Types Of Asphalt Pavement Research Articles

A Study on the Contact Characteristics of Tires-Roads Based on Pressure-Sensitive Film Technology.

Tire-road characteristics are a critical focus of research in the automotive and transportation industries. On the one hand, the research can help optimize tires' structural design; on the other hand, it can analyze the mechanical response of the pavement structure under the vehicle load. In addition, the non-uniformity distribution of the tire ground stress will also have a direct impact on the skid resistance, which determines the driving safety. Due to the limitation of testing technology, the measurement of tire ground pressure was mainly carried out on a flat test platform, ignoring the roughness of the actual pavement surface texture. The tire-road contact characteristics research on the macro-texture and micro-texture of asphalt pavement needs to be broken through. A high-precision pressure-sensitive film measurement system is utilized to examine the actual contact characteristics between two types of automobile tires and three types of asphalt pavement in this paper. The influence law of pavement texture and patterned tires on the contact area and stress was explored, and the concentration effect of tire-road contact stress was evaluated. The results indicate that the contact area of grounding tires exhibits a nearly linear relationship with tire inflation pressure and load. Notably, the change in load has a more significant influence on the contact area than tire inflation pressure. On asphalt pavement, the contact reduction rate decreases by approximately 5-10% for block pattern tires and 10-15% for longitudinal pattern tires. Furthermore, as the texture depth of the pavement increases, the contact area between tires and the pavement texture decreases. The actual tire-road interface experiences significant stress concentration due to the embedding and meshing effects between the tire and road surface. Even on a flat steel surface, the peak stress at the edge of the tread block exceeds the 0.7 MPa design load, which is about 2.5-3 times higher than the design uniform load. The peak stress between the tire and asphalt pavement reaches 4-10 times the design uniform load, with a rising trend as the pavement texture depth increases. This study can provide relevant experimental technical support for tire design and functional design of asphalt pavement.

Influence of Morphological Characteristics of Coarse Aggregates on Skid Resistance of Asphalt Pavement.

This research aims to improve the durability of skid resistance of asphalt pavement from the perspective of coarse aggregates based on on-site investigation. Firstly, the skid resistance of six representative actual roads was tested during two years by employing the Dynamic Friction Tester and the attenuation characteristics of skid resistance of different types of asphalt pavements were analyzed. Secondly, core samples were drilled onsite and coarse aggregates were extracted from the surface layer of the core samples. The morphological parameters of coarse aggregates were collected by a "backlighting photography" system and three-dimensional profilometer, and the variation rules of angularity and micro-texture of coarse aggregates were investigated. Finally, the correlation between the morphological characteristics of coarse aggregates and the pavement skid resistance was established based on the grey correlation entropy. The research results show that with the increase in service time, the attenuation rate of skid resistance of asphalt pavement gradually slows down; the angularity of coarse aggregates gradually decreases, and the micro-texture on the wearing surface gradually wears away. The grey correlation entropy between all the micro-texture indexes of coarse aggregates and dynamic friction coefficient, as well as between the roundness and skid resistance is more than 0.7, whereas the correlation between other evaluation indicators and the dynamic friction coefficient is poor, indicating that compared with the angularity of coarse aggregates, the micro-texture affects the skid resistance of actual asphalt pavement more greatly. In engineering applications, the use of coarse gradation, coarse aggregates with high roughness or high anti-wear performance can slow down the attenuation of pavement skid resistance, so that the pavement can maintain superior long-term anti-skidding performance.

Anti-Skid Characteristics of Asphalt Pavement Based on Partial Tire Aquaplane Conditions.

