Asphalt Pavements In Cold Regions Research Articles

Investigation of rheological properties and modification mechanism of SBS-modified asphalt with different warm mix additives

ABSTRACT The application of warm mix asphalt (WMA) technology in polymer-modified asphalt becomes increasingly widespread, but it lacks thorough investigation on the interaction mechanism between warm mix additives and polymers. Accordingly, two new warm mix additives, an organic viscosity-reducing modifier (A) and a surfactant-based modifier (C), were selected to prepare the warm mix SBS-modified asphalt. The basic properties, viscosity-temperature characteristics, ageing resistance and rheological properties of modified asphalt were tested. At last, the modification mechanism was elucidated through a series of microscopic tests. The results indicated that A could more effectively enhance the construction workability of SBS-modified asphalt, while C had little effect on its basic properties. Both new modifiers, especially A, reduced the high-temperature property of asphalt, with partial recovery after short-term ageing. The microstructure test results indicated that the two modifiers were physically modified with SBS-modified asphalt. Both additives improved the dispersion uniformity of SBS particles in asphalt, and the microscopic morphology parameters obtained from quantitative analysis reflect the macroscopic properties of asphalt. Moreover, the light components and rubber powder of A improved the flexibility of asphalt, and C enhanced its low-temperature performance, which demonstrated that these two modifiers were more suitable for asphalt pavements in cold regions.

Study on the design and laboratory investigation of permeable semi-rigid base material with large air voids

PurposeTo explore the economical and reasonable semi-rigid permeable base layer ratio, solve the problems caused by rainwater washing over the pavement base layer on the slope, improve its drainage function, improve the water stability and service life of the roadbed pavement and promote the application of semi-rigid permeable base layer materials in the construction of asphalt pavement in cold regions.Design/methodology/approachIn this study, three semi-rigid base course materials were designed, the mechanical strength and drainage properties were tested and the effect and correlation of air voids on their performance indexes were analyzed.FindingsIt was found that increasing the cement content increased the strength but reduced the air voids and water permeability coefficient. The permeability performance of the sandless material was superior to the dense; the performance of the two sandless materials was basically the same when the cement content was 7%. Overall, the skeleton void (sand-containing) type gradation between the sandless and dense types is more suitable as permeable semi-rigid base material; its gradation is relatively continuous, with cement content? 4.5%, strength? 1.5 MPa, water permeability coefficient? 0.8 cm/s and voids of 18–20%.Originality/valueThe study of permeable semi-rigid base material with large air voids could help to solve the problems of water damage and freeze-thaw damage of the base layer of asphalt pavements in cold regions and ensure the comfort and durability of asphalt pavements while having good economic and social benefits.

Exploring the short-term water damage characteristics of asphalt mixtures: The combined effect of salt erosion and dynamic water scouring

In icy or snowy conditions, improper application and uneven dispersion of deicing salts on roadways can lead to saltwater accumulation, subsequently causing roadway scouring when vehicles transit. This study aims to assess the combined influence of salt erosion and dynamic water scouring on short-term water damage of asphalt mixtures. A custom-designed dynamic water scouring simulation apparatus is used, employing three diverse deicing salt solutions as agents for dynamic water scouring. Numerous iterations of dynamic water scouring tests are conducted on two types of graded asphalt mixtures. Post-scouring, alterations in air void content and water stability are evaluated through void content tests, Marshall water immersion tests, and freeze-thaw splitting tests. Additionally, the GM (1,N) damage prediction model from gray theory is applied for data modeling and prediction. The results reveal a significant impact of the combined effects of salt erosion and dynamic water scouring on the short-term performance of asphalt mixtures. In the early phase, dynamic water scouring primarily influences the asphalt composite, augmenting micro-cracks and causing aggregate disintegration. The intermediate phase sees the disintegration of the asphalt membrane by deicing salts, disrupting adhesion between asphalt and aggregate, and progressively leading to the emergence of new micro-cracks. During later stages, dynamic water scouring continues to deteriorate the asphalt composite, building on the erosion instigated by deicing salts, resulting in the expansion of newly formed micro-cracks and further aggregate disintegration. Among the three deicing salts, CH4N2O exhibits the most pronounced impact on short-term water damage, followed by NaCl, while CH2CH3OH has the least effect. Increasing the fine aggregate proportion in the asphalt mixture enhances water damage resistance. The GM (1,N) damage prediction model effectively anticipates air void content and water stability of asphalt mixtures. The research outcomes offer theoretical and technical support for understanding the durability and service lifespan of asphalt pavements in cold regions.

