Showing papers in "International journal of pavement research and technology in 2020"

Experimental study on potential of oyster shell ash in structural strength improvement of lateritic soil for road construction

Abstract: This study investigated the effect of oyster shell ash (OSA) on the geotechnical properties of lateritic soil. Laboratory studies were performed using lateritic soil treated with up to 15 % OSA. The result shows a decrease in maximum dry density (MDD) with corresponding increase in optimum moisture content (OMC). Unconfined compressive strength (UCS) values generally increased with increased OSA content and curing age, while resistance to loss in strength increased to peak of 18 % at the threshold of 6 % OSA content. Peak California bearing ratio (CBR) values (soaked and unsoaked) were obtained at a threshold of 6 % PSA content. The Fourier transformation infrared (FTIR) spectroscopy of the soil, OSA and soil + OSA blend show the distinctiveness of the relevant functional groups in relation to their specific band. The treated soil show H-O-H bending of water linked to 2Al3+, Si-O, Si-O-Si. The scan electron microscopy (SEM) and electron diffraction spectroscopy of treated soil revealed the formation of compounds responsible in strength improvement of the soil. Generally, OSA show significant strength improvement on the lateritic soil. This study has shown that OSA can be beneficially used in lateritic soil improvement and is also recommended as admixture in either lime or cement stabilization of deficient lateritic soil for use in road construction.

Artificial neural network modelling to predict international roughness index of rigid pavements

Abstract: This research focuses on predicting the International Roughness Index (IRI) of rigid pavements using the Artificial Neural Network (ANN) model that uses climate and traffic parameters as inputs. A Long-Term Pavement Performance (LTPP) database is used to extract data from wet-freeze, wet no-freeze, dry-freeze, and dry no-freeze climatic zones. The climate and traffic parameters are Mean Annual Air Temperature, Annual Average Freezing Index, Annual Average Maximum and Minimum Humidity, Annual Average Precipitation, Annual Average Daily Traffic, and Annual Average Daily Truck Traffic. The ANN model is trained with 70% of climate, traffic and IRI data, rest 15% data is used to test the model, and remaining 15% data is used to validate the model. The trained and the validated models are compared by calculating Root Mean Square Error (RMSE) and Mean Absolute Percentage Error (MAPE). Among many results, the datasets that are tested with 7–9–9–1 ANN structure with hyperbolic tangent sigmoidal transfer function generated the best prediction models with an RMSE value of 0.01 and MAPE value of 0.01 (1% error) for a rigid pavement located in the wet no-freeze climatic zone.

Vibration vs. vision: best approach for automated pavement distress detection

Abstract: Roads are the largest component of infrastructure; they directly impact people’s life by providing mobility and connectivity. To ensure consistent surface quality, roads must be monitored continuously and repaired when necessary. Presently, authorities spend substantial amount of time, finance and labor for pavement distress detection by employing traditional manual and instrumented methods which are generally tedious, and time-consuming. To overcome these drawbacks, various automated techniques like Ground Penetrating Radar, Laser-Imaging-Systems, etc. are deployed. Recently, image-processing and smartphone-based systems are being devised for pavement distress detection. Here, a vibration-based method using smartphone accelerometer and gyroscope, and a vision-based method using video processing for automated pavement distress detection are designed and compared to identify the more suitable one. Both experiments are performed on same roads and results are validated by manual surveying. Accuracy of vibration-based method for detecting potholes, patches and bumps is found as 80%. Accuracy for detecting cracks, potholes and patches using vision-based method is identified as 84%. An additional effort is taken to estimate the extent of pavement distresses using vision-based approach and validate it using manual stripping method. The study reveals that, vibration-based-analysis is sufficient for routine monitoring purposes whereas vision-based-method is more appropriate for detailed analysis.

Experimental study on geocell reinforced base over dredged soil using static plate load test

Abstract: Dredging process is the process of removing sediments from a water body that has accumulated as a result of upland erosion to preserve a required depth. The accumulation of large quantities of sediment has led to significant environmental and financial problems. Due to lack of insufficient strength, dredged soils need improvement. It is thus possible to implement the geocell-reinforcement in base course to improve the strength and stiffness of the weak subgrades. This paper uses static plate loading technique to investigate the reuse of dredged soil as a subgrade in unpaved roads. Geocell is a three-dimensionally interconnected geosynthetic material used for strengthening the properties of the base course. Numerous research for planar geosynthetic reinforcement has already being carried out, but limited research has been done for three-dimensional geocell reinforcement. Geocell reinforced bases have shown significant advantages over unreinforced ones. In the present study unpaved pavements with and without inclusion of geocells were tested under static loading. Lime stone aggregates were used in base course as infill material. Subgrade used in this study were dredged soil form Dal lake having a CBR of 5%. The results have been reported in terms of deformation, vertical stress and strain within geocell. It was observed that the load bearing capacity and vertical stress distribution of the model pavement system were substantially improved due to the geocell reinforcement. It was determined that geocell can improve the behavior of unpaved road constructions quite efficiently, with decrease in permanent deformation and increase in vertical stress distribution.

