Fatigue Life Of Pavement Research Articles

Study on self-healing performance of microcracks in SBS/waste rubber powder composite-modified asphalt based on molecular dynamics simulation

The internal microcracks in asphalt materials can heal spontaneously under suitable conditions, and understanding the characteristics of the self-healing behavior of asphalt materials is crucial for evaluating the fatigue life of asphalt pavements. In this paper, a molecular model of modified asphalt microcracks was created by introducing modifier molecules into the virgin asphalt model, and the self-healing process of the asphalt microcrack model under different healing conditions was investigated, which revealed the effects of modifier materials and healing temperatures on the healing performance of asphalt. The results show that the effect of healing temperature on asphalt healing performance is more significant than the modifier material, the relative concentration of molecules at the microcrack healing and the healing temperature is positively correlated; asphalt material healing free volume fraction with the increase in healing temperature gradually increases, the incorporation of modifiers can reduce the free volume fraction growth caused by high-temperature healing, improve the healing stability of modified asphalt. The asphalt ductility specimen crack healing test shows that when the healing temperature exceeds 45 ℃, there is a decreased increase in self-healing rate; taking into account the high-temperature healing is easy to make the asphalt material produce permanent deformation, this paper determines the optimal healing temperature in the vicinity of 48 ℃. The research results have certain reference and application values for asphalt pavement damage repair.

EXPERIMENTAL STUDY OF EFFICIENCY APPLICATION OF REINFORCING SYNTHETIC MATERIALS ADFORS GLASGRID FOR INCREASE RUTTING RESISTANCE AND CRACK RESISTANCE OF ASPHALT CONCRETE PAVEMENTS OF HIGHWAYS

The effectiveness of using Adfors GlasGrid® reinforcing synthetic materials to increase the rutting resistance and crack resistance of asphalt concrete pavements of highways was experimentally studied. It has been experimentally confirmed that reinforcing the top layer of an asphalt concrete pavement with Adfors GlasGrid® reinforcing synthetic materials ensures reliable adhesion of asphalt concrete layers and can significantly increase the rutting resistance, fatigue life of the asphalt concrete pavement and its tensile strength in bending. Reinforcement of asphalt concrete pavement with Adfors GlasGrid® reinforcing synthetic materials allows increasing rutting resistance, that is, reducing the rut depth and total rutting area by 19–35%. At the same time, studies have shown that Adfors GlasGrid® reinforcing synthetic materials have confirmed their effectiveness when used under the top layer of cover. A study of the effect of reinforcement of asphalt concrete pavement on the adhesion of the upper and lower layers of asphalt concrete showed that all studied synthetic reinforcing materials Adfors GlasGrid® meet European requirements for the adhesion of reinforced asphalt concrete layers. A study of the influence of reinforcement of an asphalt concrete pavement on its fatigue resistance showed that the reinforcement of an asphalt concrete pavement with Adfors GlasGrid® reinforcing synthetic materials makes it possible to increase the number of load cycles up to a loss of fifty percent of the complex deformation modulus by 2.6 – 5.9 times compared to a non-reinforced pavement. Experiments have confirmed that reinforcing an asphalt concrete pavement with Adfors GlasGrid® reinforcing synthetic materials increases its tensile strength in bending. This confirms the possibility and feasibility of using Adfors GlasGrid® reinforcing synthetic materials under the top layer of asphalt concrete pavement, including on bridges and overpasses, to increase the crack resistance, rutting resistance and durability of asphalt concrete pavements. Keywords: rutting resistance, crack resistance of asphalt concrete pavements, asphalt concrete pavements of highways, durability, reinforcing synthetic materials, reinforced asphalt concrete layers.

