Damage In Asphalt Mixtures Research Articles

Effects of Aging and Moisture Damage on Asphaltic Mixture

Moisture damage in asphalt mixtures refers to the loss of strength and durability due to the presence of water. Road network is showing severe deterioration such as raveling and stripping because the bond between aggregates and asphalt film is broken due to water intrusion. To minimize moisture damage asphalt mixes are investigated to evaluate the effect of air voids degree of saturation media of attack and the conditioning period. Moisture damage is one of the major issues in asphalt distress. It is due to the adhesive and cohesive failure of the asphalt mixture and it will shorten pavement life. Moisture-sensitive mixtures need to be identified during the course of the mixture design process which fulfil the specified minimum standard. The laboratory testing procedures currently available for compacted Hot Mix Asphalt (HMA) to test the moisture sensitivity were primarily developed to determine the degree of resistance to moisture damage by a particular combination of asphalt and aggregate. These moisture sensitivity tests evaluate the effect of moisture damage in the laboratory by measuring the relative change of a single parameter before and after conditioning (i.e. Tensile Strength Ratio Resilient Modulus Ratio).

Measuring moisture damage of hot-mix asphalt (HMA) by digital imaging-assisted modified boiling test (ASTM D3625): Recent advancements and further investigation

Boiling water test (ASTM D3626) has been utilized to investigate the moisture susceptibility of asphalt mixture for decades. It was originally intended to compare the relative moisture resistance of a few mixtures, and the degree of stripping after the boiling was recorded based on visual observations. In recent years, several digital imaging-assisted modified boiling tests have been proposed, which significantly improved the accuracy of test results. This paper reviewed the recent advancements (2009–2022) in different test methods by digital imaging. The limitations and challenges of each method were also discussed and compared to each other. In addition, further experiments were performed to investigate the effect of aging, boiling time and water quality on the coating ratios. The boiling test results of sixty loose mixtures were compared to the tensile strength ratios (TSRs). Based on the results, the boiling water test with enhanced accuracy by image processing can be potentially developed as a measure of field performance. More importantly, the test should be conducted immediately after the mixing of asphalt and aggregate, and the aging of asphalt mixtures could significantly increase the results of coating ratios up to 100%, which made the boiling test unable to identify moisture susceptibility. It was found that the boiling water could not strip asphalt from aggregate after a long time of aging even though the moisture damage occurred and weakened the bond between asphalt and aggregate. In addition, the water quality could considerably influence the boiling test results, and the use of distilled water might underestimate the moisture damage of asphalt mixtures subjected to acid rain.

Wavelet and fractal analysis of acoustic emission characteristic of fatigue damage of asphalt mixtures

Fatigue cracking of asphalt materials directly affects the performance and safety of asphalt pavements. It is necessary to identify the materials condition with acoustic emission (AE) as the real time monitoring technique. The objective of this study was to diagnose the damage behavior of asphalt mixtures from the time and frequency characteristics of AE signals. Firstly, the semi-circular bending (SCB) fatigue test and AE detection were conducted to explore the AE response of asphalt mixtures subjected to cyclic loads. Then, the Fast Fourier Transform (FFT) and Continuous Wavelet Transform (CWT) were applied to discuss the dominant frequency characteristics and time–frequency distribution of AE waveforms. Finally, an index (RBD), defined as the ratio of fractal dimension of AE waveforms decomposed by the Discrete Wavelet Transform (DWT), was proposed to evaluate the damage state of asphalt mixtures. The results show that AE energy rate exhibits distinct variation signatures at different damage stages. The average frequency (AF) and rise angle (RA) of AE signals reveal that the coupling effect of tensile and shear cracks promotes the deterioration of asphalt mixtures. Most of the dominant frequencies of AE events generated from cracks are concentrated within the range of 13 to 30 kHz. The discrepancies in the time–frequency distribution of AE events could effectively discriminate the types of damage sources. The proposed index RBD is sensitive to the change of damage state of asphalt mixtures, producing corresponding reductions.

