Properties Of Mix Asphalt Research Articles

The Effect of Crumb Rubber on Properties of Asphalt Mix by Dry Process

the use of crumb rubber modifiers by dry processis not used extensively in asphalt applications as the wet process. This study aims to investigate the effect of crumbrubber modifiers on properties and performance of asphaltmix by dry process. Thus, a set of asphalt mixturescontaining various percentages of crumb rubber modifiersmixed by the dry process were tested. Moreover, the effectof modifying conventional asphalt mixture with crumbrubber polymers was evaluated. In addition, a comparativeassessment was made to evaluate rubberized mixtures andunmodified bitumen mixture. The mixtures were assessedby using the Marshall Stability test, the wheel tracking testand the moisture susceptibility test. The study revealed thatan addition of crumb rubber modifiers to conventionalasphalt mixture enhances pavement stability and increasesits resistance to rutting and moisture damage. The studyconcludes that an addition of 2% of CR to unmodified AC16gives the most satisfactory results among other rubberizedmixtures.

Laboratory and Field Performance Evaluation of Cracking of Airfield Warm Mix Asphalt with Reclaimed Asphalt Pavement at the National Airport Pavement and Materials Research Center

The U.S. Federal Aviation Administration is exploring initiatives to decrease transportation greenhouse gas emissions by developing carbon reduction strategies, including using low-embodied carbon materials, such as reclaimed asphalt pavement (RAP), in airport pavement construction. However, verifying RAP’s viability for airfield pavements with laboratory and field performance measures is essential. This study compared the cracking susceptibility of a P-401 hot mix asphalt and warm mix asphalt (WMA)+RAP airfield mixes using laboratory performance tests and conducted a preliminary evaluation of pavement responses from accelerated pavement testing (APT) fatigue tests. The observations and outcomes presented in this paper found that adding 20% of recycled materials with WMA additives had a decreasing impact in mix performance but did not overly affect the asphalt mix properties, as cracking properties from the different test procedures were found with comparable outcomes. Additional observations from strain gauges and temperature probes in the National Airport Pavement and Materials Research Center test cycle 2 APT fatigue test sections showed that the maximum tensile strains in the WMA surface lane 5 south section were consistently higher than those in the WMA+RAP lane 6 south section, which may be because of the higher load level that it was exposed. Additionally, the hardened or aged RAP binder in the entire lane 6 south section may have increased its stiffness, resulting in lower strain levels than in the lane 5 south section. Notably, both sections showed an increase in tensile strains with an increase in asphalt concrete temperature, which confirmed the temperature dependency behavior of asphalt concrete.

Integration of nano Al2O3 and nano SiO2 in asphalt mixes: A comprehensive performance and durability evaluation

The current research work, examines efficacy of asphalt mixes prepared with varied proportions of nano SiO2 and nano Al2O3. The study assessed the performance of modified asphalt mixes through Marshall stability, flow, indirect tensile strength, resilient modulus, Dynamic modulus, Flow number, and 4-Point bending tests. Elevated nanomaterial dosages notably enhanced high and intermediate temperature performance, nearly tripling rutting resistance, and augmenting fatigue resistance by approximately 130%. Elevated tensile strength ratios confirmed improved moisture resilience. The statistical analysis showed that nanomaterials had a significant influence on properties of asphalt mixes. Overall, diverse test approaches underscored the potential of nanomaterials in enhancing asphalt mix properties, promising durable and long-lasting pavements.

