WMA Technology Research Articles

Comparative Study on the Performance of Open Graded Friction Course using Hot and Warm Mix Technology

Conventional pavements and parking lots are constructed as impervious structures which leads to large volumes of stormwater runoff. This increases the load of stormwater drains besides the water carries the dirt and debris present on the surface and pollutes the water bodies. Surface detention basins are usually provided to collect the runoff and slow down its rate. But this requires additional land space. So, a solution in this regard is to provide a permeable pavement system that permits the infiltration of the stormwater. Open graded friction courses are provided as the surface course of such pavements. This research aims at assessing the feasibility of using warm mix technology in the production of open graded friction course mixes. The focus was on the benefits that could be acquired by the use of WMA technology in a porous asphalt mix. In this study a chemical additive namely sasobit was used to prepare warm mixes. A comparative assessment between hot and warm porous bituminous mixes was made. The fundamental parameters evaluated includes volumetric properties of the mix, permeability, drain down, Cantabro abrasion loss, and moisture susceptibility. It was found that the warm mix additive was capable of reducing the production temperature and the maximum temperature reduction was obtained in the case of 3% sasobit. About 100C reduction in mixing and 130C reduction in compaction temperature could be achieved. The results indicate that open graded mixes prepared with warm mix technology met the performance criteria and hence it is suitable for application in porous pavements. This reduction in temperature could be translated to reduced fuel consumption for heating the binder and reduced level of emissions. Thus, it leads to better working environment for those involved in road construction.

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

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

Evaluate Resistance of Warm Asphalt Mixtures to Rutting

WMA is a new technology, which is based on reduced temperature for mixing, and compaction of asphalt mixture, like any pavement material, testing the compatibility of this technology with domestically obtainable material is essential. The objective of the current research is to assist Iraqi establishments in addressing the issues related to resistance to rutting when adopting this technology. An intensive study on the performance of WMA mixtures with local materials was carried out. Job mix formulas with 12.5 mm and 25 mm aggregate size were chosen for HMA and WMA. One WMA technology was used which is an organic additive; two additives were used Asphaltan A® and Asphaltan B®. All the mixture types are testes and compared with each other. The rutting sensitivity of the mixtures is evaluated using Wheel Track test. From the results, for surface mixtures, rut depth is directly proportional to WMA additive content. For base mixtures, more Asphaltan A® leads to more rut depth, but more Asphaltan B® leads to less rut depth. Permanent deformation results of all mixtures, WMA and HMA mixtures are within the acceptable criteria.

Laboratory and Full Scale Evaluation of Recycled and Warm Mix Asphalts

This study evaluated the cracking characteristics of asphalt materials containing RAP/RAS and prepared with WMA technology. Tests were performed in the laboratory and at a full-scale testing facility. Ten test lanes were built at FHWA’s Accelerated Loading Facility (ALF). The experimental design included three RAP percentages up to 44% by weight (40% recycled binder ratio, RBR), two WMA technologies (water foaming and chemical additive), one RAS percentage with 20% RBR, and two different virgin binders (PG 58-28 and PG 64- 22). Specimens prepared from loose mixes sampled from the construction and field cores sampled at different times were evaluated using the direct tension monotonic test. Performance grade and cracking resistance of asphalt binders recovered from tested loose mix and field cores were determined. The laboratory monotonic testing results were compared to and statistically correlated to the ALF field cracking performance. Experimental results from both laboratory mix and binder tests capture the oxidative aging that occurs with time in the top lift. Aging observed in the bottom lift of the asphalt pavement was considerably less. One of the mechanical parameters developed from the mix monotonic test closely correlated with the binder tolerance strain obtained from the binder DENT test. Long- term oven aging aged the mix significantly more severely than was observed in threeyear old ALF sections. Testing of ALF materials shows that the mixtures with 40% RAP RBR or 20% RAS RBR and stiff binder exhibited the worst cracking performance. A softer PG grade was found to be effective at improving the performance for 40% RAP RBR mixes but ineffective at improving the performance of 20% RAS RBR mix. No difference in field performance was observed between the HMA and WMA mixtures having the same mix design. Statistical analysis indicated a strong correlation between the direct tension monotonic mix test and ALF field testing in terms of evaluating the cracking

Performance of Chemical WMA Mixtures – A review

In recent years, a new approach called WMA technology is developed, which include reduces binder viscosity and accordinglyallows lower temperatures for mixing and compaction. This technology gives several benefits, such as reduce emission, less odor,and energy saving. This study gives a comprehensive review on the use of WMA with chemical technology. In addition, give anintroduction to use chemical additives into the bitumen, in order to understand the application of these additives, the problems,benefits and how they act are reviewed.

