Types Of Asphalt Mixtures Research Articles

Laboratory Evaluation of Mechanical Properties of Asphalt Mixtures Exposed to Sodium Chloride

Spreading sodium chloride salt is one of the most effective operations to tackle ice formation on the surface of a road pavement during cold seasons, thus ensuring safer driving conditions. However, in addition to negative environmental impact, sodium chloride solution could influence the properties and durability of asphalt mixtures. Based on these premises, this laboratory study aims to characterize the mechanical properties of different asphalt mixtures exposed to sodium chloride solution. Four types of asphalt mixtures were immersed in 10 wt% sodium chloride solution for four cycles. The macroscopic surface, moisture absorption, Marshall stability, Marshall quotient, dynamic modulus, and resilient modulus were evaluated. The behavior of the asphalt mixtures was severely deteriorated by the exposure to sodium chloride solution and immersion cycles, resulting in damaged surface, loose structure, degraded stability, and stiffness. The mixture with polymer modified asphalt binder showed the best overall performance. Traditional asphalt mixtures with neat bitumen showed a better performance to resist sodium chloride solution compared with stone mastic asphalt mixtures with neat bitumen because of their dense structure, whereas traditional asphalt mixtures with polymer modified bitumen had a sensitivity to sodium chloride solution similar to that of stone mastic asphalt mixtures with polymer modified bitumen. Based on the findings of this study, using asphalt mixtures with polymer modified bitumen is recommended when road maintenance operations entailing the use of sodium chloride are envisaged.

Performance of Asphaltic Concrete Incorporating Fly Ash under Low Temperature

One of the most common asphalt concrete pavement distresses is low temperature cracking, also known as thermal cracking. Characterizations of low temperature cracking and formulation for pavement design have taken a lot of effort. Asphalt binder has viscoelastic behaviour, so asphalt mixture behaviour changes as the temperature changes. At high and low temperatures, the asphalt binder shows viscoelastic plastic behaviour and elastic behaviour. Low temperature cracks that grow day by day due to the movement of vehicles are the most significant pavement cracks caused by cold climates. It needs early and premature repairs to build and expand low temperature cracks. The aim of this research is to perform Low Temperature Cracking analysis of asphalt materials (laboratory and analytical assessment), in light of the latest update of binder cracking temperature. The role of basic material properties in low-temperature cracking was studied in this work. As a result, statistical analysis in the cohesive failure condition revealed that the asphalt mixture aggregate's free energy was ineffective in this cohesion failure. Fly ash had been used in the other type of asphalt mixture. It was proven that the addition of fly ash as an additive can improves the low temperature resistance of the asphalt mix. The binder with 60/70 penetration grade was used. The different amount of fly ash (0%, 1%, 3% and 5%) was added to the asphalt mixture. Marshall Stability and flow, resilient modulus and dynamic creep were carried out to investigate the mechanisms of cracking at low temperature. From the results obtained, there are significant effect comes from the addition of the fly ash. The result show that the addition of 5% fly ash produce the best outcomes for the density, stability, stiffness, resilient modulus and dynamic creep. Thus, it can conclude that the existence of fly ash in the mixture is able to enhance the mechanical performance of the AC14 dense-graded asphalt.

Influence of temperature on the dielectric properties of asphalt mixtures

ABSTRACT When using non-destructive testing equipment to evaluate the quality of asphalt pavement, the asphalt pavement mixtures will exhibit different dielectric properties under dissimilar temperature conditions since the external electric field is affected by ambient temperature, which interferes with the accuracy of non-destructive testing. To improve the accuracy of non-destructive testing and quantify the influence of temperature on the dielectric properties of asphalt mixtures, a dielectric model suitable for describing the relationship between the relative dielectric constants of asphalt mixtures and temperature is established. The relative dielectric constant and dielectric loss of the two types of asphalt mixtures are measured at different temperatures to verify the accuracy of the dielectric model, and the goodness of model fit verifies wide applicability of the model. This temperature-based asphalt mixture dielectric model has great significance for quantifying the influence of temperature on the dielectric properties. Furthermore, the model shows that the dielectric properties of different asphalts and aggregates have different temperature sensitivity, and the concept of conductance activation energy proposed in this research provides innovative approaches for the optimisation of asphalt mixtures and raw materials.