Experimental Investigation of Mechanical and Electromagnetic Performance of Asphalt Concrete Containing Different Ratios of Graphite Powder as a Filler to be Potentially Used as Part of Wireless Electric Roads

This study experimentally investigates the usability of asphalt concrete pavement containing five different ratios of graphite powder (0%, 1.25%, 2.5%, 3.75% and 5% by weight of the aggregate blend or 0%, 25%, 50%, 75% and 100% of the filler content) as a filler to be potentially used as part of wireless electric roads (ER). As part of the study, first, optimum asphalt binder content for the asphalt mixes without graphite powder was determined as 5%. Then, using the determined optimum asphalt binder content, asphalt mixes containing five different ratios of graphite powder as a filler were prepared and their mechanical and volumetric properties based on Marshall mix design methodology were evaluated. As graphite powder ratios in the asphalt mixes increased, their Marshall stability, flow, voids filled with asphalt and unit weight test results mostly decreased but their air content and voids in mineral aggregate test results increased. Possible reasons for this could be: (1) lower bulk specific gravity of graphite powder, (2) higher asphalt absorbance, (3) having greater surface area compared to that of limestone filler, and (4) weak bonds between sheet-like graphite layers. Furthermore, another batch of asphalt mixes containing five different ratios of graphite powder were prepared and tested in the frequency range of 3–18 GHz for their electromagnetic permittivity properties. It was observed in this study that, except for the specimens with 100% graphite powder ratios, transmission magnitudes of all specimens were above 50% up to 8 GHz, indicating that they had comparably high transmission magnitudes so as comparably low tangent loss values. In the frequency range of 3–13 GHz, transmission magnitudes of the specimens with 25% and 50% graphite powder ratios were consistently higher than that having no graphite powder, the ones with 25% powder ratios had the highest transmission magnitudes in most of the cases in this frequency range. Considering the mechanical, volumetric and electromagnetic property test results of the asphalt mixes with five different ratios of graphite powder, it can be concluded that the use of 25% graphite powder ratio (corresponding to 1.25% of the aggregate blend used in the mixes), has a comparably lower negative effect on mechanical and volumetric properties of asphalt mixes and has a positive effect on electromagnetic permittivity properties of asphalt mixes. Asphalt mixes produced with this graphite powder ratio can be considered to be used as part of wireless ER.

Experimental Investigation of Mechanical and Electromagnetic Performance of Asphalt Concrete Containing Different Ratios of Graphite Powder as a Filler to be Potentially Used as Part of Wireless Electric Roads

This study experimentally investigates the usability of asphalt concrete pavement containing five different ratios of graphite powder (0%, 1.25%, 2.5%, 3.75% and 5% by weight of the aggregate blend or 0%, 25%, 50%, 75% and 100% of the filler content) as a filler to be potentially used as part of wireless electric roads (ER). As part of the study, first, optimum asphalt binder content for the asphalt mixes without graphite powder was determined as 5%. Then, using the determined optimum asphalt binder content, asphalt mixes containing five different ratios of graphite powder as a filler were prepared and their mechanical and volumetric properties based on Marshall mix design methodology were evaluated. As graphite powder ratios in the asphalt mixes increased, their Marshall stability, flow, voids filled with asphalt and unit weight test results mostly decreased but their air content and voids in mineral aggregate test results increased. Possible reasons for this could be: (1) lower bulk specific gravity of graphite powder, (2) higher asphalt absorbance, (3) having greater surface area compared to that of limestone filler, and (4) weak bonds between sheet-like graphite layers. Furthermore, another batch of asphalt mixes containing five different ratios of graphite powder were prepared and tested in the frequency range of 3–18 GHz for their electromagnetic permittivity properties. It was observed in this study that, except for the specimens with 100% graphite powder ratios, transmission magnitudes of all specimens were above 50% up to 8 GHz, indicating that they had comparably high transmission magnitudes so as comparably low tangent loss values. In the frequency range of 3–13 GHz, transmission magnitudes of the specimens with 25% and 50% graphite powder ratios were consistently higher than that having no graphite powder, the ones with 25% powder ratios had the highest transmission magnitudes in most of the cases in this frequency range. Considering the mechanical, volumetric and electromagnetic property test results of the asphalt mixes with five different ratios of graphite powder, it can be concluded that the use of 25% graphite powder ratio (corresponding to 1.25% of the aggregate blend used in the mixes), has a comparably lower negative effect on mechanical and volumetric properties of asphalt mixes and has a positive effect on electromagnetic permittivity properties of asphalt mixes. Asphalt mixes produced with this graphite powder ratio can be considered to be used as part of wireless ER.

