Critical assessment of new polymer-modified bitumen for porous asphalt mixtures

ABSTARCT: New experimental polymer-modified bitumen with a high-vinyl content polymer was fabricated for porous asphalt (PA) mixtures. The bitumen with maximum stability was achieved using storage stability, gelation criteria and physical bitumen tests. A dynamic shear rheometer was used to compare the complex modulus, number of fatigue cycles, yield stress, and non-recoverable creep compliance of the experimental bitumen with a reference virgin bitumen 50/70 and a PMB 45/80-65 binder. PA mixtures were also designed to analyze the abrasion resistance and binder drainage characteristics. It was concluded that the experimental bitumen with 4.5% polymer content showed higher elastic response, better fatigue resistance, and improved rutting behavior than the reference PMB. PA mixtures with the new experimental bitumen exhibited higher abrasion resistance, but underwent higher binder drainage, which was addressed by the incorporation of aramid pulp and glass-hybrid fibers

Laboratory Characterization of Porous Asphalt Mixtures with Aramid Fibers

ABSTRACT: Recent studies have shown that fibers improve the performance of porous asphalt mixtures. In this study, the influence of four different fibers, (a) regular aramid fiber (RegAR), (b) aramid fiber with latex coating (ARLat), (c) aramid fiber with polyurethane coating (ARPoly), (d) aramid fiber of length 12 mm (AR12) was evaluated on abrasion resistance and toughness of the mixtures. The functional performance was estimated using permeability tests and the mechanical performance was evaluated using the Cantabro test and indirect tensile strength tests. The parameters such as fracture energy, post cracking energy, and toughness were obtained through stress-strain plots. Based on the analysis of results, it was concluded that the addition of ARLat fibers enhanced the abrasion resistance of the mixtures. In terms of ITS, ARPoly and RegAR have positively influenced mixtures under dry conditions. However, the mixtures with all aramid fibers were found to have adverse effects on the ITS under wet conditions and energy parameters of porous asphalt mixtures with the traditional percentages of bitumen in the mixture used in Spain (i.e., approximately 4.5%).This work and the APC are funded by SAFERUP! Project, from the European Union’s Horizon 2020 research and innovation program under, the Marie Skłodowska-Curie grant agreement No. 765057

Assessment of carbon black modified binder in a sustainable asphalt concrete mixture

Carbon black has been used as a modifier in conventional binders together with a relatively low percentage of SBS polymer. In addition, an Evotherm additive has been combined by the wet way with the aim of decreasing the manufacturing temperature of the asphalt mixtures. The impact of these two has been analysed with a DSR rheometer, showing an increase in stiffness. An Asphalt Concrete mixture was then designed using the experimental binder and the warm mix additive and compared with a reference mix, using a commercial polymer modified bitumen. The final experimental mixture was manufactured 15?°C cooler than usual, showing good mechanical performance despite the low percentage of natural aggregate, which was mostly composed of reclaimed asphalt and slag. Its stiffness and fatigue resistance were also investigated. Finally, the mixture was laid in an experimental road section under real conditions as proof of concept of the technology.The authors would like to acknowledge that the research leading to these results has received funding from the European Union’s Seventh Programme for Research, Technological Development and Demonstration under Grant Agreement nº 605404

Second Life for Plastic Fibre Waste Difficult to Recover: Partial Replacement of the Binder in Asphalt Concrete Mixtures by Dry Incorporation

ABSTRACT: In previous studies, different additives and modifiers have been studied to improve the properties of asphalt concrete mixtures, whose main failures are plastic deformation and cracking. In this research, the improvement of the properties of asphalt concrete mixtures were investigated by introducing residual plastics as a substitute for virgin bitumen, which improves the sustainability of the mixtures. Furthermore, the results obtained from these new mixtures were compared with a mixture designed with polymer-modified bitumen (PMB). Ten experimental designs were tested with three types of waste fibre plastics from a municipal solid waste treatment plant and two percentages of bitumen replacement (15% and 25%). The experimental testing plan included air void characterization, moisture sensitivity, stiffness and fatigue resistance, among others. An increase of approximately 5% in voids could be observed when introducing the plastic material and therefore some tests were carried out to over-compact the specimens. The results showed an improvement in the mechanical performance of the experimental mixtures, highlighting the resistance against plastic deformations, which even reached similar values to the mixtures made with PMB.This publication is part of the I+D+I project PID2019-110797RB-I00, funded by MCIN/AEI/ 10.13039/501100011033. PRE2020-093516 assistance financed by MCIN/ AEI/10.13039/501100011033 and FSE “FSE invests in your future”

Recyclability potential of asphalt mixes containing reclaimed asphalt pavement and industrial by-products

