Freeze-thaw Test Research Articles

Research on Capillary Water Absorption Characteristics of Modified Recycled Concrete under Different Freeze–Thaw Environments

Recycled coarse aggregate is processed through the second crushing, which causes some internal damage, resulting in its physical indicators being far worse than natural coarse aggregate; its durability is relatively poor, and in the northern region, the soil contains a large number of acidic salt ions from the erosion of concrete, resulting in a decline in its durability. In this test, concrete was made from the single and composite immersion of recycled coarse aggregate using 5% water glass and 8% silane solution and subjected to a rapid freeze–thaw test in water, 3.5% NaCl solution, and 5% Na2SO4 solution, followed by a capillary water absorption test. The study was conducted to test the durability of recycled concrete, establish the initial capillary water absorption prediction model under freeze–thaw in different media, and analyze the internal structure of the RAC group after freeze–thaw using SEM. The test results showed that the composite-modified water absorption decreased the most, which can effectively improve the durability of recycled concrete, and the chloride salt caused the greatest erosion of recycled concrete and had the least clear water. The predictive model has high accuracy and can be used as a reference for capillary water absorption experiments on recycled concrete.

Study on the freezing resistance and repair technology of prestressed high-strength concrete pipe piles

This article takes a prestressed high-strength concrete tube pile (PHC tube pile) in Tianjin Port as the research object, considers the influence of the type of admixture, forming process, and maintenance method in the process of concrete fabrication, and carries out a rapid freeze-thaw test of PHC tube pile concrete. The changes in the mass loss rate, relative compressive strength, and relative dynamic modulus of elasticity with the number of freeze-thaw cycles, as well as the influence characteristics and mechanism of the admixture type, forming process, and curing method, were obtained. Based on this study, the repair and reinforcement of the base concrete were carried out using ultrahigh toughness cementitious composites and cementitious permeable crystalline composites, and a rapid freeze-thaw test was conducted on the repaired concrete specimens to verify the repair and reinforcement effects of the two materials. The study showed that the mass loss rate, relative strength, and relative dynamic elastic modulus can better characterize the freezing resistance of PHC piles, and it is safer to use the relative dynamic elastic modulus as the evaluation index of the freezing resistance of PHC pile concrete than the mass loss rate. The concrete admixture, forming process, and maintenance method have significant effects on the freezing resistance of the PHC pipe pile mix. The splitting damage surface of both ultrahigh-toughness cementitious composites (UHTTC) and cementitious capillary crystalline waterproofing (CCCW) repaired concrete is a reinforced surface, and both repair materials can improve the freezing resistance of PHC pipe piles through the crack arresting effect and reduction in initial porosity.

STUDI STABILITAS FORMULASI SELF NANO EMULSIFYING DRUG DELIVERY SYSTEM (SNEDDS) EKSTRAK DAUN SERUNAI SEBAGAI ANTI DIABETES DENGAN VARIASI KONSENTRASI ASAM OLEAT

Management of diabetes mellitus can use chemical drugs and traditional medicine. One of the medicinal plants used by the community is chrysanthemum leaves (C.Odorata). The use of traditional medicine still has drawbacks, one of which is that its pharmacological effects are relatively weak and slow, affecting bioavailability and the therapeutic effect is not optimal. The aim of the study was to determine the stability of the formulation of the SNEDDS of chrysanthemum leaf extract as an anti-diabetic agent and to determine the effect of variations in the concentration of oleic acid in the formulation of the SNEDDS on evaluation and stability testing. This research method uses the Quasy Experimental Design method. The simplicia was made into an extract and then made into a nanoemulsion preparation with varying concentrations of oleic acid. The results of this study in the centrifugation test were stable at F3. Unstable hot-cold and freeze-thaw cycle tests. Stable resistance to dilution test at F2 250 ml. Week 0 and 4 accelerated storage tests were stable on F3 and F1. The evaluation results showed that variations in the concentration of oleic acid had no effect on particle size and PDI values ​​but had an effect on the transmittance value (%) as shown in the One Way Anova statistical analysis (p<0.05). The evaluation results showed that F2 with 10% oleic acid concentration was a stable formula because it had the smallest particle size and PDI (Polydispers Index) value.