Adhesion property of municipal solid waste incinerator bottom ash and limestone with asphalt based on surface energy theory

ABSTRACT The aim of this paper is to investigate the adhesion of municipal solid waste incinerator bottom ash (MSWIBA) and limestone to asphalt using the principles of surface energy theory. MSWIBA asphalt mixes are known for their satisfactory water stability, with adhesion being a crucial factor, as demonstrated in previous freeze-thaw splitting tests. Contact angles of ground MSWIBA and limestone were measured using a capillary rise test, eliminating the influence of material surface structure. Subsequently, adhesion work and spalling work were calculated to correlate with water-induced damage. The results showed that the sequence of adhesion work was fine MSWIBA > limestone > coarse MSWIBA, while the sequence of spalling work was coarse MSWIBA > limestone > fine MSWIBA. The adhesion of MSWIBA asphalt mixes was evaluated using the water boiling test image method to validate the findings of surface energy theory. In both asphalt tests, the spalling rate followed this sequence: coarse MSWIBA > limestone > fine MSWIBA. The Adhesion index ER ranked as follows: ER Fine MSWIBA > ER limestone > ER coarse MSWIBA. These results suggest that the water stability of MSWIBA asphalt mixes is influenced by the surface energy of the components. Consequently, indices derived from surface energy theory can be applied in formulating and predicting the properties of MSWIBA asphalt mixes.

An ensemble tree-based prediction of Marshall mix design parameters and resilient modulus in stabilized base materials

A flexible pavement with an adequate Marshall mix design for the asphalt mixture surface layer(s) and appropriate subbase/base design offers a proper pavement structure for driving safety and comfortability. The conventional approach of calculating the Marshall mix design properties (e.g., stability and flow) and resilient modulus of base materials typically requires laborious, expensive, and time-consuming laboratory sample preparation and testing, such as the Marshall stability test and Resilient modulus test. Therefore, this study conducts research on the application of tree-based ensemble methods specifically, random forest (RFR) and eXtreme gradient boosting regression (XGBR) to predict the properties (mainly including Marshall stability, flow, VMA, VFA, and unit weigh) of asphalt mix following Marshall mix design and resilient modulus (Mr) of stabilized aggregate base material. To develop the prediction models, a comprehensive database was established using existing literature. The performance of the prediction models was evaluated using statistical parameters, performance index (p), and other suggested model performance criteria from external research. Additionally, the Shapley Additive exPlainations (SHAP) interpretation technique was employed to explain the models. The analysis results demonstrate that both RFR and XGBR methods have the excellent fitting capability (R > 0.9). However, XGBR has superior performance in predicting Marshall mix properties and Mr value. Comparison with previous research studies reveals that the proposed models show superior performance than genetic programming-based Marshall mix design models. The RFR model performs approximately similar to ANN, while XGBR outperforms ANN, and particle swarm optimization-extreme learning machine-based models for Mr prediction. Furthermore, the equation developed based on multi expression programming for Mr value prediction exhibits superior performance compared to previous research study gene expression programming model.

Design and Low-Temperature Performance Evaluation of High-Modulus Co-Modified Asphalt Mixes with Rock Asphalt/Rubber Powder

High-modulus asphalt mixes are effective means to solve rutting problems, but they perform poorly at low temperatures. This study aims to enhance the modulus and low-temperature properties of mixes. Firstly, composite-modified asphalts and mixes were prepared by incorporating rubber powder and rock asphalt. Secondly, their mechanical and viscoelastic properties were investigated to determine the appropriate mass ratios of rubber powder and rock asphalt in asphalt to be 20% and 6%, respectively. The results show that both rock asphalt and rubber powder can enhance the softening point and viscosity of basic asphalt while reducing penetration. Furthermore, their combination significantly improves the high-temperature performance of the material. It is noteworthy that the rubber powder also improves the weakening of rock asphalt for mixtures at low temperatures. Finally, this study employs dynamic and static modulus tests, rutting tests, and beam bending tests to clarify the road properties of composite-modified asphalt mixes. The results indicate that mixes have high-modulus and water damage resistance while considering acceptable low-temperature performance. This paper not only enhances the adaptability of high-modulus asphalt in different environments but also expands its application range.

