Superpave Method Research Articles

Comparative analysis of HMA aggregate variability based on impacting and gyratory compaction

In proportion design of hot mix asphalt (HMA), the aggregate gradation in HMA is one of the most important influencing factors on HMA mechanical behavior. During the process of aggregate compaction, the gradation of the aggregate will change at some extent, namely, the aggregate gradation after compaction will be different from the original design gradation, it will influence the HMA design results. Therefore, study on the variability of aggregate gradation at different compaction conditions has a theoretical and practical value. The objective of the project is to explore the influence of different compacting methods on aggregate gradation between Marshall and Superpave methods. Different compaction methods are used to compact different aggregates, then the variability of aggregate gradation under different compaction conditions is analyzed. The research results have shown that although the method of Superpave gyratory compaction generally has the less influence on aggregate gradation than that of Marshall impacting compaction, the detailed influence on the gradation of coarse, medium and fine aggregates between two methods is different. The findings can provide a technical reference for aggregate gradation in HMA proportion design.

Utilização do ensaio de flexão sobre amostra semicircular para avaliação da propagação do trincamento em misturas com diferentes ligantes

Neste trabalho é estudada a propagação de fissuras e ruptura em misturas asfálticas através do ensaio de flexão semicircular. Trincamentos que surgem nos revestimentos asfálticos revelam-se como um dos principais danos que afetam diretamente a serventia e qualidade dos pavimentos flexíveis. Esta pesquisa busca contribuir para a análise da resistência ao trincamento, bem como propagação do trincamento até a ruptura de misturas asfálticas onde são utilizados três diferentes tipos de ligantes. Para este fim empregou-se o ensaio de flexão em amostra semicircular com fenda, estático (EEFAS) e dinâmico (EDFAS). Foram analisadas três composições, dosadas pelo método Superpave: uma com cimento asfáltico de petróleo (CAP), outra com asfalto modificado por polímero (AMP) e a terceira com asfalto borracha (AB), denominadas, respectivamente, como misturas A, B e C. Os resultados indicaram maior rigidez da mistura com AMP, que também apresentou maior vida de fadiga. Por outro lado, as amostras com CAP e AB apresentaram-se dúcteis e com menor velocidade de propagação das microtrincas.

Evaluation of Mixing and Compaction Temperatures (MCT) for modified asphalt binders using zero shear viscosity and Cross-Williamson model

The current study was conducted to examine the rheological properties and the performance characteristics of polymer-modified asphalt binders at various temperatures. Different types and concentrations of polymers were used; including Styrene Butadiene Styrene (SBS) with or without a cross linker, Honeywell (HW) and polyphosphoric acid (PPA) which were added based on the total weight of different Performance Grade bitumen contents. Two methodologies (traditional Superpave and zero shear rate viscosity (ZSV)) were used for comparing binder viscosity and mixing and compaction temperatures. Theory of ZSV measurement was used to assess the rheological characteristics of the asphalt binder while a rotational viscometer device was used to measure the relation of viscosity changes with shear rate for neat and modified Iraqi asphalt binders. The Cross Williamson model was used for the simulation of the viscosity–shear rate dependency for each of the studied temperatures. From the results, there were changes in the rheological properties of the bituminous binders after the modification process. The neat bitumen showed improved rheological properties after mixing with the modifiers. It was noticed that increases in the percentage of polymer had no effect on the calculated mixing and compaction temperatures by ZSV; however, an increase of about 8% was observed with the traditional system. Furthermore, the two methods were observed to provide slightly different values for the viscosity when applied over a considerable range of test temperature. For the modified binders, they showed different mixing and compaction temperatures when ranked according to their Superpave grading protocol or their ZSV. The ZSV for mixing temperature was lower by about 42–54 °C compared to the Superpave method.