Investigation of the solution effects on asphalt binder and mastic through molecular dynamics simulations

• Solution increased the electrostatic effect and interaction energy in asphalt binder and mastic. • The moisture damage on the asphalt-aggregate interface was the most obvious under alkaline erosion. • The moisture susceptibility of interface of mastic is lower than that of the binder. The asphalt mixture is easily affected by water erosion with different solutes. The molecular dynamics (MD) simulation method was adopted to explore the influence of solute on the nanostructure and interface interaction of both virgin/SBS asphalt binder and mastic. The changes of potential energy of asphalt solution erosion model (ASEM), as well as fractions aggregation caused by water molecules were observed. Moreover, differences on diffusion of water molecules caused by the studied solutes were explained. On this basis, the analysis of hydrogen bonds is also carried out. The results showed that saline/alkali solutes hindered the diffusion of water molecules, where water molecules in saline environment behaved the slowest diffusion rate. Meanwhile, salt maximized the hydrogen bond adsorption of water molecules on the surface of filler (silica). The mastic with a filler/binder ratio of 1.2 had the highest diffusion coefficient. From the interface perspective, an obvious interaction between calcite and solution was detected, and the salt and alkali proceeded the debonding effect of original water condition. The alkali solution led to the greatest moisture damage to the asphalt-solution-aggregate model (ASAM), followed by the saline solution. In this case, the SBS asphalt binder/mastic exhibited a higher water stability than the virgin. This study contributed to a basic reference for understanding the moisture-induced damage of asphalt mixtures under various solution conditions.

Characterization of mesoscale fracture damage of asphalt mixtures with basalt fiber by environmental scanning electron microscopy

The crack resistance of asphalt mixture determines the service life of asphalt pavement to a great extent. Pavement cracking is strongly influenced by the internal structures of asphalt mixtures, such as the aggregate skeleton and the interstitial components (i.e., fine aggregate matrix (FAM)). Basalt fiber is widely used for cracking resistance in asphalt mixtures because of its excellent mechanical properties. However, due to the lack of an effective real-time observation technique, the damage suppression mechanism of basalt fiber in the asphalt mixture is unclear.This study aims to develop a novel methodology that can effectively characterize the evolution of instantaneous damage of asphalt mixture with basalt fiber and assess its fracture properties. This methodology is based on the characterization of the FAM (i.e., the fine matrix portion that governs cracking performance) through a mesoscopic tension test termed the in-situ direct tension (ISDT) test. The mixtures with and without basalt fiber were designed for consideration. The semicircular bending (SCB) and the ISDT tests were conducted to compare the fracture properties between the asphalt mixture and FAM. The fracture property indices were calibrated using the feature parameters of force–displacement curves. The sigmoidal-shaped crack area density model was proposed with consideration of the full development of the cracking area density curve.The results show that the asphalt mixture and FAM have a comparable increasing trend in fracture energy and fracture toughness with the increase of basalt fiber content. The lagging effect of crack initiation and propagation was observed in fiber asphalt mixtures and FAM. The results indicate that the lagging effect of the asphalt mixture on the fine portion controls the crack propagation speed. It is valuable to investigate the fracture property of the fine portion rather than focusing on that of the whole asphalt mixtures. The proposed ISDT test can be recognized as an efficient implementation to evaluate the fracture performance of fiber asphalt mixtures.

Waste Polyethylene Terephthalate granules modified by gamma irradiation and their effect as fine aggregates on moisture damage of asphalt mixtures

Recently, the excessive quantity of waste polyethylene terephthalate (WPET) creates a significant environmental concern globally. One way to reuse WPET is in the pavement industry as secondary materials. Nevertheless, based on works of literature review on the use of WPET in asphalt materials, inconsistent findings were reported with an increase and decrease in mechanical properties. To overcome this issue, gamma radiation has been utilized on the WPET. This study investigated the effect of using non-irradiated and irradiated WPET on some engineering properties of asphalt mixes. Marshall Samples incorporating a various amount of WPET (Plastiphalt); 0%, 0.5%, 1.0%, 1.5%, 2.0% and 2.5% by weight of total aggregates were tested based on Marshall Stability (MS), indirect tensile strength (ITS), and resistance to moisture damage. The results of x-ray diffraction (XRD) on the irradiated WPET showed that the degree of crystallinity had increased. The results of Marshall Stability (MS) showed an enhancement with increasing WPET content up to 2.0% for the plastiphalt mixes. Marshall Quotient, and ITS show a decreasing trend with increasing WPET amount for the plastiphalt mixes. Furthermore, results on moisture damage resistance indicated that indirect tensile strength and Marshall Stability ratios were marginally increased for plastiphalt mixes compared to the reference mixture (0% WPET). Comparing the moisture sensitivity tolerance results for the WPET modified mixes shows that irradiated WPET plastiphalt mixes had a better outcome than non-irradiated WPET plastiphalt mixes.