Integrated design optimization method for pavement structure and materials based on further development of finite element and particle swarm optimization algorithm

The maintenance design for existing asphalt pavements, characterized by their typical structure and material composition, falls short of meeting the diverse requirements of pavements. There is an urgent need for a more rational design approach that can achieve accurate pavement design while also reducing construction costs. This paper focuses on selected conventional road surface structures and conducts an analysis of how pavement structure and materials impact fatigue life and construction expenses. It employs Python to perform three-dimensional finite element road modeling, analysis, and data extraction at specific locations, using normalized fatigue equation to calculate pavement fatigue life. The optimization variables selected are the modulus E and thickness h, with pavement maintenance cost serving as the optimization target function. The particle swarm optimization algorithm is employed for optimizing these variables. A comparative analysis is carried out for five improved optimization algorithms, optimizing combinations of inertia weight, learning factors, particle speed, number of particles, and iteration times. The results reveal that the enhanced optimization algorithms significantly improve iteration trends, featuring velocity limitations and natural selection mechanisms. Between 0 and 20 iterations, all algorithms search for the optimal solution over a wider interval with greater fluctuations. Between 20 and 30 iterations, each algorithm gradually converges towards its solution, stabilizing in the later stages. Based on optimization speed and actual engineering cost benchmarks, the NDPSO algorithm is selected, resulting in a 52.8% reduction in actual engineering costs. Adjustments to the particle count and iteration number of the NDPSO algorithm are made based on computational cost and optimization accuracy, thus choosing 20 particles and 50 iterations as the recommended parameter combination. By combining automated finite element modeling, analysis, and particle swarm optimization, this paper offers a novel and effective automated design reference for extending the lifespan of asphalt pavement structures.

Behaviours of geogrid-reinforced asphalt pavement over a localized void under cyclic loading

A set of large-scale physical model tests were performed to investigate the performance of unreinforced and glass fibre geogrid-reinforced asphalt pavement under the development of a void in the subgrade. Traffic loadings were simulated with repeated sinusoidal loadings of different amplitudes. The formation of the void was simulated using a novel displacement control device between loading cycles. The accumulative permanent deformation of the asphalt pavement, the composite resilient modulus and dissipated energy were presented and analysed. It was found that the inclusion of geogrid greatly improved the fatigue life of asphalt pavement, and the stronger the geogrid, the greater the improvement if a void was formed below the asphalt layer. After forming the void, the composite moduli of the pavements increased compared with that during the first cyclic loading stage (without the void) and seemed to be not much affected by the geogrid type. The effect of cyclic loading level on the composite modulus was not significant. The inclusion of geogrid in asphalt had a limited effect on the dissipated energy in the pavements with and without voids. The dissipated energy increased with the cyclic loading amplitude.

Influence of Deck Butt Weld Seams on Fatigue Life of Steel Bridge Decks Pavement: Parameter Optimization

Abstract The butt weld at the connection between orthotropic steel bridge decks (OSBDs) can potentially pose a hazard to the fatigue endurance of the steel bridge deck pavement. This study aims to optimize the parameters of the butt weld seam using finite element (FE) analysis. The optimized parameters will provide valuable guidance for the design of pavements with a focus on antifatigue properties. Initially, the dynamic modulus of the epoxy asphalt mixture (EAM) was determined through laboratory experimentation at various frequencies and temperatures. These material parameters were then used to compute the pavement’s fatigue life. Additionally, a well-established FE model was employed to analyze the deformation and fatigue life of the pavement structure. The validity of the model was verified by the theoretical calculation results. Various factors were considered, including vehicle velocities, pavement temperatures, and weld seam misalignments as well as weld seam dimensions such as height and width. The analysis was conducted using a three-dimensional steel bridge model. The results showed that decreasing pavement temperature, weld seam height, and misalignment led to an increase in pavement fatigue life. Conversely, reducing the weld seam width resulted in a decrease in fatigue life. Furthermore, the study investigated the coupling effect of different weld seam heights and widths on the fatigue life of the pavement. Contour figures were used to establish the parameter relationship formula for weld seam height and width. These findings are significant for pavement and deck designers because they enhance the understanding of the sensitivity of weld seams as design variables affecting the fatigue characteristics of pavement structures. Moreover, special attention should be given to the impact of welding parameters on the fatigue design of steel bridge deck pavement under high-temperature conditions of pavement structures.