This study presented a finite element model of radial tire–asphalt pavement interaction using ABAQUS 6.14 software to investigate the skid resistance properties of asphalt pavement under partial tire aquaplane conditions. Firstly, the pavement profile datum acquired by laser scanning were imported to Finite Element Analysis (FEA) software to conduct the pavement modeling. Secondly, a steady state rolling analysis of a tire on three types of asphalt pavements under drying conditions was carried out. Variation laws of the friction coefficient of the radial tire on different pavements with different pavement textures, tire pressures, and loads on the tire were examined. Subsequently, calculation results of the steady state rolling analysis were transmitted to dynamic explicit analysis, and an aquaplane model of a radial tire on asphalt pavements was built by inputting the flow Euler grids. The tire–pavement adhesive characteristics under partial aquaplane conditions are discussed regarding the aquaplane model. Influences of the thickness of water film, the texture of asphalt pavement, and the rolling speed of the tire on the vertical pavement-tire contact force are analyzed. It is found that the vertical contact force between open graded friction course (OGFC) pavement and tire is the highest, followed by stone mastic asphalt (SMA) pavement and dense graded asphalt concrete (AC) pavement surface. The vertical contact force between tire and pavement will be greatly reduced, even with increasing speed or water film thickness. As tire speed increases from 70 km/h to 130 km/h, the tire–pavement contact force is reduced by about 25%. Moreover, when the thickness of water film increases from 0 (dry condition) to 4 mm and then to 12 mm, the vertical contact force reduced 50% and 15%, respectively, compared with under the dry contact condition. This study provided a key theoretical reference for safe driving on wet pavements.

Viscoelastic-Thermodynamic Model and Crack Propagation in Asphalt Concrete Pavement

Asphalt concrete pavement has a wide range of applications in the construction of high-grade highways. Asphalt concrete pavement has elastic properties, and its viscoelasticity and viscoplasticity are obviously affected by temperature. To determine whether a structure can continue to be used safely, it is most important to determine whether microscopic or macroscopic cracks present in the structure continue to propagate and cause structural failure. The purpose of this study was to study the effects of different ambient temperatures and mobile vehicles on the stress around the crack tip and the propagation path of different types of asphalt pavements. Based on the theory of fracture mechanics and viscoelasticity, this work studies the problem of crack propagation from a macroscopic perspective. It proposes to use the finite element method to analyze the crack problem in the pavement structure. With the help of ABAQUS software, a curved beam model with cracks was established for calculation, and moving loads and ambient temperature fields were added for analysis. The experimental results in this study show that with the decrease in the ambient temperature, the stress at the crack tip increases continuously. As the analysis time increases, the stress also increases. When the crack is smaller, the stress value at the tip is larger. When a = 15 mm, the stress value at the crack tip is the largest. However, when a = 20 mm and a = 25 mm, the stress at the crack tip is significantly reduced. It shows that the crack is easier to crack when the crack value is smaller. After the crack has grown to a certain length, the growth rate will slow down.

Evaluation on Distribution Characteristics of Pore Water Pressure within Saturated Pavement Structure Based on the Proposed Tire-Fluid-Pavement Coupling Model

To investigate the flow characteristics of pore water in asphalt pavement and the variation law of the pore water pressure under vehicle loading, a novel method based on BA network and quartet structure generation set method was proposed to reconstruct the three-dimensional (3D) pavement model with pores. The permeability coefficient and the gradation curve were adopted to evaluate the reliability and stability of the random growth pavement model. Then, the tire-fluid-pavement coupling model was established with FLUENT 3D based on the fluid Mie–Gruneisen state equation. According to the built fluid-solid coupling model, the pressure-velocity coupled finite volume algorithm was applied to study the distribution of the pore water pressure in asphalt pavement. Results show that the pore water pressure in asphalt pavement decays periodically with time under vehicle loading. For different types of asphalt pavement, the pore water pressure in open-graded friction course (OGFC) pavement is the smallest during the whole process. Moreover, the peak values of the pore water pressure decrease in the order of asphalt concrete (AC) pavement, stone mastic asphalt (SMA) pavement, and OGFC pavement. The maximum negative value of the pore water pressure is generally less than 0.3 times the maximum positive values. As for saturated pavement pores, the pore water pressure is hardly affected by the water film thickness. The positive peak value of the pore water pressure increases on an approximate parabolic curve as the vehicle speed improves gradually, while the negative one remains largely unchanged. The results are expected to help reduce tire hydroplaning risk and provide guidance for the selection of asphalt mixtures of drainage asphalt pavement.

