Pavement Stress Research Articles

Performance Investigation of Diatomite Modified Asphalt Mixtures for Different Diatomite Ratios and Grinding Sizes

Modification of asphalt mixtures has become almost mandatory today due to increased stresses in pavements, shortening of load cycle times, and decreases in binder quality. For this reason, many additives can be added to bitumen or asphalt mixture. Industrial material wastes can also be among these additives. When diatomite material is used as a performance enhancer in asphalt mixtures, it significantly improves the main performance indicators of the asphalt mixture. However, low temperature cracking of diatomite-modified asphalt mixtures is still controversial in the literature. This study evaluated the asphalt mixture in terms of low-temperature cracking, water damage, and rutting, depending on the diatomite grinding size (gradation) and addition ratio. Three different sizes of diatomite additives (106, 212 and 300-micron maximum diameter) were used at three addition ratios (5, 10 and 15% by weight of bitumen). According to the test results, it was seen that the mechanical properties of asphalt mixtures were significantly affected by the addition ratios and diatomite sizes, and the use of 300-micron maximum diameter diatomite at the rate of 10% and 15% was more effective. However, according to the BBR test results, the use of diatomite additives with a maximum size of 106 µm at 5% slightly increased the low temperature cracking resistance.

Modeling and Assessment of Temperature and Thermal Stress Field of Asphalt Pavement on the Tibetan Plateau

The Qinghai–Tibet Plateau (QTP) is the highest altitude plateau in the world, characterized by strong solar radiation and large diurnal temperature differences and so on, which brings a great negative impact on the temperature and thermal stress field of asphalt pavement. The purpose of this study is to analyze the temperature field and thermal stress status of asphalt pavement in the QTP to provide a reference for pavement design and maintenance in high-altitude areas. The finite element method was applied to establish the temperature field model to study the distribution and variation of pavement temperature. On this basis, the influence of cooling amplitude on pavement thermal stress was studied during cold waves. In addition to this, the key internal factors affecting the thermal stress of pavement, such as surface thickness, surface temperature shrinkage coefficient, surface modulus, and base modulus, were analyzed by an orthogonal test. It was found that temperature and solar radiation have a significant effect on the pavement temperature field. When the cold wave came, the cooling rate had a considerable impact on the thermal stress of the pavement, that is, every 5 °C increase in cooling rate would increase the thermal stress by more than 50%. The temperature shrinkage coefficient and surface modulus of the surface layer material had the greatest influence on the pavement thermal stress. The thermal stress could be reduced by more than 0.4 Mpa for every 5 × 10−6/°C reduction in the surface temperature shrinkage coefficient or every 1000 Mpa reduction in the surface modulus. This study can provide a reference for improving the temperature field and thermal stress field of asphalt pavement in the plateau area.

Stress and Strain of RCC Pavement with Cement Stabilized Base Depending on Load and Season of the Year

Stress and Strain of RCC Pavement with Cement Stabilized Base Depending on Load and Season of the Year

Stress and Strain Characteristics in Flexible Pavement Using Three-Dimensional Nonlinear Finite Element Analysis

AbstractA new numerical simulation was developed to obtain various structural parameters by employing a nonlinear finite element method using ABAQUS: stress, strain, and the displacement response of five layers on the flexible pavement. The primary purpose of this study was to develop a new simulation that can accurately and effectively characterize stress and strain problems in flexible pavement. New constitutive model equations were developed based on Hooke’s law the three-dimensional model for stress and strain. 40 kN wheel load was used to represent a set of dual tires, assuming a uniformly distributed contact area between the tire-pavement surfaced using linear viscoelastic and nonlinear viscoelastic materials. Four tire-inflation pressures were used 380, 490, 630, and 700 kPa. Results indicated that each flexible pavement layer created with a nonlinear viscoelastic material exhibited a 40% vertical plastic strain reduction compared to linear viscoelastic materials after 7000 s and repeated for 30,000 cyclic loadings. The implication of this newly developed constitutive model was verified against published experimental data. Analyses were completed to simplify the results model results considering the effects of stress and strain on flexible pavement layers. The newly developed constitutive model for solving stress and strain characterization problems can predict the effects on flexible pavement layers and various types of observed flexible pavement failure.