Transfer learning for pavement performance prediction

Abstract: Accurate pavement performance prediction models are essential to ensure optimal allocation of resources in maintenance management. These models are developed using inventory and monitoring data regarding pavement structure, climate, traffic, and condition. However, numerous road agencies have limited pavement data. Due to the inexistence of historical data, data collection frequency, and/or quality issues, the amount of data available for the development of performance models is reduced. As a result, the resource allocati on process is significantly undermined. This paper proposes a transfer learning approach to develop pavement performance prediction models in limited data contexts. The proposed transfer learning approach is based on a boosting algorithm. In particular, a modified version of the popular TrAdaBoost learning algorithm was used. To test the proposed transfer learning approach, a case study was developed using data from the Long-Term Pavement Performance (LTPP) database and from the Portuguese road administration database. The results of this work show that it is possible to develop accurate performance prediction models in limited data contexts when a transfer learning approach is applied. All the models resulting from this approach outperformed baseline models, especially in what regards long-term forecasts. The results also showed that the transfer learning models perform consistently over different time frames, with minor performance losses from one-step to multi-step forecasts. The findings of this study should be of interest to road agencies facing limited data contexts and aiming to develop accurate prediction models that can improve their pavement management practice.

Research progress on cement-based materials by X-ray computed tomography

Abstract: X-ray computed tomography (CT), as an imaging technique, has played an important role in the area of material characterization in civil engineering during the past 40 years. It has promoted the investigation of materials from the macroscopic testing to the microscopic characterization. Though numerous researches have been done by using X-ray CT technique to investigate the microstructure, the mechanical behavior, and the durability of cement-based materials, there is no comprehensive review on the testing process and the results obtained. Based on the research progress in the past 40 years made on the cement-based materials, the relevant issues to the X-ray CT technique are reviewed in this study in terms of the equipment used, the sample preparation, the test methods, the data processing, and the results obtained. Particularly, this article focuses on assessing microstructure, mechanical behavior, damages from freeze-thaw cycles, carbonation, sulfate attack, alkali-silica reaction, and the quantification of permeability of cement-based materials by using X-ray CT. The results can serve as a guidance for future experimental design of the similar research and provide inspirations on improving equipment for broader applications to cement-based materials.

Extraction and recovery of asphalt binder: a literature review

Abstract: A literature review was conducted on the main aspects of asphalt binder extraction and recovery: i) extraction methods, ii) recovery methods and iii) solvents. The extraction methods include centrifuge, reflux and vacuum and others with particular focus on their effectiveness in dissolving the binder and the potential to modify it. Studies found that the centrifuge was a relatively safe cold extraction method that was fairly effective. For the recovery methods, the rotary evaporator was found to have a good reputation for relative ease of use and less binder modification than for the Abson method. The most commonly used solvents n-propyl bromide and chlorinated solvents, while being reusable, both had reported issues of ineffectiveness as well as major concerns about user safety. Bio-sourced solvents were found to be seldom used and required higher quantities. The study concluded that more research needed to be done in developing solvents.

Impact of wetting—drying cycles on the mechanical properties of lime-stabilized soils

Abstract: This article addresses the results of an experimental study on the behavior of soil; this soil was exposed to long-term treatment with lime and numerous wetting-drying cycles. This research investigated the effect of a wide range of lime contents on the soil volume, soil water content evolution and durability (unconfined compressive strength (UCS), plasticity index (PI) and cation exchange capacity (CEC)) for stabilized soil in contact with water. This experimental study was performed on soil treated with lime (varying from no lime to 8%) corresponding to three levels of improvement: soil improvement only, stabilization and insensitivity to water, and long-term stabilization during wetting-drying cycles. The results indicated that the UCS increases, PI and CEC decreases with the lime level. For lime levels above 4%, the behavior of the treated soil under wetting-drying was satisfactory. Mineralogical analyses indicated that the formation of calcium silicate hydrate C-S-H, ettringite C-S-A-H is responsible for the increased or decreased strength of the treated soil. CaO, SiO2 and Al2O3 were three important minerals responsible for the increase or decrease in soil sample stabilization. Simple model executed in JMP statistical software was proposed and validated. We note that CaO and SiO2 have the most influential effects by very low values of probability for the responses studied, which confirms the hypothesis of that these models can be used to model UCS and PI in curing time and wetting-drying cycles.

