Bearing Capacity Of Pavement Research Articles

Temperature Correction of Deflections and Backcalculated Elasticity Moduli Determined from Falling Weight Deflectometer Measurements on Asphalt Pavements

The evaluation of the bearing capacity of asphalt pavements is usually performed by analysing the deflections measured by a Falling Weight Deflectometer (FWD). The deflection changes with the pavement temperature. In evaluation is necessary to consider the thermal gradient of pavement and perform the temperature correction. The article contains an analysis of effects of the pavement temperature on FWD results on the long-term monitored sections. The temperature correction was performed on measured deflections or back-calculated elasticity moduli. The moduli recalculated to the temperature of 20 °C according to both procedures were similar. Comparison of moduli determined by recalculation to moduli backcalculated from the deflection bowls measured at the temperature of 20 °C, has proven smaller differences for the moduli determined from the deflection bowl corrected to the temperature of 20 °C.

The influence of road surface grooving on the bearing capacity of airport road surface is analyzed

Abstract: this paper is mainly to analyze splash water test pavement slot effect on airport pavement bearing capacity, according to the FAA requirements, computing pool water storage requirements, and put forward the pool building, this paper adopts the simulator ChangDao surface modeling, analysis of structures, pools on the pavement when the slot effect on airport pavement bearing capacity, explore the pool to build new methods to provide theoretical support for the follow-up.

Effect of Temperature Fluctuations on the Bearing Capacity of Cold In-Depth Recycled Pavements

This study investigates the influence of the temperature fluctuations on the bearing capacity of cold in-depth recycled (CIR) pavements stabilized with foamed asphalt (FA). Aiming to achieve this goal, non-destructive testing was conducted during mild and high temperatures on a highway CIR pavement, utilizing mainly the FWD device. The back-calculated moduli values were utilized to estimate the strain values within the body of the pavement, while the strains induced using the FWD device were measured with a fiber optic sensors (FOS) system. Moreover, data from the fatigue behavior of the layer materials was also considered. The results of the related analysis indicate that for every 1 °C temperature increase within the body of the AC overlay, an approximately 5.7% increase of the critical tensile strain is expected. Moreover, for every 1 °C temperature increase within the body of the FA layer, an approximately 1.8% increase of the tensile strain at the bottom of the FA layer is expected. The new constructed layers, i.e., asphalt concrete (AC) and FA, sustain much more damage at high temperatures. This was more evident in the upper layer, i.e., the AC overlay.

Analysis of the possibility of using a geogrid to improve load bearing capacity of natural airfield pavements

AbstractThe article presents an innovative method that was verified in the field. It is aimed to improve the load bearing capacity of airfield pavements, which are one of the elements of the flight safety system. Airfield pavements protect the runway in case when the aircraft is taxiing beyond the runway. Moreover, they are also used to perform starting and landing operations of military aircraft. Due to this, they need to have an adequate load bearing capacity that ensures the safety of performing aircraft flights. Airports cannot afford to be shut down for a long time; thus, it is essential to look for efficient and fast solutions that could improve the load bearing capacity of airfield pavements. The authors suggested to apply geogrid immersed in natural airfield pavement.

CALCULATION OF GRADING OF COLD RECYCLED MIXTURES USING NEW AGGREGATES ACCORDING TO THE DESIGNED THICKNESS OF A REHABILITATED LAYER

Technologies of cold recycling of asphalt concrete using various types of binders have been widely implemented in road building industry in Ukraine. Technologies of cold recycling allow to eliminate some types of deformations or destructions and also to enhance bearing capacity of flexible road pavements. If required, process of cold recycling assumes application of new aggregates to achieve standard grading of a recycled mixture. As the standard requirement does not state any restrictions on relative content of new aggregates, these can be applied to achieve the designed thickness of a rehabilitated layer. This article presents a method for calculation of grading of cold recycled mixtures according to the designed thickness of a rehabilitated layer assuming the amount of reclaimed asphalt pavement (RAP) equals to the amount of asphalt concrete in a milled layer. The proposed method is based on calculation of grading of a mixture of new aggregates that should be rather individual for each recycled mixture. The input data for calculation should be obtained from results of a field testing of “old” road pavement construction and also from laboratory investigation of “old” asphalt concrete cores. The article gives also some examples of calculation which are performed on base of mean values of standard grading of recycled mixtures. Nevertheless, the proposed method of calculation could be applied on the base of any values selected within the standard limits. The proposed method assures precise modeling of composition and properties of a recycled mixture and could be implemented when planning projects on rehabilitation of flexible road pavements either by cold in-plant or cold in-place recycling.