STRESS AND STRAIN ON STATE ROAD IB33 IN SERBIA

<p>In the pavement structure, stresses and deformations occur due to the effect of the environment and traffic load. The stresses that will occur mostly depend on the traffic load, the type of materials used, the modulus of elasticity of the materials used, the thickness of the layers... Due to the effect of the environment and traffic on the pavement, damage and the creation of permanent deformations, i.e. ruts, occur. If these damages are not repaired in time, the damage will develop even faster. In this paper, the traffic load on the road Požarevac - Veliko Gradište - Golubac was analyzed, the possible damage that may occur due to the effect of that load, as well as the method of maintaining that roadway in order to prevent major damage to the roadway structure.</p>

Analysis of temperature stress and critical heating temperature for hydronic airport pavement

The hydronic heated pavement system has been widely used for snow and ice removal in airports and other transportation infrastructure facilities because of its good snow melting efficiency and environment friendliness. However, the study of the temperature stress distribution in hydronic pavement and the corresponding critical operation method shows many insufficiencies, which allows security problems during system operation. This paper investigated the temperature stress of the hydronic pavement near the pipes with a 3D finite element model. This model was validated by the measured temperature stress in a full-scale hydronic snow melting experiment system. The locations of the maximum compressive and the time-varying tensile stress in the hydronic pavement were reported. The maximum temperature stresses of the hydronic pavement with various design and operation parameters were compared, and the sensitive parameters were proposed. In particular, the critical fluid temperature with various design and weather parameters was presented by comparing the maximum temperature stress in the pavement with the failure strength of concrete material. The findings show the maximum compressive stress appears near the hydronic pipe, and the maximum tensile stress appears at the midpoint between two adjacent pipes after heating for 2 h. Maximum tensile stress increases with pipe embedded depth, pipe diameter, fluid temperature, and pavement capacity, but decreases with air temperature and pipe spacing. To ensure the safety of hydronic pavement, the critical fluid temperature under different conditions is controlled within the range from 38 °C to 77 °C.

Study on the permanent deformation of asphalt mixtures based on the modified Burgers model

Based on the confined test results and the viscoelastic constitutive model of asphalt mixtures, a three-dimensional finite element model of an asphalt pavement was established to study the effect of different working conditions on asphalt pavement. With the actual pavement structure response, a comparative analysis was conducted to assess the stress and strain experienced by the asphalt pavement under various working conditions. The results show that the asphalt pavement structure model can reflect the effect of different working conditions on asphalt pavement; the transverse stress and strain of asphalt pavement are most significantly affected by the working conditions during cornering, and the position of the maximum value is concentrated on the outer edge line of the wheel and a distance away from it; however, the longitudinal tensile stress and strain of the asphalt pavement are most significantly impacted by the working conditions of driving and braking, and the position of the maximum value is mainly distributed in the center line of the single wheel. The research results can provide a reference for the design of asphalt pavement structures.

Research on dynamic stress and excess pore water pressure of asphalt pavement under hydraulic-mechanical coupling

The impact of the initial static stress field on dynamic calculation results was considered, a three-dimensional refined coupling system model was constructed using finite element software, and the time domain and space domain distribution laws of dynamic stress and excess pore water pressure of saturated asphalt pavement under moving load were investigated. The findings show that the influence of the initial static stress field on the pavement dynamic calculation results will increase as the pavement depth increases. On the bottom surface of the upper layer, when the initial static stress field is not considered, the errors in vertical dynamic stress and excess pore water pressure are 29.6% and 30.8% respectively. As compared to dry pavement, the tensile stress on saturated asphalt pavement increases, and the stress attenuation rate slows when the load passes, putting the pavement structure in an undesirable situation. The negative peak value of the hydrodynamic pressure in the higher layer drops linearly as the permeability coefficient of the upper layer increases. In contrast, the negative peaking of the vertical dynamic stress grows linearly. Under the situation of potholes, the dynamic stress components in six directions of the saturated asphalt pavement all rise dramatically. Among the three shear stress components, τyz increases the most under the condition of pavement pothole, which is 345% higher than that without pothole. Among the three normal stress components, the vertical dynamic stress has the largest increase, which is 156% higher than that without potholes, and the increase in shear failure of the pavement is greater than that of tensile failure. The research findings will be helpful in determining the degradation process of saturated asphalt pavement and in designing asphalt pavement structures in rainy areas.