The aim of this study was the evaluation and validation of the recyclability potential of asphalt mixturesthat incorporate high proportions of by-products (electric arc furnace slag and foundry sand) andreclaimed asphalt pavement in their composition. In a first stage, the performance of these asphalt mixeswas assessed using mechanical tests such as Marshall, water sensitivity, wheel tracking, stiffness andresistance to fatigue. Then, the samples underwent thermal aging treatment in order to be used asRAP in the manufacturing of new samples. Two rejuvenators were studied to check their effectivenessfor the purpose of achieving this aim. Finally, the mechanical performance of these new mixes was eval-uated. The results demonstrated a suitable technical performance and a good recyclability of the asphaltmixes used to replace practically all conventional aggregates. However, appropriate design and evalua-tion of the mixes is required, assessing the binder properties and the mechanical performance of theasphalt mix as well as evaluating its fatigue performance.This work was supported by the European Union’s Seventh Framework Programme for research, technological development and demonstration [grant numbers 1109806.0006]; and the FPU Programme of the Spanish Ministry of Education, Culture and Sport, Madrid [grant number FPU-14/06997]

Asphalt mixtures with high rates of recycled aggregates and modified bitumen with rubber at reduced temperature

An asphalt concrete and a very thin asphalt concrete have been designed with more than 80% of alternative aggregates (primary slag of electric arc furnace and RAP). A modified bitumen with rubber from end-of-life tires, and a fatty acid amide wax to decrease the manufacturing temperature were used. The process of manufacturing has been carried out at the easiest way. Both mixtures were manufactured at conventional temperature without wax (170°C), and at reduced temperature when the wax was incorporated (150°C). Their mechanical and dynamic performance was compared. The resistance against plastic deformation and the effort that has to be made for the compaction of the mixtures modified with the wax at reduced temperature did not change, but the indirect tensile strength ratio decreased. The stiffness in the mixtures with wax was slightly higher, and there were not significant differences in the resistance to fatigue, although it seemed to decrease when the wax was added

Laboratory assessment of porous asphalt mixtures reinforced with synthetic fibers

Porous asphalt (PA) mixtures have become a new alternative in the development of new road pavement surface layers given their multiple advantages such as surface runoff improvement, the decrease of the urban heat island effect, the reduction of road traffic noise and the minimization of the spray and aquaplaning effect leading to a safer driving. However, the durability of these mixtures is not as good as for dense graded mixtures. This research studies the effectiveness of adding a blend of polyolefin/aramid fibers and homopolymer polyacrylonitrile fibers in PA mixtures in terms of functionality and mechanical performance. Furthermore, changes in the filler content are assessed. The experimental testing plan includes air voids characterization, permeability, moisture sensitivity and particle loss in dry and wet conditions. Improvements in the mechanical performance can be observed in dry conditions. Finally, the fracture energy, postcracking energy and toughness are also analyzed. The results show that the addition of fibers brings ductility to the PA mixture improving toughness while maintaining functionality since the air void content remains over 20%

Mechanical performance of fibers in hot mix asphalt: a review

The use of fibers in hot mix asphalt (HMA) has become a much more attractive alternative for the con-struction of road pavements. Numerous studies have shown that the incorporation of fibers in the mix-ture improves fatigue resistance, permanent deformation and stiffness. The aim of this paper is to presenta review of the mechanical impact of fibers in HMA by analyzing their reinforcement effect in a qualita-tive and quantitative manner. Fiber properties and characterization tests on fiber-modified bitumen arediscussed. Quantities, blending procedures and performance of bituminous mixtures with different typesof fibers are presented. Results of mechanical improvement are displayed. Based on the current researchresults, depending on the properties and the type of mixture in which they are used, each type of fiberseems to improve certain parameters more than others. Coconut fibers and waste fibers are describedas environmentally friendly alternatives

Recyclability Potential of Induction-Healable Porous Asphalt Mixtures

ABSTRACT: The potential recyclability of healable asphalt mixtures has been analyzed in this paper. A healable porous asphalt mixture with steel wool fibers was artificially aged in order to assess its recyclability. This mixture was used as reclaimed asphalt in a new porous asphalt mixture, whose mechanical and healing capacities were studied and compared with the behavior of the original porous asphalt mixture. The quantity of reclaimed asphalt mixture added was 40%; besides, in order to recover the properties of the aged binder, and incorporate the last advances in the recyclability of bituminous mixtures, a rejuvenator was also added (SYLVAROADtm RP1000). The voids test, Cantabro particle loss test, water sensitivity test, stiffness test, and fatigue resistance test were performed to mechanically study the experimental mixture, while the last one (fatigue resistance test) was also used to assess its healing capacity. The results have shown that the healing capacity of the original healable porous asphalt mixture is maintained with similar mechanical performance