Eco-friendly design of Warm mix asphalt (WMA) with recycled concrete aggregate (RCA): A case study from a developing country

Warm Mix Asphalt (WMA) is a type of asphalt concrete with growing notoriety in the paving industry since they generate economic and environmental benefits compared to traditional alternatives. Various techniques have been studied to maximize the sustainability components present in WMAs, including the Recycled Concrete Aggregate (RCA) inclusion as a partial replacement for virgin aggregates. WMA with various RCA contents has been examined in several case studies from the mechanical, performance, and economic perspectives. Nonetheless, thorough environmental studies have so far been limited, mostly assuming that the use of RCA reduces the environmental burden due to being a recycled product. However, this consideration is not entirely correct since RCA increases the optimal asphalt content. Therefore, excessive RCA contents generate a counterproductive environmental effect. The difficulty associated with the estimate of how much RCA is considered detrimental could explain why detailed environmental evaluations have not been developed on this type of material. This study develops a trade-off methodology based on the Life Cycle Assessment (LCA) technique and statistical analysis to determine the maximum RCA content to be incorporated into WMA without generating greater environmental impacts. The main contributions of this investigation to the literature are establishing the first approach to optimize the design of WMA with RCA inclusion and identifying the variables that directly affect the contaminating potential of this type of asphalt mixture.

Evolution evaluation of high-speed railway asphalt concrete waterproofing layer during laboratory freeze–thaw cycles

An in-depth understanding of internal freeze–thaw damage mechanisms in high-speed railway asphalt concrete waterproofing layer is of great importance to achieve its long-term waterproofing and mechanical performance during the prolonged service life. In this work, four types of composite polymerized railway asphalt mixtures with air voids of 2% were custom-designed and treated with a total of 20 modified freeze–thaw cycles. Meanwhile, the volume and mass measurement, X-ray CT, indirect tensile strength test, and Marshall stability test were used to characterize the internal freeze–thaw damage and evaluate the performance deterioration. The results indicated that the internal deterioration resulted from the generation, expansion, and aggregation of voids and micro-cracks. Meanwhile, a “lag effect” of the freeze–thaw damage, that is, a gradual inward erosion process, was verified by dividing the cylindrical specimens into the core layers, intermediate shell layers, and outer shell layers. The efficiency of the “lag effect” was influenced by the air void content in the outer shell layer, which meant the lower the air void content in the outer shell layer, the slower the freeze–thaw damage. In addition, all four types of asphalt mixtures exhibited promising waterproofing performance and freeze–thaw damage resistance. Binder A and AC-10 mixtures exhibited the superiority in terms of high-temperature performance and freeze–thaw damage resistance based on Marshall stability and flow value that were proved to have adequate efficiency on characterizing the freeze–thaw damage in railway asphalt mixtures.

A comparative life cycle assessment of asphalt mixtures modified with a novel composite of diatomite powder and lignin fiber

Some additives such as lignin fiber and diatomite powder were developed and used as modifiers in asphalt mixes to enhance the asphalt pavement performance by mitigating pavement distresses such as rutting, thermal cracking, and freeze–thaw cycles. Despite various advantages obtained from utilizing the additives in modified asphalt mixtures, there are many uncertainties regarding their environmental impacts. This study aims to analyze and evaluate the environmental impacts of four types of asphalt mixtures namely, Control Asphalt Mix (CAM), Diatomite Modified Asphalt Mix (DMAM), Lignin Fiber Modified Asphalt Mix (LFMAM), and Diatomite-Lignin Fiber Composite Modified Asphalt Mix (DLFMAM) through applying the life cycle assessment (LCA) methodology. Results demonstrate that DMAM and CAM offers distinct improvements in all impact categories as compared to other types of asphalt mixtures. As well as, the environmental burdens of DMAM is similar to CAM. Nevertheless, LFMAM showed higher negative impacts in all categories, followed by DLFMAM. Excluding the HTP (Human Toxicity) impact, both LFMAM and DLFMAM offer minimal negative effects in all other impact categories compared to the control asphalt mixture. Thus, it can be concluded that the usage of DMAM, LFMAM, and DLFMAM does not result in an excessive risk to the environment, and their applications as alternatives to the base asphalt mixture do not cause significant deteriorations in the environmental profile.