Road use and electrothermal performance of graphene-conductive asphalt-recycled pervious concrete under severe cold environment

Conductive-asphalt-recycled pervious concrete alleviates the urban “heat island effect” and “rain island effect” to realize the resourceful and efficient use of waste concrete and also reduces the probability of urban snow and ice disasters to ensure the safety of winter operation of asphalt pavements in cold areas. This study presents a theoretical and technical basis for ensuring the winter operational safety of asphalt pavements in cold regions. First, we compound graphene and carbon fiber as conductive phase materials and prepare graphene-conductive asphalt-recycled permeable concrete using recycled coarse aggregates with straight top and bottom holes. Then, we analyzed the electrical conductivity, road performance, and electrothermal performance of the specimens prepared using different recycled coarse aggregate substitution rates under different snowfall levels to determine their snow melting efficiency and verify their application in cold regions. The results indicate that the quality of the recycled aggregates is high, the optimal conductive filler ratio is 0.3% polyacrylonitrile-based carbon fiber and 1.5% graphene by mass of asphalt, and the resistivity of the specimens is only 3.2 Ω·m. Moreover, the conductivity and road performance of the graphene-conductive asphalt-recycled concrete decreases with an increase in the replacement rate of the recycled coarse aggregate, and the artificially prefabricated upper and lower through holes affect the conductivity of the specimens to a certain extent. Further, the graphene-conductive asphalt-recycled pervious concrete shows excellent snow melting potential, and as the required snow melting thickness and snow melting time increase, the effect of pervious asphalt slabs for snow melting efficiency becomes more significant. Moreover, when the replacement rate of the recycled concrete aggregate is within the range of 0–50%, it can be completed in 2–3 h under different snowfall levels of snow melting requirements.

Damage Characteristics of Asphalt Stabilized Macadam Under Freeze-thaw Action

In order to study the freeze-thaw resistance of asphalt stabilized macadam asphalt pavement in cold regions, the asphalt stabilized macadam specimens were subjected to freeze-thaw cycles at different times. Based on CT non-destructive testing and digital image processing technology, the change laws of porosity, void number and void equivalent diameter of asphalt stabilized macadam specimens were studied, so as to analyze the freeze-thaw damage characteristics of asphalt stabilized macadam from the micro level, The effect of adding 2% SBS modifier on the freeze-thaw resistance of asphalt stabilized macadam was studied. The results show that with the increase of freeze-thaw times, the porosity and the number of voids of asphalt stabilized macadam increases gradually, while the equivalent diameter of voids decrease first and then increase; The addition of 2% SBS can hinder the development of void connectivity and the generation of new voids, and improve the water damage resistance of asphalt stabilized macadam.

Performance zoning method of asphalt pavement in cold regions based on climate Indexes: A case study of Inner Mongolia, China

Asphalt pavements are environmentally sensitive, and their service performance is affected by the local climate. This study aims to classify asphalt pavements into specific regional zones based on their performance in the adverse environments of Inner Mongolia, which is located in Northeast China. Firstly, in view of the environmental exposure effects of premature failure of asphalt pavements in Inner Mongolia, such as temperature, precipitation, frozen soil and freeze–thaw, different performance zoning indexes of asphalt pavement layers and subgrade were proposed. Secondly, the proposed indexes were calculated based on the climate data of 36 meteorological stations in the past ten years, and spatially interpolated using the kriging interpolation method. The spatial distribution map of the zoning indexes was drawn based on the ArcGIS platform. Thirdly, the service performance of the asphalt pavement was calculated based on the performance prediction equations. The rationality of the proposed zoning indexes was verified by comparing the similarity of spatial distribution characteristics between the zoning indexes and pavement service performance. Finally, pavement performance zoning was studied using cluster analysis and layer overlay methods, and the established performance zoning was verified using historical pavement field performance detection data to better represent the performance distribution characteristics of asphalt pavements in Inner Mongolia. Consequently, different primary and secondary performance zones for asphalt pavement layers and subgrade were developed in Inner Mongolia. It was observed that different environmental factors have adverse effects on asphalt pavement layers and subgrade in different zones, and an appropriate pavement design scheme needs to be selected to adapt to the local environment of Inner Mongolia. The adverse effects on asphalt pavement layers and subgrade were observed as low-temperature frost heave, high-temperature permanent deformation, potholes formed by the combined action of high temperature and precipitation, and frost boiling caused by the combined action of temperature and precipitation. In summary, the zoning method proposed in this study can provide guidance for asphalt pavement design under the local climatic conditions of Inner Mongolia, and for the performance zoning of other regions with different climatic environments.