Long-Term Bearing Capacity of Concrete Pile Composite Foundation under Composite Salt Erosion

In order to study the long-term bearing capacity of concrete pile composite foundation in the Salt Lake area, based on the Tehran Isfahan high-speed railway project in Iran, the full (semi) immersion drying test and rapid freeze-thaw test was carried out, and the specimens were scanned by electron microscope. Numerical calculations were used to study the effects of different pile strengths and design parameters on the long-term bearing capacity of the composite foundation. The main conclusions were as follows: The concrete specimens in the adsorption zone deteriorated earlier and faster. In the rapid freeze-thaw tests, the strength attenuation of high-strength (C40, C50) specimens was smaller than that of low-strength specimens (C20). Within 20 years after construction, the additional settlement of low-strength (C20) piles was 12.21 mm, while high-strength concrete was less affected by deterioration. With pile spacing ranging from 1.8 m to 4.5 m, the maximum increase in additional settlement under the C20 condition was about 20 mm. The pile-soil stress ratio under the three conditions increased by 2.42, 6.59, and 8.63. As the pile length and diameter increased, the peak stress of the pile body moved towards the pile end, and the changes in the pile-soil stress ratio under the three conditions were similar.

Effect of deicing agents on the low-temperature performance of asphalt concrete under freeze-thaw cycling conditions

The wide application of asphalt concrete in road construction has brought convenience to human travel, but road icing requires the application of deicing agents to prevent traffic accidents. However, the use of a deicing agent will also cause damage to the pavement material, so this paper carries out the research on the low-temperature performance of asphalt concrete with different concentrations of deicing agent solutions through the freeze-thaw cycle test. The test results show that with the increase in the number of freeze-thaw cycles, the five concentrations of deicing agent solution corresponding to the flexural tensile strength and maximum flexural tensile strain are decreasing trend. Although the deicing agent solution has a certain effect on the flexural tensile strength and maximum flexural tensile strain, the main effect on the reduction of the low-temperature performance of asphalt concrete is the frost damage caused by the freeze-thaw cycle.

High-performance pervious concrete using cost-effective modified vinyl ester as binder

Pervious concrete has a unique open-skeleton structure and high permeability, which effectively control water runoff, mitigate urban heat island effects, and reduce traffic noise in urban constructions. However, low strength, easy granulation, and poor durability often limit its application in pavement engineering. As a polymer binder, vinyl ester (VE) resin has high strength, wear resistance, durability, and corrosion resistance, which can remedy the shortage of pervious concrete. In this work, by optimizing the aggregate gradation and curing temperature, high-performance pervious concrete using VE resin as binder was fabricated. To further improve the performance of VE binder, renewable acrylated epoxidized soybean oil (AESO) and diphenylmethane diisocyanate (MDI) were used to increase the crosslinking degree of the resin and the durability of pervious concrete. When using 15% AESO and 10% MDI based on the weight of VE, the pervious concrete achieved an enhanced flexural strength of up to 7.72 MPa. A significant improvement was achieved by incorporating 50 wt% solid wastes copper slag into the pervious concrete, the compressive strength and flexural strength reached 37.72 MPa and 7.53 MPa, respectively. The permeability coefficient of the permeable concrete was 2.64 mm/s, and the connected porosity was 11.33%, which are higher than the requirements of China national standard. The satisfactory durability of pervious concrete was also verified through freeze-thaw, abrasion, and aging tests. This work offers a viable strategy for cost-efficient and sustainable high-performance pervious concrete, providing insights into the utilization of renewable feedstocks and solid wastes in civil materials.