Investigation on Fatigue Performance of Diatomite/Basalt Fiber Composite Modified Asphalt Mixture.

The fatigue resistance of asphalt mixture is an important indicator to evaluate the durability of asphalt pavement. In order to improve the fatigue properties of asphalt mixture, diatomite and environmental basalt fiber were added. Four types of asphalt mixtures, ordinary asphalt mixture (AM), diatomite modified asphalt mixture (DAM), basalt fiber modified asphalt mixture (BFAM) and diatomite/basalt fiber composite modified asphalt mixture (DBFAM), were chosen, whose optimum asphalt–aggregate ratio, optimum content of diatomite and optimum content of basalt fiber could be determined by Marshall test and response surface methodology (RSM). The multi-functional pneumatic servo Cooper test machine was carried out by a four-point bending fatigue test. Through the comparative analysis of flexural-tensile stiffness modulus (S), initial stiffness modulus(S0), residual stiffness modulus ratio, lag angle (ϕ) and cumulative dissipation energy (ECD), the fatigue resistance of asphalt mixture can be effectively improved by adding diatomite and basalt fiber. Grey correlation analysis was also used to analyze the degree of correlation between the fatigue life and the influencing factors such as VV, VMA, VFA, OAC, S, and ECD. The analysis results indicate that ECD has the greatest impact on the fatigue life of the asphalt mixture.

Field Performance Evaluation of High Polymer-Modified Asphalt Concrete Overlays

The objective of this paper was to assess the viability of using high polymer (HP) modified asphalt concrete (AC) mixtures in Virginia as a reflective crack mitigation technique or when deemed appropriate as a tool for increased crack resistance on higher volume facilities. This was achieved by compiling and evaluating routine distress survey data against pre-paving distress survey data for relevant in-service HP pavements constructed between 2015 and 2018 and comparing them with several control in-service conventional polymer-modified asphalt (PMA) pavements. This is the first effort in North America to provide a detailed field performance of HP AC mixtures. In general, none of the evaluated mixtures (HP or PMA) was able to prevent reflective cracking completely. The HP sections showed the most promising performance 5 years after construction regardless of traffic level and the pre-existing pavement conditions. The pavement management system data for the reviewed sections indicated a potential controlling effect of the joint condition of the underlying jointed concrete pavement layer regardless of the asphalt mixture type employed (PMA or HP). Moreover, performance evaluations using the network-level pavement management data were conducted to estimate the life expectancy of HP AC overlays. Two different approaches and three levels of analysis were undertaken. Overall, PMA and HP AC overlays had an average predicted service life of 6.2 and 8.3 years, respectively, indicating a 34% extension of performance life of the AC overlays with high polymer modification.

Application of Biochar on the runoff purification performance of porous asphalt pavement

Abstract Biochar is currently applied in many low-impact development measures, such as biofilters and filter strips. However, its application in permeable pavement is limited. Due to the wide range of raw material sources, biochar may also contain nutrients and heavy metals. Whether its leachate will cause contamination during application remains unknown. Based on the static leachate contamination test, this study first evaluated the leachate contamination risks of three types of biochar and porous asphalt mixture (PA) with three biochar fillers. Through the pavement infiltration test, the purification performance of PA with biochar fillers and filter layers was further analysed. The results show that biochar contains nitrogen and phosphorus, and the leaching contamination of coconut shell is the most obvious; when the biochar is applied as a filler in PA, the leaching contamination decreases, while the pollutant purification performance is not obvious; when 3−5 mm rice straw biochar is used as a filter layer, the removal rate of total suspended solids can be 100%, but it is accompanied by more serious nitrogen and phosphorus leaching, and the greater the thickness, the more serious the degree of leaching. Deionized water cleaning can remove the phosphates contained in biochar, but have little effect on nitrogen. Therefore, before the application of biochar, cleaning measures should be taken to minimize its leaching contamination.