ОСОБЕННОСТИ МЕТОДА ОБЪЕМНОГО ПРОЕКТИРОВАНИЯ АСФАЛЬТОБЕТОНА ПО ТЕХНОЛОГИИ SUPERPAVE

The article describes the technology of designing asphalt pavements, according to the Superpave method. The Superpave System (SUperior PERforming Asphalt PAVEments) is developed by the US Strategic Highway Research Program (SHRP). The goal of the program is to search for new ways of designing asphalt concrete pavements that will work better under extreme temperatures and intensive traffic loads. The Superpave system is primarily concerned with two problems associated with road surface: constant deformation, which is a consequence of insufficient strength of asphalt concrete in shear at high temperatures; and low-temperature damage, which is formed during the compression of the asphalt concrete pavement, the tensile stress exceeds the tensile strength. The solution of these problems is carried out by the most rational selection of components of the asphalt concrete mix. This technology has interested Russia relatively recently. In 2016, preliminary national standards have been translated and issued. They describe requirements of materials for design and selection of the mixture. The article reviews technical documentation in order to develop a methodology for the selec-tion of asphalt mix. In the course of the research, the technological features of selection and design of the asphalt mix using the given method are considered and a block diagram is made for the selection of asphalt composition. This system makes it possible to design the fine-grained and gravel-mastic as-phalt mixes. The introduction of foreign experience in the construction of roads can contribute to the quality improvement of Russian highways

THE APPLICATION OF THE METHOD OF SELECTING A BRAND OF BITUMINOUS BINDER, IN ACCORDANCE WITH THE SUPERPAVE SYSTEM, IN THE CONDITIONS OF UKRAINE

This research is based on an analysis of native researches publications and National Standards and considered the specify of bitumen binders choice for a pavement design in Ukraine. Problem. It is found that in accordance with actual National Standards requirements the bitumen grade choice is irrelevant to a climate and pavement operating conditions. The bitumen grade БНД 60/90 is commonly used in Ukraine. The limited amount of bitumen grades with a wide range of bitumen properties in each is one of the main reasons for using only one bitumen grade over the all territory of the country. The principles and methods of bitumen binders choice in American Superpave system is considered. Superpave system based on taking into account the climate conditions in a road location area and a pavement performance (such as traffic intensity, type of transport load, etc.). Goal. The bitumen grade choice according to the Superpave system method was performed for Ukraine in an aim of this research. Method. The highest and lowest asphalt concrete pavement temperatures were calculated on the base of highest and lowest annual air temperatures for Ukrainian cities. The bitumen grades, that can be used in asphalt concrete layers, were opted with reliability indicators in 50 and 98 % for the different regions of the Ukraine. Results. It is found that the bitumen with better low temperature characteristics must be used over the all territory of the country to provide reliability in 98 % and polymer modified binders should be used in pavements design for some regions. The essential overstating of bitumen binders temperature limits in the Superpave method is shown. This is a result of a temperature limits shifting in a 6 °C per PG. Practical significance. Obtained data are used for a zoning modeling on the territory of Ukraine.

Assessment Mixing and Compaction Temperatures for Modified HMA Using Superpave High Shear Viscosity Methods

The objective of this study is determining the mixing and compaction temperature of the modified asphalt mixture. Results of binder tests showed that the addition of 3% SBS to control asphalt (PG 64-16) would achieve the desired performance level (PG 76-16) a performance grade that fits our climate with traffic loads. When using 5% SBS the performance grade of binder increased three grades (PG 82-16) and when increasing SBS content to 8% the performance grade increased four grades (PG 88-16). At shear rate of 500 (s-1), the modified asphalt viscosity can be obtained at different temperatures and the viscosity temperature curve can be achieved. As a result, the mixing and compaction temperature of modified asphalt can be determined to reach 0.17 ± 0.02 Pa.s and 0.28 ± 0.03 Pa.s for mixing and compaction, respectively. It is noted that SBS modified reached a viscosity of 3 Pa.s when 8 % additive. Additive contents above these values may not be suitable for good workability and pump ability according to Superpave specifications. While addition of 5% SBS with control asphalt, more than 3.7times at 135°C Increase the viscosity. Marshall Stability test indicated that the strength for the SBS specimens increases as compared to the conventional specimens. An increase of about 39%, 74%, 102%, was observed with 3%SBS 5%SBS 8%SBS modified binders, respectively. The Marshall test results for 8%SBS binders required compaction temperatures above 175°C need to keep up quality of HMA item while limiting natural effect amid development, these proposals are unsatisfactory Modified mixtures the 5% SBS modification was determined to be the maximum useful content. The Superpave method to estimate mixing and compaction temperatures show are not practical for use with modified binders. Also, it is observed that good agreement values between the average Marshall compaction temperature and the High Shear Viscosity Method (HSRV) and lower than Superpave methods Where the decline ranges from 15 ºC to 17 ºC.

