Durability Of Asphalt Pavement Research Articles

Development of fatigue damage model of asphalt mixtures based on small-scale accelerated pavement test

As the primary surface type for high-grade Chinese highways, the long-term performance of asphalt pavement can affect significantly transportation efficiency. It has been confirmed that fatigue cracking is one of the major failure modes for asphalt pavement, which can cause a great reduction of asphalt pavement durability. Currently, the fatigue properties of asphalt mixtures are evaluated mainly based on traditional laboratory fatigue tests, such as bending fatigue tests and indirect tensile fatigue tests. However, none of these fatigue test methods can realistically evaluate the fatigue performance of asphalt pavement under the repeated wheel load. To resolve this issue, the model mobile load simulator (MMLS3), which is a small-scale accelerated pavement test device, was utilized to evaluate the fatigue life of six kinds of asphalt mixtures. The fatigue damage variable was defined as stiffness reduction. Based on the small-scale accelerated pavement test, a stiffness reduction model for asphalt mixtures was determined. A stiffness reduction law for asphalt mixtures during the fatigue process was proposed. The stiffness evolution process could be divided into three phases, which are the adaptation phase, the quasi-stationary phase, and the failure phase. A maximum value of the rate of stiffness reduction from the quasi-stationary phase into the failure phase was proposed as the failure threshold. Besides the fatigue life obtained from the failure criteria had a good agreement with the test results. The results from this research can be used as a theoretical reference for evaluating the fatigue life of asphalt mixtures and improving the durability of asphalt pavement.

Aging and Rheological Properties of Latex and Crumb Rubber Modified Bitumen Using Dynamic Shear Rheometer

Rubberized bitumen technology has been applied for a long time to enhance the performance of the asphalt pavement. In this research, the influence of natural rubber (NR) latex and crumb rubber (CR) on the conventional and rheological characteristics of 80/100 penetration grade bitumen before and after aging was compared. Conventional tests of penetration, ring and ball temperature, and ductility were conducted to evaluate the consistency of base bitumen and rubberized bitumen. A dynamic shear rheometer (DSR) test was carried out to evaluate the viscoelastic characteristics of the base and rubberized bitumen. The results showed that the addition of NR latex and CR reduced the penetration grade and increased the ring and ball temperature and ductility of the rubberized bitumen. This indicates that promising enhancement of the bitumen properties can be expected with the addition of NR latex and CR. The rheological properties analysis results showed that addition of CR up to 8% and NR latex up to 4% improved the complex modulus and rutting resistance of the rubberized bitumen compared to conventional bitumen. This indicates that the application of NR latex and CR in bitumen modification is expected to improve the durability of asphalt pavement.

Engineering and rheological properties of asphalt binders modified with microwave preprocessed GTR

Many researches and field applications have proven that binders modified with ground tire rubber (GTR) can significantly improve rutting resistance potential and durability of asphalt pavement. However, GTR modified asphalt binder has higher viscosity and poorer hot storage stability than base one resulting in construction troubles, such as more energy consumption, extra stirring, reduction in asphalt mixtures performance and etc. The objective of this study was to investigate the engineering and rheological properties of binders prepared with microwave preprocessed GTR at high service temperature, medium temperature, and low temperature, respectively. The experiment included two particle sizes of GTR and five microwave preprocessing radiation intensities. The dynamic shear rheometer (DSR), force ductility test (FDT) and hot storage test were performed to evaluate the effect of radiation intensities and particle sizes of GTR on the engineering and rheological characteristics from low to high temperature. The test results show that microwave preprocessed GTR modified binders presented a reduction trend in composite viscosity, as well as rutting resistance potential after exposing to microwave radiation. In addition, fatigue and low temperature tension properties were jointly affected by microwave radiation intensities and GTR particle size. Otherwise, lower phase separation tendency compared with binder modified with GTR without microwave radiation was observed in this study. Thus, comprehensive consideration of radiation intensities and GTR particles sizes were recommended to apply in the field.