Dynamic response analysis of airport pavements during aircraft taxiing for evaluating pavement bearing capacity

Dynamic response analysis of airport pavements during aircraft taxiing for evaluating pavement bearing capacity

Evaluation of Natural Airfield Pavements Condition Based on the Airfield Pavement Condition Index (APCI)

Natural pavements are an important element of flights. Among other things, they allow the plane to be safely slowed down after it has exited the runway. For this reason, load bearing capacity of natural airfield pavements and strength of turf layer at a specified level are required. Currently used testing methods, such as CBR (Californian Bearing Ratio) tests or turf probe test, separately do not give a full image of pavement technical condition. The authors presented the methodology for assessing the technical condition of natural airfield surfaces based on the APCI (Airfield Pavement Condition Index). The index is based at the same time on the load bearing capacity of the surface layer up to 0.85 m and turf layer strength. The mathematical model and the classification of airfield pavements in terms of the APCI indicator are presented. The article also presents an example of using the APCI method to assess shoulders and end safety areas of the runway at one of the operating airport facilities.

Probabilistic Bearing Capacity of a Pavement Resting on Fibre Reinforced Embankment Considering Soil Spatial Variability

This paper intends to examine the influence of spatial variability of soil properties on the probabilistic bearing capacity of a pavement located on the crest of a fibre reinforced embankment. An anisotropic random field, in combination with the finite difference method, is used to carry out the probabilistic analyses. The cohesion and internal friction angle of the soil are assumed to be lognormally distributed. The Monte Carlo simulations are carried out to obtain the mean and coefficient of variation of the pavement bearing capacity. The mean bearing capacity of the pavement is found to decrease with the increase in horizontal scale of fluctuation for a constant vertical scale of fluctuation; whereas, the coefficient of variation of the bearing capacity increases with the increase in horizontal scale of fluctuation. However, both the mean and coefficient of variation of bearing capacity of the pavement are observed to be increasing with the increase in vertical scale of fluctuation for a constant horizontal scale of fluctuation. Apart from the different scales of fluctuation, the effects of out of the plane length of the embankment and randomness in soil properties on the probabilistic bearing capacity are also investigated in the present study.

The Current State and Development Tendency of the FWD Metrology Technology

As the “Outline for Building a Leading Transportation Nation” puts forward, the overall requirement of high quality development, the measurement work of transportation industry plays a much more important role. This paper introduces the measurement technology state of the FWD of the highway pavement bearing capacity measuring equipment, the technical state and error analysis of the equipment are introduced, and the calibration and comparison methods are sorted out, which provide a reference for the next generation of the equipment.

Effect of Anti-Stripping Agent with Bipolarity to Strip-Ravelling Damage Caused by Surface Shear Stress

The stripping is one of serious distresses because it causes the decline in the bearing capacity of the asphalt pavement. As the result of evaluation of the bearing capacity of the pavement by FWD, the dissipation amount of work becomes larger at the stripping area in comparison with non-stripping area. An anti-stripping agent is effective for preventing such stripping in advance. The new anti-stripping agent which used in this research forms the strong electrochemical bonding between the asphalt and the aggregate by giving bipolarity to the asphalt. Furthermore, it is clarified that the new anti-stripping agent can give improve and enhance the shear strength of the asphalt as well. The shear strength is closely related to the rutting and the fretting of the asphalt pavement in accordance with past research. Therefore, enhancing the shear strength should contribute to not only the improvement in the rutting and the fretting but also the prevention of the strip-ravelling that the fine aggregates and the asphalt mortar are washed out from the pavement surface and it often takes place in Malaysia and Asian countries. In this research, we will focus on the strip-ravelling of the asphalt pavement, and simulate the strip-ravelling by using an immersed-wearing tester. As a result, this research clarifies the relationship between the shear strength of the asphalt and the strip-ravelling of the asphalt mixture.

Investigating the use of equivalent elastic approach to identify the potential location of bending-induced interface debonding under a moving load

Poor interface bonding conditions reduce the bearing capacity of asphalt pavements and lead to several distresses. In particular, the association between localized interface debonding and near-surface longitudinal cracking was detected by field observations in the United States. Prediction of potential location and extent of localized interface debonding is important to preclude near-surface cracking. However, there is limited information regarding the onset of localized interface debonding induced by bending. Since interface debonding location and extent may depend on pavement structure, material properties, and loading conditions, a practical approach is needed. Several researchers adopted an equivalent elastic approach to overcome the complexity of modeling the viscoelastic responses of asphalt when evaluating the impact of multiple factors. Therefore, this study focused on determining whether the equivalent elastic approach can be used to identify the potential location of bending-induced localized interface debonding without a significant loss of accuracy. The viscoelastic and equivalent elastic analyses were conducted using 3-D finite element models developed to simulate an asphalt pavement subjected to a moving load. The 3-D equivalent elastic analysis appeared to be sufficient to accurately determine the potential location and extent of localized debonding induced by bending, which are mainly controlled by presence of shear stress in combination with low confinement on the horizontal interface plane. Furthermore, localized debonding was found to likely occur along a strip in the longitudinal direction which resembles a plane-strain problem. This study substantiated that future research efforts can focus on the transverse cross-section when assessing the impact of localized debonding.