Feasibility Evaluation of Preparing Asphalt Mixture with Low-Grade Aggregate, Rubber Asphalt and Desulphurization Gypsum Residues.

Road construction consumes great amounts of high-grade natural resources. Using low-grade natural rocks or some solid wastes as substitute materials is a hot topic. Considering this, the feasibility of using low-grade granite aggregate, solid waste-based filler (desulphurization gypsum residues, DGR) and binder (waste tire rubber modified asphalt, RMA) simultaneously in asphalt mixtures has been fully investigated in this research. The commonly used base asphalt and limestone powder (LP) filler were control groups. Material characteristics of raw materials mainly including micro-morphology, functional group, mineral phase, chemical composition and thermal stability were first evaluated in order to recognize them. Four asphalt mixtures (two asphalt binder and two filler) were then designed by standard Superpave method. Finally, a detailed investigation into the pavement performance of asphalt mixtures was carried out. The moisture damage resistance and low-temperature crack resistance were detected by the changing rules of stability, strength and fracture energy, and the high-temperature stability and fatigue performance were determined by wheel tracking test and indirect tensile (IDT) fatigue test, respectively. Results suggested that RMA and DGR both showed positive effects on the low-temperature crack resistance and fatigue property of the granite asphalt mixture. DGR also strengthened moisture stability. The contribution of RMA on high-temperature deformation resistance of the granite asphalt mixture was compelling. It can offset the insufficiency in high-temperature stability made by DGR. A conclusion can be made that asphalt mixture prepared with granite, DGR and RMA possesses satisfactory pavement performances.

Evaluation of Workability and Mechanical Properties of Nonfoaming Warm Mix Asphalt Mixtures

AbstractLaboratory evaluation of mix design and mechanical properties of Warm Mix Asphalt (WMA) mixtures is necessary during the design process; consequently, the ability to quantify the compactability of WMA mixtures would be very helpful. This article presents the findings of an experimental study aimed at evaluation of the influence of mixing and compaction temperature on mix design and mechanical and workability properties of nonfoaming WMA mixtures. Asphalt mix design properties were evaluated by the Marshall method and the Superpave method. Mechanical properties such as rutting resistance were evaluated by a laboratory wheel tracking test using a Wheel Rut Tester (WRT), and the resistance to moisture-induced damage was evaluated by the Tensile Strength Ratio (TSR) approach. Workability properties were evaluated in terms of Superpave Gyratory Compactor (SGC) densification indexes using the Bahia and locking point methods. Test results indicate that WMA mixtures compacted using SGC at a lower compaction temperature of 110°C, which satisfied the Voids in Total Mixture (VTM) requirement. In order to ensure the Voids in Mineral aggregate (VMA) and Voids Filled with Asphalt (VFA) requirements of WMA mixtures, compaction temperature should be restricted to 120°C. Furthermore, WMA mixtures prepared at lower compaction temperatures exhibited higher resistance to rut deformation because of higher Traffic Densification Index (TDI) values. The energy needed to compact the WMA mixtures at lower compaction temperatures was lower due to lower Compaction Densification Index (CDI) values. WMA mixtures made with surface-saturated dry aggregates and compacted at 110°C marginally fulfilled the minimum TSR requirement because of significant reduction in the Indirect Tensile Strength (ITS) values of conditioned specimen.

Analytical approach for the mix design optimisation of bituminous mixtures with crumb rubber

The present paper provides a basis for defining a mix design method specifically tailored to rubberised asphalt that takes into account the behaviour of crumb rubber. An analytical approach to quantifying the recovered deformation of crumb rubber in the post-compaction phase has been developed in order to adjust the number of gyrations proposed by the Superpave method for compacting specimens of hot mix asphalt using a Superpave gyratory compactor. The maximum allowable amount of rubber has been calculated. Finally, a step-by-step protocol has been proposed in order to fabricate and compact crumb rubber modified mixtures with the gyratory compactor.