Self-weighting of the overlying soil horizon catalyzed by freeze–thaw cycles leads to silt particle enrichment in the soil profile

Freeze–thaw cycles, as a strong weathering effect, can cause changes in the soil particle size and content, which can affect changes in the geological environment of the soil. A zone of silt enrichment was found at certain depths in the soil profile of the study regions. To understand and analyze the causes of this substratum phenomenon, a unidirectional freeze–thaw test on soil under static loading was designed and simulated in the laboratory in accordance with actual field conditions to investigate the process of changes in the physical index parameters after freeze–thaw cycles when the soil is under pressure. The changes in the parameters in the upper, middle and lower parts of the test soil column after 6, 10, 20, 40 and 50 freeze–thaw cycles were measured for the three regions. The test results show that the mechanical composition of the soil changes significantly after freeze–thaw cycles, the sand content decreases significantly, the clay and silt contents increase, and the particle frequency curve moves in the direction of particle size reduction. The freeze–thaw process is always accompanied by the fragmentation and aggregation of soil particles, and the fractal dimension is used to describe the distribution width of the soil particle population and to compare the clay content. The larger the fractal dimension is, the higher the clay content in the sample. Kvar(Coefficient of granulometric variation) decreases as the number of freeze–thaw cycles increases, the soil particles change from high-intensity to low-intensity variation, and the soil particles gradually transition to silt particles. The occurrence of silt-rich zones is the result of a combination of freeze–thaw action and static loading. This study can provide a new reference and vision for the freeze–thaw evolution process and tectonic development of soil in middle- and high-latitude cold regions.

The impact of waste brick and geo-cement aggregates as sand replacement on the mechanical and durability properties of alkali–activated mortar composites

This study explores the potential of waste brick and geo-cement aggregates as substitutes for natural sand in alkali-activated materials (AAMs) for mortar production. With a focus on achieving net-zero construction and mitigating environmental impact, the study replaces Portland Cement (OPC) and virgin aggregates with waste materials and by-products. The investigation evaluates the substitution of sand (up to 100 % by weight) in AAMs with waste brick aggregates (WBA) and waste geo-cement aggregates (WGA) obtained from demolished construction and research lab waste, respectively. The research methodology involves assessing mechanical, durability, and microstructure properties to assess the performance of the developed AAMs with waste aggregates. Notably, AAM composites containing waste brick and geo-cement aggregates surpass natural aggregate composites in terms of mechanical strength, water absorption, freeze-thaw resistance, acid ingress, and chloride attack. The 7-day 50 % waste brick mixture achieved a maximum compressive strength of 61 MPa, while a 70 % waste geo-cement mortar mixture attained a maximum flexural strength of 12 MPa. Combinations, whether comprising waste brick or geo-cement mortar aggregates, demonstrate compressive strengths well over 40 MPa, rendering them suitable for heavy load-bearing structures. The 50 % waste geo-cement mortar mixture stands out with the lowest water absorption rate of 6 % and the least compressive strength loss of 13 % after the freeze-thaw test, with reductions of 6 % and 18 %, respectively, compared to the control. Additionally, 100 % waste brick AAMs exhibit the lowest compressive strength loss after chloride and acid attack tests, with reductions of 13 % and 2.5 %, respectively. When compared to all other mixtures, the 50 % waste brick aggregates mortar mixture obtained the best overall performance. The composites developed in this study affirm their suitability for use in heavy-load structural components, showcasing favourable mechanical and durable properties. These findings underscore the need for additional exploration in this direction to advance sustainable construction practices.

Temperature Field Characterization of Iron Tailings Based on Microwave Maintenance Technology.

Microwave maintenance technology, as a new development trend, can realize the environmentally noninvasive and rapid repair of asphalt pavement and gradually replace traditional maintenance methods. Iron tailings were used as a self-healing material in this study to investigate the temperature response matching of microwave maintenance technology. Firstly, the physical properties and the mechanism of iron tailings were elaborated through macroscopic physical index testing and microscopic X-ray diffraction (XRD) analysis. Secondly, the applicability of aggregates to microwave heating was demonstrated by analyzing the temperature rise characteristics of the granules using infrared imaging. Then, the temperature field variation rules of the iron tailing asphalt mixture were summarized by microwave heating Marshall specimens. Finally, the road performance was assessed by conducting high-temperature dynamic stability, low-temperature tensile, water immersion Marshall, and freeze-thaw splitting tests. The experimental results showed that the iron tailings can be used as an aggregate for high-grade asphalt pavement and as the preferred aggregate for microwave maintenance technology. The iron tailings temperature field was radial from the inside out to provide different temperature response states for different pavement diseases, so the asphalt was dissolved and precipitated in a short time. The particle size of iron tailings was inversely proportional to the wave-absorbing heating rate, and the heating efficiency of the small particle size (0-4.75 mm) was the highest. The specimens doped with 4.75-13.2 mm iron tailings showed the best heating performance and road performance, with the average surface temperature of the specimens reaching 126.0 °C within 2 min. In summary, according to different disease types and construction needs, iron tailings can be used as an aggregate for asphalt pavement, providing an appropriate temperature field and improving the efficiency of the microwave maintenance of asphalt pavements.