Investigation of sea salt erosion effect on the asphalt-aggregate interfacial system

Abstract: Under high-temperature and hygrothermal conditions, sea salt erosion can lead to asphalt-aggregate interfacial failure in porous asphalt concrete and cause aggregate raveling in coastal areas. Therefore, studying the damaging effect of sea salt erosion on an asphalt-aggregate interfacial system in a hygrothermal environment is necessary. First, the asphalt film thickness of a standard asphalt-aggregate specimen used in the simulation tests was determined according to the relationship between the tensile strength of the asphalt-aggregate specimen and the thickness of the asphalt film. The damaging effect of the salt solution was simulated by the 60°C high-temperature erosion test, and the solution type, solution concentration, and immersion duration were considered. The tensile strength and asphalt film-stripping ratio of the eroded specimens were analyzed, and the interfacial asphalt film dynamic equation σ2(t) and the stripping region interface dynamic equation σ2(t) were deduced. The results show that the 6 μm asphalt film thickness corresponds to the maximum tensile strength of the asphalt-aggregate specimen. With the increase of immersion duration, the tensile strength of asphalt-aggregate specimen decreased, and the asphalt film-stripping ratio of failure surface increased. In addition, the tensile strength of the interfacial asphalt film increased gradually due to the aging effect of the salt solution. The tensile strength of the stripping region’s interface did not descend to zero, but was obviously lower than the asphalt film. The 5% Na2SO4 solution has the highest damaging effect on the asphalt-aggregate interfacial system, followed by the 5% composite salt solution, 5% NaCl solution, water, and 10% NaCl solution..

Performance evaluation of warm mix asphalt using natural rubber modified bitumen and cashew nut shell liquid

Abstract: Warm Mix Asphalt (WMA) is an innovative technology that aims at decreasing the mixing and compaction temperature of asphalt mixtures as compared to the conventional Hot Mix Asphalt (HMA) thereby reducing harmful emissions and fuel consumption. The rubberized asphalt mixtures are found to have better physical and strength properties, but they are compacted at a higher temperature than that of conventional mixes. In this study Cashew Nut Shell Liquid (CNSL), an organic additive, was added from 0.5% to 3 % by weight of the binder at an increment of 0.5 % to modify the bitumen. The optimum content of CNSL to reduce the viscosity was found to be 2% and the viscosity reduction was 44.4 % at 140°C The modified NRMB (Natural Rubber Modified Bitumen) was used to prepare Dense Bituminous Macadam (DBM) and a comparison of volumetric, stability and rutting characteristics of both Natural Rubber modified Hot Mix Asphalt (RHMA) and Natural Rubber modified Warm Mix Asphalt with CNSL additive (RWMA) was made. Storage stability results indicated that there was no phase separation between rubberized bitumen and additive at high temperature and will act as uniform blend at high temperatures. Dynamic Shear Rheometer test results showed that the addition of CNSL to rubberized bitumen increased the values of G*/sinδ and could improve the resistance of asphalt binder against rutting. Stability value of RWMA was 11.5 % higher than that of RHMA and rutting depth was 10.1 % less than that of RHMA. The fatigue strength results obtained from Repeated Load Testing showed that the number of cycles to failure at 20% stress level was 9.04 % more for RWMA than RHMA. All volumetric properties of both RHMA and RWMA were within the limits specified by Ministry of Road Transport and highways (MoRTH) 2013. The statistical analysis authenticates the experimental findings. ANOVA analysis for Marshall Quotient revealed that RWMA had improved compaction characteristics than RHMA and the result for rutting and fatigue strength showed that the additive CSNL and temperature had significant effect on rutting resistance and fatigue life.

Porous asphalt concrete: A review of design, construction, performance and maintenance

Abstract: Porous asphalt concrete (PAC) is an open-graded friction course that is specifically designed to have high air void contents for removing water from the pavement surface. PAC surfaces, which include open-graded friction courses, permeable friction courses, and drainage asphalt pavements, have increasingly gained acceptance among agencies and industry in the world. PAC might be susceptible to freeze-thaw damage in cold climates and require winter maintenance practices. The life span of PAC pavements shows a large variation depending on climates, traffic volumes and loadings, design and construction practices. The objective of this paper was to review design, construction, and performance that could maximize the advantages and minimize the disadvantages associated with the use of PAC mixtures. A consolidated review of the worldwide literature on PAC applications was conducted, with attention to the use of PAC in agency practices, and specifications for PAC from the world were evaluated. Based on an analysis of the results of this review, two key features were emphasized: (1) a recommended practice for material selection and design of PAC, and (2) a recommended practice for PAC construction and maintenance. Key points include a careful assessment of the PAC drainage and an adequate asphalt content to improve the performance of the pavement surface. A proper binder content stabilized by additives such as fibers and polymers is essential to ensure sufficient film thickness that is critical to the durability of the PAC mix in the long run.

