Comparative study of ethanol foamed asphalt binders and mixtures prepared via manual injection and laboratory foaming device

The consistency of the ethanol foamed binders and mixtures prepared using asphalt binders foamed by the manual injection technique and laboratory foaming device were evaluated and compared in this study. The asphalt binders foamed using both methods was prepared at 120 °C, 130 °C and 140 °C. The performance of ethanol-foamed binders was evaluated in terms of rotational viscosity, expansion ratio, and low temperature cracking. Meanwhile, the performance of foamed WMA mixtures was tested using semi-circular bending (SCB), disk-shaped compact tension (DCT), and tensile strength ratio (TSR) tests. In order to conduct the TSR test, the samples were conditioned using the Moisture Induced Stress Tester (MIST) to simulate the pore pressure and scouring effects due to a tire passing over wet pavement. The foamed WMA mixtures were produced using pre-heated aggregates at 80 °C and 100 °C and foamed asphalt binders produced at 130 °C. The nano-hydrated lime was used as the filler and anti-stripping agent. Overall, the properties of ethanol-foamed binders and WMA mixtures produced via both methods are significantly comparable, except the resistance to moisture damage test result. However, the findings indicate that the ethanol-foamed WMA mixtures prepared using both techniques are having good resistance to moisture damage, based on the TSR values more than 0.8. The foamed WMA mixtures also exhibited a better resistance to cracking, as indicated by a higher tensile strength compared to the control HMA. Additionally, the WMA specimen prepared at 100 °C was less susceptible to rutting than the samples produced at 80 °C

Ethanol based foamed asphalt as potential alternative for low emission asphalt technology

Foamed asphalt typically relies on water as a foaming agent because water becomes gaseous at elevated temperatures, generating numerous tiny bubbles in the asphalt and causing spontaneous foaming. In this study, ethanol was used as a potential alternative to water as a foaming agent. Ethanol is expected to be a physical blowing agent in the same manner as water, except it requires less energy to foam due to its 78 °C boiling point. This study compares the performance of water and ethanol as foaming agents through the measurements of rotational viscosity, the reduction in temperature during foaming, and volatile loss. The ethanol-foamed asphalt binders were prepared at 80 °C and 100 °C, while the water-foamed asphalt binders were prepared at 100 °C and 120 °C. Additionally, the rolling thin film oven (RTFO) was used to generate short-term aging of the foamed asphalt binders. A rotational viscometer was used to determine the viscosity of the asphalt binders at 80 °C, 100 °C, 120 °C, 140 °C, and 160 °C. Overall, ethanol can function in the same manner as water but requires less energy to foam. It is proven based on the smaller drop in temperature of the asphalt binder foamed using ethanol compared with that prepared with water. This is due to the lower latent heat capacity of ethanol, which requires less energy to vaporize compared with water. Through the rotational viscometer test, ethanol performs better in lowering the viscosity of asphalt binders, which is essential in allowing production processes at low temperatures, as well as a better workability and aggregate coating. Ethanol can be expelled from the foamed asphalt binders at a higher rate due to its lower boiling point and latent heat

Studies On Binder Creep, Abrasion Loss And Dynamic Stripping Of Porous Asphalt

After several years in service, porous asphalt looses permeability primarily due to clogging. This study presents a phenomenon postulated as binder creep, as another source of permeability loss in porous asphalt. To ascertain the binder creep, samples were separately conditioned at 15oC, 20oC, 30oC and 35oC. Permeability measurements were carried out at regular intervals up to 120 days using a falling head water permeameter. Apart from clogging, the most serious problem that limits porous asphalt durability and service life is ravelling

Effects of crumb rubber and styrene-butadiene rubber additives on the properties of asphalt binder and the Marshall performance properties of asphalt mixtures

The primary aim of this study is to evaluate the impact of incorporating crumb rubber (CR) and styrene-butadiene rubber (SBR) additives, ranging from 0% to 5% by weight of bitumen, on the performance of a bituminous concrete mixture using the wet process. Laboratory experiments, including the Marshall test, were conducted to establish the optimum bitumen content (OBC) for the hot mix. The study focuses on determining the optimal proportions of CR and SBR to achieve maximum strength. The results show that increasing the proportions of both CR and SBR leads to significant improvements in strength, with the maximum stability recorded at 16.14 kN and a flow of 1.23 mm for a mix containing 5% CR and 4% SBR. The findings further suggest an inverse relationship between CR content and strength, while an increasing SBR content enhances strength. Consequently, the optimal proportions for incorporating CR and SBR additives are identified as 5% and 4%, respectively

Rheological behavior and sensitivity of wood-derived bio-oil modified asphalt binders