Evaluating the low-temperature performance of asphalt mixtures based on the contraction and relaxation properties

The thermal cracking of asphalt pavement has been the focus of research in cold regions of the world. The contraction and relaxation properties of asphalt mixtures were crucial for investigating the thermal stress of asphalt pavement based on the thermal cracking mechanism. This paper proposed a novel evaluation index for characterizing the low-temperature performance of asphalt mixtures by considering their contraction and relaxation properties. Firstly, the rank during the evaluation indexes for low-temperature performance was determined by comparative analysis of method. Secondly, the thermal contraction coefficient was used to characterize contraction properties and cumulative stress at per unit strain rate (CSSR) was used to characterize relaxation properties in this paper. According to the cumulation process of thermal stress, a novel index was constructed based on the contraction and relaxation properties. Finally, considering the correlation between the failure temperature and the novel indexes, the prediction model of low-temperature performance consistent with the order of failure temperature was established based on the multiple linear regression method. Through the standardized analysis of the prediction model, the influence of novel indexes for the low-temperature performance of asphalt mixtures under different temperature conditions was clarified. A novel evaluation index provided a theoretical basis for unifying the evaluation indexes of asphalt mixtures.

Experimental Study and Numerical Analysis of Temperature Stress in Carbon Fiber-Heated Concrete Pavement

Carbon fiber heating technology has been widely used in pavement surfaces in practical engineering projects as an environmentally friendly, efficient, and safe ice melting technique. However, the current design of carbon fiber-heated pavement focuses primarily on the ice melting effect while neglecting the crucial mechanical performance evaluation. Therefore, this study aims to investigate the temperature and thermal strain distributions of concrete pavement through model tests and develop a corresponding three-dimensional numerical model to analyze the temperature stress field distribution of carbon fiber-heated pavement. The accuracy of the numerical model is verified by comparing the model test results with the numerical analysis results. The numerical model test results indicate that the maximum compressive stress near the carbon fiber wire is 4 MPa, while the maximum tensile stress between the two carbon fiber wires is 1 MPa. According to the design standard for highway cement concrete pavement, the temperature stress induced by temperature change is significantly lower than the design value of the material’s inherent strength. In addition, a linear relationship between the depth and temperature gradient affecting temperature stress is observed after establishing a correlation between the temperature gradient and temperature stress. The findings of this study can provide valuable insight into the design of carbon fiber-heated concrete pavements.

Innovative design of self-adhesive basalt fiber mesh geotextiles for enhanced pavement crack resistance

This study introduces a novel design of self-adhesive basalt fiber mesh geotextile, aiming to significantly enhance the crack resistance of asphalt pavements. Reflective cracks from environmental and traffic stresses in traditional semi-rigid asphalt pavements, compounded by current geotextiles' mechanical and adhesion limitations, reduce service life. This study explores the mechanical properties, adhesion to asphalt, and resistance to simulated cracking of self-adhesive basalt fiber mesh geotextiles within pavement structures. This is accomplished through a series of mechanical tests, interfacial adhesion tests, and advanced characterization using Digital Image Correlation. The results indicate that the distinctive pore structure of basalt fiber mesh geotextiles introduces an embedded interlocking reinforcement effect, which significantly enhances the strength of the composite geotextile. The SAM-160M specimen demonstrates a maximum tensile strength of 3.599 kN, surpassing that of the plain fabric specimen by over 34%. The twisted weaving process of the mesh fabric improves adhesion to asphalt by 14.54% compared to plain fabric, thereby enhancing the performance of the pavement structure's interlayer and its resistance to cracking. The mesh fabric excels at dispersing concentrated stresses, enhancing weak interface zones, and increasing the structural capacity and longevity of pavements. These improvements support sustainable road construction with broad engineering applications.

