Showing papers in "International Journal of Pavement Engineering in 2022"
35 citations
TL;DR: In this article , a methodology was developed to optimize the design of Warm Mix Asphalt (WMA) with the inclusion of three recycled materials as partial replacement of natural aggregates (NAs), namely Crumb Rubber (CR), Reclaimed Asphalt Pavement (RAP), and Recycled Concrete Aggregate (RCA).
Abstract: In this research, a methodology was developed to optimize the design of Warm Mix Asphalt (WMA) with the inclusion of three recycled materials as partial replacement of natural aggregates (NAs), namely Crumb Rubber (CR), Reclaimed Asphalt Pavement (RAP), and Recycled Concrete Aggregate (RCA). The methodological proposal is composed of 4 sections denominated: (I) environmental module, (II) economic module, (III) decision-support module, and (IV) results report module. Initially, a Life Cycle Assessment (LCA) is carried out to quantify the environmental impacts associated with WMA production. Similarly, in the second module, a Life Cycle Costing (LCC) is performed to estimate the financial investment required by the process under evaluation. Meanwhile, a computational model based on genetic algorithms (GAs) is created in the decision-support module to execute multi-objective optimization (minimization of costs and contaminating potential). In the last module, the more accurate WMA designs are presented employing a Pareto front, ternary plot, composition pie chart, and statistical analysis of the influence of the CR, RAP, and RCA on the validation criteria. This study concludes that even under long hauling distances and huge prices, it is possible to design WMA with CR, RAP, and/or RCA additions that form sustainability benefits compared to conventional WMA.
35 citations
TL;DR: Asphalt deposits are distributed in many areas on earth and released natural asphalt of various chemical composition as mentioned in this paper, and the rheological properties of natural asphalt are usually improved by the addition of chemical composition.
Abstract: Asphalt deposits are distributed in many areas on earth and released natural asphalt of various chemical composition. Rheological properties of natural asphalt are usually improved by the addition ...
33 citations
TL;DR: This study presents a framework that improves any analytical pavement damage accumulation approach to take a lateral position of loading as an explicit input and was applied on the state-of-the-practice pavement design approach, Mechanistic-Empirical Pavement Design Guideline (MEPDG).
Abstract: The lateral position of truck loading is a random phenomenon for human-driven trucks because they do not follow a straight path as they travel. Therefore, this variable has been called as w...
29 citations
TL;DR: In recent years, two types of test methods have emerged to evaluate the susceptibility of asphalt mixtures to cracking at intermediate temperatures as part of performance-related mix design specifi... as mentioned in this paper.
Abstract: In recent years, two types of test methods have emerged to evaluate the susceptibility of asphalt mixtures to cracking at intermediate temperatures as part of performance-related mix design specifi...
27 citations
TL;DR: The British pendulum test is commonly used to measure low-speed pavement friction and provide a measure of the quality of pavement surface micro-texture in terms of skid resistance contribution as mentioned in this paper.
Abstract: The British pendulum test is commonly used to measure low-speed pavement friction and provide a measure of the quality of pavement surface micro-texture in terms of skid resistance contribution. Ge...
24 citations
TL;DR: In this article , the development law of low-temperature mechanical properties of waterborne epoxy resins at different curing time was studied systematically, and different types of polyurethane-modified waterborne resins were prepared.
Abstract: The purpose is to clarify the development law of mechanical properties of waterborne epoxy resin coatings at low temperatures and further promote its application in cold areas. Different types of polyurethane-modified waterborne epoxy resins were prepared. The development law of low-temperature mechanical properties of waterborne epoxy resin at different curing time was studied systematically. The improvement effect of polyurethane on the mechanical properties of waterborne epoxy resin at low temperatures was evaluated. The prediction models of low-temperature mechanical properties of waterborne epoxy resin based on Grey–Markov chain method was established. The results show that the mechanical properties of waterborne epoxy resin decrease after low-temperature treatment for 15 days. Its strength and flexibility are reduced by 3% and 10%. Polyurethane could improve the low-temperature durability of waterborne epoxy resin. The retention rates of the various mechanical properties of modified waterborne epoxy resin increase significantly. Among them, the retention rate of elongation at break increases by more than 50%, and the bending deformation is almost no longer attenuated. The prediction model based on BP–Elman neural network has a higher accuracy, and the relative error is less than 0.04%.