Modelling and analysis on bearing capacity of asphalt pavement in dense traffic flow of urban areas

Aiming at the problems of low fitting degree and high complexity between the research results and the actual situation, the bearing capacity model of asphalt pavement in dense traffic flow area based on combination forecasting is put forward. Cellular automata is used to calculate the relative position and speed change of vehicles in the popularisation process. According to Orkut model, the relative position and speed change of each vehicle on the road is calculated and analysed. Through calculation and analysis, the vehicle load concentration value is obtained. The experimental results show that the SSE, MAE, MSE and complexity coefficient of the bearing capacity model for asphalt pavement in heavy flow area based on combined prediction are lower than 0.05, lower than 0.15, lower than 0.16 and lower than 0.2, which are the minimum values in the comparison method, indicating that the model has high accuracy, low complexity and good reliability.

Effect of bitumen type, temperature and aging on mixed I/II fracture toughness of asphalt binders-experimental and theoretical assessment

The overall characteristics and fracture behavior of asphalt pavements and overlays is significantly controlled by the mechanical behavior of bitumen used in the mixture of asphalt concrete. The bitumen behaves like a dominantly brittle and elastic medium under subzero temperatures. In practice, cracked asphalt pavements experience mixed mode tensile-shear deformations due to moving traffic loads or cyclic thermal gradients. On the other hand, aging phenomenon can affect significantly the overall strength and load bearing capacity of pavements and bituminous asphalt mixtures. Different binders with different penetration grades and performance characteristic are often used for paving the roads. In order to investigate the effect of binder type and aging condition on the mixed mode I/II cracking response of bitumen materials, an experimental and theoretical study is performed in this research. Three binders: namely 30/40 bitumen, 60/70 bitumen and modified bitumen with SBS polymer (i.e. polymeric binder) are used to conduct a full set of mixed mode I/II fracture toughness experiments using an inclined edge notched bend beam specimen. The experimental results showed significant influence of mode mixity, bitumen type and aging on the fracture toughness data. The fracture toughness is reduced for the whole tested binders by moving from pure mode I to pure mode II. While aging has negative effect on the crack growth resistance of 30/40 and 60/70 binders, the mixed mode I/II fracture toughness of polymeric modified bitumen was increased after aging. The morphology of fracture surface and direction of fracture was studied for the tested binders under different environmental and loading conditions. The mixed mode I/II fracture toughness data were also predicted using two generalized tangential stress/strain based fracture criteria.

Research on Rotational Speed of Road Mixing Device for Large-Sized Cement Stabilized Crushed Stone

In order to prevent the reflection crack from happening in cement stabilized macadam base frequently, which lead to the decrease of pavement bearing capacity and working life, a new base structure- large sized cement stabilized crushed stone was raised. The rotational speed of mixing facility for this material was researched in this paper so as to obtain the best base performance, therefore, the construction process was simulated and analyzed in EDEM, which accepted the dispersion coefficient as the mixing quality index. The result shows that the index decreases with the increase of rotational speed between 65r/min and 120r/min and it rises a little and then remains stable when the speed is 120-150r/min. Finally, the 120r/min is regarded as the appropriate speed considering the index and power consumption.

Shear-Torque Fatigue Performance of Geogrid-Reinforced Asphalt Interlayers

Interlayer reinforcement systems represent a valid solution to improve performance and extend the service life of asphalt pavements, reducing maintenance costs. The main issue is that the presence of reinforcement may hinder the full transmission of stresses between asphalt layers, reducing the overall pavement bearing capacity. This study aimed at evaluating the mechanical behavior of geogrid-reinforced asphalt interlayers under cyclic shear loading. To this purpose, a trial section, characterized by three types of interface (reinforced with carbon fiber grid, reinforced with glass fiber grid and unreinforced), was built. Cores were taken from the trial section to carry out shear-torque fatigue tests. Static Leutner shear tests were also performed on cored specimens having the same interface configuration. From data gathered in the present study, shear-torque fatigue tests have proved to be a powerful tool for investigating reinforced specimens. Results clearly ranked the investigated materials, showing that the glass fiber grid has the lowest shear fatigue performance in comparison with the other two interfaces at 20 °C. However, the shear fatigue resistance of glass fiber grid increases significantly at 10 °C. Finally, an interesting correlation was found between cyclic and static shear test results that should be better investigated in future studies.