Finite Element Analysis of Tyre Contact Interaction Considering Simplified Pavement with Different Aggregate Sizes

This study considered the effect of pavement aggregate grain size on tyre–pavement contact interaction during the late stages of pavement skid resistance. First, hemispherical shells 7, 9, and 13 mm in diameter were used to simulate coarse pavement aggregates. Subsequently, a three-dimensional finite element tyre–pavement contact model developed using ABAQUS was employed to analyse the contact interaction between each simplified pavement type and the tyre under steady–state rolling and braking conditions. Finally, the concept of occlusal depth was proposed and applied to characterise pavement skid resistance. The results showed that under steady–state rolling conditions, the peak contact stress of the simplified pavement increased with the pavement mean texture depth, whereas the contact area decreased. Under steady–state braking conditions, the effect of the contact interaction between the tyre and simplified pavement aggregates was ranked in order of superiority as aggregate grain sizes of 9, 7, and 13 mm, indicating that aggregate grain size did not exhibit any correlation with tyre–pavement contact interaction. Additionally, the squares of linear correlation coefficients between the pavement cumulative occlusal depth and horizontal braking force reached 0.921, 0.941, 0.889, and 0.894 for vehicle speeds of 30, 60, 90, and 120 km/h, respectively, indicating that they could be used to assess pavement skid resistance.

Fatigue damage caused by superload vehicles in concrete pavements

Superload vehicles (SLs) are typically defined as vehicles having a gross vehicle weight (GVW) greater than 890 kN. SLs often consist of unique axle configurations that may cause significant damage to pavements. Research has been mainly limited to SLs on asphalt pavements, therefore the effect of SLs on concrete pavements is not well established. In this study, fatigue stresses in concrete pavements were quantified for a database of pavement structures and SLs to identify critical conditions that contribute to fatigue damage. A series of load pulses were constructed from a database of finite element results to identify conditions and locations within the slab for peak stress development. Tensile stress greatest in thin pavements with a stiff base layer and large positive temperature gradients subjected to tandem axle SLs. Fatigue damage was calculated for the critical cases using several damage models, and significant variation was found between models based on inputs used.

Dynamic Response Analysis of JPCP with Different Roughness Levels under Moving Axle Load Using a Numerical Methodology

In-service Portland cement concrete (PCC) pavements are subject to repeated dynamic loads from moving vehicles; thus, the actual stress generated in a PCC pavement may significantly differ from the static stress, which is normally used in the design and evaluation of pavement performance. Calculating the stress in PCC pavements under moving vehicle loads is of importance to assess their actual service condition, particularly for pavements with different surface roughness levels as the deteriorated roughness might cause large stress in PCC pavement subject to dynamic loads. In this paper, a method is proposed to compute the dynamic response in terms of loads and stresses generated in jointed plain concrete pavements (JPCPs) under a moving axle load, considering the effects of the pavement surface roughness, the vehicle parameters (including vehicle speeds and axle weights), and the pavement structure parameters (including thickness and elastic modulus of different layers and the existence of dowel bars). The dynamic axle load is firstly generated based on the quarter-car model, running through three successive slabs of which the surface roughness is determined by the power spectral density method, and the critical locations in slabs where the largest tensile stresses occur are identified. The combined effects of various pavement surface roughness levels, vehicle speeds, axle weights, and pavement structure parameters are evaluated in terms of the stress and the dynamic factor defined as the ratio of the tensile stress under dynamic load to the tensile stress under static load. For the roughness level D, the tensile stress can reach a maximum value of 3.13 MPa, and the dynamic factor can reach a maximum value of 2.46, which is much larger than the dynamic factor of 1.15 or 1.2 currently used in design guidebooks. Increasing the thicknesses of pavement slab or the subbase layer is an effective way to reduce the tensile stress in JPCP, while increasing the thickness of base layer is not effective. The results of this study can benefit future pavement design and pavement performance evaluation by providing the actual stress and the useful dynamic factor values for various conditions of field pavements. Moreover, preventive maintenance, particularly the improvement of pavement surface roughness, can be planned by referring to the results of this study, to avoid large tensile stress generated in JPCPs.