Environmental evaluation of pavement system incorporating recycled concrete aggregate

Abstract: Environmental benefits of using recycled concrete aggregate (RCA) regarding a concrete pavement structure should be evaluated because standard specification for RCA as a raw material in RMC is not currently in place in many locations. This work aims to address environmental benefits of using RCA of concrete pavement structures using a Life Cycle Assessment (LCA) analysis. Two concrete mix designs and two mix ingredients containing RCA and natural aggregate (NA) are determined at 10% and 20% replacement levels. Results indicate that using RCA in pavements can result in decreases of environmental impacts regarding energy consumption, water consumption and CO2, PM10, and RCA waste generation, but result in increases of NOx and human toxicity potential (cancer and non-cancer) generation. Using the RCA in concrete pavement can ultimately reduce the negative environmental impacts, especially for energy consumption. Nonetheless, selecting the suitable concrete mix design should be carefully determined for each application since the negative environmental impacts can be significantly decreased.

Sensor-based pavement diagnostic using acoustic signature for moduli estimation

Abstract: The diffusion of smart infrastructures for smart cities provides new opportunities for the improvement of both road infrastructure monitoring and maintenance management. Often pavement management is based on the periodic assessment of the elastic modulus of the bound layers (i.e., asphalt concrete layers) by means of traditional systems, such as Ground Penetrating Radar (GPR) and Falling Weight Deflectometer (FWD). Even if these methods are reliable, well-known, and widespread, they are quite complex, expensive, and are not able to provide updated information about the evolving structural health condition of the road pavement. Hence, more advanced, effective, and economical monitoring systems can be used to solve the problems mentioned above. Consequently, the main objective of the study presented in this paper is to present and apply an innovative solution that can be used to make smarter the road pavement monitoring. In more detail, an innovative Non-Destructive Test (NDT)-based sensing unit was used to gather the vibro-acoustic signatures of road pavements with different deterioration levels (e.g. with and without fatigue cracks) of an urban road. Meaningful features were extracted from the aforementioned acoustic signature and the correlation with the elastic modulus defined using GPR and FWD data was investigated. Results show that some of the features have a good correlation with the elastic moduli of the road section under investigation. Consequently, the innovative solution could be used to evaluate the variability of elastic modulus of the asphalt concrete layers, and to monitor with continuity the deterioration of road pavements under the traffic loads.

Rutting resistance of toner-modified asphalt binder and mixture

Abstract: Asphalt binder resistance to permanent deformation considerably influences total pavement resistance to rutting at the high service temperatures. To improve asphalt shear strength against rutting resistance, researchers have been used various modifiers and recently the use of waste materials as binder rheological enhancement agents is paid lots of attention. In this study, waste toner was adopted as an anti-rutting enhancement agent, and then neat asphalt binder was modified by waste toner at four dosages: 4, 8, 12 and 16% based on asphalt binder’s weight. The effectiveness of binder modification by waste toner to improve asphalt binder and mixture’s resistance to permanent deformation has been assessed by means of different met hods: the Superpave specification parameter, G*/sinδ, and the multiple stress creep and recovery (MSCR) test for asphalt binder and wheel track test for asphalt mixture to determine the rut depth for a certain number of loadings. Results showed that adding toner to neat asphalt binder can meaningfully enhance the anti-rutting performance of asphalt binder and subsequently asphalt mixture. Moreover, increasing the dosage of toner up to 12% in the modified asphalt binder amplifies the trend of rutting resistance improvement.

Coupling effects of wasted cooking oil and antioxidant on aging of asphalt binders

Abstract: The service life of asphalt pavement will be reduced with the aging of the asphalt binder. In this study, wasted cooking oil (WCO) and an antioxidant (Tns-(2.4-di-tert-butyl)-phosphite, 168) are utilized to retard aging of 60/80 pen grade asphalt binder and SBS modified asphalt. The influences of short-term aging at high temperature (180°C, 5 h) on physical and chemical properties of asphalt binder with WCO and 168 are investigated. Experimental results showed that aging resistance of asphalt binder with WCO and 168 can be improved effectively. The chemical composition and molecular weight of asphalt binder are distinguished by Fourier transform infrared (FTIR) spectroscopy and Gel Permeation Chromatography (GPC). The results indicated that no new substances are obtained when WCO and 168 added to the asphalt binder. The molecular weight of asphalt binder containing WCO and 168 after aging could be achieved at the level of unaged asphalt binder. Furthermore, grey relational analysis is used to investigate correlation coefficients between increment of carbonyl index (ICI) and increment of softening point (ISP), ductility aging ratio (DAR), penetration aging ratio (PAR), increment of sulfoxide index (ISI) and growth rate of LMS (LAI). The results indicated that ICI, ISI, LAI and DAR are reliable methods to evaluate the aging resistance of asphalt binder.

