil under Freezing-Thawing Cycles

To explore the effect of snow-melting agents on the glass fiber-reinforced cemented soil under freezing-thawing cycles, three widely used snow-melting agents, including potassium acetate, magnesium chloride, and sodium sulfate, were used in this article. The effects of snow-melting agent types on the apparent damage, mass loss, and mechanical properties of fiber-reinforced cemented soil under freezing-thawing cycles were analyzed through salt freezing and unconfined compressive strength tests. The results show that the snow-melting effect of potassium acetate is the best, the snow-melting effect of magnesium chloride is the second, and the snow-melting effect of sodium sulfate is the worst. Notably, as the number of freezing-thawing cycles increases, the strength of the test block decreases to varying degrees. After the fifth freezing-thawing cycle, the strength of the block without fiber decreased by 61.30%, 70.22%, and 81.58% in clear water, potassium acetate, and magnesium chloride solution, respectively, while the test block in sodium sulfate solution lost its bearing capacity. A series of studies proved that the snow-melting agent with sodium sulfate as the main component has the most apparent erosion effect on the cemented soil, followed by magnesium chloride, and the erosion effect of potassium acetate is the weakest. The incorporation of glass fiber can effectively improve the resistance of the cemented soil under the action of various salt solution erosion and freezing-thawing coupling and has a significant effect on slowing the development of surface cracks, improving peak strength, and reducing the mass loss rate. This research will provide theoretical support for the design of subgrade and the selection of snow-melting agents in cold areas.

Enhanced chloride-free snow-melting agent generation from organic wastewater by integrating bioconversion and synthesis

In this study, a new process for producing chloride-free snow-melting agents (CSAs) was proposed. Organic wastewater was converted to total volatile fatty acids (TVFA) by anaerobic acidogenic fermentation. The experiments for acid generation showed that the maximum TVFA concentration of 45.9 g/L was obtained at an organic loading rate of 5 g chemical oxygen demand /(L·d), and the proportion of acetic acid reached 78.8 %. Forward osmosis was used for concentrating the TVFA solution. The obtained CSAs, after evaporation and crystallization, had a better ice-melting capacity and less corrosion on metal and concrete than NaCl and CaCl2. Additionally, the damage caused by CSAs to the germination of plant seeds was significantly lesser than that caused by chloride salts. This study proposed a feasible method for the high-value conversion of organic wastewater, providing a new direction for the reuse of organic wastewater.

Characteristics of slow-release ice and snow melting micro-surfacing materials

ABSTRACT In order to solve the problem of frequent snow and ice removal in winter, a micro-surfacing pavement with active snow and ice removal and slow-release function is developed. The snow-melting agent with sodium acetate, calcium acetate, and potassium acetate as the main components was prepared, and the optimum proportion was determined. With the help of hygroscopicity and oil absorption tests, the optimum surface modifier and its optimum concentration were determined. The microstructure of the snowmelt agent were characterized by infrared spectroscopy and scanning electron microscopy. The influence of snow-melting agent on the road performance was explored. The results show that the optimum proportion of sodium acetate, calcium acetate and potassium acetate is 37, 15 and 48 % respectiveiy. When the surface modifier: hydrogen silicone oil and KH560 solution concentration was 4.0% and 1.0% respectively, the slow-release effect was the optimum. The wear resistance and high temperature stability of micro-surfacing with the snowmelt agent were increased by 2.5 % and 8.2 %, respectively. It is most reasonable to determine that the optimal replacement amount of mineral powder is 50%. It is necessary to study the distribution of self-made snowmelt agent in the mixture in the future.

Optimal exogenous calcium alleviates the damage of Snow-melting agent to Salix matsudana seedlings.