Influence of Natural Zeolite and Paraffin Wax on Adhesion Strength Between Bitumen and Aggregate

Asphalt mixture that is used for the construction of flexible pavements is mainly composed of two constituents i.e. bitumen and aggregate. Sturdy adhesion among bitumen and aggregate is the sign of durability of asphalt pavements. Adhesion is considered as one of the most important factors for sustainable asphalt pavement. This is the motive why its miles utmost important to deeply understand the phenomenon of adhesion considering the effect of alternate in temperature, moisture conditions. In this study softer binder 80/100 was selected that has less adhesion compared to hard pen grades. Limestone aggregates which is commonly used for the construction of asphalt pavements has also been selected. Two types of modifiers (Zeolite and Paraffin Wax) were selected because of the extensive use in asphalt foaming and the polymer modified asphalt mixtures as temperature reducing agent. To investigate the strength of adhesive bond, Bitumen Bond Strength (BBS) was performed at different temperatures, in dry, and wet conditions. To quantify the effect of modifiers on penetration grade and softening point conventional testing is performed. For performance grading, the PG test was performed using Dynamic Shear Rheometer. The comparisons were developed among pull of tensile strength at dry and after 72hrs water conditioning while preserving the temperature at 25 .To check the effect of temperature BBS is performed at 15 . The results illustrate that 2% zeolite shows best results in terms of adhesion and performance grade while Paraffin wax has less adhesion and poor performance grade.

Influence of Coarse-Aggregate Angularity on Asphalt Mixture Macroperformance: Skid Resistance, High-Temperature, and Compaction Performance

AbstractMacroperformance, i.e., skid resistance, high-temperature, and compaction performance, are related to the functional performance, safety, and durability of asphalt pavement. Currently, the ...

Comparative study on durability of different composite modified asphalt mixtures

The durability of asphalt mixture is one of the main indicators of the mechanical performance of asphalt pavement. Three kinds of composite modified asphalts (4%SBS/3%SBR, 4%SBS/15% rubber powder and 4%SBR/15% rubber powder) were chosen as binders. Three kinds of aggregate gradation (AC-13, AC-16, AC-20) were used to design composite modified asphalt mixture. The durability (ageing, accumulation and fatigue) of composite modified asphalt mixture was compared and analysed. The study includes comparative study on mechanical performance of composite modified asphalt with different ageing time (0, 5 and 20 h), comparative study on plastic deformation accumulation of composite modified asphalt mixture with different loading times and comparative study on fatigue characteristics of different composite modified asphalt mixtures based on strain. The findings have some theoretical and practical values for increasing the durability of asphalt pavement.

Mixture-based rheological evaluation tool for cracking in asphalt pavements

Cracking is a major distress that limits the durability of asphalt pavements. Various fatigue and fracture-based tests and analyses can be used to assess cracking resistance of asphalt mixtures in order to design more economical and durable mixtures. This mixture cracking resistance is affected by the rheological properties of the asphalt binder, both stiffness and relaxation ability as indicated by measured dynamic modulus and phase angle, respectively. One significant breakthrough involves the use of binder Black space (shear modulus versus phase angle) and the Glover–Rowe (G-R) parameter that is a function of these two rheological properties as an indication of cracking resistance. However, binder characterisation is not adequate to fully represent mixture performance and therefore there is a need for a mixture-based evaluation tool. The objectives of this study were to: (1) investigate the applicability of a representative temperature and frequency combination for mixture-based Black space evaluation; (2) evaluate the ability of mixture Black space to track the effect of aging and rejuvenation (when recycling agents are used with recycled materials); (3) explore the use of a mixture-based G-R parameter (G-Rm) for cracking resistance evaluation and (4) investigate a possible correlation between G-Rm and Flexibility Index (FI) from a semi-circular bending (SCB) test. Test results indicate a reliable temperature–frequency combination for G-Rm, which was sensitive to aging, recycled materials content, binder performance grade and recycling agent dose. Test results also indicate a good correlation between the G-Rm parameter and the FI.