Studies on fatigue performance of modified dense bituminous macadam mix using nano silica as an additive

Abstract: In this project work, organized study was carried out to evaluate the fatigue performance of dense bituminous macadam (DBM) mix using nano silica as an additive and the results were compared with the conventional DBM mix. For this purpose, Marshall stability and indirect tensile strength (ITS) tests were conducted to find out optimum bitumen content, optimum nano silica content and tensile strength of the mix. Repeated load fatigue test was carried out for DBM mix with and without nano silica at different failure loading or stress level which was obtained from ITS test. The nano silica modified DBM mixes shows higher fatigue life across all failure loading compared to conventional DBM mix. Also, it was seen that the increase in failure loading resulted in decrease of number of fatigue cycles and increase in the initial tensile strain of the mix. The DBM mix with 4% (optimum) nano silica shows 1.85, 1.67, 1.74, 2.16 and 1.98 times higher resilient modulus when compared to conventional DBM mix at 10%, 20%, 30%, 40% and 50% failure load respectively. Fatigue line constants were calculated for both conventional and nano silica modified DBM mixes and the values were comparable with the literature.

Erratum to: Porous asphalt concrete: A review of design, construction, performance and maintenance

Abstract: The article Porous asphalt concrete: A review of design, construction, performance and maintenance, written by Jian-Shiuh Chen and Chin Hung Yang, was originally published electronically on the publisher’s internet portal on 30 September 2020 without open access. With the author(s)’ decision to opt for Open Choice the copyright of the article changed on 30 September 2020 to © The Author(s) 2020 and the article is forthwith distributed under a Creative Commons Attribution 4.0 International License ( https://creativecommons.org/licenses/by/4.0/ ), which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made.

Determination of moisture damage mechanism in asphalt mixtures using thermodynamic and mix design parameters

Abstract: The shortcoming of the available laboratory methods for determining the moisture susceptibility of asphalt mixtures has led researchers to think about providing new methods based on effective parameters on moisture damage process. Accordingly, this research is an attempt to provide a prediction model using thermodynamic and mix design parameters that can predict and analyze the performance of asphalt mix against moisture. T he results of this study indicate that the use of anti-stripping additives can generally improve the performance of asphalt mixtures against moisture; however, the type and percentage of these additives should be determined according to the type of aggregate, the type of bitumen and the properties of the mixing plan of the asphalt mix. Based on the proposed model, it can be stated that an increase in cohesion free energy, adhesion free energy, aggregate wettability by bitumen, surface area of aggregates, and apparent asphalt film thickness on the aggregate surface improve the moisture resistance of mixtures. On the other hand, debonding energy, saturation percentage, and permeability negatively affect the asphalt mixture’s resistance to moisture damage.

Evaluation on moisture sensitivity of asphalt mixture induced by dynamic pore water pressure

Abstract: Moisture damage induced by dynamic pore water pressure commonly occurs in asphalt pavement with a service environment of frequent contact with liquid water. Dynamic water environment exhibits a different mechanism of moisture damage comparing with traditional static water immersion and freeze-thaw. The influencing factors of dynamic water environment mainly include the magnitude of pore water pressure, water temperature, and conditioning duration. This paper presents a study on evaluating and quantifying these factors’ degree of influence on moisture sensitivity of asphalt mixture using the orthogonal test and the gray correlation analysis method. A new method for moisture sensitivity evaluation was thus proposed based on dynamic water environment conditioning and uniaxial penetration strength test. Finally, the influence of materials’ properties on moisture sensitivity were further investigated. The results indicated that the ranking of factors impacting the indicator of fracture work density was water temperature, followed by pore water pressure and conditioning duration. A representative parameter combination of 60℃, 0.345 MPa, and 4000 cycles was thus recommended. It was found that dynamic water environment was harsher than static water immersion and almost equal to and even harsher than freeze-thaw. The indicator of fracture work density ratio, which took deformation feature of asphalt mixture into account, could well assess moisture sensitivity. Retained mechanical performance of water-conditioned asphalt mixture decreased with the increase of air void content. SBS modified asphalt binder significantly improved the resistance to moisture damage for asphalt mixture.

