WMA Additives Research Articles

Effect of Long-Term Aging on the Tensile Strength, Flexural Strength and Creep Behaviour of Asphalt Mixtures Containing Different WMA Additives

Effect of Long-Term Aging on the Tensile Strength, Flexural Strength and Creep Behaviour of Asphalt Mixtures Containing Different WMA Additives

Economic and environmental aspects of warm mix asphalt mixtures: A comparative analysis

This paper assessed the impact of five different WMA additives categorized under organic, chemical and foaming-based technologies on the energy requirement and green house gas (GHG) emissions. The maximum bearable cost, corresponding to different additives, was determined to assess the optimal choice of warm mix technologies. Results demonstrated that the addition of WMA additives lowers the heat energy by 3–12% compared to HMA. Although diesel is the most expensive fuel (considered in this study), its use can offset the cost of additives, for some WMA additives, namely: SR0.7, C0.2, C0.35, and R0.4. Calculations indicated that among the various warm mix additives, Sasobit Redux produces least emissions, followed by Aspha-min, Rediset, Sasobit, Cecabase, and viscosity graded binder. It was concluded that the use of WMA technologies can provide possible cost savings, and reduction in GHG emissions.

Evaluating the Efficiency of SMA Mixtures Containing Crumb Rubber and WMA Additives

Evaluating the Efficiency of SMA Mixtures Containing Crumb Rubber and WMA Additives

Effects of Short-Term Ageing Temperature on Conventional and High-Temperature Properties of Paving-Grade Bitumen with Anti-Stripping and WMA Additives.

The presented study explores the effects of decreased temperatures utilized in rolling thin-film oven (RTFOT) laboratory short-term ageing of asphalt binders based on 35/50- and 50/70-penetration paving-grade bitumen. Additionally, the effects of three additives used with these binders at different concentrations are evaluated: liquid anti-stripping agent, liquid warm-mix additive, and solid warm-mix additive. The resulting asphalt binders were subjected to basic (penetration at 25 °C, softening point, dynamic viscosity) and functional high-temperature characterization (G*/sin(δ), high critical temperature, non-recoverable creep compliance). It was found that the decreased short-term ageing temperatures may detrimentally impact the high-temperature grade of bituminous binders, but this effect can be mitigated by the use of appropriate additives. What is more, it was found that bituminous binders may respond differently to the aforementioned factors. Based on the results, it is advised that asphalt binders intended for use in warm-mix asphalts should be thoroughly tested to appropriately simulate the mixture production process and its effects.

Investigation of fatigue behaviour of warm modified binders and warm-stone matrix asphalt (WSMA) mixtures through binder and mixture tests

ABSTRACT The purpose of this study was to investigate the effect of warm additives on the fatigue behaviour of binder and stone matrix asphalt (SMA) mixtures. To achieve this, several tests were carried out on original and modified binders such as the G*.sin δ, the multiple stress creep recovery (MSCR), and the Linear Amplitude Sweep (LAS) test. Also, in order to authenticate the binder fatigue tests the indirect tensile strength and four-point bending beam tests were performed. SMA mixtures were fabricated from one original binder type (60–70 penetration grade), one gradation by NMAS of 12.5 mm and three WMA additives (Sasobit, Rheofalt LT70, Zycotherm) with different percentages. In regard to binder and mixture fatigue test, the results of this study indicated that the G*.sin δ parameter is incapable of evaluating the fatigue behaviour of binders. It was also found that MSCR test showed the best correlation with asphalt mix fatigue resistance compared to LAS test and G*.sin δ parameter.

Performance of Crumb Rubber Modified Bitumen Added with WMA Additives under Freeze-Thaw Action

Performance of Crumb Rubber Modified Bitumen Added with WMA Additives under Freeze-Thaw Action

Evaluation of typical wma additives on design parameters of SMA mixtures

Warm Mix Asphalt (WMA) technologies have made a considerable development in recent years, where studies on environmental pollution and protection of natural resources have become prominent all over the world. Thanks to the rapidly developing and renewed WMA technologies, nonrenewable resources can be saved while environmental effects caused by asphalt production can be reduced. In recent years, WMA technologies have begun to gain importance in the production of Hot Mix Asphalt (HMA), particularly in developing countries where energy supplying is quite expensive for economic reasons. In this study, Stone Mastic Asphalt (SMA) was produced by using pure and modified bitumen with three different WMA admixtures. Marshall tests were carried out to examine the design parameters of these samples. As a result, Marshall Design parameters of Warm Mix Stone Mastic Asphalt (WM-SMA) blends have been produced with WMA additives by decreasing the construction temperature. The resulting mixtures fall within specification criteria.