21 citations
TL;DR: In the current approaches to structural analysis for asphalt pavements, the entire pavement material is usually treated to identical material, which disregards the distinct heterogeneity of asphalt as mentioned in this paper, which is not the case for concrete.
Abstract: In the current approaches to structural analysis for asphalt pavements, the entire pavement material is usually treated to identical material, which disregards the distinct heterogeneity of asphalt...
18 citations
TL;DR: In this paper, the performance of mixture with waste tire rubber (WTR) and amorphous poly alpha olefin (APAO) modified asphalt was explored, the 12% WTR+4% APAO and 15%WTR+ 4% APO modified asphalt mix was shown.
Abstract: In order to further explore the performance of mixture with waste tire rubber (WTR) and amorphous poly alpha olefin (APAO) modified asphalt, the 12%WTR+4%APAO and 15%WTR+4%APAO modified asphalt mix...
17 citations
TL;DR: In this paper , a semi-circular bend geometry (SCB) sample containing vertical and angular cracks was used to evaluate the fracture energy of modified WMA and WMA mixtures.
Abstract: Freeze-Thaw Damage (FTD) is one of the most important factors that can reduce the Warm Mix Asphalt's (WMA) crack resistance. In this study, modified WMA and WMA mixtures' fracture behavior containing vertical and angular cracks was evaluated using semi-circular bend geometry (SCB). For this purpose, SCB samples containing vertical cracks (Pure mode II) and angular cracks (Pure mode I) were made first; Then, FTD conditions were applied to the samples to condition them. The results showed that all the mixtures modified with Calcium Lignosulfonate (CL) and polyester fibers (PE) had a better crack resistance than the base sample under FTD conditions. As a result, the fracture energy of WMA mixtures containing 6% CL increased by about 146, 141, 75, and 93%, respectively, while the fracture toughness of WMA mixtures containing 3% CL increased by about 103, 95, 97, and 92%, respectively. The results of the brittleness indices showed that mixtures containing 6% CL, 0.25% PE-6% CL, and 0.25% PE had a more flexible behavior than other mixtures under FTD conditions, respectively. Therefore, using these mixtures, in addition to improving the fracture performance, was also recommended for environmentally friendly purposes.
13 citations
TL;DR: Fracture simulation of asphalt mixtures based on 3D finite element (3D-FE) simulation considering the mesostructure consumes too much computing resources and has low efficieness as discussed by the authors.
Abstract: Fracture simulation of asphalt mixtures based on three-dimensional finite element (3D-FE) simulation considering the mesostructure consumes too much computing resources and has low efficien...
TL;DR: In this article , the authors explored the long-term aging influence on chemo-rheological properties and developed novel consecutive models for the longterm aging reaction kinetics of bitumen.
Abstract: This study aimed to explore the long-term aging influence on chemo-rheological properties and develop novel consecutive models for the long-term aging reaction kinetics of bitumen. The results revealed that the aging index was significantly dependent on the types of selected parameters. The Zero-order model was suitable to describe the long-term aging reaction kinetics of bitumen based on the oxygen-containing functional groups with the reaction rate constants in 0.7–3.3*10−4 (mol L−1·h−1). In the SARA-based consecutive reaction model, the most optimum kinetics model for aromatic fraction was the Third-order reaction model and the corresponding reaction kinetics constant (k1) was 0.02 (mol·L−1)−2(h)−1. The Zero-order model could well fit the generation kinetics of asphaltene molecules with the reaction rate constant k2 of 3.85*10−4 mol·(L·h)−1. Further, the transformation reaction from the resin to asphaltene molecules was the control step of the whole consecutive reaction model. In this study, when one-unit resin fraction was generated, the consumption amount of aromatic fraction was about 2.82 units. Meanwhile, when one-unit resin fraction was consumed, only 0.58-unit asphaltene could be generated. The developed reaction kinetics models could be beneficial to predict the functional groups distribution and SARA fractions in aged bitumen with different aging degrees.