Evaluation of climate effect on resilient modulus of granular subgrade material

This study examines the effects of freeze-thaw actions and the concurrent seasonal fluctuations in water content, named as climate effect in this study, on the resilient modulus of subgrade materials to evaluate their mechanical behavior in cold regions. A series of suction-controlled resilient modulus tests on subgrade materials with variant freeze-thaw, wheel loads, and water contents conditions were conducted using a newly developed test apparatus. Test results were used to construct a simple model to estimate the climate effect on the resilient modulus by considering the synergistic effects between water content and freeze-thaw. Besides, this study calculated the fatigue life of eight local flexible pavement projects with variant subgrade layer moduli considering climate effect by combining the newly proposed model and long-term in-situ measured data. Results proved that climate-related degradation of the subgrade materials decreases the fatigue life of asphalt pavements in cold regions.

Effects of different colorants on service performance for colored asphalt pavement in cold regions

PurposeThe service performance for colored asphalt pavement is inevitably affected by the addition of different colorants, especially the challenge of low temperature environment in cold regions. Therefore, the purpose of study is to explore the effects of different colorants on the service performance for colored asphalt pavement and to provide a foundation for improving the applicability of colored asphalt pavement in cold regions.Design/methodology/approachIn the study, three kinds of colorants (iron oxide red, iron oxide yellow, iron oxide green) were used to compare the influence of different colorants amounts and different colorants kinds on the service performance for colored asphalt pavement in cold regions. According to the characteristics of low temperature in cold regions, the effects of different colorants on the low temperature performance for colored asphalt pavement were studied.FindingsThe study shows that different colorants have different effects on the service performance of colored asphalt pavement. The high temperature performance increases with the increase of the colorants amount, but the low temperature performance is opposite. Additionally, the yellow colored asphalt pavement has more advantages of low temperature adaptation than the red and green colored asphalt pavement.Originality/valueThe study results provide a certain theoretical foundation for the application of colored asphalt pavement in cold regions and have certain value and significance for the further development of colored asphalt pavement.

Parameter Optimization of Graded Macadam Transitional Layer for Inverted Asphalt Pavement Based on the Mechanical Response and Strength Standard

To improve the durability of asphalt pavement with heavy traffic conditions in cold regions, the parameter optimization of graded macadam transitional layer (GMTL) for the inverted asphalt pavement based on the mechanical response and the strength standard was studied. The stress distribution laws of GMTL were studied with different loads by means of BISAR3.0. The influences of the thickness and the modulus of GMTL on the pavement stress were analyzed. The optimal thickness and the modulus range of the GMTL were determined. Combined with a self-developing real-time data acquisition and a processing system for aggregate attitude (RDAPS), the strength control standard of the GMTL was established. Finally, the performance of the optimized inverted asphalt pavement structure was verified through the MEPDG design method. The results show that the tensile stress at the bottom of the surface layer reduced by about 58%, and the shear stress in GMTL increased by about 17% when the modulus of GMTL increases from 300 MPa to 800 MPa. However, the change in modulus has no significant influence on the maximum shear stress in the asphalt surface layer and the tensile stress in the base layer bottom. When the thickness of GMTL increases from 12 cm to 20 cm, the tensile stress in the bottom of the base layer reduced by about 31%. Based on the mechanical results from simulation calculation and the technical indicator required in the field, the recommended optimal parameters of GMTL are the modulus of 700 MPa and the thickness of 18 cm. In addition, the spatial attitude angle ΦN of wireless intelligent attitude aggregate (WIAA), the compressive strength Rc standard, and the California Bearing Ratio (CBR) standard were analyzed, and the strength control standard of inverted asphalt pavement with GMTL was proposed, namely, CBR ≥ 354%, Rc ≥ 1.06 MPa, and ΦN ≤ 3°. A significant improvement in the resistance to crack can be seen in the inverted asphalt pavement when the optimized structure was applied. Taking the 20-year service life as an example, the top-down cracks reduced by 29.3% and the bottom-up cracks reduced by 32.6% in comparison to the original structure. The recommended structural parameters of GMTL could be used to guide the construction and design of inverted asphalt pavement in cold regions.