Rational relationship between the fatigue curves of asphalt mixes obtained from tension/compression and 4-point bending tests

The fatigue properties of asphalt mixes are usually established according to a series of laboratory cyclic loading tests at fixed temperature (θ) and frequency (f). Unfortunately, the results are different when considering different types of tests. This paper proposes a rational method to link the 4-point bending (4PB) and tension/compression (TC) fatigue test results. First a theoretical analysis of the 4PB fatigue test is presented. This analysis allows to introduce a link between the fatigue curves (modulus or damage versus number of cycles) of this type of test with the results from uniform TC tests. The 4PB fatigue curve is superimposed with the TC fatigue curve if the reference strain amplitude is correctly chosen. This amplitude must not be the maximum strain at the boundary fibre of the beam (ε 0max), as usually considered, but a lower proposed value (ε 0h0). Then, the previous approach is extended to the fatigue failure Wöhler’s law, which is a line in the Log–Log plot of the number of cycles at failure versus the loading amplitude (stress or strain). An experimental campaign on a Canadian asphalt concrete (HMAC) validates the developped approach. It is an important output from this research as fatigue life from one type of test can be obtained from the other type of test in the case of strain (or displacement) control tests.

Experimental Study of the Effect of Crumb Rubber on Properties of Asphalt Mix by Wet Process

The increase in the number of vehicles during the past twenty years has dramatically increased the traffic density and axial loading. In addition to the construction failures and lack of periodic maintenance, rapid deterioration of the road condition happens. So, it was necessary to find solutions to these problems that have been growing for years. One of these solutions is to improve the asphalt mixture to resist excessive loads and weather fluctuations. This research aims to investigate the addition of crumb rubber derived from recycled tires; to the asphalt mixture for improving performance characteristics and to compare the improved and unimproved samples. It is worth mentioning that crumb rubber addition to the asphalt mixture is considered one of the smart solutions for sustainability that the world is heading towards today, considering that the crumb rubber comes from waste tires, which is difficult to eliminate and pollute the environment. Four different proportions of crumb rubber have been added in this research (6, 9, 12, and 15%); by weight of bitumen to (60-70) asphalt binder, with a particle size passing from sieve no.50 (0.3 mm). The aggregate gradation is designed according to the Marshall method with a (12.5 mm NMAS) wearing course to obtain the optimum asphalt content and to prepare laboratory samples to perform various laboratory tests. Marshall Stability and flow, indirect tensile strength (ITS), moisture susceptibility, and permanent deformation of asphaltic mixes with different contents of crumb rubber were investigated. The results of the tested samples were compared with the original samples. It is shown that the asphaltic mixes performance has been improved when adding a certain amount of crumb rubber. Marshall Stability is increased by 29.2% when adding 9% CR by the weight of bitumen. However, the addition of crumb rubber can increase the stiffness of the asphalt mixture resulting in a more rigid pavement structure that is less prone to moisture damage and rutting under traffic load.

Study of Anti-Stripping Measures to Improve the Adhesion of Asphalt to Granite Aggregates