TL;DR: In this paper , an approach for stabilising high plastic soil (HPS) with fly ash-based geopolymer and its application in flexible pavement is presented. But, the results clearly indicate that the mechanical performance of (FA)-based geo-merger stabilised HPS increases up to 25% (FA) content and was less prone to swelling and shrinkage behavior.
Abstract: This paper presents an approach for stabilising high plastic soil (HPS) with fly ash-based geopolymer and its application in flexible pavement. The mechanical performance of HPS with various proportions of fly ash (FA) (10, 15, 20, 25, and 30%) based geopolymer were evaluated through a series of experimental investigations. The soil was mixed with sodium hydroxide of 6 and 8 molar concentrations (6M & 8M) and a sodium silicate mixture of ratio 1.5 was used as alkaline activators for (FA). The results clearly indicate that the mechanical performance of (FA)-based geopolymer stabilised HPS increases up to 25% (FA) content and was less prone to swelling and shrinkage behaviour. Also, the microstructure of HPS was studied through the Scanning Electronic Microscope (SEM) with energy dispersive x-ray (EDX), X-ray Diffraction (XRD), and Fourier Transformed Infrared Spectra (FTIR), and results showed significant alteration of the microstructure of HPS due to the formation of geopolymeric gel. The application of stabilised HPS is demonstrated for the design of flexible pavement thickness for low and high-volume roads. It has been observed that there is a significant reduction in pavement thickness for stabilised HPS compared to HPS. Thus, it can be used as a sustainable alternative to conventional stabilisers.
TL;DR: Wang et al. as discussed by the authors proposed an efficient deep learning framework for automated asphalt pavement distress segmentation, which consists of two parallel feature extraction branches, the P branch to extract prior global information and the U branch to obtain local information.
Abstract: Recently, many deep learning methods have achieved great results in the field of automated pavement distress detection, but most of them ignore other types of distresses beyond cracks. This paper proposes an efficient deep learning framework for automated asphalt pavement distress segmentation called pavement distress segmentation network (PDSNet). PDSNet can effectively segment multiple asphalt pavement distresses, including crack, pothole, raveling, patch, and sealed crack. It consists of two parallel feature extraction branches. One is the P branch to extract prior global information. The other is the U branch to obtain local information. By utilising the global and local features together, PDSNet can produce precise segmentation results under complicated circumstances. For deep learning purposes, a pavement distress dataset consisting of 4000 pavement images is collected and manually labelled at pixel level. Each image of the pavement dataset is a two-channel image, which is concatenated by a 2D pavement image and the correspondingly 3D pavement image. Particularly, it is the first pavement distress dataset that utilises two-channel pavement images. According to the experimental results, PDSNet yields a performance with a MIoU of 83.7%. Compared with the state-of-the-art networks, PDSNet achieves the best MIoU and has considerable parameter number and inference time.
TL;DR: In this article , the effects of the crystalline wax on optical properties of the asphalt binder were investigated using the spectroscopic ellipsometry (SE) technique, and a new method for quantification of the crystal wax in asphalt was also developed.
Abstract: Asphalt pavement possesses the characteristics of strong sunlight absorption, which lead to the aging of asphalt binder. Asphalt aging is one of the leading causes of the performance deterioration in the asphalt pavement, and the appearance of crystalline wax (paraffin wax) during aging has a significant effect on optical properties (absorption and reflection) of the asphalt binder. In this paper, effects of the crystalline wax on optical properties of the asphalt binder were investigated using the spectroscopic ellipsometry (SE) technique, and a new method for the quantification of the crystalline wax in asphalt was also developed. Cold Lake asphalt doped with different contents of n-alkanes (eicosane, triacontane, and tetracontane) were tested by the SE. The results showed that there is a close linear relationship between the optical constants and wax content of the asphalt binder. In addition, with increasing both the chain length of n-alkanes and their content, the reflection intensity of the asphalt binder decreased, and the refractive index and extinction coefficient increased accordingly. On the whole, ellipsometry-based optical testing is a promising method for rapid and non-destructive identification of wax in asphalt.