Evaluation of drastic temperature change on temperature stress of asphalt mixture during microwave deicing

Microwave deicing is an efficient and environment-friendly technology for asphalt pavement. Previous studies have shown that silicon carbide can improve the deicing efficiency of pavement, but the influence of drastic temperature change during microwave deicing on the temperature stress and temperature fatigue life is undefined. In this study, the temperature stress during heating and cooling were analysed by numerical simulation, and the mechanism of stress change was discussed. Finally, the temperature fatigue performance of pavement was evaluated. The simulation results showed that an increase in the temperature rising rate did not necessarily increase the temperature stress, and there was no stress accumulation after microwave deicing. The temperature stress was affected by both the temperature change rate and the heat transfer performance, and good heat transfer performance of asphalt mixture could reduce the temperature stress. Besides, the drastic temperature change did not necessarily reduce the temperature fatigue life of pavement.

Effect of spatial variability in asphalt layer on critical pavement strains

This study aims to assess the impact of spatial variability in the asphalt layer on the critical pavement responses using random field finite difference analysis. A parametric study was conducted to investigate the influence of key factors such as the coefficient of variation (COVE) and scale of fluctuation (SOF) of the asphalt modulus. Further analysis was conducted to explore the statistical and mechanical mechanisms behind the impacts of spatial variability by studying the overall modulus and local variability within the key influence zone. In addition, the combined effects of asphalt spatial variability and weak subgrade on the pavement performance were examined. Finally, a case study was conducted to explore the effect of long-term pavement degradation and the subsequent escalating asphalt spatial variability on critical pavement responses and fatigue life prediction. It is observed that (a) spatial variability in the asphalt layer have adverse effects on critical pavement response, (b) small values of SOF are found to be unfavourable to critical asphalt strain, (c) the effects of asphalt spatial variability on critical asphalt strain are more pronounced than that on critical subgrade strain (d) weaker subgrade can exacerbate the adverse effects of asphalt spatial variability, and (e) to evaluate the asphalt fatigue life of in-service pavements, engineers and practitioners should consider additional uncertainties associated with pavement degradation and the consequent escalating asphalt spatial variability.

Engineered cementitious composites design framework for pavement applications

Engineered cementitious composites (ECCs) have gained attention as a potential material alternative for extending the lifespan of pavements and overlays due to their exceptional mechanical strength and ductility. This study presents a novel thickness design framework that incorporates the elastic and plastic regimes of ECCs, along with a wide range of mechanical properties, to develop general thickness design equations for the fatigue failure mode of ECC pavements. The pavement thickness design framework proposed in this study integrates three components: (1) experimental models characterizing the beam flexural fatigue performance of ECC materials; (2) Finite Element (FE) analysis to quantify the stress response of ECC pavements under vehicular loading; and (3) empirical stress equivalency functions to combine the FE analysis results with the beam flexural fatigue models and predict the fatigue life of ECC pavements during the plastic regime. Using the proposed framework, two general thickness design equations predicting the service life of ECC pavements were developed, one for the elastic regime and one for the plastic regime of ECCs. The thickness design equations developed are in terms of ECC material properties and empirical coefficients, which can be determined through experimentation and modeling. The analysis of the results indicates that the proposed framework provides a more accurate representation of the service life of ECC pavements, particularly during the plastic deformation regime, compared to previous design frameworks discussed in the literature.