Improvement of Asphalt-Aggregate Adhesion Using Plant Ash Byproduct

The adhesion bonding between asphalt and aggregate significantly influences field performance and durability of asphalt pavement. Adhesion promoters are typically used to improve asphalt-aggregate bonding and minimize moisture-related pavement damage, such as cracking and raveling. This study evaluated the effectiveness of plant ash byproduct as adhesion promoter to improve asphalt-aggregate adhesion performance. Three commonly used aggregate types (granite, basic rock, and limestone) and two asphalt binder types were used in laboratory testing. A modified stripping test method was developed to evaluate test results with image analysis and measurement of asphalt film thickness. The contact angle test and scanning electron microscopy (SEM) with energy disperse spectroscopy (EDS) were conducted. Test results showed that plant ash lixivium significantly improved asphalt-aggregate adhesion. Among three aggregate types, granite yielded the worst asphalt-aggregate adhesion for both control and treated specimens. The effectiveness of adhesion promotion varied depending on the type of asphalt or aggregate and temperature. The SEM/EDS observations showed that the mesh-like crystalline was formed at the interface between asphalt binder and aggregate in the treated specimen, which was believed to enhance the interfacial bonding and prevent asphalt film peeling off from aggregate.

Influence of Overheating Phenomenon on Bitumen and Asphalt Mixture Properties

In the course of manufacturing, transport and installation, road bitumens and asphalt mixtures can be exposed to the impact of elevated process temperatures exceeding 240 °C. This mainly applies to the mixtures used for road pavements and bridge deck insulation during adverse weather conditions. The heating process should not change the basic and rheological properties of binders and the asphalt mixtures that to a degree cause the degradation of asphalt pavement durability. The work involved analyzing the properties of non-modified bitumens and SBS polymer modified bitumens, heated at temperatures of 200 °C, 250 °C and 300 °C for 1 h. Next, the asphalt mixtures were heated in the same temperatures. Based on the developed Overheating Degradation Index (ODI) it was demonstrated that polymer-modified bitumens were characterized by higher overheating sensitivity A(ODI) than non-modified bitumens, which was confirmed by mixture test results. Overheating limit temperatures T(ODI) were determined, which in the case of polymer-modified bitumens are up to 20 °C lower than for non-modified bitumens. When the temperature increases above T(ODI), loss of viscoelastic properties occurs in the material which causes, among other effects, a loss of resistance to fatigue cracking.

Atomic force microscope study of the aging/rejuvenating effect on asphalt morphology and adhesion performance

Asphalt aging is one of the most severe threats to the asphalt pavement durability and rejuvenation with cooking oil can help to resolve this issue. Currently, the influence of aging/rejuvenation on the bonding performance of asphalt binder has not been fully understood. This study aims to unveil the influence of aging/rejuvenation on the adhesion performance under both micro and macro scale tests. Three type asphalt binders were examined in this study, including the original, aged and rejuvenated samples. The atomic force microscope (AFM) was first applied to examine the surface morphology and adhesion performance of the three type asphalt samples. It is found that the aging effect can increase the adhesion between asphalt binder and silica particles and the adhesion force can be further enhanced through rejuvenation. Then the three-point bending was further conducted to examine adhesion performance at the macroscale, and the obtained results are in accordance with those obtained at the microscale. However, the slant shear test indicated the shear bond strength can be reduced due to the rejuvenation with vegetable oil, which can be generated due to the lubrication effect of the oil. The results in this study can help to better understand the influence of aging and rejuvenation on the bond performance between asphalt binder and mineral aggregate.