TL;DR: In this article , a robust prediction algorithm, Random Forest Regression (RFR), is applied to predict the pavement International Roughness Index (IRI) and multiple linear regression (MLR) is employed to assess the performance of the proposed technique in terms of IRI prediction accuracy.
Abstract: Developing an accurate pavement prediction model plays a dominant role in pavement M&R optimization. Despite employing different robust machine learning techniques to predict pavement conditions, these methods have some weaknesses in synchronising with exact optimization algorithms. The main contribution of this study is to propose a novel method for optimizing the pavement M&R plan with high accuracy. Contrary to conventional approaches, a robust prediction algorithm, Random Forest Regression (RFR), is applied to predict the pavement International Roughness Index (IRI). In addition, Multiple Linear Regression (MLR) is employed to assess the performance of the proposed technique in terms of IRI prediction accuracy. Whale Optimization Algorithm (WOA), as a powerful metaheuristic optimization algorithm, is utilised to obtain the optimal solution to the pavement M&R optimization problem. RFR is run as an internal part of the WOA in the introduced method. Furthermore, Genetic Algorithm (GA) is used to examine the performance of the proposed approach in finding the optimal solution. The RFR results conclude a more accurate prediction of IRI than MLR based on all machine learning performance indicators. Furthermore, the newly developed hybrid model significantly outperforms GA in finding the optimal and cost-effective solution to the M&R optimization problem.
TL;DR: In this article , the Qinghai-Tibet Highway (QTH) pavement distress was investigated in 550 km-long permafrost regions based on the field surveys in 2014 and 2019 and the unmanned aerial vehicle (UAV) imagery.
Abstract: For the particular engineering-geological conditions and natural environment in permafrost regions, the highway has a high damage ratio during the operation. In warm and ice-rich permafrost regions, highway pavement and embankment have poor serviceability, which threatens driving the vehicle and safe operation. Traditional field surveys on highway damage cannot entirely, rapidly and precisely obtain the distress information along the whole road. In this paper, the Qinghai-Tibet Highway (QTH) pavement distress was investigated in 550-km-long permafrost regions based on the field surveys in 2014 and 2019 and the unmanned aerial vehicle (UAV) imagery. The type and damage ratio of distress were extracted by the remote sensing image classification method. The pavement roughness and embankment height were acquired by the spatial analysis of geographical information system. This paper provides a novel insight and efficient method for the distress investigation and exploration of distress formation in permafrost region, which can be applied in other similar engineering projects in the cold and inclement permafrost region. Furthermore, this paper also presents valuable and first-hand field data for evaluating highway serviceability and prevention of road damage during operation and maintenance stages.
TL;DR: In this paper , the authors proposed two concrete and valuable models in the finite element method for simulating the fracture behaviour of the huge structure with asphalt and asphalt concrete, and compared with the plastic coupled cohesive model coupled with the Ramberg-Osgood elasto-plastic harden model is promising for investigating the physical mechanism underlying the nonlinear fracture of BFRAC.