Experimental Study on Performance of Asphalt Mixture Designed by Different Method

In order to explore the Marshall, Superpave and GTM methods, the similarities and differences of the three design methods are detail studied. Experimental study on performance of asphalt mixture AC-13、AC-20 and AC-25 designed by different method were executed in this paper. Test results show that, GTM method gives lower void and lower bitumen aggregate ratio than other two methods, it have very better water stability and high-temperature stability. The DS value is 3256 / mm by GTM design method, is 1.91 times of the Marshall and 1.33 times of the Superpave. Superpave method gives lower bitumen aggregate ratio than Marshall method. The asphalt mixture designed by Superpave method has longer fatigue life than the mixture designed by other two methods. The volume parameters of asphalt mixture designed by Marshall can conform specification very well, but the performance of asphalt mixture seems to be worse than other two methods.

Experimental Characterization of Rutting Performance of HMA Designed with Aggregate Gradations According to Superpave and Marshall Methods

The permanent deformation (rutting) of pavement is a major distress in flexible pavement. It is related to vehicles properties and/or pavement materials and conditions. This article presents an extensive experimental investigation in order to compare between the aggregate gradation according to Superpave and Marshall methods of asphalt concrete mix design on pavement rutting and to examine the sensitivity of rutting resistance to aggregate gradation. A wheel truck machine has been used for measurement of pavement rutting (permanent deformation). The tests were carried out at two controlled different air temperature 55℃ and 25℃. The results obtained showed that the adopting of aggregate gradation procedure of Superpave method of pavement mix design for Marshall method of asphalt concrete mix design can reduce the pavement rutting by about 50%. This achievement may be related to missing of three sieves in aggregate gradation procedure of Marshall method which controls rounded and finer aggregate particles. These sieves provide more continuity for aggregate gradation to ensure filling unnecessary gaps and produce more contact points between the aggregates in Hot Mix Asphalt (HMA). The outputs of the research support modifying Marshall method of asphalt concrete mix design by adopting aggregate gradation proposed in Superpave method. The results of study also showed that the coarser aggregate provided more resistance to pavement rutting.

Evaluation of the Permanent Deformations and Aging Conditions of Batu Pahat Soft Clay-Modified Asphalt Mixture by Using a Dynamic Creep Test

This study aimed to evaluate the permanent deformation and aging conditions of BatuPahat soft clay–modified asphalt mixture, also called BatuPahat soft clay (BPSC) particles; these particles are used in powder form as an additive to hot-mix asphalt mixture. In this experiment, five percentage compositions of BPSC (0%, 2%, 4%, 6%, and 8%) by weight of bitumen were used. A novel design was established to modify the hot-mix asphalt by using the Superpave method for each additive ratio. Several laboratory tests evaluating different properties, such as indirect tensile strength, resilient stiffness modulus, and dynamic creep, was conducted to assess the performance of the samples mixed through the Superpave method. In the resilient modulus test, fatigue and rutting resistance were reduced by the BPSC particles. The added BPSC particles increased the indirect tensile strength. Among the mixtures, 4% BPSC particles yielded the highest performance. In the dynamic creep test, 4% BPSC particles added to the unaged and short-term aged specimens also showed the highest performance. Based on these results, our conclusion is that the BPSC particles can alleviate the permanent deformation (rutting) of roads.

PENGGUNAAN CAMPURAN PLASTIK DAN KACA KITAR SEMULA SEBAGAI AGREGAT GANTIAN DALAM CAMPURAN BERASFALT

The major problem in landfill is the large amount of solid wastes dumped in landfill. Waste plastics and glass contribute greatly to the problem and this needs to be managed in order to extend the life of landfill sites. Hence, this study was conducted to investigate the feasibility of using these waste materials in asphalt mixtures for pavement applications. The mixtures were designed by means of the Superior Performing Asphalt Pavements (Superpave) method. Various types of recycled waste plastics and glasses; namely bottle glass, LCD glass and sheet glass were selected in this study. Approximately 5% of recycled materials (by the total weight of asphalt mixtures) were used as an aggregate replacement. In this study, asphalt mixtures were aged in the laboratory to simulate the in-situ conditions of short-term and long-term ageing. After completion, samples were tested for resilient modulus, dynamic creep and static creep tests. It was found that replacements of 1% recycled plastics and 4% recycled glass show almost similar and satisfactory result compared to control sample for all tests. Consequently, recycled plastics and recycled glass, at their optimum blending, can be considered feasible to be used as an aggregate replacement in asphalt mixtures for road surfacing.