Surface Temperature Prediction of Asphalt Pavement Based on GBDT

Asphalt is a temperature sensitive material, distribution characteristics and vary rules of asphalt pavement temperature have an important impact on the bearing capacity and performance of pavement, which is a concern of domestic and foreign researchers. The objective of this study was to explore the correlation between pavement temperature of asphalt pavements and meteorological factors and implement an accurate trend prediction of the asphalt pavement temperature. First, errors and missing data in the meteorological dataset were cleaned. Then, the three kinds of temperature prediction models of asphalt pavements in winter were established by Gradient Boosting Decision Tree (GBDT), Random Forest (RF) and Linear Regression (LR). The results indicate that GBDT would perform an excellent ability on prediction. The mean-square-error of the GBDT predicting results has a lower value of 1.5 when compared with the Random Forest and Linear Regression owing to the high robustness and the good generalization ability, which reflects the GBDT model has a good applicability in the field of prediction. The research would serve as a technical support for the machine learning algorithms applied in the field of the application of prediction problems.

Influence of Temperature and Moisture Content on Pavement Bearing Capacity with Improved Subgrade.

Environmental conditions (temperature, moisture and the intensity of the sun) influence variation in asphalt pavement strength during the year. Lithuania is situated in a zone by average warm summers and average cold winters, and the most important climatic factor is the variation of the air temperature. This study presents the influence of temperature (of asphalt concrete (AC) and subgrade layers) and moisture content (of subgrade layers) to the pavement bearing capacity. The experimental research was obtained in five pavement sections of the experimental road. This experimental road was constructed in 2007 in Lithuania and is operated for more than 12 years. This paper presents a statistical analysis between the bearing capacity and the thickness of the asphalt concrete layers, the temperature and moisture content of different pavement layers, among sections, loaded and unloaded lanes (right and left wheel paths and tracks). The bearing capacity was evaluated by a falling weight deflectometer (FWD), temperature and moisture content by electronic sensors and thickness of AC layers by Georadar. Analysis of overall E0 and E0,h9 (bearing capacity at a depth of 9 cm from asphalt surface) data declares that seasonal impact on pavement structural strength due to a change of subgrade bearing capacity remains after correction of asphalt stiffness dependent on the temperature in the layer. However, it was detected that neither E0 nor E0,h9 are related to moisture content at a depths of 100 cm, 130 cm and 150 cm.

Experimental Study of Subgrade Bearing Capacity and Deformation Behavior of Rigid Pavement Due to Wet-Dry Cycles

Experimental Study of Subgrade Bearing Capacity and Deformation Behavior of Rigid Pavement Due to Wet-Dry Cycles

Ways to Minimize Volume (Weight) and Increase the Bearing Capacity of Rigid Pavement

The objective of research is finding of a possibility economy of rigid pavement weight and volume of material. The subject of the research is a mathematical model of rigid pavement in the form of a multilayer structure on an elastic foundation. The method of a research consists in modeling the behavior of rigid pavement in the form of a set of equations. These equations reflect the change in the stress-strain state of such structures. The system of equations takes into account the geometric nonlinearity of the work of materials and makes it possible to investigate the influence of various parameters on the values of stresses and displacements. Critical force coefficient and stress of shells are calculated by Bubnov-Galerkin. The formation way of the elastic foundation allows modeling the spreading layers with various characteristics. Use of two-layer model allows considering of a surface course and base course of road pavement designing (for example concrete and crushed stone). The graphs show the patterns of change of the stress of rigid pavement when changing the characteristics. The form of rigid pavement allowing to maintain big loadings is exposed to improvement. Findings shows the possibility of optimizing the geometric parameters of the design and achieving the savings in weight and volume of the consumable material.

Analysis of Load Bearing Capacity of Cement Concrete Airfield Pavement’s Construction in Relation to its’ Changes of Physico-Mechanical Parameters

An airfield pavement is a designated and properly prepared surface of an airfield functional element (AFE) fulfilling a specific task as part of air operations. A structural system of an airfield pavement is a set of layers, the task of which is to safely take over and transfer loads coming from moving aircraft onto the subsoil. The safety of air operations conducted by aircraft over airfield pavements most of all depends on the load-bearing capacity of their structures. The basic type of airfield pavements includes rigid pavements (elastic) made of cement concrete. The load-bearing capacity state of cement concrete airfield pavements are strongly impacted by concrete properties (physical, mechanical, rheological and resistance to environmental factors), as well as the condition and type of the subsoil directly under the evaluated pavement structure. Adopting an appropriate computational model for the evaluated structure, correct identification of the layers comprising the airfield pavement, accuracy of determining the technical parameters of materials sampled from the structure and a correct assessment of the load-bearing parameter of the subsoil directly under the assessed structure make the load-bearing end result expressed by a PCN index or the permissible number of air operations to be similar to actual conditions. The article presents the dependencies showing the impact of varying physico-mechanical parameters of concrete on the end results of the pavement load-bearing capacity.