Abstract: In this study, the plastic coupled cohesive model and enhanced virtual crack closure technique (VCCT) are used to investigate the fracture behaviour of the basalt fibre reinforced asphalt concrete (BFRAC). In the plastic coupled cohesive model, the separation and traction response along the cohesive zone advance ahead of a crack tip is governed by an exponential cohesive law. The double-K fracture theory is integrated into the enhanced VCCT model. It is shown that the simulated load-cracking mouth opening displacement (P-CMOD) curves from both the plastic coupled cohesive model and the enhanced VCCT model compares favourably with the measured curves from the single-edge notched beam. The parameters used in the plastic coupled cohesive model cannot directly be obtained from the standard test, and the inverse analysis method is always necessary for identifying the fracture parameters. On the contrary, the fracture parameters in the enhanced VCCT method can be directly calculated from the P-CMOD curves based on the double-K fracture theory and the finite plastic fracture theory (Hutchinson, Rice, Rosengren singular crack tip fields, abbreviated as HRR field). Meanwhile, compared with the plastic coupled cohesive model, the enhanced VCCT model coupled with the Ramberg–Osgood elasto-plastic harden model is promising for investigating the physical mechanism underlying the nonlinear fracture of BFRAC. This paper proposed two concrete and valuable models in the finite element method for simulating the fracture behaviour of the huge structure with asphalt and asphalt concrete.
TL;DR: In this paper , a parametric study using multiphysics modelling approaches to evaluate the e ff ects of material thermal properties, air voids content and distribution, mastic coating thickness, oxygen accessibility and binder oxidative kinetics on the spatial and temporal evolution of the asphalt pavements.
Abstract: Oxidative ageing in fi eld asphalt pavements is a complex process with coupled multiple physics. This parametric study uses Multiphysics modelling approaches to evaluate the e ff ects of material thermal properties, air voids content and distribution, mastic coating thickness, oxygen accessibility and binder oxidative kinetics on the spatial and temporal evolution of the oxidative ageing in the asphalt pavements. Results suggest that increasing the thermal conductivity of asphalt layers leads to a lower ageing gradient. The variations of base and subgrade layers ’ thermal properties cause little to no e ff ects on the oxidative ageing. A high activation energy of the asphalt binder (e.g. by adding anti-ageing additives) reduces the oxidative ageing signi fi cantly. Asphalt layers built on unbound granular base will experience greater overall ageing with a C-shaped ageing gradient compared to that built on treated base. Air voids content of <5% yields limited oxidative ageing. Five to nine percent air voids generate a gradually increased oxidative ageing with an obvious gradient across pavement depth. Air voids content beyond 9% leads to a consistently high oxidative ageing due to a full access to the oxygen. Finally, the fi ndings were validated using available literature results and fi eld data from 14 European road sections.
TL;DR: In this paper , the feasibility of using industrial waste fly ash (FA) and agricultural waste rice husk ash (RHA) for sustainable pervious concrete production was examined and compared.
Abstract: Pervious concrete is a special type of concrete consisting of cement, coarse aggregate and water. Cement is a widely used raw material for construction including pervious concrete and had led to the release of huge amounts of CO2 to the environment. Therefore, there is lot of research interest in finding supplementary cementitious materials. The present study examined and compared the feasibility of using industrial waste fly ash (FA) and agricultural waste rice husk ash (RHA) for sustainable pervious concrete production. An experimental program was performed with substitution of FA and RHA contents of 5%, 10%, 15% and 20% as cement replacement and water to binder ratio of 0.3, 0.35, 0.4 and 0.45. The characteristics of pervious concrete and sustainability analysis were compared for both FA and RHA replacement with control concrete mortar. The results showed that both FA and RHA have a negative effect on permeability. The compressive strength was optimum for FA content lies between 10% and 15% replacement level and RHA content of 5% replacement level. Furthermore, the utilisation of FA and RHA decreased production cost, the total embodied energy and carbon emission, resulting in cost-effective and eco-friendly pervious concrete.
TL;DR: In this article, a dynamic backcalculation of pavement layer properties, and more specifically the ability to determine the asphalt concrete master curve, using Falling Weight Deflectometer (FWD) data has been proposed.
Abstract: The dynamic backcalculation of pavement layer properties, and more specifically the ability to determine the asphalt concrete master curve, using Falling Weight Deflectometer (FWD) data has caught ...
TL;DR: In this paper , the effect of zeolite as a WMA additive on Hot Mix Asphalt (HMA) and Rubberized-Asphalt (RA) mixtures was investigated.