Response Prediction of Asphalt Pavement in Cold Region with Thermo-Hydro-Mechanical Coupling Simulation

Although the theoretical pavement structure design method (TPSDM) is widely used for designing asphalt pavements in Japan, it still exhibits certain limitations, such as not considering the variation in moduli of the base and subgrade layers due to water contents, freeze–thaw action, and stress states. This study aims to enhance Japanese TPSDM’s accuracy by considering variations in the resilient modulus of environmental impacts, pavement materials, pavement structure, and traffic load actions to accurately calculate the mechanical responses and predict pavement fatigue life. Firstly, the study develops a 3D Thermo-Hydro-Mechanical (THM) model using the finite element method (FEM) to investigate temperature and moisture distributions of the pavement with time. Then, based on the numerical results of the moisture, temperature, and stress state obtained from the THM analysis, the constant resilient modulus of the base and subgrade layers in the Japanese TPSDM is replaced with a resilient modulus that considers the stress state and the combined effects of water content fluctuations and freeze–thaw action. Finally, the fatigue life of the pavement is calculated based on the obtained mechanical response in THM analysis. The reliability and validity of the proposed fatigue life prediction method are well verified by comparing the calculated with the actual pavement fatigue life. Results indicate that the modifications improve the Japanese TPSDM by considering the environmental impacts, traffic load actions, pavement materials, and pavement structure, thereby improving the accuracy of predicting the fatigue life of asphalt pavements, particularly in cold regions.

Critical fatigue strain calculations of flexible pavements in the mechanistic-empirical pavement design method, shortcomings, and improved methodologies

Fatigue Performance is considered one of the most effective measures for designing and maintaining flexible pavements. AASHTO proposed a Pavement Mechanistic-Empirical (PME) design framework in which the fatigue strains are calculated by the mechanistic part and then turned to fatigue cracking by the empirical part. However, it fails to compute actual fatigue strains since it utilizes multilayered linear elastic analysis and predefined calculation points. This paper aims to discuss the PME approach's deficiency in calculating fatigue strains and to develop simplified methodologies for addressing this issue. This study presents three solutions by comparing the fatigue life estimated from the multilayered linear elastic and viscoelastic analysis. The first solution modifies Asphalt Institute's model by suggesting adjusting factors for each axle load configuration. The second one proposes new response locations instead of predefined ones. The last solution involves developing an Artificial Neural Network (ANN) model to predict pavement fatigue life more accurately.

Study on anti-crack effect of semi-rigid base pavement with stress absorbing layer

For the characteristics of semi-rigid base asphalt pavement prone to cracking, various stress-absorption layers are applied widely by decreasing stress concentration, improving interlayer bonding and waterproofing. Existing studies on the anti-cracking effect of stress absorbing layers rarely consider top-down fatigue cracking on the outside of the boundary of the vehicle loading zone. Firstly, this paper proposes a finite element model setting a downward expansion of fatigue crack in pavement based on fracture mechanics. The influence law of modulus and thickness of stress absorbing layer on stress intensity factor of crack tip and the fatigue life of the pavement is analyzed furthermore. Numerical calculation results demonstrate that shearing stress intensity factor increases with stress absorbing layer thickness and decreases with stress absorbing layer modulus, while fatigue life of pavement grows with the modulus of the stress absorbing layer and decreases with its thickness. Sensitivity analysis indicates that the modulus of the stress absorbing layer has a greater effect on the fatigue life of the pavement relative to thickness, which offers reference for further promotion and application of stress absorbing layer.

Fatigue of Cold Recycled Cement-Treated Pavement Layers: Experimental and Modeling Study