Investigation of the fatigue characteristics of warm stone matrix asphalt (WSMA) containing electric arc furnace (EAF) steel slag as coarse aggregate and Sasobit as warm mix additive

Investigation of the fatigue characteristics of warm stone matrix asphalt (WSMA) containing electric arc furnace (EAF) steel slag as coarse aggregate and Sasobit as warm mix additive

Application of Fly Ash Derived Zeolites in Warm-Mix Asphalt Technology.

In recent years, numerous studies have been carried out on new technologies allowing to reduce of mix asphalt production temperatures. One of the possibilities is to foam the asphalt with “water-containing” additives, which include zeolites. So far, mainly synthetic zeolites of the Linde A structure type, obtained from chemical reagents, and natural clinoptilolite have been used in WMA technology. In this studies, the synthetic zeolites produced from fly ashes with 4 different types of crystalline structure were analyzed. Zeolite materials were characterized by textural parameters and thermal analysis. The amount of zeolite added to asphalt was 0, 3, 5, 7 wt % in relation to the weight of asphalt. Determination of dynamic viscosity was performed at two temperatures: 135 and 160 and 4 time intervals. The tests were performed for two asphalt binders: 35/50 and 100/150 penetration grade. As a conclusion, it was found that the viscosity of asphalt pastes with zeolitic materials increases with the increase in the amount of zeolite added. The increase level depends mainly on the textural parameters. The potential usefulness of fly ash derived zeolites in the process of asphalt foaming, which depends mainly on the amount of water contained in the zeolite structure and the method of its release, has been proved.

Application of WMA Technology to Bituminous Base Course Mixes

Warm Mix Asphalt, due to lower mixing and compaction temperatures, provides some engineering benefits over conventional Hot Mix Asphalt. In this study, an attempt is made to assess the viability of using Warm Mix Asphalt technology in bituminous base courses. An organic wax-based Warm Mix Asphalt additive was used in this study to produce Dense Bituminous Macadam, a commonly used bituminous base course mix in India. Experimental variables included three additive contents and four mixing temperatures. Rheological properties of binder modified with different doses of additive were examined. In all, twelve Warm Mix Asphalt Dense Bituminous Macadam mix types were prepared, evaluated and compared with Hot Mix Asphalt Dense Bituminous Macadam (control) mix. Rheological test results showed the addition of wax-based additive improved stiffness and resistance against permanent deformation of the base binder. Tensile Strength Ratio and retained Marshall Stability results indicated that Warm Mix Asphalt Dense Bituminous Macadam mixes were resistant to moisture-induced damage.

Influence of wax additives on the properties of porous asphalts

Influence of wax additives on the properties of porous asphalts

Long-term ageing of asphalt mixtures

Ageing of asphalt mixtures occurs during production and construction and continues throughout the service life of the pavement. Although this topic has been studied extensively, recent changes in asphalt mixture components, production parameters, and plant design have raised a need for a comprehensive evaluation that considers the impacts of climate, aggregate type, recycled materials, WMA technology, plant type, and production temperature. In this study, field cores were acquired from seven field projects at construction and several months afterwards, and raw materials were also collected for fabricating laboratory specimens that were long-term oven aged (LTOA) in accordance with selected protocols. The resilient modulus and Hamburg wheel tracking tests were conducted on both specimen types to evaluate the evolution of mixture stiffness and rutting resistance with ageing. The concepts of cumulative degree days and mixture property ratio were proposed to quantify field ageing and its effect on mixture properties. Test results indicated that the LTOA protocols of two weeks at 140°F (60°C) and five days at 185°F (85°C) produced mixtures with equivalent in-service field ageing of 7–12 months and 12–23 months, respectively, depending on climate. Finally, among the factors investigated in the study, WMA technology, recycled materials, and aggregate absorption exhibited a significant effect on the long-term ageing characteristics of asphalt mixtures, while production temperature and plant type had no effect.

Viscoelastic Properties of Polymer Modified Bitumen in Warm Mix Asphalt Technology in Terms of Ageing

Viscoelastic Properties of Polymer Modified Bitumen in Warm Mix Asphalt Technology in Terms of Ageing

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.