Study on flexural properties of coal gangue powder asphalt mixture under freeze-thaw cycles

In order to study the influence of freeze-thaw cycle on the flexural performance of asphalt pavement, semi-circular flexural test (SCB) is carried out. Coal gangue powder (accounting for 0%, 25%, 50%, 75% and 100% by weight of ore powder) is used to replace ore powder to improve the freeze-thaw resistance of asphalt.According to the test data, the load-displacement curve is drawn, the ultimate tensile stress() is studied, and the variation law of different coal gangue powder replacement rates under different freeze-thaw cycles (0, 2, 4, and 6 times) is analyzed by ultimate tensile stress. The test results show that the best replacement rate of coal gangue powder is 50%, and decreases with the increase of freeze-thaw cycles, so adding coal gangue powder can reduce the influence of freeze-thaw cycles on the bending performance of asphalt pavement. By analyzing the load-displacement curve, energy indexes such as WD(total work from initial failure to complete failure), WU(energy dissipation from initial failure to complete failure), WS(work from initial failure to specimen failure) and are obtained. In the freeze-thaw cycle, with the increase of cycle times, the energy consumption of WD, WU and WS decreases, which aggravates the damage of asphalt mixture and reduces the flexural capacity of specimens. Among them, six freeze-thaw cycles have the lowest flexural capacity of specimens, indicating that freeze-thaw damage directly affects the flexural performance of asphalt mixture.

Moisture Damage Assessment of Asphalt Mixture using Eatons Reagent

Abstract: The main purpose of this research work was to create a correlation model called a moisture damage index, that could predict moisture damage probability in both qualitative and quantitative test regimes. To determine the effect on moisture damage of asphalt mixture, chemical-based modifiers and single aggregate sources, such as calcium carbonate, were selected. Eaton's Reagent, i.e., Phosphorous Pentoxide in Methane Sulphonic Acid, is used to make modified bitumen in this research. Eaton's Reagent is made in a laboratory with a 1:10 synthesis formula and a unique technique. Base binders are changed with varied amounts of Phosphorus Methyl Compound (PMC) by weight of optimum binder content i-e 0.25%, 0.50%, 0.75% & 1.00%. To establish a moisture damage index, the dosage of Eaton's Reagent was optimised using both qualitative and quantitative measurements. This reagent interacts strongly with the asphaltene fraction of bitumen rather than the maltenes portion, resulting in a higher service temperature than the base binder. Asphalt mixtures were prepared and tested using performance testing to verify the effect of phosphorous methyl compound on their performance. The boiling water test was simple to administer and took less time, while the rolling bottle test was found to be more reliable than other qualitative tests. Although Marshal stability was easy to perform in quantitative tests, while the Hamburg wheel track test were shown to be more effective in determining moisture susceptibility with a reasonable level of confidence. A testing regime compromises of qualitative as well as quantitative tests to ascertain relative accuracy of each test on moisture damage. Keywords: Eaton’s Reagent; Asphalt mixtures; Loss of adhesion; moisture damage; limestone

Moisture susceptibility of asphalt mixtures: 2S2P1D rheological model approach and new index based on dynamic modulus master curve changes

A methodology is proposed for evaluating the induced moisture damage in asphalt mixtures via a new index called the dynamic modulus area ratio (DMAR), which is used to calculate the difference under the areas of the dynamic modulus master curves fitted by the 2S2P1D model before and after conditioning. Were evaluated 21 mixtures applied in the field by comparing data obtained via empirical tests, e.g., the tensile strength ratio and dynamic modulus ratio, using AASHTO T283. The behavior that moisture damage analysis based on stiffness loss measurements in modulus tests can lead to different conclusions than those based on damage resistance tests like TSR. The 2S2P1D model proved to be adequate to evaluate the changes promoted by the deleterious effect of water on the stiffness of the mixtures after the induced moisture damage cycle. For the DMAR, the results clearly differed according to the type of binder, indicating that the impact of water damage on the linear viscoelastic behavior depends on the type of binder used in the mixture. The estimation of susceptibility to moisture using the DMAR, which assesses broader temperature and frequency ranges, enables a stiffness evaluation that is closely related to the field impact on this property, making it possible to evaluate variations in the entire stiffness spectra of the mixtures; thus, it can be used in methods based on the performance for the selection of asphalt mixtures.