Laboratory Batching Procedure Corrected for Fines and Moisture

A key step in mix design is the selection of an appropriate aggregate structure since this affects mix performance and the amount of asphalt in the mix. This paper explores the effects that fines adhered to larger particles have on the batch gradation and the resulting optimum binder content and dust proportion. It shows that conventional batching procedures can produce gradations with a substantially larger percent passing the sieve No. 200 relative to the target gradation. A batching procedure that corrects for fines adhered to larger particles and trapped moisture is proposed and shown to replicate the target gradation. Asphalt content was determined using the superpave method for both a gradation batched conventionally and a gradation batched with the corrected procedure. It is shown that the asphalt content and volumetrics obtained in both cases are substantially different. To obtain more-representative batch gradations, the corrected procedure is recommended for routine batching of specimens. Further research is recommended to assess potential changes in mix design criteria and effects on performance tests.

Estudo da incorporação de argilas montmorilonitas em cimentos asfálticos de petróleo

A utilização de nanotecnologia em pavimentos asfálticos é uma revolução, pois esta permite construir pavimentos mais resistentes à deformação, à trinca por fadiga, à trinca por temperatura e à ação da água.Nesse contexto uma alternativa é o uso da nanoargila. Sua incorporação ao cimento asfáltico de petróleo (CAP) proporciona melhoria nas propriedades físicas e reológicas e nas propriedades mecânicas das misturas asfálticas. Para o desenvolvimento deste trabalho utilizou-se o método da dosagem SUPERPAVE para a análise do comportamento das misturas asfálticas utilizando o CAP 50/70 modificado com as seguintes adições: Argila Montmorilonita organofílica (OMMT) e a Argila Montmorilonita pura (MMT). Foram analisados os efeitos dos modificadores por meio de ensaios mecânicos de Resistência à Tração por Compressão Diametral e Módulo de Resiliência, sendo todas as amostras submetidas ao processo de compactação por amassamento. Os resultados indicaram que as adições das argilas OMMT e MMT as misturas asfálticas promoveram aumento no valor do Módulo de Resiliência e da Resistência à Tração quando comparados ao ligante asfáltico sem modificador.

An approach to the usage of polyethylene terephthalate (PET) waste as roadway pavement material

This study investigates an application area for Polyethylene Terephthalate (PET) bottle waste which has become an environmental problem in recent decades as being a considerable part of the total plastic waste bulk. Two novel additive materials, namely Thin Liquid Polyol PET (TLPP) and Viscous Polyol PET (VPP), were chemically derived from waste PET bottles and used to modify the base asphalt separately for this aim. The effects of TLPP and VPP on the asphalt and hot mix asphalt (HMA) mixture properties were detected through conventional tests (Penetration, Softening Point, Ductility, Marshall Stability, Nicholson Stripping) and Superpave methods (Rotational Viscosity, Dynamic Shear Rheometer (DSR), Bending Beam Rheometer (BBR)). Also, chemical structures were described by Scanning Electron Microscope (SEM) equipped with Energy Dispersive Spectrometer (EDS) and Fourier Transform Infrared (FTIR) techniques. Since TLPP and VPP were determined to improve the low temperature performance and fatigue resistance of the asphalt as well as the Marshall Stability and stripping resistance of the HMA mixtures based on the results of the applied tests, the usage of PET waste as an asphalt roadway pavement material offers an alternative and a beneficial way of disposal of this ecologically hazardous material.

Influence of Bitumen and Filler on the Selection of Appropriate Mixing and Compaction Temperatures

This paper presents a rheological evaluation, based on viscosity variation with temperature and shear rate, of several mastics combining six bitumens (two neat and four SBS polymer modified) and three fillers (two limestone and one lime). Filler content (filler-to-bitumen ratio) was defined according to two methods (fixed mass ratio and fixed volume ratio as a function of the Rigden voids and the increase of the softening point). The Superpave method and two other alternative methods (High Shear Rate Viscosity and Zero Shear Rate Viscosity), which were proposed in literature to select appropriate mixing and compaction temperatures of hot-mix asphalt, were implemented to assess the effect of the bitumen-filler combination on construction procedures. Results have shown that the mastic behaviour is highly dependent on the filler-to-bitumen ratio and that the filler type has a relevant and similar influence on mixing and compaction temperatures. Natural hydraulic lime showed a very high stiffening power, while the gradation differences of the limestone fillers showed a very limited effect. The temperature variation with the bitumen type, the SBS content, and the filler type and content differs with the method used for the selection of working temperatures. Nevertheless, working temperatures are more dependent on SBS modification (25-35˚C) than on the filler (＜ 10˚C).