As the main component of snowmelt agents, NaCl is widely used in northern winters and significantly impacts the expected growth of garden plants in north China. Salix matsudana is also faced with salt stress caused by snowmelt, which seriously affects its development as the main tree species in the northern landscape. However, how exogenous calcium alleviates salt stress in Salix matsudana is not yet clear. In this study, the indicators of growth indices, photosynthetic characteristics and stress resistance were measured by hydroponic assays in combination with three NaCl conditions (0, 50 and 200 mmol·L-1) and five calcium concentrations (0, 2.5, 5, 10 and 20 mmol·L-1). The study’s results indicated that the application of exogenous calcium remarkably promoted the growth of Salix matsudana seedlings under NaCl stress. When the exogenous calcium concentration was 10 mmol·L-1, the plant height and basal diameter of Salix matsudana seedlings increased significantly, and the biomass of all parts reached the maximum (P< 0.05). Exogenous calcium can substantially improve the photosynthesis of Salix matsudana seedlings under salt stress. The photosynthetic parameters, photosynthetic pigment content and photosynthetic product synthesis of Salix matsudana seedlings were significantly increased at an exogenous calcium concentration of 10 mmol·L-1, and the photosynthetic level of Salix matsudana seedlings reached the highest value. The chlorophyll fluorescence parameters (F v /F m, F v /F 0) of Salix matsudana seedlings were significantly decreased under different concentrations of NaCl stress. The maximum photochemical efficiency (F v /F m) and potential photochemical efficiency (F v /F 0) of Salix matsudana seedlings peaked when the exogenous calcium concentration was 10 mmol·L-1, which was significantly higher than that of the other treatments (P< 0.05). The water use efficiency of Salix matsudana was affected considerably by NaCl stress. The WUE and iWUE peak values of Salix matsudana were significantly higher than those of other calcium concentrations at 10 mmol·L-1 (P< 0.05). Exogenous calcium can increase the activities of CAT, SOD and POD enzymes in Salix matsudana seedlings under different NaCl concentrations. Under NaCl stress, adding exogenous calcium promoted the survival rate and growth of Salix matsudana seedlings. In conclusion, the optimum exogenous calcium concentration for Salix matsudana seedlings was 10 mmol·L-1. High or low concentrations of exogenous calcium did not achieve the best results in alleviating salt stress in Salix matsudana.

Enhanced Chloride-Free Snow-Melting Agent Generation from Food Wastewater by Integrating Bioconversion and Synthesis

Enhanced Chloride-Free Snow-Melting Agent Generation from Food Wastewater by Integrating Bioconversion and Synthesis

Deterioration of modern concrete structures and asphalt pavements by respiratory action and trace quantities of organic matter.

In concrete structures (concrete), damage from cracks, deterioration, amorphization, and delamination occur in some structures, causing disaggregation (concrete changed to very fine particles) and hollowing out of the concrete. In concrete pavements, damage from large amounts of pop-out of aggregate occurs from the surface of the concrete pavement 4-5 hours after spraying of snow melting agent on the surface of the pavement. The damage from disaggregation, blistering, cracks, and peeling-off of a surface course have also been observed in asphalt runways and highways. The damage from disaggregation, cracks and pop-out of aggregate in asphalt pavements and concrete structures have long been seen as strange and unexpected and have defied explanation. As a result of examinations in various experiments, it was concluded that all of the unexplained kinds of damage of both asphalt pavements and concrete structures were caused by Trace Quantities of Organic Matter (TQOM), Air Entrained (AE) water reducing agent in air and/or cement, and surfactant in snow melting agent. The emission sources of TQOM and these organic substances were also identified by chemical analysis for these unexpected and unexplained phenomena. The TQOM includes phthalate compounds (phthalates in the following), amine compounds, phosphate compounds, snow melting agent and Sodium Polyoxyethylene Nonyl phenyl Ether Sulfate (SPNES). SPNES is a surfactant in windshield washer fluid for automobiles. We found that the water content and content of organic matter in damaged asphalt pavements and concrete structures are also important indicators for the damage. Further, a new evaluation method for amorphization was proposed in this study and it appears suitable for evaluating the safety of concrete structures along roads which were exposed to TQOM in severely air-polluted environments.