Analysis methodology and assessment indices of vulnerability for asphalt pavement in cold regions

Asphalt pavement structures in cold regions, which suffer from complicated environmental and geological conditions, such as large temperature difference and frozen soil, are prone to cracking, rutting, and moisture damage. However, most of the existing assessment methodologies focus on the vulnerability of the overall road traffic network, ignoring the impact of regional differences and pavements’ structural performance. To establish a highly targeted vulnerability analysis methodology for cold regional asphalt pavements, the concept of highway vulnerability and the assessment model composed of exposure, fragility, and resilience were proposed in this paper firstly. Meanwhile, the assessment indices and standards for exposure, fragility, and resilience were respectively discussed. Then, the calculation process for each index weight and vulnerability index was proposed based on AHP-fuzzy comprehensive assessment methodology. Consequently, the vulnerability grade of asphalt pavements in cold regions could be determined. Finally, the vulnerability assessment indices and methodology for cold regional asphalt pavements were illustrated and presented, providing a theoretical basis for asphalt pavement performance evaluation and vulnerability assessment serviced under cold regional climate.

Study on dynamic modulus of asphalt mixture in cold regionunder rotary accelerated loading

In order to study the evolution law of mechanical properties of asphalt pavement mixture in cold regions under long-term load, the rotary accelerated loading equipment was used to carry out a total of 500,000 accelerated loading tests on the full-scale pavement, and the dynamic modulus test of the mixture before and after wheel load was carried out respectively. The master curve of dynamic modulus and dynamic modulus ratio (dynamic modulus value after wheel load / dynamic modulus value before wheel load) of the mixture at -20ºC were established to predict the long-term mechanical response of the mixture at low temperature. The results show that: low-frequency (or high temperature) has a more significant effect on the viscoelastic properties of the asphalt mixture. In the conversion frequency range of 1.6×10–3~1.6×102 Hz, the dynamic modulus ratio decreases with the increase of frequency, and the maximum ratio is 0.62 when the frequency is 1.6×10–3 Hz, which indicates that the high frequency (low temperature) has little effect on the performance of asphalt mixture. This study can be used as a theoretical reference for the structural design and performance optimization of asphalt pavement in cold regions.

Obtaining asphalt binder rheological properties from BBR strength test—the effect of loading rate

Selecting asphalt binders that have good cracking resistance at low temperatures is the first step in designing asphalt mixtures for durable asphalt pavements in cold regions. To evaluate low-temperature cracking resistance of binders, rheological properties (creep stiffness and m-value), and fracture properties (failure stress and strain) are required. Recently, a new strength test was developed to measure the fracture properties of binders using a modified BBR (Bending Beam Rheometer), called BBR-Pro. In this paper, we investigate the idea of using the BBR strength test to also obtain rheological properties. We performed strength tests at different loading rates and verified the assumption of linear viscoelasticity (LVE) condition of binders at these loading rates. We used analytical and numerical methods to obtain creep compliance from strength test experimental data and compared the results to experimental creep compliance data. We have found that both methods predict creep compliance and creep stiffness values similar to the experimental results, whereas the numerical method is more accurate than the analytical method for obtaining the $m$ -value. We also found that the BBR strength test performed using the original loading rate is too short to accurately predict rheological properties for 240 s. We show that by reducing the loading rate we achieve good estimation of creep compliance.