An overview of the airport pavement management systems (APMS)

Abstract: Airport Pavement Management System (APMS) is a useful tool, including a set of procedures for collecting, analyzing, maintaining, and reporting pavement data, thus assisting airports in finding optimum cost-effective treatments to preserve their pavement assets. The paper provides an in-depth overview of the APMS from an extensive literature review with the aim to identify numerous issues within APMS, such as the components, Pavement Condition Indices, software utilization, and the comprehensive implementation process. The methodology adopted for this research is a descriptive-based study approach on the various airport pavement manuals, guidelines and advisory circulars, journal articles, and book publications for the APMS applications. The airport pavement management systems and the case studies in various airports internationally will be included in the review. The study includes various subjects such as major components, benefit and cost approach, management in different levels, software utilization, maintenance, and rehabilitation (M&R) policies in the implementation of the APMS. Additionally, the research examines the pavement performance indicators that are the key elements for evaluating pavement conditions. Besides, the APMS software programs can store historical information, analyze data, develop models, and generate reports for M&R in association with the budget, including estimating future pavement life. The study summarizes the condition data required for the implementation and operation of an APMS, as well as the information generated by the APMS. The review highlights the benefits of an APMS in providing the airport operators and engineers far more informed position for decision-making to forecast future pavement maintenance requirements for an adequate and timely M&R.

Evaluation of bio-based fog seal for low-volume road preservation

Abstract: While asphalt pavement is common in the United States, it is susceptible to oxidation as being exposed to environmental effects, resulting in the surface deterioration. To maintain the performance of a road surface and extend its service life, traditional fog sealers such as asphalt emulsion are used to mitigate micro-cracking, prevent oxidation and reduce water infiltration. Due to the relatively high cost and environmental concerns of petroleum-based sealants, the use of bio-based products as fog sealers has attracted more and more attention. Some new bio-based sealants derived from agricultural oil have been used as fog sealers in many states. To evaluate the effectiveness of a bio-sealant as an alternative to preserve asphalt pavements, a 5.3 km test section was selected for application of a soy-based fog sealant with three different application rates to conduct a two-year investigation of pavement marking retroreflectivity, surface friction, growth rate of cracking, laboratory water absorption, and air permeability. A control section without bio-sealant was also set up for comparison purposes. The field results revealed that, after application, a short-term decrease in retroreflectivity and skid resistance was restored to the original condition after two weeks and several months, respectively. The treated sections also exhibited a better control of growth rate of cracking than that of control section. The laboratory results indicated that the bio-sealant treated specimens applied at the highest application rate exhibited the lowest water absorption and air permeability. Such findings indicate that bio-sealant can be a sustainable preservation alternative for asphalt pavement.

The potential use of lightweight cellular concrete in pavement application: a review

Abstract: Protecting the pavement subgrade to increase the service life of road pavements is an aspect currently being explored. Several alternative pavement subbase materials are being considered, including Lightweight Cellular Concrete (LCC). Due to its lower weight, LCC incorporating industrial by-product, making it sustainable, and ease of use amongst other benefits, is seen as a potential candidate. This paper reports reviewing the potential application of LCC within the pavement structure with a specific application as a subbase. It examines the various properties such as modulus of elasticity, compressive and tensile strength, Water absorption, and freeze-thaw resistance necessary for pavement application. It also assesses its use in the field in Canada considering the design methods utilized. Some limitations and gaps for LCC application in pavements are also established and recommendations on how to further its use and performance. This review concludes that LCC possesses potential as a pavement subbase alternative; however, other mechanical properties like LCC’s fatigue life is essential. A comparative field study is also recommended to monitor actual performance and various factors on performance.

The feasibility of waste nylon filament used as reinforcement in asphalt mixture

Abstract: The recycle and reuse of waste nylon filament is a new problem. The aim of this paper is to discuss the feasibility of waste nylon filament used as reinforcement in asphalt mixture (AM). Before preparation, the physical and mechanical properties of waste nylon filament were investigated. Then the waste nylon filament was mixed with asphalt and aggregate to prepare waste nylon filament asphalt mixture (WNFAM) using Marshall design method. The properties of WNFAM were evaluated through Marshall stability test, rutting test, flexural test and freeze-thaw split test. The related results indicate as follows: waste nylon filament has an excellent physical and mechanical property, and can be used as reinforcement in asphalt mixture; the reasonable asphalt content is 5.0%-5.5%, and the waste nylon filament is 0.1%-0.2%. Besides, the addition of waste nylon filament can improve the high-temperature stability, low-temperature crack resistance and durability of asphalt mixture. It is the binding effect provided by the waste nylon filament on the aggregate and the fiber reinforced composite strength theory that are attributed to this improvement and reinforcement. The research result can offer technical support for waste nylon filament used in road construction materials.