Hysteresis friction modelling of BPT considering rubber penetration depth into road surface

ABSTRACT The British pendulum tester (BPT) provides a method to measure the skid resistance of pavement, which possesses both theoretical and practical engineering significance. This article aims to establish a numerical hysteresis friction model for BPT to reproduce the dynamic motion of the slider and estimate the pavement friction based on surface texture roughness, rubber viscoelasticity property and contact characteristics. The analytical hysteresis friction model was introduced based on one of the modern rubber friction theories. As an input parameter of this model, the average penetration depth of rubber was calculated based on the interfacial separation assumption. A numerical model was established by combining the geometric and motion characteristics of BPT. To validate the model, the self-affine characteristics of texture from four types of asphalt pavement were analysed; simultaneously, the storage and the loss modulus of rubber slider at various frequencies were obtained using the Zener constitutive model. As a result, the velocity of the slider decreases gradually with the dynamic fluctuation of the friction coefficient. A significant linear correlation was found between the predicted values and the measured data. This numerical friction model performs some potential for friction estimation. However, more conditions need considering for the improvement and practicability of the model.

スペクトログラムを用いた車いす走行時の路面推定

The sidewalks we use in our daily lives are made of various surface materials, such as asphalt pavement and concrete pavement. In terms of barrier-free access, Braille blocks are provided on the sidewalks. Barrier-free maps are also available to assist wheelchair users in their daily lives. The Barrier-Free Map shows the location of wheelchair-accessible restrooms and the status of barrier-free facilities at stations and stores. However, it does not indicate the type of road surface, deterioration conditions and other information necessary for wheelchair users to travel. Wheelchair users may experience problems in riding and driving due to uneven road surfaces, bumps, and joints between blocks. However, it is difficult to select a comfortable travel route in advance because the road surface condition cannot be determined without visiting the road. In addition, wheelchair users have the problem of not knowing whether they can drive on their own or need assistance without directly checking the road surface conditions. If the road conditions can be provided to wheelchair users in advance, they can take the most appropriate route. In this study, we report on a road surface estimation method that uses the vibrations generated during wheelchair driving. The following six types of road surfaces were used in the experiment. These road surfaces were wood flooring, two types of asphalt pavement, two types of interlocking block pavement, and a wood deck floor. The wheelchair used was equipped with four vibration sensors for data collection. The vibration sensors were mounted on a frame with casters and tires on its axis. The vibration data collected in the experiment was the result of a 20 [m] straight run on each of the road surfaces. For road surface estimation, a learning model was built for deep learning using spectrum images for the vibration data. As a result, five types of road surfaces could be discriminated with an accuracy of more than 80%.

Comparison of Treatment Timing between Aggregate Base and Full-Depth Asphalt Roads

AbstractAggregate base-course (ABC) pavements and full-depth asphalt (FDA) pavements are the two most commonly used types of asphalt pavements. During pavement design and pavement management, engin...

Comparative analysis of strain-pulse-based loading frequencies for three types of asphalt pavements via field tests with moving truck axle loading

The asphalt-based pavement performance evaluation includes the derivation of the dynamic moduli and loading frequencies of pavement layers under various traffic- and climatic-induced loading conditions. The traffic-induced strain pulses and loading frequencies of commonly used (semi-rigid, flexible, and steel deck) asphalt pavements were experimentally determined by vehicular loading field tests with embedded strain gauges for different axle loads, motion speeds, and temperatures. It was found that the axle load values had no noticeable effect on the pavement loading frequency, which was mainly controlled by the vehicular motion speed. The transverse frequencies were found to be higher than longitudinal ones, while the distributions of loading frequencies by pavement depth differed for three pavements under study. The frequency values at temperatures over 35 °C exceeded those at lower temperatures, while in the temperature range from 4 to 31 °C, the motion speed vs. loading frequency relations for three pavements were nearly identical. The loading frequency f increased approximately linearly with the motion speed V, according to the unified fitting equation for three types of pavements under study, namely f = 0.127 × V. This unified equation was further proved valid to predict the dynamic modulus properties of field asphalt pavement layers. Moreover, several previous prediction models for loading frequency, including the Brown model, Ullidtz model, MEPDG procedure and Ulloa model, were compared to the results in this study. These previous models were found to overestimate the loading frequencies within the asphalt layer. The prediction errors of the Brown model and the Ullidtz model were pronounced. The loading frequencies calculated by the MEPDG procedure and the Ulloa model need to be modified by dividing 2.8 and 1.7, respectively.