Mechanical and compaction properties of graphite nanoplatelet-modified asphalt binders and mixtures

This paper presents an experimental investigation of the properties of asphalt binders and mixtures modified with graphite nanoplatelets (GNPs). The focus is on studying the effects of GNP addition on low-temperature rheological and fracture properties of asphalt binders and mixtures and on compaction effort of asphalt mixtures. This is the first time that these effects are investigated and significant findings are reported. The study considers three types of GNP materials, including graphite nanoplatelets and sub-microscale graphite flakes. The cost of these materials is reasonably low, which makes them suitable for large-scale applications, unlike other types of graphite and graphene materials. The experimental results indicate that the addition of GNPs leads to considerable improvements of low-temperature strength and fracture properties of asphalt binders and mixtures. While the properties of asphalt binders at intermediate temperatures are minimally affected, for some combinations of binders and GNPs the increase in low-temperature strength is over 100%. A similar effect is observed for some of the asphalt mixtures investigated, in which the low-temperature fracture energy almost doubles. The laboratory compaction experiments show that the number of gyrations required for achieving a target density can be reduced by as much as 20–40% by adding a small percentage of GNPs into asphalt binders. The results of this experimental study indicate that GNP-modified asphalt binders and mixtures have significant potential for increasing the durability of asphalt pavements in cold regions, by reducing the compaction effort and improving the low-temperature strength and fracture properties of asphalt materials.

Experimental Study on the High-Temperature and Low-Temperature Performance of Polyphosphoric Acid/Styrene-Butadiene-Styrene Composite-Modified Asphalt

The high-performance asphalt materials are used to replace the ordinary road asphalt that cannot meet the requirements of natural environment and traffic situation, which is the effective way to solve poor asphalt pavement durability. In this paper, polyphosphoric acid- (PPA-) modified asphalt and polyphosphoric acid (PPA)/styrene-butadiene-styrene (SBS) composite-modified asphalt with different PPA content were prepared by using two-type asphalt. The effect of PPA modifier on asphalt was analyzed by using the creep elastic recovery rate, accumulating strain and creep modulus tests. The results showed that asphalt types and the PPA could significantly improve the elastic recovery rate of asphalt, reduce the cumulative strain and creep stiffness of the viscosity part, improve the high-temperature performance, and reduce the permanent deformation of the asphalt under repeated load. The high-temperature performance and low-temperature performance of PPA-modified asphalt were studied by the chemical and physical modification techniques. The advantages of modified asphalt are well developed while reducing the price of it, which has important technical and economic significance.

Improvement of moisture damage resistance and permanent deformation performance of asphalt mixtures with marginal porous volcanic aggregates using crumb rubber modified bitumen

The main volumetric and engineering characteristics of hot mix asphalt with crumb rubber modified bitumen from used tyres and high-porosity volcanic aggregates are presented and compared to the same mixtures with conventional bitumen. In volcanic territories, these marginal aggregates are the most common lithotypes and environmental protection conditions require the reuse of both wastes. Two aspects were evaluated: a) characterization of volcanic aggregates and their classification for construction purposes; b) characterization of asphalt-rubber mixtures with highly-vesiculated basalt and different binder contents. It was found that most of the properties of these mixtures efficiently improved due to the utilization of asphalt-rubber, specially the rutting resistance, water damage resistance and stability, thus complying with the standard specifications for pavements and offering sufficient dynamic stiffness modulus. This technique may be applied to other volcanic territories where these local natural aggregates are found in abundance and so contribute to better development of these regions as well as ensuring longer durability of asphalt pavements.

Effect of Aging on Chemical and Rheological Properties of Bitumen.

Engineering performance of asphalt pavement highly depends on the properties of bitumen, the bonding material to glue aggregates and fillers together. During the service period, bitumen is exposed to sunlight, oxygen and vehicle loading which in turn leads to aging and degradation. A comprehensive understanding of the aging mechanism of bitumen is of critical importance to enhance the durability of asphalt pavement. This study aims to determine the relations between micro-mechanics, chemical composition, and macro-mechanical behavior of aged bitumen. To this end, the effect of aging on micro-mechanics, chemical functional groups, and rheological properties of bitumen were evaluated by atomic force microscope, Fourier transform infrared spectroscopy and dynamic shear rheometer tests, respectively. Results indicated that aging obviously increased the micro-surface roughness of bitumen. A more discrete distribution of micromechanics on bitumen micro-surface was noticed and its elastic behavior became more significant. Aging also resulted in raised content of carbonyl, sulfoxide, and aromatic ring functional groups. In terms of rheological behavior, the storage modulus of bitumen apparently increased after aging due to the transformation of viscous fractions to elastic fractions, making it stiffer and less viscous. By correlation analysis, it is noted that the bitumen rheological behavior was closely related to its micro-mechanics.