Adapting of Performance Grading System for Local Asphalt Cement

The General Specifications for Roads and Bridges (SCRB) don't adopt the performance grading (PG) based system suggested by Superpave program to evaluate the currently used asphalt cements for paving works. The air temperature data used in this study covers approximately 20 years time period (1982-2002) for seven Iraqi cities (Kirkuk, Mosul , Rutba , Baghdad , Kut , Najaf , and Basrah) which represent climatically unique regions in Iraq. The currently used asphalt cements with penetration grades (40-50) and (60-70) were tested by both of conventional test methods and Superpave methods to determine the equivalent performance grade for each type of the penetration graded asphalt and to evaluate the capability for these two types of asphalt cement to satisfy the required performance of pavement for each region of country. The paper results indicate the following for the required PG asphalt binders: Region Performance Graded (PG) Asphalt Binder North governorates 70-16 Middle governorates 70-10 West governorates 64-10 South governorates 76-4 The Daurah asphalt cements with penetration grade (40-50) are equivalent to PG 70-16, PG70-10 and PG76-4 while asphalt with penetration grade (60-70) is equivalent to PG 64-10. The rotational viscosity , dynamic shear rheometer and creep stiffness versus penetration relationships have been developed to estimate the some Superpave asphalt binder tests based on penetration values.

A Performance-based Evaluation of Superpave Design Gyrations for High Traffic Surface Mixes

The number of design gyrations (Ndes) is an extremely important parameter in the asphalt concrete mix design procedure using the Superpave method. The choice of Ndes is a function of total traffic during the pavement service life, expressed in ESALs. Asphalt concrete mixes for higher traffic levels are compacted to a higher Ndes as a denser mix resists rutting more effectively. However, this leads to a lower design asphalt content, which decreases fatigue performance of the mix. Therefore, a performance-oriented approach to determine Ndes was developed that optimizes mix performance with respect to both rutting and fatigue cracking.In this paper, the research methodology adopted to compare the relative performance of surface mixes with 12.5mm nominal maximum aggregate size is presented, along with recommended Ndes values for C and D-level mixes, designed to handle traffic levels of 3-30 Million and greater than 30 Million ESALs, respectively. Asphalt concrete mixes were designed at Ndes levels of 50, 75, 100 and 125 gyrations to determine asphalt content using Superpave design method. Dynamic modulus (E*) was measured at design asphalt content for different gyration levels using the Asphalt Mixture Performance Tester device. The E* data and corresponding binder properties were used as input in the AASHTO Darwin-ME software to predict rutting and fatigue performance of the mixes by assuming a model pavement section and appropriate traffic levels. Relative performance indicators were developed for both rutting and fatigue, and plotted against the asphalt content to determine optimum Ndes. For both surface mixes, the optimum Ndes value was determined to be 85 gyrations.

English

The finding of other alternative material that has become the concern of various works lies in the fact that the material is to serve as an additive in asphalt mixes to enhance its physical properties. This paper deals with a laboratory study which compares the performance of hot mix asphalt (HMA) with the use of palm oil shells (POS), also with coconut shells (CS) as an additive and control samples. Both the palm oil shells and coconut shells are put in separately, taking up the shape of coarse aggregate with the size of 4.75 mm. The amount of these palm oil shells and coconut shells blended into the mixes is expressed in respective percentage (0,5, 10, 15 and 20%) of the total weight of the size 4.75 mm of aggregate. The Superpave method was employed to design the mixes. Samples were prepared and put to the test for the rutting characteristic as the indicator to the performance examined. It was observed that the addition of the coconut shells has made the HMA better with respect to their resilient modulus under 40˚C of temperature, it is cleared that 20% of CS as additive is the best percentage in term of resilient modulus among the percentages that have been chosen. However, it is contrary for the POS. The POS and CS addition will lead to that the asphalt concrete becoming more responsive to permanent deformation (static and dynamic creep) for more than 5% of shells content. In general, the CS emerges as better additives than POS in the HMA.