Maintenance prioritization of interlocking concrete block pavement using fuzzy logic

Abstract: The combined influence of traffic and environment causes every pavement to deteriorate over time. Maintenance actions help to delay the rate of pavement deterioration. Pavement maintenance demand large amount of fund, resources and time. Prioritization of maintenance work enables to allocate fund and resources in an effective way based on the performance evaluation of the pavement section(s). There are different maintenance prioritization mechanisms exist to evaluate a pavement. From the review of past literature, it is observed that fuzzy logic has not been used to evaluate interlocking concrete block pavements (ICBP). This research is an attempt to implement fuzzy logic for the purpose of maintenance prioritization on ICBP. The distresses of ICBP considered in this study are rutting, depression and damaged paver blocks. The distress density is given as inputs in the fuzzy prioritization model. The outputs are the pavement condition index (PCI) and the maintenance strategy to be adopted. An experts’ survey was conducted to define the boundaries of the membership functions of the input (distresses) and output (PCI and maintenance strategies) parameters. The triangular membership function is used in this study. The maintenance strategies suggested are routine and preventive maintenance, major and minor rehabilitation and reconstruction. The fuzzy model developed in this work has been demonstrated with a case study.

Mechanical properties of styrofoam-modified asphalt binders

Abstract: In this research, Styrofoam in its waste form was first collected, disintegrated, washed and then dried prior to mixing it with asphalt. A 70-80-penetration grade asphalt binder was used and mixed with the processed waste Styrofoam. Mixing percentages of Styrofoam to asphalt (S/A) were: 0.0 % (control sample), 0.2%, 0.4%, 0.6%, 0.8%, 1.0%, 1.2%, and 2% by weight of asphalt binder. Two sets of Styrofoam asphalt binders were p repared. One set of the samples was subjected to only the mixing conditions without further aging (this set consists of the unaged Styrofoam asphalt samples). The other set was subjected to short-term aging using the rotating thin-film oven test. Consistency tests including penetration, ductility, and softening point were conducted on both sets of samples. The flash point test was also conducted on both unaged and aged samples. Superpave tests including the rotational viscosity (RV) and the Dynamic Shear Rheometer (DSR) were performed. Findings of the study found that the addition of Styrofoam to asphalt binders resulted in a significant change in the asphalt binder properties at 5 percent significance level. The ratio of the ductility of aged samples to the ductility of unaged samples ranged from 0.84 to 0.92. On the other hand, the ratio of the penetration of aged samples to the penetration of unaged samples ranged from 0.75 to as high as 0.97. It was also found that the RV and the complex shear modulus (G*) value increased with the increase in the S/A percentage. Styrofoam asphalt binder is expected to produce rutting resistant mixtures that can be used for asphalt pavements at high pavement service temperature s up to 64°C.

Utilization of lateritic soil stabilized with alkali solution and ground granulated blast furnace slag as a base course in flexible pavement construction

Abstract: The natural aggregates are depleting in developing countries due to the excessive usage in road and building construction. In the present study, the engineering properties of abundantly available lateritic soil stabilized with Ground Granulated Blast Furnace Slag (GGBS) and alkali solutions like Sodium hydroxide and Sodium silicate was evaluated. The suitability of stabilized soil as a base course in flexible pavements was investigated. The lateritic soil was treated with 15, 20, 25 and 30% of GGBS and alkali solutions consisting of 5% of Sodium oxide with Silica Modulus (Ms) of 0.5, 1.0 and 1.5 at a constant water binder ratio of 0.25. The improved unconfined compressive strength, flexural strength, and fatigue life were observed from the soil treated with 30% of GGBS and alkali solution having Ms 1.0 air-cured for 28 days at ambient temperature. The improvement is due to the formation of Calcium Silicate Hydrates and Calcium Alumino Silicate Hydrates from an exothermic reaction between Calcium ions and the dissolved silicates and aluminates present in GGBS and alkali solutions. The samples treated with 25, 30% of GGBS and alkali solution having 1.0 Ms cured for 28 days found to be durable in Wetting-Drying and Freezing-Thawing tests. The compact and densified crystal orientation of the treated soil samples was observed from the microstructure images obtained from the Scanning Electron Microscope technique. The design of low and high volume roads was suggested with stabilized soil and strains developed at different locations on the proposed pavement were analyzed using pavement analysis software.