Evaluation of Optimum Content of Rice Husk Ash to Improve the Hot Asphalt Concrete Performance

Durability of asphalt pavements is related to choosing proper materials. Fillers as the smallest particles of stone materials, and one of the most important parts of asphalt mixtures, exert pivotal effects on the performance of asphalt mixtures, by filling empty spaces and because of their softness, surface features and chemical compounds. Rice husk ash is one of the waste products of burning rice husk in powerhouses that is accounted as biomass. Recently, a good many of investigations have shown that rice husk ash, as a high quality pozzolan, can be properly replaced of common aggregates. In this study rice husk ash was used as filler in hot mix asphalt, and the result mixtures’ mechanical properties was compared with ordinary mixtures whose filler was stone powder. Asphalt mixture samples with two different aggregate graded, and 0, 25, 50, 75 and 100 percent of rice husk ash which were the substitution of stone powder content, were made and the effects of using rice husk ash on the moisture sensitivity, resilience modulus, rutting and dynamic creep of asphalt mixtures were investigated. The results demonstrated that increase of using rice husk ash as the replacement of prevalent fillers in hot mix asphalts, noticeably improves their performance; however, because of excessive stiffness created by rice husk ash, it's better to use it in optimized percentage. Accordingly, statistical analysis of the tests’ results leads to presenting an optimized model for the content of Rice Husk Ash to be used in hot mix asphalt. Finally, Rice Husk Ash content were suggested 26% for graded number 4 and 48% for graded number 5 as replacements for stone powder filler.

Comparative study on asphalt pavement rut based on analytical models and test data

ABSTRACTAsphalt pavement rut influences the durability of the pavement as well as traffic safety. The influence of a flexible and a semi-rigid base on asphalt pavement rut has not been researched in detail. Using theoretical and experimental research on asphalt pavement rut, the objective of this project is to determine the differences in asphalt pavement rut for different base types and the influence of the base on the pavement’s performance. The research details include an analysis of asphalt pavement rut for different base conditions using ABAQUS FEA software, an indoor rut test, and actual engineering data. For rut of asphalt surface and base(Surface and base rut means the total deformation of asphalt surface layer and base.), semi-rigid base asphalt pavement is less than flexible base asphalt pavement, but for rut of surface(Rut of surface means the deformation of asphalt surface), flexible base asphalt pavement is less than semi-rigid base asphalt pavement. This demonstrates a greater durability of asphalt pavement with a flexible base compared to a semi-rigid base. The research results provide reference values for asphalt pavement design and the described applications have economic and social benefits.

The FHWA’s Demonstration Project for Enhanced Durability of Asphalt Pavements through Increased In-Place Pavement Density

Recognizing the importance of in-place density in building cost-effective asphalt pavements, a Federal Highway Administration (FHWA) Demonstration Project was created for “Enhanced Durability of Asphalt Pavements through Increased In-Place Pavement Density.” The objective of the demonstration project was to determine the benefit of additional compaction and show that additional density could be obtained through improved techniques. This project effort included two major components: (1) a literature search to serve as an educational component regarding the best practices for increasing density, and (2) the construction of 10 field demonstration projects. Eight of the 10 states improved densities by at least 1% compared to a control section on their field demonstration projects. There were at least two pavement sections (a control and at least one test section) constructed within each of the 10 states that participated in this field demonstration project. Many of the states constructed more than two pavement sections for a total of 38 sections. There were many variables, including mixture type, construction equipment, and procedures between states and within states. A summary of the methods that states used to obtain increased density generally fell into one of five categories: (1) improving the agency’s specification by including or increasing incentives and increasing the minimum percentage density requirements; (2) making engineering adjustments to the asphalt mixture design to obtain slightly higher optimum asphalt content (although not part of the original goal of the demonstration project); (3) improving consistency as measured by the standard deviation; (4) following best practices; and (5) using new technologies.