Development of temperature differential maps for rigid pavements in tropical climates for quick estimation of thermal stresses

ABSTRACT Accurate estimation of the thermal stresses in rigid pavements is essential for the assessment of its service life. Thermal stress (an outcome of temperature differential) within the slab is significantly dependent on local weather conditions. This article presents a methodology for prediction of temperature profiles in rigid pavement. In this work, partial differential equations governing heat transfer through concrete pavement are numerically solved. The boundary conditions of the heat transfer model were formulated based on the real-time weather data. The temperature profiles predicted by solving the model were used to calculate the temperature difference between the top and bottom of the rigid pavement slab. The proposed methodology was implemented using 30 years of gridded weather data for whole of India. From the predicted temperature profiles, the annual M P T D and M N T D of the pavement slab were calculated. The mean values for each grid point observed over 30 years were used to develop temperature differential maps. The predicted values of maximum positive and negative temperature differentials had significantly higher values compared to the current codal recommendations of India. Developed maps can be used for estimating the design temperature differentials in places having similar climatic conditions presented in this study. Abbreviations: DLC: dry lean concrete; GSB: granular subbase; IRC: Indian Road Congress; MMMT: mean monthly maximum temperature; MMRH: mean monthly relative humidity; MTD: maximum temperature differential; MPTD: maximum positive temperature differential; MNTD: maximum negative temperature differential; PDE: partial differential equation; PQC: pavement quality concrete; SG: subgrade; TD: temperature differential

Study on Impact of Various Void Conditions on Shallow Rectangular Masonry-Concrete Power Tunnel and Surrounding Roads

To solve the problem of a potential void near a shallow rectangular masonry-concrete power tunnel, the ground-penetrating radar (GPR) detection technology is used and multiple GPR detection lines are placed to detect concealed void. The GPR images of circular and square voids are obtained, which can help increase accuracy of void identification. The models that cover 9 circular voids and 9 square voids are created to investigate how various forms and positions of void will affect the internal forces of the power tunnel structure and surrounding roads. In terms of morphological characteristics, according to the research results, the impact of a circular void on tunnel and surrounding roads is slightly stronger than that of a square void. If the circular void and square void are at 135° and 115°, respectively, the maximum shear force of the tunnel structure occurs at the floor. If both circular and square voids are at 115°, the maximum axial force of tunnel structure occurs at the right side wall. If both circular and square voids are at 135°, the maximum bending moment of tunnel structure occurs at the floor. If both circular and square voids are at 155°, the ground settlement and pavement stress of surrounding roads are maximized. Generally, if a void occurs at the middle or lower part of the side wall or near the side of the floor in a shallow rectangular masonry-concrete power tunnel, its adverse impact is at its worst. Therefore, GPR detection of the voids at the lower and middle parts and the side of the floor in the power tunnel should be intensified, in order to eliminate the risk of a void near power tunnel.

Discrete-continuous coupling simulation and analysis for asphalt pavement dynamic stress responses under a moving wheel load

Asphalt pavement stress responses are analyzed with the layered elastic system under static loads in the most popularly-used design specifications. In reality, however, traffic loads are moving and the pavement layer materials are mainly aggregated. In order to reasonably consider vehicular loads and layer material features, this paper presents a discrete-continuous coupling model for analyzing asphalt pavement dynamic stress responses under moving loads. The numerical model is divided into an asphalt pavement structure and a moving wheel load. Specifically, the wheel load and the asphalt layer under its load were modelled with the discrete element method to simulate the actual vehicle loads and meso-scopic components of the asphalt mixture. In contrast, the remaining parts of the pavement structure were modelled with the finite difference method. The wheel load was set to move on the surface layer of asphalt pavement at a constant speed as the numerical simulation was conducted. The results were analyzed based on special points of dynamic stress curves. The results showed that: different from the static stress responses, in a typical asphalt pavement dynamic stress curve, there existed three stages of stress responses, namely the stress smoothing stage, stress surge stage, and stress dissipation stage, which had significant fluctuations at high levels and asymmetry. Besides, the loading velocity and mixture meso-structure significantly influenced on the dynamic stress responses of asphalt pavement. Especially the average peak stress calculated by the discrete-continuous coupling model, which considered the mixture meso-structure decreased by 10% compared to the finite-difference model.