Impact of superabsorbent polymer on self-compacting concrete's workability, strength, carbonation and freezing-thawing

Superabsorbent Polymer, an internal curing material, is a significant development in concrete technology. Self-compacting concrete is popular due to high flowability or pumpability. However, the higher quantity of cementitious materials required higher moisture consumption to complete the hydration. Further moisture unavailability leads to shrinkage increment. External curing cannot give proper moisture to cementitious material at higher depth. Hence, internal curing with super absorbent polymer is an economical solution for this problem. This study examines the impact of super absorbent polymer on the mechanical and durability properties of concrete. Laboratory tests were conducted to evaluate the workability, mechanical characteristics of the concrete, such as compressive strength and flexural strength. In addition, freezing-thawing tests and carbonation tests were conducted to investigate the durability performance of concrete. Scanning electron microscopy images were also used to observe the concrete's microstructure after freezing-thawing cycles. The findings demonstrate that Compressive strength and flexural strength values decreased in water curing while in air curing, those were increased. Additionally, it was discovered that the freezing-thawing cycles decreased the compressive strength of reference concrete in standard water curing. However, compressive strength increased after freezing-thawing cycles in air-curing super absorbent polymer mixes. Scanning electron microscopy images have confirmed that the microstructure of air-curing super absorbent polymer mixes was improved

The durability of spray steel fiber-reinforced recycled coarse aggregate concrete

To boost the application scope of coarse recycled aggregates (RA) with particle size in the range of 5–10 mm, a spray steel fiber reinforced coarse aggregate concrete (SSFRCAC) is developed, and the impact of cube compressive strength, RA replacement ratio, and steel fiber (SF) volume fraction on the durability of SSFRCAC is comprehensively examined through carbonization, sulfate attack, penetration, and freeze-thaw cycle tests. The anti-carbonation test results reveal that as the RA replacement ratio increases, the carbonation resistance of SSFRCAC decreases. The best anti-carbonation performance is achieved when the SF volume fraction is 1%. Additionally, a formula for calculating the carbonation depth is established. Based on the experimental data, the dynamic elastic modulus is recommended as the measurement standard for the freeze-thaw resistance cycle test. The sulfate resistance test results indicate that as the RA replacement ratio increases, the Sulfate Resistance coefficient also increases. SF block the thermal cracks of specimens and corrosion products as well as the formation of expansion cracks, so the corrosion resistance coefficient gradually tends to a certain stable level. According to the anti-permeability test results, the increase in the RA replacement ratio can suppress the anti-permeability performance. When the SF volume fraction is 1%, the concrete has the highest density and the best anti-permeability performance. Overall, the durability of SSFRCAC is found to be much better than that of general recycled SF Recycle aggregates concrete, which makes it more suitable for practical engineering applications.