Fatigue is the main design criterion for cold recycled cement-treated mixtures (CRCTMs). However, the literature shows that the fatigue behavior of such mixtures is still not well known. For example, the effect of increasing reclaimed asphalt pavement (RAP) contents is yet a topic of discussion. This experimental and modeling study helps fill knowledge gaps on CRCTM fatigue behavior using long-term curing fatigue tests and three design methods currently being used in different countries. The objectives of this study were: (1) to characterize the mechanical and fatigue behavior of mixtures of RAP, aggregates and cement; (2) to evaluate the fatigue life of pavements with base and subbase layers of such mixtures using the novel Brazilian design method (MeDiNa); and (3) to compare the results with those obtained using the South African Pavement Engineering Manual (SAPEM) transfer functions and the American Association of State Highway and Transportation Officials AASHTOWare Pavement Mechanistic-Empirical Design (PMED) software. The mixtures were tested in the laboratory using flexural static and cyclic tests, and the required parameters to use the methods were obtained. Experimental results and modeling demonstrated a superior fatigue behavior of recycled layers with higher RAP contents. On the other side, layers with lower RAP contents abruptly lost stiffness in short periods, making thicker structures necessary. Therefore, using high RAP contents is not only a sustainable practice, but also a technical benefit. The equivalent single axle loads obtained using the SAPEM were higher than those obtained using MeDiNa, while the PMED ones were higher than both previous methods. Despite the inherent differences, this suggests that MeDiNa is more conservative. It also highlights the importance of calibration based on long-term pavement performance data.

Rest Period Characteristics under Highway Truck Traffic for Mechanistic-Empirical Design of Asphalt Concrete Pavement

Fatigue cracking due to repeated truck traffic loads is the leading cause of failure of asphalt concrete pavement in many locations. Rest periods, referring to the time intervals between successive trucks, may allow for partial or full recovery from fatigue damage and in turn extend pavement fatigue life. This paper delves into the characteristics of rest periods between highway truck traffic loads using traffic data from 40 weigh-in-motion (WIM) stations installed on California state highways and evaluates their effects on pavement performance using mechanistic-empirical incremental-recursive damage and cracking simulation (CalME software). Toward this purpose, truck traffic data were extracted from these WIM stations at selected periods throughout the year 2015 to calculate rest periods. The probability distribution of rest periods and quantiles of cumulative rest periods were calculated, respectively. Regression and statistical analysis for 0.5 quantiles (median) of cumulative rest periods were also performed for different spectra groups and seasons. It was found that rest periods are strongly correlated with the truck traffic volume regardless of the WIM station location and seasons of the year. The actual rest periods based on the nonuniform truck traffic measured from the WIM data were found to be slightly shorter than the corresponding theoretical average rest periods for uniform traffic (ARP-UT) currently assumed in CalME, likely due to truck-following. This theoretical value assumes an equal time interval between trucks all the time. After comparing pavement performance with and without rest periods, it was found that rest periods have a significant influence (30% in difference) on pavement cracking performance in the modeling. Based on this preliminary analysis, the difference in pavement performance caused by the difference between the actual rest periods and ARP-UT is minimal. It is therefore recommended to continue to use ARP-UT to account for the effect of rest periods in pavement design.

Comparative evaluation of dynamic responses of RCC composite pavement under different moving axles

Roller-compacted composite pavement is considered as an alternative for traditional pavements that provides the desired benefits of both rigid and flexible pavements in a cost-effective manner. To evaluate the performance of roller-compacted concrete (RCC) composite pavement under moving loads, a three-dimensional finite element model (FEM) was developed. A realistic dynamic moving load was applied to the surface of the pavement via DLOAD subroutines developed by FORTRAN. The dynamic response of the pavement at critical locations induced by single, tandem, and tridem axles at speeds of 8 and 80 km/h was determined using the developed FEM model and utilized to estimate pavement performance. Sensitivity analysis of design factors considering variations of hot mix asphalt (HMA) and RCC thicknesses, RCC elastic modulus, axle configurations, and moving speed was conducted to evaluate their impact on fatigue life and rutting development of RCC composite pavement. The results show that the performance of the pavement is significantly affected by axle configurations and moving speed. Among different axle configurations, the tandem axle creates the highest tensile stress and shear stress in the RCC base and HMA layer, respectively. The fatigue life of the pavement prolongs by increasing in the speed of moving loads, so it is expected that the pavement withstands higher load repetition when it is subjected to higher speed traffic. Moreover, increasing layer thicknesses and stiffness of the RCC layer improve fatigue life and rutting performance of the pavement. Even though increasing the thickness of the HMA layer enhances the fatigue life of pavement, increasing it to over 15 cm increases the potential of rutting.