Review of reflective cracking in composite pavements

Abstract: Reflective cracking is identified as the main weakness of composite pavement in airfield and highways forcing the authorities to devote a large portion of their budget to rehabilitation and/or reconstruction of the existing composite pavements It is, therefore, very important to have a better understanding of the reflective cracking mechanism to propose the most effective remedial solution(s), which corresponds to that mode of failure Moreover, it is inevitable to develop a proper constitutive model, which can simulate the reflective cracking performance of the composite pavements as close as possible to the field conditions The key step to develop such a model, would be therefore, identifying the current gaps within the literature to facilitate further developments and improvements in those areas This paper is the outcome of a comprehensive literature review which was carried out as part of a current research project, to better understand the problem and identify the gaps within the literature Three major gaps in terms of required laboratory testing setups, potential improvements in retardation approaches and development of proper numerical models have been identified by the authors which will be further discussed in this paper

Evaluation of hollow-fibers encapsulating a rejuvenator in asphalt binders with recycled asphalt shingles

Abstract: Self-healing products such as hollow-fibers filled with an asphalt rejuvenator present an emerging technology that aims to enhance an asphalt mixture’s resistance to cracking damage. The objective of this study was to develop a fiber synthesis procedure to prepare sodium-alginate fibers containing an asphalt rejuvenator. An optimization process was conducted to identify the most suitable hollow-fibers for asphalt pavement applications by varying production parameters and testing the thermal stability and tensile strength of the different fibers. Furthermore, the effects of adding the developed fibers on the rheological properties of asphalt binder blends containing Post-Consumer Waste Shingles (PCWS) extracted binder was evaluated using Superpave Performance Grading (PG), Multiple Stress Creep Recovery (MSCR) test, and frequency sweep test. Based on the optimization of the fiber preparation procedure, it was observed that the prepared fibers had adequate thermal stability and tensile strength to resist typical compaction operations and mixing temperature during asphalt mix production processes. PG grading test results showed improvement at both high and low temperatures with the addition of the fibers compared to the asphalt binder blends with PCWS and no fibers. In addition, low-temperature test results showed a reduction in the stiffness of the blends with fibers compared to the virgin binders (i.e., PG 64-22 and PG 70-22). An improvement in the viscoelastic behavior of the asphalt blends with fibers was also observed in the MSCR test results with an increase in the percentage of recovery. As a result, the addition of hollow fibers to the unmodified binder with a rejuvenator as the core material led to an enhancement in the fatigue performance and an improvement in the viscoelastic behavior of the asphalt blends.

Effect of surface preparation of substrate on bond tensile strength of thin bonded cement-based overlays

Abstract: The paper focuses on the debonding between a cement-based overlay and a concrete substrate under a mechanical loading. Two categories of substrate surface preparation were considered: Sawing the Substrate and Sand Blasting of the casting surface of the substrate. Untreated substrate surface used in its original state was taken as the Reference Surface. The overlay material investigated was a cement-based mortar. Direct tensile tests perpendicular to the overlay-substrate interface were carried out at the age of 28 days and the results (tensile strength, residual post peak behavior) are presented and discussed. Attention was paid to the Sand Blasted surface which is a more realistic model of practical field conditions. The debonding propagation under monotonie and fatigue loading was monitored for sand blasted surfaces using the Digital Image Correlation technique. Results indicate that both surface preparation technique has its own efficiency level and gives different roughness. Among the techniques used, greater bond strength improvement was observed with the sawn substrate surface than with the sandblasted one. Moreover, under cyclic loading, major debonding along the interface occurs from the first cycle to the 20000th cycle and is negligible thereafter.

Investigating the condition number approach to select probe liquids for evaluating surface free energy of bitumen

Abstract: Application of condition number (CN) approach is critical in selecting appropriate combination of probe liquids for evaluating the surface free energy (SFE) of bitumen. The CN approach recommends use of probe liquids with CN 10 without concerning its adverse effects on the SFE of bitumen. Inappropriate choice of probe liquids may result in incorrect SFE values of bitumen, thereby influencing its compatibility with aggregates. Therefore, the present study is strongly motivated to exhibit the application of CN approach for selecting appropriate probe liquids. Further investigating the impact of CN on aggregate-bitumen compatibility, the present research work also aims at validating CN approach. A polymer modified bitumen (i.e., PMB40) and two types of aggregates namely, quartzite, and basalt aggregates were selected in this study. Five probe liquids namely, water, formamide, diiodomethane, ethylene glycol and glycerol were selected, which formed ten different combinations of probe liquid triplets. The CN of probe liquid triplets was calculated based on singular value decomposition (SVD) method. Thereafter, using the SFE of aggregates and bitumen, compatibility of basalt-PMB40 and quartzite-PMB40 was evaluated using compatibility ratio (CR) parameter. Results revealed that except for probe liquids triplets with CN 10. Therefore, the present study addresses the adverse effect of inappropriate selection of probe liquids on aggregate-bitumen compatibility and also validates the CN approach.