Performance investigation and sustainability evaluation of multiple-polymer asphalt mixtures in airfield pavement

Abstract Increasing aircraft loads and landing frequency are becoming challenges to airfield pavement material design. The objective of this study was to give overall performances of multiple-polymer asphalt mixtures containing anti-rutting agent (ARA), polyethylene (PE) and styrene-butadiene-styrene (SBS). A series of binder and mixture tests were conducted to investigate mechanical performances, the life-cycle assessment (LCA) was used to evaluate environmental impacts. It was found that the addition of multiple-polymer resulted in excellent high temperature performance with high rutting factor and softening point, but it led to large energy consumption and GHG emission. Also, SMA-13 mixture had larger environmental impacts than AC-20 due to higher binder content. The radar chart and rheology-environment performance ratio (REPR) were proposed to compare rheological performances and environmental impacts with respect to polymer content and test temperatures. The field practice of HMA overlay selected 0.2% of ARA and 0.5% of PE by weight of asphalt mixture as the optimal polymer content. It was found that the multiple-polymer mixture had a great resistance to permanent deformation and enough resistances to moisture damage and low temperature cracking. However, the quality control of pavement construction was not effective because air voids of cored specimens exceeded the requirement even though other properties were satisfied with the requirements. In addition, compared with HMA, the WMA compacted at 155 °C had lower air void and maximum bending strain. Therefore, the application of WMA additives in multiple-polymer modified asphalt mixture should be further studied.

Effect of SBS Polymer and Anti-stripping Agents on the Moisture Susceptibility of Hot and Warm Mix Asphalt Mixtures

The primary objective of this study is exploring the moisture susceptibility of unmodified and SBS-modified hot and warm mix asphalt mixtures. To this end, two different WMA additives including Aspha-min and Sasobit were employed to fabricate WMA specimens. The moisture susceptibility of warm polymer modified asphalt (WPMA) mixes was evaluated using modified Lottman test at 25°C according to AASHTO standard (T 283). In addition, the effect of different percentages of hydrated lime (from 0% to 2%) and Zycosoil (from 0% to 0.1%) as anti-stripping additives on the moisture susceptibility of the mixtures was explored. Based on the ITS test results, WPMA prepared with Sasobit additive and polymer modified asphalt (PMA) mixes satisfied the desirable tensile strength ratio (TSR) (above 80%) but Aspha-min WPMA mixes had TSR lower than 80%.

Evaluating Performance of PPA-and-Elvaloy-Modified Binder Containing WMA Additives and Lime Using MSCR and LAS Tests

AbstractModification of asphalt binder with Elvaloy (Elv) and polyphosphoric acid (PPA) has been reported to have better performance. However, such modification may increase mixing and compaction t...

Effect of bio-derived/chemical additives on warm mix asphalt compaction and mix performance at low temperature

Two concerns for paving with asphalt in cold-regions include cool temperature paving and low-temperature cracking. Newly developed and commercially available bio-based warm mix asphalt additives were investigated for their compactability and low temperature cracking performance. A neat and polymer-modified binder was also investigated to understand the role of polymer in the compactability and low-temperature cracking resistance of a mixture. The study showed that using the WMA additives with asphalt mix at reduced temperatures help to achieve similar compaction effort to HMA when measured using shear effort energy and compaction force index. The results also showed an interaction between one of the additives and the polymer modified binder. The low temperature cracking properties were measured using the disk-compact tension test and showed that WMA polymer modified binder performed similarly to HMA.