Comparative Study on Complex Modulus and Dynamic Modulus of High-Modulus Asphalt Mixture

In the French high-modulus asphalt mixture design system, the complex modulus of the mixture under the conditions of 15 °C and 10 Hz is taken as the design index. However, in China, the dynamic modulus under the conditions of 15 °C, 10 Hz, 20 °C, 10 Hz and 45 °C, 10 Hz was taken as the stiffness modulus index of high-modulus asphalt mixture. The difference in modulus values between the two systems caused the pavement structure layer to be thicker and the construction cost to be higher in China. In order to find out the appropriate modulus value of high-modulus asphalt mixture suitable for China’s modulus parameter conditions to better carry out the reasonable design and evaluation of high-modulus asphalt mixture in China, the modulus of four types of high-modulus asphalt mixtures under the two systems through the two-point bending complex modulus test of the CRT-2PT trapezoidal beam and the SPT uniaxial compression dynamic modulus test were analyzed in this paper. Under the premise of meeting the stiffness modulus index of the French high-modulus asphalt mixture, the relationship conversion models between the dynamic modulus and complex modulus of high-modulus asphalt mixture under different temperatures were established. According to the conversion models, the design evaluation value range of dynamic modulus suitable for China’s condition was recommended. It is recommended that the dynamic modulus of China’s high-modulus asphalt mixture at 15 °C and 10 Hz is not less than 16,000 MPa, the dynamic modulus at 20 °C and 10 Hz is not less than 14,000 MPa, and the dynamic modulus at 45 °C and 10 Hz is not less than 2500 MPa. Five kinds of high-modulus asphalt mixtures used in actual road engineering were tested to verify the reliability of the recommended dynamic modulus values based on the modulus conversion model, and the results are consistent with the recommended value range of the model.

Asphalt mixture and its time delay of stress after strain at change of temperature and frequency

Abstract Materials in pavement construction are used due to their material properties. Asphalt mixtures, which are today most used during building pavement construction, have a significant place. Asphalt mixtures are classified as viscoelastic materials due to their material properties. This article focuses on the time delay of the stress behind the strain, which is a specific property for viscoelastic materials. It is particularly focused on one type of asphalt mixture, which is used in the binder course and in the upper base layer. The selected asphalt mixture was tested on a four-bending machine and the samples had a beam shape. The sample was tested at four temperatures and seven frequencies. In the discussion, the article focuses on the comparison of the time delay of the stress Δt behind the strain during the change of temperature and frequency. It is clear from the results that the selected asphalt mixture is significantly affected by the change in temperature as well as the change in frequency. The conclusion is devoted to a summary of the acquired knowledge and observation, which is focused on examples in practice.

GMA material design and construction quality control for asphalt pavement of steel box girder: Case study of the Hong Kong–Zhuhai–Macau Bridge