Abstract: One of the ways to modify bitumen and asphalt mixture characteristics is to use recycled Crumb Rubber (CR). Although using CR improves the mechanical properties of asphalt mixtures and rheological behavior of bituminous binders, it increases binder viscosity. Warm Mix Asphalt (WMA) is a practical technology to ameliorate the disadvantage of Rubberized-Asphalt (RA) mixtures. This study aimed to investigate the effect of zeolite as a WMA additive on Hot Mix Asphalt (HMA) and RA mixtures. These modifiers' effect on the properties of asphalt mixtures and binders was studied utilizing different tests such as resilient modulus, indirect tensile fatigue, dynamic creep, moisture susceptibility (TSR and RMR), and rotational viscosity (RV). The findings indicate that the addition of zeolite and CR improved mechanical properties. 16% CR along with 6% zeolite is the optimum dosage to enhance durability. Moreover, the addition of CR to mixtures without zeolite decreased the TSR, RMR, and workability of mixtures, while zeolite increased the durability and workability of HMA and RA mixtures. The cost-effective analysis results also indicated that not only does the simultaneous proper use of zeolite and CR decreases energy consumption, but it also decreases the production cost of modified asphalt mixture.
TL;DR: In this paper , the influence of aggregate gradation on compressive strength and porosity in Pervious Concrete (PC) subjected to various compaction efforts was examined, and it was shown that porosity increased with aggregate gradations with larger size particles.
Abstract: This study examined the influence of aggregate gradation on compressive strength and porosity in Pervious Concrete (PC) subjected to various compaction efforts. Two aggregate gradations 12–18 and 18–25 mm were recombined in different proportions in the range of 10–50% to obtain five different gradations. PC specimens were cast with these five aggregate gradations by applying standard Proctor compaction, varying efforts from 0 to 75 blows. Test results indicated that wet density and compressive strength increased with compaction effort at higher rate for specimens casted with Aggregate-to-Cement (A/C) ratio 2.5 than 5.0, but porosity reduced at almost the same rate for both A/C ratios. Compressive strength reduced when aggregate gradation with larger size particles increased, however porosity increased. Altering aggregate gradation or compaction effort yielded no significant change in PC properties for A/C ratio of 5.0 than it did for 2.5. The developed mathematical models predicted compressive strength and porosity of PC mixes in terms of aggregate gradation and compaction effort. The highest mean deviation and relative error of model prediction were 1.377 MPa and 10.4% for compressive strength, and 1.414% and 5.8% for porosity, respectively.
TL;DR: In this paper , the performance of asphalt concrete containing recycled plastics as synthetic aggregates in the dry mixing process was investigated, and two types of recycled plastics were used, namely, acrylonitrile butadiene styrene (RABS) and Polyethylene Terephthalate (RPET), based on the high-temperature properties of the plastics that make them suitable to be treated as synthetic aggregate (i.e. do not melt during the asphalt mixing phase).
Abstract: This study investigates the performance of asphalt concrete containing recycled plastics as synthetic aggregates in the dry mixing process. Two types of recycled plastics were used, namely, acrylonitrile butadiene styrene (RABS) and Polyethylene Terephthalate (RPET), based on the high-temperature properties of the plastics that make them suitable to be treated as synthetic aggregates (i.e. do not melt during the asphalt mixing phase). The proportions of recycled plastics were chosen at 0.5%, 1%, 2% and 4% of the mix mass. The laboratory testing programme includes the evaluation of compactability properties, moisture resistance, cracking resistance via IDEAL-CT test, fatigue resistance via four-point bending beam test and rutting resistance via Hamburg wheel tracking (wet) test. It was found that the inclusion of recycled plastics did affect the compactability of the mixes depending on their relative size and shape. On the other hand, the inclusion of recycled plastics did not significantly vary the moisture resistance of asphalt mixes. The cracking and rutting behaviour of asphalt mixes that incorporated recycled plastics were also modified and some benefits were observed depending on the plastic content and size.