Impact of Additives on Low-Temperature Cracking Properties of Soft Binders Used in Cold Regions

AbstractLow-temperature cracking is the main distress in asphalt pavement in cold regions (such as the arctic and subarctic regions) as the climate in these areas is severe in winter. While soft as...

Temporal-spatial evolution characteristics of acoustic emission in asphalt concrete cracking process under low temperature

In this study, the acoustic emission test has been performed on a three-point bending beam so as to simulate the initiation, propagation and penetration process of tensile cracks on an asphalt pavement under −10 °C. The characteristic parameters, such as the acoustic emission ringing count, signal energy, amplitude, average frequency under continuous load, have been obtained. In addition, the spatial evolution process of the internal micro-cracks have been tracked with the acoustic emission location. The results of the test show that the acoustic emission signal originates from the damage deformation in the area where the asphalt concrete specimen is weak. Its activity reflects the development level of the micro-cracks. The change curve of the acoustic emission (AE) parameters with the change in loading can be divided into three stages: calm period, slow-rapid growth period and step growth period. In the signal stepped growth period, the macro-crack “cracking point” of the specimen occurred. During this period, the sound emission ringing count and energy increased suddenly before falling back, and the signal amplitude and the dominant frequency range increased. These changes can be regarded as the forewarning generated by the acoustic emission before the occurrence of the macroscopic fracture damage of the specimen, and have certain predictability of the appearance of macro-cracks. The three-dimensional positioning of the acoustic emission technique can be utilized effectively to track the position of the main crack surface of the specimen, and reflect the dynamic evolution process of low temperature cracking of asphalt concrete. The acoustic emission has the potential for the detection of cracks in asphalt pavement in cold regions.

Effect of Freeze-Thaw Cycles on the Properties of Asphalt Pavements in Cold Regions: A Review

Asphalt pavements weaken over time due to the effect of environment and heavy traffic loading on paving constituents. Rutting, fatigue cracking and low temperature cracking are the major distresses responsible for degradation of the pavement and consequently leads to the failure of flexible pavement. Asphalt pavement is directly exposed to atmosphere and hence, suffers the effects of weather, environment and automobiles. Apparently, for a new asphalt pavement, even though there is no vehicle loading or other artificial activities, deterioration can also appear under climate and environment effects. In recent years, thermal cracks and low temperature distresses have become key concern for asphalt pavements in cold regions. In case of rutting of asphalt mixtures, aggregate characteristics play an important role, whereas, the properties of binder are more related to fatigue. Although the properties of asphalt binder can have a great influence on the performance of pavement, the role of aggregate gradation cannot be ignored in providing resistance to rutting and reducing permanent deformation. Gradation has significant effects on asphalt mixture’s Freeze-Thaw (F-T) durability. This paper reviews research conducted on the various properties viz., fatigue, rutting, air voids, compressive strength, etc. of bituminous mixes which are under the influence of F-T cycles. This paper also discusses the effect of F-T cycles on stability of bituminous mixes.

Cover Image

The cover image is based on the Review Article Hydrothermal accumulation under asphalt pavement in cold regions by Zhongqiong Zhang et al., https://doi.org/10.1002/ese3.401.

Hydrothermal accumulation under asphalt pavement in cold regions

AbstractWater and heat changes are the main problems that plague the stability and service performance of roadbeds in cold regions. Though hydrothermal transfer and accumulation directly affect roadbed properties, these processes remain poorly understood as monitoring data are often collected over short time periods and large spacing in depth. This research compares water and temperature data collected from 2012 to 2015 to elucidate the physical mechanisms of hydrothermal accumulation under both asphalt pavement and original pavement. These thermal and physical mechanisms include differences in the freezing process (FP) and the thawing process (TP), water transport, condensation, and hydrothermal accumulation. For instance, when compared to the underlying layer, the thawing of the surface layer of asphalt pavement was delayed by 35 days because of differences in hydrothermal properties. During TP, liquid water content changes from 3.31%‐13.2% to 15%‐37.67%, and the unfrozen water content of the soil layers under the asphalt pavement was approximately 6.85%‐12.34% higher than that of the soil layers under the original pavement. A layer with high water content and heat formed under the surface layer of asphalt pavement and provided the appropriate conditions for vapor transport and condensation. Soil layers thawed early in the preceding year, and this hydrothermal accumulation occurred on an annual basis. The annual minimum monthly average temperature was thus found to be increasing at the rate of 0.34°C/y. As water content also accounts for heat accumulation and was found to be more sensitive to change than temperature, the results of this study can provide theoretical and technical data useful for highway construction and design in permafrost regions.