A mass specific volume-based viscoelastic damage model to characterize fatigue damage in asphalt mixtures

Fatigue cracking is one of the most common distresses in flexible pavements, and many damage models have been proposed to predict fatigue cracking, but in these models, the evaluation of damage is related to the choice of the reference configuration, whose subjectivity may lead to subjective evaluation of damage. To describe micro-cracking in asphalt concrete under loading, this paper proposes a new viscoelastic damage model, where damage evolution is connected with the mass specific volume, which is independent of the reference configuration, and the resistance to damage is also represented as an exponential function of mass specific volume to show its decrease under destructive loading. To determine material parameters in the model, nondestructive creep test data are used to obtain the relaxation modulus, and by determining the initial resistance to damage of asphalt concrete with different air voids, the evolution of resistance to damage can be obtained. The rest material parameters can be determined by fitting the destructive test data. To verify the validity of the proposed model, the material behavior under controlled-strain repeated direct tension (RDT) is predicted and the model predictions are compared with test data. It shows and the damage increment in the first loading cycle is largest and the rate of damage increases first and then decreases in each cyclic loading period. In addition, the behavior of the pavement structure under traffic loading is simulated, and fatigue cracking in the asphalt concrete layer of the pavement can be captured by the proposed model. It shows that in thick flexible pavements, both top-down cracking and bottom-up cracking occurs, but top-down cracking is dominant.

Characterisation of fatigue damage in asphalt mixtures using X-ray computed tomography

The high-resolution X-ray CT was applied to investigate the fatigue damage evolution of asphalt mixtures. The detailed Xray CT images in the centre of the samples were used to characterise the fatigue cracking and air voids increase at different vertical deformations. Air void content and surface area distribution before and after loading were also analysed. The results show that the main failure mode of asphalt mixtures at low temperature is debonding at the interface between aggregates and mastic, which is an adhesive failure. The maximum change of air void content due to fatigue damage often occurs near the middle of the sample. Cracks were observed in and around flat and elongated aggregates and on aggregates with insufficient fracture faces, demonstrating the effects of aggregate angularity and shape on fatigue cracking. The microcracks develop continuously throughout the entire fatigue process.

Measuring moisture damage of asphalt mixtures: The development of a new modified boiling test based on color image processing

A new digital image processing method based on color images was developed to analyze the coating quality of asphalt mixtures with moisture damage. The asphalt coating ratio can be measured automatically and objectively, improving the accuracy of boiling test (ASTM D3625). This method is based on RGB color model and the characteristic color pixels representing virgin aggregate are directly utilized to search the damaged areas. The developed color image processing was compared to the two existing digital imaging methods. The selection of threshold value was a subjective process in the binary image processing. The problem of the grayscale-based image processing was the lack of a reasonable method to obtain the representative image of virgin aggregate. Also, the light reflection on asphalt and the shadow between aggregates might lead to grave errors. In contrast, the proposed method could avoid those issues and realize the objective inspection of stripping in asphalt mixtures.

Wavelet and Fractal Analysis of Acoustic Emission Characteristic of Fatigue Damage of Asphalt Mixtures

Wavelet and Fractal Analysis of Acoustic Emission Characteristic of Fatigue Damage of Asphalt Mixtures

Response of Asphalt Pavement Structure Layer and Particle Movement Velocity Based on Particle Flow Theory

AbstractAn asphalt mixture is a heterogeneous material composed of coarse/fine aggregate, asphalt, and admixtures. The damage of asphalt mixtures under vehicle load is closely related to the moveme...

Evaluation of Moisture Damage in Asphalt Mixtures at Macro- and Nanoscales

AbstractThe aim of this study was to examine the effects of different additives on the moisture resistance of asphalt binders using atomic force microscopy (AFM), and to correlate the results with ...

Evaluating Moisture Damage Using Impact Resonance Test

Abstract Moisture damage in asphalt mixtures has been a major cause for premature failure of asphalt pavements for decades. Although a lot of research has been done and many test methods have been developed to evaluate moisture damage in asphalt mixtures, not much research has been done on the use of nondestructive testing techniques to evaluate moisture damage in asphalt mixtures. The impact resonance (IR) test is a nondestructive test that is used to determine material properties like dynamic elastic modulus. The IR test on asphalt mixtures is done on a thin-disk specimen (150-mm diameter and 25-mm thickness). In this study, the IR test was used to assess moisture damage in asphalt mixtures by determining the resonant frequency of asphalt mixture samples in the unconditioned and moisture conditioned state. The relative reduction (ER) in dynamic elastic modulus was calculated as the ratio of the resonant frequency of conditioned and unconditioned specimens from the IR test, which was used to evaluate moisture damage. Moisture sensitivity of the asphalt mixtures was also determined by the tensile strength ratio (TSR) test. Two different moisture conditioning procedures were used for both the IR test and TSR test—modified AASHTO T 283 (Standard Method of Test for Resistance of Compacted Asphalt Mixtures to Moisture-Induced Damage) and Moisture Induced Stress Tester (MIST) conditioning. Six different mixtures from three different aggregate sources were used in this study. A good correlation was observed between TSR values from the TSR test using both conditioning procedures and the ER values from the IR test using both conditioning procedures for the asphalt mixtures used in this study. This study shows that the IR test can be used to evaluate moisture damage in asphalt mixtures. This study also explored the effects of various parameters such as support condition, impact source, and impact location on the resonant frequency from the IR test.