Asphalt Mixtures and Flexible Pavement Construction Degradation Considering Different Environmental Factors

Water, frost, and road salt are counted as environmental factors. They affect the pavement structure, particularly during the winter or in regions located above sea level. In the article, a literature review related to water, frost, and road salt impacts was performed. The main problem of evaluating asphalt mixture degradation and its influence on pavement fatigue life via environmental factors was stated. Four types of asphalt concrete (AC22) road mixes were prepared for laboratory tests. They differed in production technology and the type of binder applied. One binder content level was tested. To investigate the impact of water, frost, and road salt on mineral-asphalt mixtures utilized in flexible constructions, two proprietary experimental methods were applied. Methods allowed for determining the mixtures’ degradation level using the measured stiffness modulus in the 4-PB-PR test. Based on the obtained results, it was found that both interactions cause a significant decrease in the value of the stiffness modulus. In the article, a degradation ratio was proposed. The ratio expressed the impact of water, frost, and road salt on the stiffness mix variability. Its value was considered for pavement fatigue life based on the AASHTO 2004 fatigue criterion. The article demonstrates that the type of binder used influences the mix’s resistance to water, frost, or road salt impact. The highest resistance was reached by a mixture with highly modified asphalt (hot technology), and the worst was with asphalt WMA (warm technology). It has also been proven that the impact of water, frost, or road salt on pavement fatigue life is significant. The drop was significant, amounting to a few dozen percent. It was stated that environmental impacts (such as water, frost, or road salt) should be considered in asphalt mixture and pavement construction design.

Laboratory study on mechanical properties of composite pavement under partial compression-shear load

To investigate the mechanical characteristics of asphalt pavement over rigid base, a loading device with an inclined indenter was designed to simulate the partial compression-shear of moving traffic loading. A series of tests were conducted to comparatively study the mechanical properties, including compression-shear strength and fatigue life of composite pavement. Temperature and asphalt overlay thickness were identified as the two most influencing factors on compression-shear strength, based on which a strength model was proposed. Substantial differences were found between asphalt pavement with and without rigid base in energy distribution and damage evolution. Due to the support and confinement provided by the rigid base, the mechanical properties and resilience of asphalt pavement are significantly improved: the fatigue life of composite pavement specimen was nearly 35% higher than that asphalt pavement specimen without rigid base. Fatigue life was significantly reduced by heavy load, whilst proportionally increased with asphalt overlay thickness. Fatigue life prediction model of asphalt layer over rigid base was characterized and validated by the multi-stress fatigue test. The results can provide reference for the design and promotion of composite pavement.

A critical review of the fatigue life prediction of asphalt mixtures and pavements

New pavement construction techniques and the increased use of recycled materials have led to unexpected and premature pavement failure in recent years. The pavement's exposure to daily and seasonal extreme temperature and repeated vehicular loads accumulate damage. Pavement cracking occurs once the cumulative damage surpasses the material's cracking threshold. Fatigue crack is the most common pavement cracking type. Over the past four decades, researchers have carried out numerous experiments and analyses to understand pavement cracking. This paper aims to provide an overview of fatigue cracking and discuss various fatigue test methods for characterizing asphalt concrete mixtures. The article also discusses the most common phenomenological and mechanistic models for predicting the fatigue life of asphalt concrete pavements based on different fatigue test results. The paper details the implementation of the commonly used numerical models found in numerical simulation software and their prediction ability for the fatigue life of a pavement structure. Two major flaws in current evaluation methods are the sensitivity of experimental results and the lack of reliability of some predictive models. Multiscale asphalt material characterization is the ongoing practice for determining the most appropriate performance evaluation tool. However, proceeding with future research objectives is unrealistic until the accuracy of the tests and reliability of the predictions can be verified against actual field results. This critical review of the fatigue life predictions of asphalt mixtures and pavements should help to refine or redefine the right course of action for future research. • Summarize the fatigue cracking, fatigue test methods, constitutive models, and numerical simulation software programs. • Study the theory, application, advantages, and disadvantages of mechanistic and phenomenological models. • Comparing the three prediction approaches reveal that mechanistic models accurately rank pavement mixture performance according to actual pavement conditions.