An equivalence between methods of aging for determining the low-temperature performance of hot-mix asphalt concrete mixtures containing reclaimed asphalt pavement

Asphalt pavements in cold regions are susceptible to thermal cracking. Current construction practice of adding reclaimed asphalt pavement to virgin materials further deteriorates the low-temperature performance of asphalt concrete. This study concentrates on finding equivalence between short-term aging of loose asphalt mixtures and long-term aging of compacted mixtures by following the AASHTO TP125-16. Asphalt mixtures made from two Superpave® mix designs, four different Reclaimed Asphalt Pavement (RAP) contents and six different aging periods at two different temperatures were analyzed in this study. RAP and Aging Indices were proposed to demonstrate the combined change in the performance of asphalt mixtures due to the addition of RAP and aging. It was found that four hours of additional loose-mixture-aging at 135 °C yields low-temperature performances similar to five days of compact-mixture-aging at 80 °C. Results found from this study contribute to the benefits of Bending Beam Rheometer as a potential quality control tool for low-temperature performance during construction.

Mechanical and compaction properties of graphite nanoplatelet-modified asphalt binders and mixtures

This paper presents an experimental investigation of the properties of asphalt binders and mixtures modified with graphite nanoplatelets (GNPs). The focus is on studying the effects of GNP addition on low-temperature rheological and fracture properties of asphalt binders and mixtures and on compaction effort of asphalt mixtures. This is the first time that these effects are investigated and significant findings are reported. The study considers three types of GNP materials, including graphite nanoplatelets and sub-microscale graphite flakes. The cost of these materials is reasonably low, which makes them suitable for large-scale applications, unlike other types of graphite and graphene materials. The experimental results indicate that the addition of GNPs leads to considerable improvements of low-temperature strength and fracture properties of asphalt binders and mixtures. While the properties of asphalt binders at intermediate temperatures are minimally affected, for some combinations of binders and GNPs the increase in low-temperature strength is over 100%. A similar effect is observed for some of the asphalt mixtures investigated, in which the low-temperature fracture energy almost doubles. The laboratory compaction experiments show that the number of gyrations required for achieving a target density can be reduced by as much as 20–40% by adding a small percentage of GNPs into asphalt binders. The results of this experimental study indicate that GNP-modified asphalt binders and mixtures have significant potential for increasing the durability of asphalt pavements in cold regions, by reducing the compaction effort and improving the low-temperature strength and fracture properties of asphalt materials.

The impacts of type and proportion of five different asphalt modifiers on the low temperature fracture toughness and fracture energy of modified HMA

Low temperature fracture toughness and fracture energy are two important measures that could be used to investigate the impacts of using asphalt modifiers on the performance of asphalt pavements in cold regions. The aim of this research was to identify the impacts of using various proportions of five different asphalt modifiers on the fracture toughness and the fracture energy of Hot Mix Asphalts (HMA) under mode I loading and at low environmental temperatures. The asphalt modifiers used for this purpose were: Elastoplastomer Polymer Strings (EPS), Parafiber, Sulfur Polymer, Polyolefin-Aramid Compound Structural Fibers (PACSF) and Sasobit. These modifiers were individually used at three different proportions to produce Semi-circular Bend Specimens containing vertical edge crack. Each specimen was then tested under symmetric monotonic three-point bend loading at -15°C. The results indicated that, except for the EPS, both measures were increased with an increase in the modifier proportion. The most increase in the both measures was observed in the specimens modified with the PACSF, closely followed by specimens modified with the Parafibers. The least increase in these two measures were observed in the specimens modified with the Sulfur Polymer. The results indicated the applicability of examined modifiers to improve the resistance of HMA to crack initiation and crack growth at low temperatures.