Granite is very widely distributed in the world, but granite is an acidic aggregate with poor adhesion to asphalt. In untreated asphalt mixtures, asphalt pavement water damage and loose disease are more prominent, affecting the service life of the pavement and service level. Enhancing the road performance of granite asphalt mixture generally improves the adhesion properties of asphalt and granite. Qingchuan rock asphalt, anti-stripping agent KH5, aliphatic amine anti-stripping agent AJ-1 and two groups of the composite anti-stripping agents were used to modify the asphalt and analyze the effect of different anti-stripping agents on the improvement of asphalt-granite aggregate adhesion properties based on the surface free energy (SFE) theory. Second, the effect of anti-stripping agents on the rheological properties of asphalt were analyzed by rheological tests, and the modification effect of granite asphalt mixture road performance was evaluated by Marshall tests. The aging of asphalt and asphalt mixture was simulated by thermal oxygen aging, and the durability of different anti-stripping agents was investigated by comparing the performance of asphalt and asphalt mixtures before and after aging. The results showed that Qingchuan rock asphalt can effectively enhance the high-temperature stability and anti-aging properties of asphalt mixes, but the low temperature performance was relatively poor. KH5 and AJ-1 can make up for the lack of low temperature performance of rock asphalt, but the water stability of asphalt mixes decreases after aging. All five groups of anti-stripping agents improve the adhesion of granite-asphalt and the water stability of the asphalt mixture to some extent. Considering the aging effect, the order of granite-asphalt mixture water stability is: KH/RAMA > AJ/RAMA > RAMA > KHMA > AJMA.

Evaluation of the Effect of Recycled Waste Plastic Bags on Mechanical Properties of Hot Mix Asphalt Mixture for Road Construction

Abstract: The use of recycled waste materials in road pavements is currently seen as a viable solution not just in terms of environmental sustainability, but also in terms of improving service performance.[1] This is particularly true when it comes to recycled plastics. Thin plastic bags are primarily composed of low-density Polyethylene and it’s commonly used for packaging, protecting and many other applications. Nevertheless, disposal of waste plastic bags in large quantities constitutes an environmental problem, as they considered non-biodegradable materials. Hence, there is a real need to find useful applications for these growing quantities of wastes. In this research, Waste Plastic Bags (WPB) as one form of polymers are used to investigate the potential prospects to enhance asphalt mixture properties. Research aims include studying the effect of partial replacing of different percentages of WPB pieces of the bitumen as binder modifiers on the properties of asphalt mix comparing it with conventional mix properties, besides identifying the optimum percent of WPB to be added in the hot mix asphalt. WPB were presented in the asphalt mixture in pieces with size (2 x 5 mm2 ). Marshal mix design procedure was used, first to determine the Optimum Bitumen Content (OBC) and then further to test the modified mixture properties. In total, (39) samples were prepared, 15 samples were used to determine the OBC and the remaining were used to investigate the effects adding different WPB percentages to asphalt mix. The OBC was 5.6 % by weight of asphalt mix. Seven proportions of WPB by weight of OBC were tested (2, 4, 8, 12, 16, 20 and 24%), besides testing of ordinary asphalt mix. Tests include the determination of stability, bulk density, flow and air voids

Use of New Green Bitumen Modifier for Asphalt Mixtures Recycling.

Nowadays, an increasing amount of reclaimed asphalt pavement (RAP) is being produced from the reconstruction and/or modernisation of asphalt pavements. It is necessary to recycle the obtained RAP according to principles of sustainable development. Therefore, this work includes the design of asphalt mixtures containing RAP with bio-derived modifier and evaluates their performance properties. Crosslinked sodium alginate was applied for bitumen modification. The studies were carried out for four different modifier contents, i.e., 1.0%, 2.5%, 4.0% and 5.5%, with and without crosslinking agent. On the basis of the binder test results, the optimal amount of the additive was found to be 2.5%. The nanostructure analysis for the base and modified binders indicated a dual crosslinked biopolymer effect. As a result of the bee structure size decrease, the binder softening effect was observed. The asphalt mix properties showed that application of biopolymer-modified binder is fully justified due to the functional parameters of the mixture, especially the increased resistance to water and frost by about 9%.

Laboratory Evaluation of the Properties of Dense Graded Asphalt Mixtures Containing Waste Glass Fibre and Crumb Rubber

Due to environmental issues and rising costs of construction materials, there is an increasing desire to use reclaimed asphalt pavement (RAP) material in road construction. However, using too much of this material may lead to impairment of fundamental properties of asphalt mix. Glass fibre material is a well-known modifier and could be used to compensate possible downgrade of properties. Research articles and theoretical material have shown that adding too much fibre glass reinforcement could cause damage to asphalt mixture. Therefore, in this research, reference mixture has been compared to three projected AC 11 surface mixtures with different amount of fibre glass. The same has been done to HMAC mixtures, but in this case, there is crumb rubber used as mixture modifier. Experimental part has shown that using fibre glass in asphalt mixtures for both construction layers may have positive influence on fundamental parameters of HMAC and AC asphalt mixes, which can be a good solvation for using waste glass fibre in road construction.