To improve the quality of the Hong Kong–Zhuhai–Macao Bridge paving project, a new paving layer material, Guss-mastic asphalt (GMA), was proposed in this paper by combining the advantages of two types of cast asphalt mixtures: mastic asphalt (MA) and Guss asphalt (GA). Based on the characteristics of GMA, to simulate its actual production process, this study developed a small-simulated cooker mixing equipment. Moreover, the flow degree, 60 ​°C dynamic stability, and impact toughness were proposed to be used to evaluate the construction and ease, high temperature stability, and fatigue resistance of GMA cast asphalt mixtures, respectively. Moreover, the quality control standards for GMA paving materials by indoor tests, field trial mix GMA material performance tests, and accelerated loading tests were finalized. The study showed that the developed simulated cooker yielded consistent mixing results in the same working environment as the engineering cooker device. Increasing the coarse aggregate incorporation rate, coarsening the mastic epure (ME) gradation composition, and using a smaller oil to stone ratio can reduce the flowability of the GMA materials to varying degrees. The four-point bending fatigue life and impact toughness of the different GMA materials are correlated well. A mobility of <20 ​s, 60 ​°C dynamic stability of 400–800 ​times/mm, 15 ​°C impact toughness of ≥400 ​N·mm, and cooker car mixing temperature control standard of 210 ​°C–230 ​°C form an appropriate control index system for the design and production of GMA cast asphalt mixtures. Simultaneously, accelerated loading tests verified the accuracy and reliability of the quality control index system that has been used in the GMA paving project of the Hong Kong–Zhuhai–Macao Bridge deck and has achieved good application results.

Investigation of fatigue performance of asphalt mixtures and FAM mixes with high recycled asphalt material contents

Using a high content of recycled asphalt material, including reclaimed asphalt pavement (RAP) or recycled asphalt shingles (RAS), can be economically and environmentally beneficial. However, aged binder in RAP/RAS is a main concern for fatigue cracking resistance, therefore a reliable and efficient performance-related test for evaluating the effect of RAP/RAS on pavement performance is critical for the best use of these materials. In this study, four types of asphalt mixtures with various RAP/RAS contents higher than 20% were sampled from Southern California after different times at high temperature in the silo. To investigate the fatigue performance of these mixtures, four-point beam (4PB) fatigue testing was performed on full asphalt mixtures, and the linear amplitude sweep (LAS) testing was applied to their corresponding fine aggregate matrix (FAM) mixes. Testing results from FAM mixes have been analyzed within the viscoelastic continuum damage (VECD) framework. The relationships between fatigue life and strain level have been established for FAM mixes and full mixtures separately. The LAS testing results were compared among the FAM mixes with the same type of asphalt material but with different silo hours, which shows a good agreement with the observations from the 4PB testing results from full mixtures. Analyses of fatigue performance of both FAM mixes and full mixtures indicate that fatigue life decreases with the increase of RAP content, as expected, and that silo time shows an important effect. Finally, a strong linear correlation has been found between the strain value at failure of LAS tests of FAM mixes and the strain value at one million cycles to failure predicted from 4PB tests of full mixtures. This indicates that LAS fatigue testing on FAM mixes could predict the fatigue performance of asphalt materials containing high contents of RAP/RAS and potentially be developed as a surrogate performance-related test for asphalt mix design and/or QC/QA.

Comparative Life Cycle Assessment of Asphalt Mixtures Using Composite Admixtures of Lignin and Glass Fibers.

Lignin and glass fiber were used as additives to improve the quality of road pavements and minimize moisture damage and cracking at low temperatures on asphalt pavement, according to a previous laboratory study. The aim of this paper is to make a significant contribution to the environmental assessment of the construction of road pavements using four types of asphalt mixtures based on the life cycle assessment (LCA) methodology according to the requirements of ISO 14040, considering the impact of raw material extraction, asphalt mixture manufacturing, transportation, and wearing surface construction. The results of the environmental assessment showed that all studied asphalt mixtures do not offer any improvement in all impact categories, and three modified asphalt mixtures have a slight negative effect in all impact categories. The composite mixture has the highest negative effect of the studied three modified asphalt mixtures in all categories except in the marine aquatic ecotoxicity potential category and freshwater aquatic ecotoxicity potential category, where the lignin modified asphalt mixture has the highest negative effect in these two categories but has the best environmental impacts on most of other impact categories. Furthermore, the negative effect caused by composite asphalt mixtures is minimal and thus can be used to improve the overall performance of asphalt pavement.