Performance of Sustainable Road Pavements Founded on Clay Subgrades Treated with Eco-Friendly Cementitious Materials

Clays encountered during road construction are mostly weak and result in major pavement failures due to their low California bearing ratio (CBR) and high swelling potential. In this study, sustainable and eco-friendly waste materials including brick dust waste (BDW), ground granulated blastfurnance slag (GGBS), recycled plastic (RP) and recycled glass (RG) at varying proportions of 11.75% and 23.5% were used as partial replacement for cement and lime in clay treatment. After determining the water content by conducting Atterberg limit and compaction test, A CBR and swell characteristics of treated and untreated clay were also conducted. A road pavement design was conducted using the Design Manual for Road and Bridges (DMRB) as a guide to determine the performance of treated clay with varying CBR values. A road pavement failure analysis was also conducted to understand the defect formation within pavement structures supported by eco-friendly treated clay. The embodied carbon of treated clay was calculated and a life cycle cost analysis (LCCA) of flexible pavement with treated clay and road with imported materials was conducted. The results show a liquid limit of 131.26 and plastic limit of 28.74 for high plasticity index (clay 1) and liquid limit of 274.07 and a plastic limit of 45.38 for extremely high plasticity index (clay 2). An increase in CBR values from 8% and 9% to 57% and 97% with a reduction in swell values from 4.11% and 5.03% to 0.38% and 0.56% were recorded. This resulted in a reduction in pavement thickness and stresses within the road pavement leading to reduced susceptibility of the pavement to fatigue, rutting and permanent deformation. Very low embodied carbon was recorded for eco-friendly treated clay and a high life cycle cost (LCC) with clay removed and replaced with imported materials compared with clay treated using eco-friendly waste materials. The study concluded that carbon and overall construction costs can be reduced using waste materials in road construction. Owners and operators can save money when clay is treated and used in road construction instead of removing clay and replacing it with imported materials.

Theoretical analysis of stress of asphalt mixture bridge deck pavement based on design index

At present, the specification for the design of asphalt mixture bridge deck pavement is missing, so it is of great significance to research on it. In order to study the design theory of asphalt mixture bridge deck pavement, the bottom tensile strain of asphalt mixture layer and the permanent deformation of asphalt mixture layer as the design index of asphalt mixture bridge deck pavement have been selected. Combined with a specific simply supported slab bridge, the mechanical properties and influencing factors of asphalt mixture bridge deck pavement based on the design index have been analyzed. Firstly, the section characteristic calculation basis of fatigue checking calculation is proposed by using the standard method, and the fatigue section characteristic of simply supported solid slab bridge is analyzed. Considering different load positions, the calculation method of fatigue stress under design load and ultimate load is proposed, and the fatigue stress is calculated. According to the equal strain principle, the bottom stress of asphalt mixture is calculated. Secondly, based on the assumption of plane section, the strain calculation formula of rectangular section with two parameters under temperature load is deduced. Using the derivation formula, the stress distribution of the section under the action of uniform temperature and gradient temperature is calculated, and the general stress distribution law is obtained. Finally,take Specification for design of highway asphalt pavement (JTG D50-2017) for reference to calculate the permanent deformation of asphalt mixture bridge deck pavement; Compared with the field measured value, the theoretical calculated value is less than the field measured value, which may be related to the insufficient compaction of asphalt on the bridge deck.

Theoretical analysis of stress of asphalt mixture bridge deck pavement based on design index

At present, the specification for the design of asphalt mixture bridge deck pavement is missing, so it is of great significance to research on it. In order to study the design theory of asphalt mixture bridge deck pavement, the bottom tensile strain of asphalt mixture layer and the permanent deformation of asphalt mixture layer as the design index of asphalt mixture bridge deck pavement have been selected. Combined with a specific simply supported slab bridge, the mechanical properties and influencing factors of asphalt mixture bridge deck pavement based on the design index have been analyzed. Firstly, the section characteristic calculation basis of fatigue checking calculation is proposed by using the standard method, and the fatigue section characteristic of simply supported solid slab bridge is analyzed. Considering different load positions, the calculation method of fatigue stress under design load and ultimate load is proposed, and the fatigue stress is calculated. According to the equal strain principle, the bottom stress of asphalt mixture is calculated. Secondly, based on the assumption of plane section, the strain calculation formula of rectangular section with two parameters under temperature load is deduced. Using the derivation formula, the stress distribution of the section under the action of uniform temperature and gradient temperature is calculated, and the general stress distribution law is obtained. Finally,take Specification for design of highway asphalt pavement (JTG D50-2017) for reference to calculate the permanent deformation of asphalt mixture bridge deck pavement; Compared with the field measured value, the theoretical calculated value is less than the field measured value, which may be related to the insufficient compaction of asphalt on the bridge deck.