Effect of reactive ethylene terpolymer modification on bitumen’s microstructure, rheology, and porous asphalt mix properties

ABSTRACT The specific objective of this study was to investigate the effect of reactive ethylene terpolymer (RET) modification on bitumen properties at the nano and macro scales, as well as on porous asphalt (PA) mix properties. Measurements using the dynamic shear rheometer (DSR) and the bending beam rheometer (BBR) showed that RET modification of bitumen significantly improved the high-temperature properties, while intermediate- and low-temperature properties were similar to the base bitumen. The linear amplitude sweep (LAS) test conducted using the DSR showed that RET modification improved fatigue resistance. Consequently, chemical analysis and PeakForce™ Quantitative Nano-Mechanical™ (PF-QNM) atomic force microscopy (AFM) imaging were used to evaluate the microstructure and nanomechanical properties of the polymer modified bitumen (PMB) and the base bitumen before and after long-term ageing. The chemical analysis provided useful insights that complemented and helped to explain the AFM and rheology tests. The AFM results supported the LAS test findings in showing that RET modification improved the resistance of aged bitumens to cracking. The results of testing the PA mix showed significant improvements in moisture damage and ravelling resistance due to RET modification.

A REVIEW ON EFFECT OF SOLID WASTE FILLERS ON ASPHALT MASTIC AND ASPHALT MIXTURE

The pavement works consumes more of natural resources through which depletion take place due to continuous consumption. So, it is required to regulate the usage of natural material and recommended to use some alternate materials in the form of replacement. Conventional fillers that are used in asphalt mix are stone dust, limestone, Portland cement, etc. In order to regulate usage of these materials utilization of waste/by-products as a filler such as marble dust, calcium carbide residue (CCR), Fly-Ash, brick dust, etc. In this review analysis the effect of solid waste products as fillers in asphalt concrete mixes and asphalt mastics were elaborated by means of mechanical properties, rheological properties and performance properties like resistance against rutting, cracking and fatigue. As a result, from various research works, the improvement in performance and properties of asphalt mastic and asphalt mixes were observed with utilization of solid waste mineral fillers. KEYWORDS: Asphalt Mastic, Asphalt Mix, filler, CCR, Marble Dust

Waste Polyethylene Terephthalate granules modified by gamma irradiation and their effect as fine aggregates on moisture damage of asphalt mixtures

Recently, the excessive quantity of waste polyethylene terephthalate (WPET) creates a significant environmental concern globally. One way to reuse WPET is in the pavement industry as secondary materials. Nevertheless, based on works of literature review on the use of WPET in asphalt materials, inconsistent findings were reported with an increase and decrease in mechanical properties. To overcome this issue, gamma radiation has been utilized on the WPET. This study investigated the effect of using non-irradiated and irradiated WPET on some engineering properties of asphalt mixes. Marshall Samples incorporating a various amount of WPET (Plastiphalt); 0%, 0.5%, 1.0%, 1.5%, 2.0% and 2.5% by weight of total aggregates were tested based on Marshall Stability (MS), indirect tensile strength (ITS), and resistance to moisture damage. The results of x-ray diffraction (XRD) on the irradiated WPET showed that the degree of crystallinity had increased. The results of Marshall Stability (MS) showed an enhancement with increasing WPET content up to 2.0% for the plastiphalt mixes. Marshall Quotient, and ITS show a decreasing trend with increasing WPET amount for the plastiphalt mixes. Furthermore, results on moisture damage resistance indicated that indirect tensile strength and Marshall Stability ratios were marginally increased for plastiphalt mixes compared to the reference mixture (0% WPET). Comparing the moisture sensitivity tolerance results for the WPET modified mixes shows that irradiated WPET plastiphalt mixes had a better outcome than non-irradiated WPET plastiphalt mixes.