Evaluation of fatigue life of semi-flexible pavement with cement asphalt emulsion pastes

Semi-flexible pavement (SFP) has been receiving more attention in pavement engineering due to its excellent rutting resistance. However, conventional SFP has a lower cracking fatigue resistance than conventional asphalt mixture due to its brittleness. To improve its fatigue resistance, cement-asphalt emulsion paste (CAEP) is employed as a more suitable grouting material to prepare SFP, and the effect of asphalt emulsion content in grout on the fatigue resistance of SFP is investigated. Since the elastic modulus of SFP with different CAEPs differs significantly, the typical tensile stress response of different SFPs in pavement structure varies greatly; thus, the fatigue resistance of SFPs is influenced considerably. To reasonably evaluate the fatigue resistance of SFPs, the fatigue life of SFPs at the typical tensile stress is studied. To this end, firstly, the fatigue models of materials were established for long-term performance evaluation and fatigue life prediction by employing indirect tensile fatigue test. Secondly, the tensile stress at the bottom of surface layer materials under realistic tire-pavement interactions was estimated by a three-dimensional (3D) finite element method (FEM). Finally, obtained tensile stresses from pavement response analysis were used in fatigue models to select an ideal SFP in terms of fatigue performance. The fatigue evaluation results indicated that conventional SFP with cement paste has much lower fatigue resistance than conventional asphalt mixture. The fatigue resistance of SFP can be greatly improved when CAEP is used as grout in SFP. When the asphalt emulsion to cement ratio by mass (AE/C) is 0.4, SFP can have better fatigue resistance than conventional asphalt mixture. Therefore, CAEP with AE/C at 0.4 is recommended as the best grout in SFP to obtain the best fatigue resistance.

Influence of Axle Load and Asphalt Layer Thickness on Dynamic Response of Asphalt Pavement

Based on the test data of vehicle load test on asphalt pavement, the significance of dynamic response index of different asphalt pavement to axle load change of single and double rear axle trucks is analyzed. The changes of horizontal strain at the bottom of asphalt layer, vertical compressive stress at the top of subgrade, and vertical displacement of transition layer and bottom compressive stress before and after laying of middle and upper layers are revealed. The test results show that reducing the thickness of asphalt layer or increasing the vehicle axle load can lead to the more unfavorable stress-strain distribution in asphalt pavement under driving load. The influence of the fluctuation of truck axle load or asphalt layer thickness on the stress-strain distribution in asphalt pavement varies with the type of pavement structure, pavement response index, vehicle driving speed, vehicle type, and the horizon of the measuring point. The transverse strain at the bottom of the asphalt layer is more affected by the axle load and the thickness of the asphalt layer than the longitudinal strain at the bottom of the asphalt layer. The measured value of the dynamic response index of the semirigid asphalt pavement is more affected by the axle load than that of the inverted asphalt pavement. However, the measured value of the dynamic response index of the semi-rigid asphalt pavement is less affected by the thickness of the asphalt layer when the thickness of the asphalt layer changes within a certain range. The tensile strain part of the longitudinal strain at the bottom of the asphalt layer and the compressive strain part of the transverse strain at the bottom of the asphalt layer are greatly affected by the thickness of the asphalt layer. The sensitivity of fatigue life of asphalt pavement of inverted structure to driving speed and axle load is less than that of semirigid structure. The research results can provide reference for the analysis of the asphalt pavement disease mechanism and provide guidance for asphalt pavement structural design and service life analysis.

Influence of tire pressure on the rutting and fatigue life of bituminous pavement

Influence of tire pressure on the rutting and fatigue life of bituminous pavement