TL;DR: In this article , a Life Cycle Assessment (LCA) was conducted to compare the potential environmental impacts associated with the use of Recycled Concrete Aggregate (RCA) as a partial replacement of natural aggregates in the production of Warm Mix Asphalt (WMA), with those of a conventional hot mix asphalt (HMA).
Abstract: A Life Cycle Assessment (LCA) was undertaken to compare the potential environmental impacts associated with the use of Recycled Concrete Aggregate (RCA) as a partial replacement of natural aggregates in the production of Warm Mix Asphalt (WMA), with those of a conventional Hot Mix Asphalt (HMA). The LCA was conducted according to the ‘cradle-to-laid’ approach, including four pavement LCA phases. Three percentages of RCA replacement for natural coarse aggregates in WMA were considered: 15, 30 and 45%. The results of laboratory tests were used as inputs in the design of pavement structures with different percentages of RCA for typical Colombian pavement design conditions. Primary data and SimaPro 8.4.0 software were used in modelling the processes analysed in the case study. All the life cycle inputs and outputs related to the functional unit were characterised according to the impact assessment methodology TRACI v.2.1. The results show that the potential environmental benefits arising from the combined effect of reducing the consumption of natural aggregates and reduced mixing temperature are offset by the reduced performance and the increased optimum asphalt content when incorporating RCA in WMA. The highest relative increase in the environmental impacts, at 29%, was observed in the Ecotoxicity impact category.
TL;DR: In this paper , the authors make use of a sieve analysis method and tracer-based microscopy analysis to quantify recycled binder availability and design asphalt mix design procedures to account for partial availability.
Abstract: The use of reclaimed asphalt pavement (RAP) and recycled asphalt shingles (RAS) in asphalt mixtures is a routine process. Recycled binder availability reflects the proportion of the total recycled binder in a given recycled asphalt material (RAM) that is available to blend with the virgin binder. Studies show that agglomerations of adhered RAM particles preclude complete availability. However, the Superpave volumetric mixture design methods adopted by the majority of state agencies assume complete availability. This study makes use of a sieve analysis method and tracer-based microscopy analysis to quantify recycled binder availability. Revisions to asphalt mix design procedures to account for partial availability are proposed, including consideration of the unavailable binder as part of the bulk aggregate volume and the use of the RAM gradation (i.e. black curve) rather than the recovered aggregate gradation (i.e. white curve) to design the mixture’s aggregate structure. Three high RAM content ‘control’ mixtures that were originally designed under the assumption of complete recycled binder availability are redesigned according to the proposed approach. The redesigned mixtures had notably higher virgin binder content than the control mixtures. The redesigned mixtures also had significantly better cracking resistance than the control mixtures while still meeting permanent deformation requirements.
TL;DR: In this article , a temperature-based asphalt mixture dielectric model has been proposed for quantifying the influence of temperature on the dielectrics properties of asphalt mixtures, and the model has great significance for measuring the influence on the properties.
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.
TL;DR: In this paper , artificial neural networks and the random forest method have been used to predict the amount of this failure in concrete pavement design, and it is shown that the simplified model developed by Artificial Neural Networks is the best model to accurately predict the faulting considering the number of input variables.
Abstract: Predicting faulting failure is useful in the optimal concrete pavement design. In this study, artificial neural networks and the random forest method have been used to predict the amount of this failure. The general prediction model was created by inserting 32 available input variables into artificial neural networks. An integer two objectives optimisation problem was designed to select features that significantly affect the faulting. After applying this method, 19 important variables were identified and used to develop two simplified models based on artificial neural networks and the random forest method. It is shown that the simplified model developed by artificial neural networks is the best model to accurately predict the faulting considering the number of input variables. The cumulative number of days when the precipitation is more than 12.7 mm, the elastic modulus of concrete slab, the number of days passed since the pavement was built, base thickness, the cumulative ESALs in the traffic lane, and the annual average number of days when the temperature is more than 32°C were identified as the most important parameters in predicting faulting using the random forest method. A Sensitivity analysis has been then performed on these variables and optimal values were determined.