Full components recovery of organic matter and indium from discarded liquid crystal display panels

In the present study, organic matter and indium were fully recycled from discarded LCD panels by microwave extraction - nitrogen pyrolysis - vacuum reduction. Triphenyl phosphate, an environmentally friendly halogen-free flame retardant, was extracted from the polarizing film using microwave extraction technology. The extraction rate under optimized conditions (acetone, 55 °C, 20 min, 1:50) was 95.89%. After the microwave extraction process, the polarizing film was treated with nitrogen pyrolysis. Uncondensed pyrolysis gas/oil (mainly acetic acid) was used to prepare an environmentally friendly snow melting agent. In addition, 26.42 wt% of the pyrolytic carbon residue was obtained under the optimized conditions (350 °C, 2 °C·min−1, 0.05 L min−1, 120 min), which could be used as a reductant to recycle indium from waste LCD panels. In the vacuum reduction process, the indium conversion rate could reach 99.92% without the addition of reductant. The reaction dynamics results show that the reduction process of pyrolytic carbon and In2O3 is initially controlled by a chemical reaction, followed by a mixed control that transitions to a diffusion control. Moreover, the results of the contrast experiment show that the conversion efficiency of pyrolytic carbon to indium was comparable to that of activated carbon, and both were better than that of coke. This study can be used as a practical reference for the recycling of major components of LCD panels.

高汞背景土壤中Hg在NaCl型融雪剂作用下迁移规律研究

高汞背景土壤中Hg在NaCl型融雪剂作用下迁移规律研究

Photosynthesis Characteristics of Tall Fescue under Snow-Melting Agent, Acid Precipitation and Freeze-Thaw Stress

To explore the physiological response characteristics of plant photosynthesis under acid precipitation stress (A stress), snow-melting agent stress (S stress), and freeze-thaw stress (F stress) as well as their various combinations, the net assimilation rate (NAR), intercellular CO2 concentration (Ci), stomatal conductance (Gs) and water use efficiency (WUE) of tall fescue (Festuca arundinacea Schreb.) under these three stresses respectively and four kinds of combined stresses were measured. The effects of these different kinds of stresses on the photosynthesis parameters were then evaluated, and the major mechanisms of main factors affecting the interactions between stresses were speculated. The experimental results indicated that both NAR and WUE decreased significantly in response to all stresses and Ci increased dramatically in response to all stresses, while Gs ascended under F stress but descended in response to A stress and S stress. The photosynthetic efficiency significantly decreased as the temperature decreased and did not clearly recover as the temperature increased. Moreover, the combination of A stress and S stress had fewer effects on photosynthesis than did the S stress alone, while the effects resulting from F stress were similar at low temperature. The major controlling mechanism is most likely the strong inhibition of photosystem II and the promotion of antioxidant enzymes resulting from acid precipitation as well as NaCl may strengthen the freezing tolerance of plants.

Preparation of Calcium Magnesium Acetate Snow Melting Agent Using Raw Calcium Acetate-Rich Made from Eggshells

A large number of discarded eggshells bring serious environmental pollution and waste of resources. To solve this problem, raw product of calcium acetate was prepared from waste eggshell by the ultrasonic assisted neutralization method, thus, the best material ratio of calcium and magnesium, a non-chloride environment-friendly snow melting agent, which took calcium acetate as raw material by optimizing the experimental conditions, was determined. In this paper, the eggshell powder with a recovery rate of 90% was firstly obtained through the separation of eggshells and shell membrane; then, calcium acetate was prepared with a high yield of about 95.29% using ultrasonic neutralization treatment and suction filtration, and its properties including the calcium content, pH, moisture determination, sulfate, chloride, etc. were characterized with satisfaction according to the national standard, China (GB/T 23851-2009, China), the U.S. Pharmacopeia and related literature. Furthermore, different ratios of calcium and magnesium products were prepared and its properties on the pH, freezing point, dissolution rate, ability to melt snow and ice, concrete corrosion rate, carbon steel corrosion rate and plant salt tolerance test, were compared with commercially available snow melting agents. The best snow melting agent with calcium to magnesium ratio of 5:5 was picked over to be a substitute for the chlorine salt snow melting agent which can reduce the environmental pollution by discarded eggshells caused. The results obtained also provided a new theoretical basis and credible experimental data for the preparation of environmentally friendly snow melting agents.