Characteristics of a Surfactant Produced Warm Mix Asphalt Binder and Workability of the Mixture

Abstract Warm mix asphalt (WMA) technologies significantly reduced the mixing and compaction temperatures in the construction of asphalt pavement, which thus lowered the energy consumption and gas emissions. Different types of WMA additives have been developed and applied in the past decade. However, there are still several concerns associated with the application of WMA technologies. The objective of this study was to address the characteristics of WMA binder produced using a surfactant additive namely, ADDITIVE-A. Two binders, 70 penetration grade (70#) asphalt and 90 penetration grade (90#) asphalt were applied as the base binder to produce the WMA in this study. A portable workability device was presented in this paper to evaluate the torque values of WMAs since the workability is the main property to determine the mixing and compaction temperatures of WMA and a laboratory workability test has yet to be developed. The proper mixing and compaction temperatures were also obtained based on the proposed test. A series of tests, including penetration, softening point, ductility and viscosity of different WMA additive concentrations (0, 0.3, 0.5, 0.7, and 0.9 % by the weight of asphalt binder) were conducted to investigate the mechanisms of the surfactant on asphalt binder. The contact angles of WMA binders were tested to investigate the modification mechanism of surfactant additive on asphalt binder. The laboratory tests indicate that the surfactant additive (ADDITIVE-A) makes the asphalt binder softer, more temperature sensitive, and having better low temperature property. However, the surfactant does not show a significant impact on the high temperature property and viscosity. The addition of the surfactant additive increased the workability of asphalt mixture and decreased the mixing and compaction temperatures of asphalt mixture. Based on the workability test results, the 0.7 % concentrations of the ADDITIVE-A provided a more obvious effect to reduce the production temperature of asphalt mixture.

Linear and nonlinear viscoelastic and viscoplastic analysis of asphalt binders with warm mix asphalt additives

ABSTRACTWarm-Mix Asphalt (WMA) is a widely used product, which proved a contribution to the reduction in asphalt mixing and compaction temperatures. This reduction leads to lower fuel consumption and smoke emission in asphalt plants. Most of the characterisation of binders used in WMA has focused in the past on measuring linear viscoelastic properties and associated Superpave parameters. Several studies have shown that the average stresses and strains of the asphalt mixture remain mostly within the linear viscoelastic response. However, localised strains in the binder phase of the mixture could reach values high enough to induce nonlinear viscoelastic and viscoplastic deformations. Therefore, this study focuses on an experimental and analytical evaluation of linear, nonlinear viscoelastic and viscoplastic responses of selected binders modified for use in WMA. The first part of the paper analyses the linear viscoelastic material properties and their ability to evaluate permanent deformation resistance. Then, the non-recoverable creep compliance parameter obtained from the Multiple Stress Creep Recovery (MSCR) test is analysed to assess the nonlinear response and permanent deformation of asphalt binders. The paper utilises a nonlinear plasto-viscoelastic (NPVE) approach to assess and quantify the nonlinear plasto-viscoelastic response of binders by separating the recoverable and irrecoverable strains measured in the MSCR test. Two WMA additives were included in this study by mixing them with polymer-modified and unmodified asphalt binders. Analysis of results showed that the NPVE approach captured a higher percentage of recovery than the NLVE approach. However, binder’s performance evaluation and ranking did not change by adopting the NPVE approach. The nonlinear viscoelastic parameters provided insight on the behaviour of asphalt binders mixed with WMA additives during loading cycles. Sasobit showed higher influence than Advera on binders in resisting permanent deformation by increasing the recoverable strain during the unloading phase.

Influence of selected WMA additives on viscoelastic behaviour of asphalt mixes and pavements

Warm mix asphalt additives are effective in decreasing production, laying and compaction temperatures of asphalt mixes. However, there are still questions concerning influence of warm mix additives on properties of asphalt mixes and pavement performance. This paper presents results of the comprehensive research of viscoelastic behaviour of asphalt mixes and pavement structures with layers made with warm mix asphalt additives at high temperatures. Two additives of significantly different effects on mixes at higher temperatures were selected for analysis, namely aliphatic synthetic wax produced with the use of Fisher–Tropsch method and formulation of surfactant- based molecules (ionic and non-ionic). Viscoelastic properties of mixes with these two additives and, as a reference mix, with neat unmodified asphalt binder were determined in uniaxial compression with sinusoidal loading using Asphalt Mixture Performance Test. The viscoelastic analysis of pavement structures was performed with use of the VEROAD software and data from laboratory testing. Two different pavement structures were analysed, for light and heavy traffic. The temperature distribution in pavement structure during the hottest summer day in northern Poland in 2012 was taken into account. The model of pavement was loaded with moving wheel at different speeds. The analysis has shown that two tested warm mix additives had different effect on viscoelastic transient response at high temperatures. One of them (Fischer–Tropsch wax) evidently caused an increase in resistance of asphalt mix and pavement structure to loading at high temperature. The second additive (formulation of surfactant-based molecules) slightly reduced resistance of asphalt mix and pavement to loading at high temperatures as compared with the reference mix.