A Study On Warm Mix Asphalt Technology On Bituminous Mixesusing Rediset-Wmx

All around the world efforts are made and being forward to protect the environment. At present the main emphasis is on reducing CO2 emissions in the view of reducing the greenhouse gases and effect. Nowadays the construction of roads can be done by using the hot mix asphalt (HMA) technique which consists of aggregates and bitumen mixed at the higher temperature approximately 150° to 170° C. The main concern with this HMA technology is, it requires great amount of energy for the production of bituminous mixes and also emits the massive amount of greenhouse gases in to the environment.Warm mix asphalt (WMA) is the recent technology and one of the solutions used to reduce the mixing temperature of bituminous concrete without affecting the quality of pavement and act as the alternative of the HMA technology. WMA technology reduces the mixing temperature about 20° to 40°c. In this study, warm mix design of bituminous concrete for surface course is carried out by using the WMX additive with the bitumen of viscosity grade-30 (VG-30). The optimum binder content to produce the bituminous mix using the WMX additive will be achieved by the marshall test. Then after optimum dosage of WMX additive and favourable temperature for WMX additive at which it can perform successfully. Qualified study can be done to know the stability of WMX additive with binder. Laboratory testing is also carried out to find the physical properties of aggregate and bitumen of VG-30 grade tests with or without the WMX additive.

Superpave evaluation of higher RAP contents using WMA technologies

Superpave evaluation of higher RAP contents using WMA technologies

Laboratory and Construction Evaluation of Warm-Mix Asphalt

AbstractWarm mix asphalt (WMA) describes various technologies that allow asphalt mixtures to be produced at lower temperatures as compared with hot mix asphalt (HMA). WMA technologies also offer improvements in workability, cost, and environmental sustainability, such as reduced fuel usage, greenhouse gas emissions, and wear and tear at plants, while enhancing worker health and safety conditions. The objective of this study was to quantify the laboratory performance of field-produced mixtures that utilize WMA technologies and to evaluate the influence of lowering the production temperature on the mixture properties in the field. To achieve this objective, three field projects across Louisiana were selected to provide eight mixtures for the evaluation of WMA technologies. Plant-produced mixtures were sampled and the laboratory performance of WMA mixtures and conventional HMA was evaluated. Further, the characteristics of WMA mixtures were compared with conventional HMA mixtures during production and constr...

Laboratory moisture susceptibility evaluation of WMA under possible field conditions

Laboratory moisture susceptibility evaluation of WMA under possible field conditions

Evaluation of Moisture Susceptibility Minimization Strategies for Warm-Mix Asphalt: Case Study

AbstractWarm-mix asphalt (WMA) technologies aid in reducing mixing and compaction temperatures for asphalt concrete mixtures, allowing for savings in fuel consumption and extending haul distances and construction season. The reduced temperatures also provide a greener technology as emissions are lowered at the plant and the construction site. Engineering and environmental benefits promoted the rapid implementation of WMA technologies, but concerns remain regarding the difference in mixture performance of WMA versus hot-mix asphalt (HMA) because of the changes in the production process, specifically in terms of moisture susceptibility. This case study evaluates moisture susceptibility through the use of laboratory tests including the wet indirect tensile (IDT) strength test, the tensile strength ratio (TSR), and the Hamburg wheel tracking test (HWTT) analyzed with a novel methodology. The performance of two WMA technologies (Evotherm DAT and foaming) versus a control HMA is analyzed with and without antist...

The Evaluation of SMA Mixture Properties with the Surface-active Agent in WMA Technology

The Evaluation of SMA Mixture Properties with the Surface-active Agent in WMA Technology

Influence of waxes on adhesion properties of bituminous binders

Influence of waxes on adhesion properties of bituminous binders

Louisiana’s Experience with WMA Technologies: Mechanistic, Environmental, and Economic Analysis

AbstractWarm mix asphalt (WMA) describes various technologies that allow asphalt mixtures to be produced at lower temperatures as compared to hot mix asphalt (HMA). WMA technologies also offer improvements in workability, cost, and environmental sustainability such as reduced fuel usage, greenhouse gas emissions, and wear and tear at plants, while enhancing worker health and safety conditions. These benefits, as well as the mechanical properties of WMA mixtures, need to be quantified and compared to that of HMA. The primary objective of this study was to evaluate the laboratory performance of plant-produced lab-compacted mixtures utilizing various WMA technologies. The secondary objective of this study was to compare WMA energy consumption cost and emission data to conventional HMA mixtures in terms of fuel/energy savings at the plant and in terms of CO and CO2 emissions. Three projects in Louisiana utilizing four different WMA technologies were considered in this study, yielding 11 mixtures total. Each p...