Study on the performance of basalt fiber geopolymer concrete by freeze-thaw cycle coupled with sulfate erosion

In this research, double-blended materials such as fly ash and slag are used as binders, and basalt fibers (BF) are mixed in varying volume fractions (0.2%, 0.4%, 0.6%, 0.8%, and 1.0%) relative to the volume of concrete. Besides, sodium silicate (Na2SiO3) and sodium hydroxide (NaOH) served as activators. The study investigates the freeze-thaw resistance, microstructure, performance mechanism, and internal freeze-thaw damage distribution of basalt fiber geopolymer concrete (BFGPC) through freeze-thaw cycle tests coupled with sulfate attack, SEM, and energy dispersive spectrometer analyses. The results indicated that BFGPC possesses excellent freeze-thaw resistance, achieving a minimum frost-resisting grade of F200. Increasing the BF content significantly enhances the frost resistance of the concrete. The hydration products of BFGPC include C–(A)–S–H gel, C–S–H gel, and a minor amount of N–A–S–H gel, which contribute to its structural density and homogeneity. The high compressive strength of BFGPC (87.7 MPa) further contributes to its outstanding freeze-thaw durability.

High Temperature Performance of Rubber-Modified Asphalt Mixtures in Water-Light-Heat Coupled Environment

Asphalt pavement has been repeatedly subjected to vehicle loads during service. The probability and risk of water damage and asphalt deterioration of asphalt pavements is relatively higher in high temperature and rainy areas such as the Guangxi region of China. In this paper, the changes in rubbermodified asphalt and its mixtures under high temperature, water cycling, and ultraviolet light have been investigated. The coupled water-light-heat effects on asphalt pavements were simulated by developing a freeze-thaw cycle test protocol and a UV environment simulator. The high temperature performance of asphalt and asphalt mixtures before and after aging was compared and statistically analyzed by indoor tests of needle penetration, ductility, softening point, rutting factor and dynamic stability. Under water-light-heat coupling, rubberized asphalt showed a deeper degree of aging, accelerated conversion of asphalt to a highly elastic material, and an increased tendency to reduce flow capacity. The results showed decreasing dynamic stability of rubberized asphalt mixtures with decreasing needle penetration and ductility, increasing softening point, increasing rutting factor and decreasing phase angle. The effect of UV light on asphalt needle penetration was more significant, while the number of freeze-thaw cycles had a more pronounced effect on softening point.

Evaluation of cooling effect and road performance of warm mixed high viscosity porous asphalt mixture.

In order to study the effect of different warm mixing agents on the cooling and road performance of porous mixture bonded with High Viscosity Asphalt (HVA), the Superpave Gyratory Compactor (SGC) was proposed to conduct variable temperature compaction test on the warm mixed porous asphalt mixture. The relationship between the compaction difficulty coefficient and the temperature of the mixture was obtained by regression, and the mixing and compacting temperature and cooling effect of the warm mixed porous asphalt mixture were determined. Then, the influence of Evotherm M1 and EC120 warm mix agents on the performance of porous asphalt mixture was compared by rutting tests, beam bending tests, immersion Marshall tests, freeze-thaw splitting tests, and penetration strength tests. The results show that two types of warm mixing agents can reduce the mixing and rolling temperatures of the mixture by more than 10°C. The addition of warm mix agents will increase the high temperature stability, water stability, and shear resistance of porous asphalt mixtures. For the improvement effect of high temperature stability, EC120 warm mixing agent is greater than Evotherm M1 warm mixing agent, and for the improvement effect of water stability, Evotherm M1 warm mixing agent is greater than EC120 warm mixing agent. For shear resistance, the improvement effect of both is equivalent, with a penetration strength increase of about 3% to 4%. For low temperature performance, Evotherm M1 warm mixing agent improved the low temperature performance, while EC120 warm mixing agent showed the opposite effect.

Enhancing high-content recycled asphalt pavement regeneration: A laboratory separation and treatment approach