Multiscale model for predicting freeze-thaw damage in asphalt mixtures

ABSTRACT Freeze-thaw cycles in combination with long-term moisture exposure and traffic is a major threat to the performance of asphalt pavements. To enable characterisation and understanding of the damage process, this paper presents a new thermodynamics-based multiscale model of freeze-thaw damage in asphalt mixtures which also accounts for the damage due to moisture and traffic. The developed model consists of a microscale and a macroscale and is thereby able to account for the effect of the different microscale material components on the homogenous macroscale damage development. Additionally, the model is able to account for the acceleration of freeze-thaw damage which occurs when moisture infiltrates a damaged pavement with an increased effective air void content between freeze-thaw cycles. The novelty of the model lies in the ability to simulate the in-time acceleration of damage, the combined deteriorating effect of freeze-thaw cycles, moisture and traffic, as well as the coupling of the two scales to enable accurate predictions and understanding of the damage evolution. These features are demonstrated through a set of parametric examples which demonstrate the importance of including the effect of long-term moisture exposure and freeze-thaw cycles as well as the coupling between the different damage modes.

Damage Fracture Characterization of Asphalt Mixtures Considering Freeze-Thaw Cycling and Aging Effects Based on Acoustic Emission Monitoring.

Freeze–thaw (F–T) cycling and aging effects are the main factors contributing to the deterioration of asphalt mixtures. The acoustic emission (AE) technique enables real-time detection regarding the evolution of internal damage in asphalt mixtures during the loading process. This study set out to investigate the effects of F–T cycling and aging on the damage characteristics of asphalt mixture under splitting loads. Firstly, the Marshall specimens were prepared and then exposed to various numbers of F–T cycles (one, three, five, and seven) and different durations of aging (short-term aging and long-term aging for 24, 72, 120 and 168 h), after which the specimens were loaded by means of indirect tensile (IDT) testing, and corresponding parameters were synchronously collected by the AE acquisition system during the fracture process. Finally, the energy, cumulative energy and peak frequency were selected to investigate the damage mechanisms of asphalt mixtures. The findings demonstrate that the AE parameters provided effective identification of the deterioration for all specimens in real-time, and that the F–T cycling and aging effects altered the damage characteristics of asphalt mixtures, causing early damage, exacerbating the formation of micro-cracks in the early stage, accelerating the expansion of macro-cracks and advancing the debonding between the asphalt and aggregates. The findings of this study provide further insight into the mechanism of F–T cycling and aging effects on the deterioration of asphalt mixture.

Effectiveness of Loaded Wheel Tracking Test to Ascertain Moisture Susceptibility of Asphalt Mixtures

Moisture damage of asphalt mixtures is a major distress affecting the durability of asphalt pavements. The loaded wheel tracking (LWT) test is gaining popularity in determining moisture damage because of its ability to relate laboratory performance to field performance. However, the accuracy of LWT’s “pass/fail” criteria for screening mixtures is limited. The objective of this study was to evaluate the capability of the LWT test to identify moisture susceptibility of asphalt mixtures with different moisture conditioning protocols. Seven 12.5 mm asphalt mixtures with two asphalt binder types (unmodified PG 67-22 and modified PG 70-22), and three aggregate types (limestone, crushed gravel, and a semi-crushed gravel) were utilized. Asphalt binder and mixture samples were subjected to five conditioning levels, namely, a control; single freeze–thaw-; triple freeze–thaw-; MiST 3500 cycles; and MiST 7000 cycles. Frequency sweep at multiple temperatures and frequencies, and multiple stress creep recovery tests were performed to evaluate asphalt binders. LWT test was used to evaluate the asphalt mixture samples. Freeze–thaw and MiST conditioning resulted in an increase in stiffness in the asphalt binders as compared with the control. Further, freeze–thaw and MiST conditioning resulted in an increase in rut depth compared with the control asphalt mixture. The conditioning protocols evaluated were effective in exposing moisture-sensitive mixtures, which initially showed compliance with Louisiana asphalt mixture design specifications.

Research on Asphalt Mixture Bending Test and Micromechanical Evolution Based on 2D Discrete-Element Method

AbstractThe damage of asphalt mixture is closely related to its internal material heterogeneity and discontinuity. The mechanical evolution of asphalt mixture is analyzed by meso-mechanics theory, ...