The demand for bituminous materials is continuously growing; crude oil-based asphalt binders are non-renewable, and are facing rapid depletion. With the increase of petroleum-based asphalt prices, seeking an alternative, renewable material such as bio-asphalt has become a hot research topic. However, shortcomings in this research area have been identified, notably concerning the high-temperature performance of bio-asphalt at present. This research aims to comprehensively apply conventional tests to, and study the rheological behavior of, the high-temperature performances of bio-asphalt binders, i.e., by temperature and frequency sweeps, using a dynamic shear rheometer (DSR). It will also assess the chemical functional groups of specimens prepared by different aging conditions. Fifty penetration grade base asphalt binder (50#), bio-oil modified asphalt binders with 0%, 5%, 10%, and 30% bio-oil contents by mass, and bio-oil modified asphalt binder with combinations of 5% bio-oil-1% SBS, and 10% bio-oil-1% SBS were used in this study. The conventional performance of bio-asphalt binders was tested using penetration, ductility, and softening point, before and after short-term aging conditioning. The temperature sweep and frequency sweep of bio-asphalt under different bio-oil contents were carried out via DSR. Two-logarithmic equations of rutting factor and temperature were established, and the temperature sensitivity of bio-asphalt was analyzed. The master curves of virgin asphalt and bio-asphalt were constructed at 64 °C. The results indicate that the incorporation of bio-oil reduced the anti-rutting performance of asphalt, and the bio-oil content had a significant effect on the mass loss of the bio-asphalt binder. The performance of bio-oil modified asphalt binders using 5% bio-oil, 5% bio-oil-1% SBS, and 10% bio-oil-1% SBS, could meet the requirements of 50# grade asphalt. The temperature sensitivity of bio-asphalt did not show obvious change before and after short-term aging, whereas the temperature sensitivity of bio-asphalt with 5% bio-oil was relatively small. With an increase in temperature, the phase angle increased gradually. In contrast, the storage modulus, loss modulus, and complex modulus decreased progressively. The complex modulus and rutting factor of bio-asphalt with 5% bio-oil steadily increased with the increase in testing frequency. Otherwise, chemical reactions were detected in the 50# base asphalt modified with the bio-oil

Experimental assessments of methanol-based foaming agent in latex modified foamed binders and warm asphalt mixtures

Latex is one of the natural rubbers that is used to enhance the performance of asphalt pavement for the last few decades. The presence of latex, which is categorized as an elastomer, helps to improve pavement performance and durability. Conversely, higher viscosity of latex modified asphalt binder increases the production-temperatures of asphalt mixture, thus consuming higher energy during asphalt mixture’s production stage. In this study, the effectiveness of methanol as an energy-efficient foaming agent was assessed to reduce the viscosity and enhance the workability of the modified asphalt binder. The basic and rheological properties of the asphalt binders were determined through multiple laboratory tests including expansion ratio and half-life, rotational viscosity, softening point, torsional recovery, and dynamic shear rheometer. The properties of asphalt mixtures were assessed through the service characteristics, mechanical performance, and moisture resistance criteria. It was found that the presence of latex results in an approximately twofold higher expansion ratio and a lower half-life of the asphalt binder at about the same ratio. Through the rotational viscosity test, the application of methanol into asphalt binder decreased the viscosity and led to better workability, despite the addition of latex as an asphalt modifier. The application of methanol into asphalt binder improved the workability of mixture samples and lowered the compaction energy of the compaction process, which are the crucial criteria for a better mixing and compaction process. Methanol foamed asphalt mixtures with latex show much higher resistance to moisture damage and stiffness than control sample even though they were prepared at a lower temperature

Study on Wash-out of Asphalt Mixture Caused by Repeated Heating and Cooling Immersion Test

Stripping generates within the asphalt pavements due to continuous effect of moisture has been one of the concerns by the road authorities worldwide. Without a proper treatment, it could cause potholes and lower the bearing capacity of asphalt pavements. With regard to this, it is well known that the bipolar anti-stripping agent is effective to prevent the stripping due to its electrochemical bonding characteristics between aggregate and asphalt. Wash-out is a dynamic water action that could strip the asphalt mortar from pavement surfacing. Such distress spotted on many roads, whereby, granite aggregates are normally used as the main material in asphalt mixtures. In this study, the experimental work is focused on stripping phenomenon caused by multiple moisture conditioning cycles at 80 °C, and a newly developed evaluation protocol using a Repeated Heating and Cooling Immersion test is adopt-ed. The Wash-out, which is closely associated with stripping, is studied to evaluate the resistance of asphalt pavement against moisture damage. This study is a laboratory scale evaluation and the phenomenon in the field is not yet adequately considered. The repeated heating and cooling immersion procedure is an accelerated strip-ping conditioning without applying an external force. It is clarified that the resistance to the Wash-out of asphalt mixture is improved with the presence of the bi-polar anti-stripping agent, known as Tough Fix Hyper at the rate of 0.15% or more