The escalating costs of aggregates and stringent sustainable development policies have emphasized the significance of effective high-content recycled asphalt pavement (RAP) regeneration technology. This study aims to present a novel laboratory separation and treatment approach for RAP materials, ensuring optimal performance of high-content RAP recycled asphalt mixtures. The proposed method is compared against factory-separated RAP materials in terms of agglomeration evaluation and mixture performance comparison. High- and low-temperature performance of the recycled asphalt mixture were evaluated through wheel tracking and trabecular bending tests. Furthermore, the moisture sensitivity of the recycled mixture was studied through immersion Marshall and freeze-thaw splitting tests. The uniformity and fusion between aggregates and asphalt in the recycled asphalt mixtures were meticulously analyzed using advanced techniques such as Scanning Electron Microscope and industrial Computed Tomography scans. The laboratory separation method encompasses flexible separation for 5–10 mm RAP materials and rigid separation for 10–20 mm RAP materials. Notably, the laboratory separation methods proved more effective in removing aged asphalt from the surface of 10–20 mm RAP materials compared to factory separation, thereby enhancing the adhesion between aggregates and asphalt and ensuring a more uniform recycled mixture. Although the dynamic stability of recycled asphalt mixture was reduced using laboratory separation, it still meets the requirements of relevant specifications. Moreover, the low-temperature maximum flexural tensile strain of the recycled asphalt mixture increased by 16%, with the residual stability and tensile strength ratio rising by 1.33% and 2.69%, respectively. Compared with the factory separation method, the laboratory separation method reduces the porosity percentage of the recycled asphalt mixture cross-section by 3.47%. Overall, the laboratory separation method for RAP materials provides valuable insights for enhancing the factory processing of RAP materials, contributing to the successful application of high RAP content regeneration technology in the pursuit of sustainable and cost-effective road construction practices.

Mitigation of freeze-thaw damage to open-graded friction courses in seasonal climate areas via a binary phase change system

For the road performance deterioration of the open-graded friction courses (OGFCs) due to the scenarios of rainfall, snowfall, rapid temperature change, large temperature difference, and freeze-thaw cycle in seasonal climate areas, it will be necessary to utilize new techniques for improving the temperature regulation capability and freeze-thaw damage resistance of OGFC mixtures. A combined technique of mixing simultaneously two microencapsulated phase change materials (MPCMs) with different phase change temperature ranges and proportions has a special attractiveness for asphalt pavement. Successful application of a binary phase change system concept to improving asphalt pavement temperature regulation still has many problems, such as environmental conditions, coating MPCMs with Portland cement, mixing contents and proportions of different MPCMs, and factors affecting the temperature regulation capability and improving the freeze-thaw damage resistance of OGFCs. Composite MPCMs (CMPCMs) were prepared by two MPCMs of P46 and P5 coated by cement, in which P46 and P5 use paraffin and n-tetradecane respectively as the core material and SiO2 as the shell. The heating, cooling, freeze-thaw, and uniaxial compression tests on CMPCM-OGFC specimens were performed, to evaluate the temperature regulation capability of OGFC mixtures with different contents and proportions and the dependences of compressive strength, strength loss rate, and strain of OGFC mixtures on freeze-thaw cycle. The results reveal that the OGFC mixtures with different CP46 contents have a cooling effect due to the phase change heat absorption in a higher temperature range during the rising temperature and with different CP5 contents have a warming effect due to the phase change heat release in a lower temperature range during the cooling temperature. After mixing simultaneously CP46 and CP5 in different proportions, the temperature regulation capability of mixtures with a 3% content has a great improvement due to triggering respectively two types of phase change effects in a higher temperature range for CP46 and in a lower temperature range for CP5. Adopting this binary phase change system as mixing CP46 and CP5 can reduce the rising/cooling temperature rates in the freeze-thaw process and mitigate the damage of OGFC mixtures due to the high-temperature thawing and low-temperature frost heave effects.

Testing historical recipes with organic additives to alter the water absorption of traditional lime mortar

This research aims to investigate the effect of organic additives on the properties of hydraulic lime mortars, primarily focusing on water absorption properties and freeze-thaw durability. Four organic additives are selected based on historical mortar recipes from different European sources dating back to the 17th, 18th and 19th century. These additives are linseed oil, egg white, ghee (Indian clarified butter) and oxblood. Basic hydraulic lime mortars have been gauged with the respective additives in different quantities. The analysis include open porosity, capillary water absorption, and effects of freeze-thaw tests. To gain insight on the effectiveness of the organic additives in mitigating freeze-thaw action due to less water absorption, these results are applied to assess the durability of the different mortars, which is physically tested in a freeze-thaw experiment. The use of ghee shows promising results.