Laboratory moisture susceptibility evaluation of WMA under possible field conditions

One of the major concerns with WMA is degradation due to the presence of moisture during production. In the field, moisture in the aggregates may not be completely expelled due to a lower production temperature which increases the potential for moisture damage, including stripping. The objectives of this paper are: (1) to investigate the impact of hydrated lime on the moisture resistance of WMA mixtures prepared using saturated surface dried (SSD) moist aggregates; (2) to examine the effects of multiple freeze–thaw cycles on the moisture susceptibility of WMA mixtures. Testing samples were prepared in the laboratory with the materials from a local asphalt plant in Michigan according to the Superpave mix design. The control samples (HMA) were mixed and compacted at 165°C and 155°C, respectively. The WMA samples were prepared using different additives, which were Advera, Sasobit, Cecabase RT, and water as a foaming agent. For the moisture susceptibility evaluation, the mixtures were prepared using SSD aggregates and the WMA mixtures were both mixed and compacted at a similar temperature, 130°C. Hydrated lime was added as an anti-stripping agent to determine whether or not it can improve the moisture susceptibility of the HMA and WMA prepared using SSD moist aggregate. The samples for the multiple freeze–thaw study were prepared according to a similar mix design at numerous temperatures (100°C, 115°C and 130°C) and different percentages of WMA additives based on the specific ranges recommended by the manufacturer of each WMA technology. Each additive was added to the asphalt binder prior to mixing with aggregate based on the designated percentage. Based on the results, the presence of hydrated lime in the WMA has resulted in the TSR values passing the minimum requirement of 0.80. This indicates that by adding hydrated lime, the moisture susceptibility of the WMA can be improved. The WMA samples that were tested under multiple freeze–thaw cycles do not perform as well as the HMA samples. Different additives perform better at different quantities in the mixture, as well as at different temperatures. Lower mixing and compaction temperatures negatively affect the TSR after repeated freeze–thaw conditions.

Rheology evaluations of WMA binders using ultraviolet and PAV aging procedures

Oxidation of an asphalt binder affects the long term performance of an asphalt pavement, especially under thermal and/or ultraviolet (UV) radiation conditions. The objective of this study is to investigate the rheological behaviors of various WMA binders after long term UV aging and conventional PAV aging procedures. The following rheological properties were tested and evaluated in this study: complex shear modulus, phase angle, elastic modulus, viscous modulus at an intermediate service temperature, and deflection, stiffness, and m-value at a low temperature. The experimental design included four asphalt binder sources (two grades); four WMA additives and control. Two aging methods of UV and PAV aging were utilized and a total of 40binders were tested and evaluated. The test results indicated that UV and PAV aging procedures are significantly affected by asphalt binder source and grade. In addition, WMA additives generally have no influences on rheological properties of UV and PAV aged binders. Moreover, the differences in deflection, creep stiffness, and m-values of UV and PAV aged binders are generally not affected by their grade, source and WMA additives. Therefore, UV aging procedure used in this study may be an effective method in investigating rheological characteristics of WMA binder after a long term aging process.

MIX DESIGN PROPERTIES AND MOISTURE SENSITIVITY CHARACTERISTICS OF DENSE BITUMINOUS MACADAM MIXES MODIFIED WITH REDISET, A WARM MIX ADDITIVE