Splitting Strength Detection Test of Shallow Asphalt Pavement and Master Curve of Splitting Strength

In order to realize effective detection of the splitting strength of shallow asphalt pavement, using the self-researched and developed Strength Detector of Shallow Pavement, researched deep into the change regulation between shallow pavement strength and temperature by laboratory and spot penetrating experiments in multiple temperatures. First of all, the splitting strength is found to be a linear function of the average penetrating depth; Secondly, on the basis of temperature and average penetrating depth equivalence principle, obtained the master curve of the splitting strength by translation and fitting. Established a unified and practical test standard for the Strength Detector of Shallow Pavement; At last, analyzed the spot penetrating experiments data of three different types of asphalt pavement in Harbin district. The results show that the splitting strength curve of asphalt pavement in Harbin district appear a deep V-shaped character from April to October. The differentials between splitting strength of the three different types of asphalt pavement maximize in July.

The Improvement of PQI Density Testing Method of Considering Texture Depth of Asphalt Pavement

In recent years, nondestructive testing is applied more and more widely on the road detection, PQI as a kind of advanced testing equipment in asphalt pavement detection, it has been paid great attention by the road testing personnel. Based on the analysis of the densities which measured by PQI of different types of asphalt pavement, it sums up that the surface texture depth of asphalt pavement significantly affects the measuring accuracy of the density of PQI. In this paper, it suggests to use sand to fill the surface texture depth of asphalt pavement combining with PQI for pavement density measurement. Field testing shows that, compared with the bulk density of core sampling method, the density measured by PQI has obviously been affected by the surface texture depth of asphalt pavement. As the surface texture depth of the asphalt pavement is deeper, the error between the two methods is larger. Considering the influence of texture depth, the author improved the PQI detection method. The improved method shows that, compared with the bulk density of the core sampling, the coefficient of variation of the original testing method is 10.2%, and the new method is 3.8%. In the original testing method , it use the average value of the core sample densities as the compensation value of PQI measurement in the degree of compaction testing, and the maximum measurement error reached up to 2.2%. While, the improved testing method use the average value of the core sample densities as the compensation value of PQI measurement, the maximum measurement error reduces to 0.7%, the accuracy of the testing result is significantly improved.

CT Real-Time Analysis of Meso-Damage Propagation Law of Asphalt Concrete

Cracking is one of the major distress types of asphalt pavements. Expected life of pavements, pavement condition and maintenance cost are directly related to pavement cracking. It is necessary to promote the understanding of cracking mechanism of hot mix asphalt (HMA) based on fracture mechanics. Simulation, surveying, observation, and measurement of cracking in pavement structures have been reported in literature in last three decades. However, cracking process in asphalt mixtures in a three dimensional scale is still a great challenge to road engineers. This paper reports a research effort of dynamic observation of the micro-fracture process of asphalt mixture under compressed condition using CT (computerized tomography) method. Through CT scanning, the clear CT images, which include the microcrack compressed, growth, bifurcation, development, the crack fracture, and the asphalt concrete sample failure were obtained. The CT numbers, CT images and the other data were analyzed. Analysis of the relationship between of CT number and volumetric strain suggests that damage value at zero volumetric strain can be used as threshold point in damage analysis. Corresponding stress value can be used as maximum allowable stress in design practice.