Evaporation and desiccation cracking of soils: Experiment evidence and insight on the freeze-thaw cycle dependence

The cracking of clayey soils in seasonally frozen regions is affected by cyclic drying-wetting and freezing-thawing. Understanding the mechanism governing soil cracking behavior is crucial for the construction and long-term operation of infrastructures and earthworks. In this study, a series of laboratory tests were conducted on clayey soils, including freezing-thawing tests and evaporation tests. The evaporation rate and surface cracks evolution were monitored. The cracking mechanism of soils were analyzed. Results show that both the initially unsaturated and oversaturated soils exhibit an increase in evaporation rate with increasing freeze-thaw (FT) cycles in the early stage. Under the same FT and drying conditions, initially unsaturated soils show a higher evaporation rate in the early stage than oversaturated soils, followed by a lower rate after entering the residual stage. In addition, cyclic FT accelerates the propagation of the number of crack segments, surface crack ratio, and total crack length, but weakens the propagation of average crack width. Moreover, it was found that for initially unsaturated soils, desiccation-induced matrix suction plays a leading role in producing wide, rough, and curved desiccation cracking patterns. While for initially oversaturated soils, freezing-induced ice pressure/cryogenic suction dominates, resulting in short, fine, and straight frost cracking patterns.

EFFECT OF DEICING AGENTS ON THE WATER STABILITY OF ASPHALT CONCRETE UNDER FREEZE-THAW CYCLES

Asphalt concrete pavement, as the main form of high-grade roads today, occupies an important place in modern road construction due to its advantages such as low noise level, ease of repair and short construction period. This road type is widely adopted worldwide and provides a reliable foundation for road networks in cities and villages. In cold regions, snowy weather tends to cause ice on the road surface, posing a serious safety hazard for vehicle travel. The problem of road accidents in winter is relevant both for regions with extremely cold climatic conditions and for the temperate continental climate that prevails almost throughout Ukraine. To solve this problem, deicing agents are widely used to improve the safety of road travel. The application of deicing agents effectively reduces the impact of snow and ice on roads and ensures the safe passage of vehicles in adverse weather conditions. However, while deicing agents play an important role in improving traffic flow, their widespread use has also brought some problems that should not be ignored. The chemicals in deicing agents may have adverse effects on pavement materials, especially on asphalt concrete roads. For studying the effect of deicing agents on asphalt concrete, this paper presents an experimental investigation of the effect of deicing agents on the water stability of asphalt concrete under the conditions of freeze-thaw cycle test. The impact of deicing agents and freeze-thaw cycles on asphalt concrete was investigated by evaluating the variation patterns of three key parameters: stability, residual stability and air void content. The experimental results showed that the stability and residual stability of asphalt concrete showed an overall decreasing trend with the increase of the number of freeze-thaw cycles, indicating that the asphalt concrete was damaged or degraded under the conditions of freeze-thaw cycles. The higher concentration of the deicer solution corresponded to the more pronounced changes in the test parameters, indicating a significant effect of the deicer on the asphalt concrete. At the end of 27 cycles, the average loss of stability, residual stability and void ratio were 29%, 22% and 73%, respectively. This indicates that the combined effect of freeze-thaw cycles and deicing agent is more significant for air void content.

Optimised performance of ultrahigh-performance silicomanganese slag concrete by water glass immersion

Silicomanganese slag (SS) is a byproduct of the ferroalloy industry. It causes environmental pollution and consume resources. In this study, water glass immersion was used to improve the performance of SS, which was utilised in the production of ultrahigh-performance concrete (UHPC). The results show that SS treated with a 2% water glass concentration for 24 h had 16 MPa higher compressive strength for composite than pure UHPC. Additionally, the treated composite had approximately half the mass and compressive strength losses of pure UHPC after freeze–thaw testing, indicating that the treatment had a significant positive effect on the freeze–thaw resistance of ultrahigh-performance silicomanganese slag concrete (UHPSSC). Microstructural analysis also showed that water glass immersion optimised the morphology of UHPSSC, contributing to improved mechanical performance and freeze–thaw resistance of the composite.