Warm mix asphalt is a developing technology which allows the mixing, lay down and compaction of asphalt mixes at lower temperatures. Warm mix asphalt mixes can be produced at temperature about 120o C or lower which helps in saving the fuels and proves Eco friendly. A number of researchers evaluated various WMA mixtures using selected testing procedure in the laboratory. But only few of them varied both the temperature and additive dosage rate. In this study, the main objective is to study the effect of WMA additive Rediset on the viscosity of bitumen at different temperatures and to evaluate the properties like Marshal Stability, Indirect Tensile Strength and Moisture Susceptibility of DBM mix along with the warm mix additive. The binder showed a decreasing trend in viscosity with increase in the temperature as well as additive dosage rate. The DBM mix with 2.5% WMA additive exhibits higher stability values even at 135° C or lower the temperatures. The specimens with additive showed the lowest value of air voids which were within the limit of 3-6%, which indicate WMA additives are effective in compacting mixtures at 120° C or lower. Indirect Tensile Strength and Tensile Strength Ratio values of the mixtures with WMA additive were found to be higher than the mixtures without additive Rediset. Based on the overall test results it can be concluded that WMA additive Rediset is effective in producing the mixtures with high strength at mixing temperatures of 135° C and 115° C.

Laboratory performance of warm mix asphalt containing recycled asphalt mixtures

This study aims to evaluate the laboratory performance of warm mix asphalt containing reclaimed asphalt pavement (WMA–RAP) materials. The WMA mixtures containing 0% and 40% RAP were produced using Evotherm-DAT and S-I WMA additives. The laboratory performance tests included rutting, bending, freeze–thaw splitting, Marshall immersion, aging, freeze–thaw cycles splitting, and fatigue tests. The moisture and low temperature cracking resistance were evaluated for aged mixtures. The results showed the WMA mixtures without RAP performed better moisture and low temperature cracking resistance, and lower rutting resistance than the WMA–RAP mixtures. The WMA mixtures suffered from the short-term aging exhibited a slight increase as compared to the unaged mixtures, whereas the long-term aging resulted in a distinct reduction in terms of the moisture resistance. After the short- and long-term aging, the WMA mixtures exhibited a greater decrease than the unaged mixtures in terms of the low temperature cracking resistance. The tensile strength ratio (TSR) results of the WMA–RAP mixtures generally decreased with the increase of freeze–thaw cycles, while the TSR results showed an obvious increase after three freeze–thaw cycles. The addition of RAP significantly reduced the fatigue resistance of the WMA–RAP mixtures in comparison with the WMA mixtures without RAP. Based upon the study findings, the moisture resistance under freeze–thaw cycles conditioning remains an issue to be considered in the WMA–RAP mixtures.

다짐온도에서 골재 거칠기와 아스팔트 피막두께에 따른 중온화 첨가제의 윤활특성 평가

PURPOSES : This study is to develop a method to evaluate lubrication of asphalt binder using WMA additives and compare their lubrication effects on two types of WMA additives and three types of asphalt film thicknesses. METHODS : This study is based on laboratory experiments and rheological analysis of the experimental results. Testing materials are aggregate diskes, asphalt, and WMA additives. The main testing method is stress sweep test by using dynamic shear rheometer (DSR). RESULTS : Sasobit gives more lubrication effects on film thicknesses 0.2mm and under but LEADCAP does on film thicknesses over 0.3mm. CONCLUSIONS : LVE-Limit is a better parameter to discern the lubrication effects on the thin film asphalt thickness. Both Sasobit and LEADCAP WMA additives provide effective lubrication at the compaction temperature.

DSR을 이용한 온도변화에 따른 중온화 첨가제의 다짐특성 연구

PURPOSES : This study is to develop a method to evaluate the compaction effects of asphalt binders using WMA additives and compare their compaction effects on two types of WMA additives, two types of testing temperatures, and three types of asphalt film thicknesses. METHODS : This study is based on laboratory experiments and rheological analysis of the experimental results. Testing materials are aggregate disks, asphalt, and WMA additives. The main testing method is the stress sweep test by using dynamic shear rheometer (DSR). In addition, the testing parameters obtained from the stress sweep results to evaluate lubrication effects are complex modulus and LVE-Limit. RESULTS : At both the first compaction condition (, 0.3mm) and second compaction condition (, 0.2mm) assumed, LEADCAP showed better compaction effects than Sasobit. CONCLUSIONS : The temperature lower than general compaction temperatures can provide a better sensitivity for the evaluation of compaction effects. If a testing temperature and film thickness are grouped for the proper compaction conditions in the testing results, the compaction performance of each WMA additive can be more clearly discriminated in the grouped testing results matched with the grouped conditions.