Review of experimental characterisation and modelling of asphalt binders at low temperature

Asphalt binder represents the main constituent of asphalt paving mixtures. The functional performance and durability of asphalt pavements strongly depend on the rheological and mechanical properties of the binder. Asphalt binder is a highly temperature susceptible material that becomes brittle and more prone to failure at low temperature, which may ultimately result in thermal cracking at the mixture level. Significant effort was devoted over the years to reduce the occurrence of this distress. For this purpose, a number of experimental methods were developed to characterise asphalt binders at low temperature. At the same time, different models were formulated to better understand and predict the material behaviour while extrapolating more information from the testing measurements. In this paper, a comprehensive review on the behaviour of asphalt binders at low temperature is presented. First, a synthetic introduction and background on the development of the criteria for asphalt binder low-temperature behaviour are provided. Then, the current testing procedures for characterising asphalt binders are presented and the validity of the current PG specification is discussed. Finally, the most significant modelling developments are reviewed.

Influence of Fiber Type on Low‐Temperature Fracture Performance of Presawed Asphalt Mixture Beams

In order to improve the durability of asphalt pavement, low‐temperature fracture performance of AC‐13 asphalt mixture with different fiber types were studied by three‐point bending fracture test under different temperatures and presawed positions. Test results show that the improvement effect of basalt fiber is obvious and stable. The improvement effect of polyester fiber is not obvious to resist I crack, and the resistance effect of I‐II compound crack is obvious. Lignin fiber mixed in the asphalt mixture has no obvious effect on improving the crack resistance property under low temperature. Fiber cooperated with asphalt mixture can improve the ability of low‐temperature fracture performance, while the improvement degree is effected by fiber type. Low‐temperature fracture performance of asphalt mixture improves with the increase of temperature within a certain temperature range. The presawed position has significant effect on the low‐temperature fracture performance of asphalt mixture. The larger the horizontal distance of the presawed position and center load is, the stronger the low‐temperature fracture performance of asphalt mixture presents.

Determination of oxygen diffusion coefficients of compacted asphalt mixtures

The oxidative aging of asphalt binder in asphalt mixture is a key factor that affects the long-term durability of asphalt pavement. The aging susceptibility of an asphalt mixture is dependent on oxygen transport and consumption in the mixture. In this study, an apparatus was developed to measure oxygen diffusion and consumption in compacted asphalt mixtures, and methods to compute oxygen diffusion and possible consumption of asphalt mixtures were evaluated and compared. Oxygen diffusion coefficients of samples prepared with different asphalt mixture designs and air void contents were determined, and correlations between the diffusion coefficients and samples’ volumetric characteristics were examined. The oxygen environment exposed by asphalt binders in pavements and its implication on pavement durability were also discussed based on simulated oxygen concentration profiles with time. The developed apparatus and test procedure were found to be suitable to measure the oxygen diffusion coefficients of compacted asphalt mixtures. It was also found that oxygen consumption during the diffusion test at room temperature is negligible, and both numerical and analytical methods perform equally well in calculating oxygen diffusion coefficients. The oxygen diffusion coefficients of the tested asphalt samples vary in orders of magnitude, dependent not only on air void contents but also on other volumetric characteristics. The traditional models to predict the oxygen diffusion coefficients of dry porous media are not fit for compacted asphalt mixtures. The oxygen diffusion coefficients of asphalt mixtures have significant implications on oxygen level exposed by asphalt binders inside of the pavements; therefore, they may be used as an indicator in asphalt mixture design and construction quality control.