Investigation of chloride release characteristic of Chlorine-Based Anti-Icing asphalt mixture

Anti-icing asphalt pavement is an effective way to alleviate snow and ice disasters in winter roads, and the release characteristics of active ingredients determine the snow melting effect of the asphalt pavement. By using the ion-selective electrode (ISE) method, the cumulative release concentration and single release concentration were used as indicators to analyze the macro release characteristics of the snowmelt active ingredients, chloride ions. The release of chloride goes through the rapid release stage, stable release stage, and release stop period. The effects of asphalt mixture type, asphalt type, and temperature on the macro release characteristics were also discussed. In order to explain the release characteristic of active ingredients at a molecular level, a simulation system of asphalt and finite components were developed with the help of molecular dynamics research methods. The absorption and diffusion characteristics of active ingredient and asphalt at the molecular scale were explored in combination with variations in binding energy, radial distribution function, and chloride diffusion coefficient. The effects of temperature, pressure, and the agent proportion on the micro-release characteristics of active ingredients were clarified.

Design and Evaluation of Asphalt Concrete Incorporating Plastic Aggregates Fabricated Using 3D Printing Technology.

Environmental protection and sustainability have been a serious challenge due to the excess amount of waste plastic, and the inefficient methods of its disposal. This study aims at exploring the feasibility of using plastic material in asphalt concrete followed by the design and evaluation of modified asphalt mix. Four different types of asphalt mixtures were made by mixing mineral aggregates with plastic aggregates of different shapes and sizes. The conventional dense-graded asphalt concrete incorporating mineral aggregates was selected as control material, whereas the other three types of asphalt mixtures were produced by substituting 3D-printed plastic aggregates for mineral aggregates. Marshall characteristics were utilized to evaluate the volumetric and mechanical properties of the asphalt mixtures. Test results show that the asphalt mixture containing solid plastic aggregate appears to have a 14.3% reduction in bulk density, thereby potentially reducing the haul costs. Due to the angular shape of the aggregate, the stability for the asphalt mixture containing the 3D-printed aggregate is 1.95 times higher than that for the asphalt mixture incorporating all mineral aggregates. The addition of the plastic printed aggregate enhances the strain capacity to achieve failure of the asphalt mixture. However, caution should be taken when incorporating the hollow or fine printed aggregates into the asphalt mixture due to their variation of volumetric properties.

Study on the Road Performance of Foamed Warm-Mixed Reclaimed Semi-Flexible Asphalt Pavement Material.

Warm-mixed reclaimed asphalt pavement (RAP) technology has been widely studied worldwide as a recycled environmental method to reuse waste materials. However, the aggregate skeleton structure of the warm-mixed reclaimed asphalt mixture is not stable because of the existence of the recycled materials. Warm-mixed recycled semi-flexible pavement material can solve the defects of the above materials. In this study, five different types of open-graded asphalt mixtures containing different contents of RAP were designed, and relevant laboratory tests were conducted to assess the road performance of the warm-mixed recycled semi-flexible pavement material. The test results indicated that the road performance of warm-mixed reclaimed semi-flexible pavement materials has good resistance to rut deformation ability. Furthermore, the materials also had good water stability and fatigue performance. The grey correlation analysis shows that the asphalt binder content has the most significant correlation with the high-temperature stability, and the correlation between RAP content and the fatigue performance was the greatest. Furthermore, the curing age has the most remarkable with the low-temperature crack resistance of the warm-mixed reclaimed semi-flexible material.

Comparative study on permanent deformation in asphalt mixtures from indirect tensile strength testing and laboratory wheel tracking