Prediction of the hot asphalt mix properties using deep neural networks

BackgroundMarshall design process is the most common method used for estimating the Optimum asphalt content (OAC) and this process is called the asphalt mix design. However, this method is time-consuming, labor-intensive, and its results are subjected to variations.ResultsThis paper employs artificial neural network (ANN) for the estimation of Marshall test parameters (OAC, Stability, Flow, Air voids, Voids in mineral aggregate) using the aggregate gradation as the input of the prediction process. Multiple ANNs are tested in order to optimize the NN hyperparameters and produce accurate predictions. Different activation functions, number of hidden layers, and number of neurons per hidden layer are tested and heatmaps are generated to compare the performance of every ANN. Results show that the optimum ANN hyperparameters change depending on the predicted parameter. Finally, the deep NN can predict the OAC, stability, flow, density, air voids, and voids in mineral aggregate with R values of 0.91, 0.8, 0.53, 0.65, 0.77, and 0.66.ConclusionThe linear activation function is the most efficient activation function and generates more accurate results than the logistic and the hyperbolic tangent functions. Additionally, it is shown that the deep neural network approach represents a major innovative tool for the prediction of the asphalt mix properties as results of this approach outperforms results of the shallow ANN that consists of a single hidden layer which is the only approach used in the literature. Thus, the use of the deep ANN can be useful during the phase of the design of the asphalt mix process because of its ability to predict variables with high accuracy. For example, the ANN with 3 hidden layers and 16 neurons per layer with the linear activation function can predict the OAC with high accuracy (R = 0.91), which can be helpful in the design process as the ANN can be employed for the prediction of the OAC of the asphalt mix.

Properties at Low Temperatures of Asphalt Mixes Containing High Content of Multi-recycled RAP

Abstract The reuse of reclaimed asphalt pavement (RAP) in the production of new asphalt mixes is a valuable environmental approach. Likewise, new lower-temperature manufacturing processes (warm) of asphalt mixes have an impact in the reduced fuel consumption and gas emissions during production. In 2014, the French National Research Agency launched the French national project “Innovation for Materials and Processes for Improving the Multi-Recycling of Mixtures” (IMPROVMURE). The main objective of the IMPROVMURE project was to determine, over the life cycle of pavement materials, the impact of successive recycling at different rates and for different manufacturing techniques (hot and warm processes). To estimate the thermomechanical properties of multi-recycled asphalt mixes, a characterization of behavior by coupling the thermal and mechanical effects at low temperatures was carried out. This paper presents the thermal stress restrained specimen test (TSRST) results of six asphalt mix types, three hot asphalt mixes, and three half-warm asphalt mixes using a foamed binder. Some of these asphalt mixes were manufactured with a content up to 70 % RAP and 70 % multi-recycled RAP. TSRST were performed on cylindrical specimens at the University of Lyon/école nationale des travaux publics de l’état (ENTPE). The failure temperature (TF), failure stress (σF), and failure radial deformation (εrF) were evaluated to analyze and compare the behavior of mixes at low temperature. The influences of RAP content, recycling cycle, air void content, and manufacturing process were studied, and the air void content showed an effect inversely proportional to the failure stress.

Use of nano-materials to enhance the properties of asphalt mixes

Nanotechnology is being used in different aspects of life to solve different problems. Highway researchers and practitioner are also using nano-materials to modify asphalt binders. Studies associated with the use of nano-materials in pavement construction are still very limited. In order to make this more applicable in the field, there is a need of more studies on this topic. The current study investigates the influence of the nano-based chemical warm mix additive zycotherm on the characteristics of asphalt mixes. In the study zycotherm was added into the mix in different proportions and the properties of the asphalt mixes were examined. In order to assess the moisture damage resistance of the mix, parameters like retained marshall stability (RMS) and tensile strength ratio (TSR) were calculated. Based on the results of these tests, comparisons are made and conclusions are presented in this paper.