Study on Wash-out of Asphalt Mixture Caused by Repeated Heating and Cooling Immersion Test

Stripping generates within the asphalt pavements due to continuous effect of moisture has been one of the concerns by the road authorities worldwide. Without a proper treatment, it could cause potholes and lower the bearing capacity of asphalt pavements. With regard to this, it is well known that the bipolar anti-stripping agent is effective to prevent the stripping due to its electrochemical bonding characteristics between aggregate and asphalt. Wash-out is a dynamic water action that could strip the asphalt mortar from pavement surfacing. Such distress spotted on many roads, whereby, granite aggregates are normally used as the main material in asphalt mixtures. In this study, the experimental work is focused on stripping phenomenon caused by multiple moisture conditioning cycles at 80 °C, and a newly developed evaluation protocol using a Repeated Heating and Cooling Immersion test is adopt-ed. The Wash-out, which is closely associated with stripping, is studied to evaluate the resistance of asphalt pavement against moisture damage. This study is a laboratory scale evaluation and the phenomenon in the field is not yet adequately considered. The repeated heating and cooling immersion procedure is an accelerated strip-ping conditioning without applying an external force. It is clarified that the resistance to the Wash-out of asphalt mixture is improved with the presence of the bi-polar anti-stripping agent, known as Tough Fix Hyper at the rate of 0.15% or more

Effect Of Double Fuzzy Logic Controller (DFLC) Based On Power System Stabilizer (PSS) On A Tie- Line Two Generators System

This research was proposed a new type of power system stabilizer based on fuzzy set theory, to improve the dynamic performance of a multi-machine power system. To have good damping characteristics over a wide range of operating conditions, speed deviation and it is derivative of a machine are chosen as the input signals to the fuzzy stabilizer on that particular machine. Fuzzy logic controller (FLC) Two area symmetrical systems connected via tie-line are measured to show via performance of these controllers. This research presents the analysis of change of speed (Δω), change of angle position (Δδ) and tie - line power flow (Δp). In tie-line system two generators control arrangement single fuzzy logic controller (SFLC) have been used as a primary controller, whereas double fuzzy logic controller (DFLC) used as a secondary controller. In addition to this, the system shows comparative between two controller single and double fuzzy controller has been used for the system to achieve the best results using Simulink/MATLAB. Double fuzzy controller has a greater effect on the tie-line system and become more smoothing than single fuzzy controller because has increased the damping of the speed Δω, angle rotor Δδ and power Δp

The Characterisation of Fracture Resistance of Asphalt Mixtures Containing Rubber Modifiers and a Wax-Based Additive

Asphalt mixture modifcation with rubberised material frequently results in improved characteristics and extended service life in actual application. Tis research characterised the synergistic consequences of rubber modifers (crumb rubber powder (CRP) and natural rubber latex (NRL)) and wax-based admixtures (Tough Fix Hyper (TFH)) on the performance of the asphalt mixture from the fracture energy and laboratory fracture resistance perspectives. Semicircular bending (SCB) and indirect tensile strength (ITS) tests were conducted to assess the fracture properties of the asphalt mixture samples. To prepare asphalt mixture samples, the wet method was utilised. Higher CRP levels resulted in greater strength and a longer time to attain peak force for both control and mixtures containing wax admixture, as determined by SCB. Te interaction between the higher CRP or NRL content and the TFH additive enhanced the fracture resistance, indicating that the components are highly compatible. Te 10L + TFH additive produced the highest fraction of energy, indicating a more signifcant improvement than the counterpart mixes containing the CRP modifer. In addition, incorporation of the CRP and NRL increased the fracture plastic zone (FPZ), resulting in increased fracture toughness. Terefore, the gradient of fracture toughness and fracture energy in the asphalt mix depends on the rubber type, content, and TFH. Although the higher CRP, NRL, and TFH improve the fracture energy and cracking resistance, they increase the crack initiation and propagation velocities, whereby the high bitumen stifness makes the mixture more brittle than the control mixture. Caution should be exercised when selecting the content of rubber modifer and TFH for the asphalt pavements in low-temperature service. Also, there is a direct interconnection between fracture resistance and fracture energy in the mixtures containing CRP, NRL, and TFH. Such correlations can be used as the premise of predictive micro- and macromodels to evaluate mixture performance in terms of fracture resistance