For an asphalt mixture to present rutting resistance, it must have a high shear strength. In an abbreviated protocol, the shear strength of an asphalt mixture can be estimated in the laboratory through the indirect tensile (IDT) strength test and the unconfined compression test, using the Mohr-Coulomb failure theory. So, taking advantage of the simplicity of the IDT test, this research investigated whether the other relationships between stress and strain, derived from the indirect tensile strength test, also demonstrated the potential to explain the shear strength of an asphalt mixture. The correlation between the mechanical properties observed in the stress–strain curve of the asphalt concrete under the indirect tensile strength test and parameters of accumulated permanent deformation with the French wheel tracker was analyzed. The research was conducted with two types of binders and three gradations of granitic aggregates (small, medium, and intermediate) within the same maximum nominal size range adopted by airport agencies, totaling six types of asphalt mixtures. After the Marshall mix design, the mixtures were mechanically tested with a wheel track device. A SUPERPAVE mix design was conducted with two of these mixtures to obtain the Flow Number parameters. Finally, a good relationship was established between the indirect tensile strength test and permanent deformation, using tensile yield modulus and the ratio between total dissipated tensile and compressive energies. The interaction between the two situations predicted by the biaxial stress test (tensile and compression), mainly by the relations between dissipated and recoverable energies and by the tensile parameters, allowed an inference about the shear strength of the material.

Distribution of dissipated pseudo-strain energies and temperature effect on fatigue cracking resistance in asphalt mixtures under destructive tensile loading

This paper studies the effect of temperature on the resistance of asphalt mixtures to fatigue cracking by calculating the parameters of the modified Paris’ Law more accurately at multiple temperatures in the basis of separating the DPSE components. Firstly, the repeated direct tensile (RDT) tests with two strain levels were performed on four types of asphalt mixtures to obtain the mechanical properties in the non-destructive and destructive stage under 5 sets of temperatures including 0 °C, 10 °C, 20 °C, 30 °C and 40 °C.The results show that energy ratio to develop fatigue cracking (DPSEF) increases first and then decreases with the temperature increasing, while energy ratio to develop permanent deformation (DPSEP) decreased continuously. If only considering for the relative proportion of the two destructive effects, it was found that the dominant damage mode is fatigue cracking in the 0 °C to 20 °C interval. The dominant damage mode at 40 °C is permanent deformation, and the dominant damage mode at 30 °C depends on material types. This finding helps to understand the development and distribution of fatigue cracking and permanent deformation at different temperatures.Then the DPSEF is further introduced to the modified Paris’ Law to derive the coefficients AJR and nJR. The logarithmic form of AJR and nJR at different temperatures follow the same linear relationship while remaining consistent model fitting coefficients. The damage density follows a good linear relationship with the logarithmic form of the parameter nJR which is independent of temperature. Parameter nJR can reflect the level of cracking resistance performance which is not limited by material type and temperature conditions.

The Addition of a High Dosage of Rubber to Asphalt Mixtures: The Effects on Rutting and Fatigue

Bitumen is subjected to cracks and damage during its service life. Adding a material with the potential to increase the durability of bitumen can expand its service life and reduce maintenance costs. Previous studies indicate that adding crumb rubber into asphalt has a positive effect on the performance of the mixture. Using crumb rubber may solve environmental problems due to vehicle tire waste disposal by reducing maintenance costs needed to increase asphalt’s strength. Some studies have investigated the effect of bitumen mixed with crumb rubber; however, it seems that the effect of different types of rubber mixtures used has been overlooked. Therefore, this study aims to better understand the effects of the increasing amount of rubber addition in various types of asphalt mixtures and determine the optimal mixture that could be used in road construction. A series of experiment was conducted, incorporating various tests (such as Marshall stability, rutting, and fatigue), to test various mixtures of asphalt in the form of dense-graded asphalt (DGA), fine gap-graded asphalt (FGG), gap-graded asphalt (Stone Mastic Asphalt, SMA), and open-graded asphalt. The amount of added crumb rubber was 25% by weight of bitumen. All mixtures were classified as superior in rutting and fatigue resistance, since they all reached a maximum depth of rutting less than 15 mm and generated two times more failure cycles compared to the conventional asphalt. The most optimal performance asphalt mixture was showed by the SMA10 mixture, resulting in a minimum rut depth of less than 1.2 mm and producing 750% more fatigue cycles than conventional asphalt. The result indicates that the addition of 25% of the rubber particles in the binder can increase the properties and durability of asphalt mixtures.