Soft Matrix Research Articles

Bioinspired Ultra‐Stretchable and Highly Sensitive Structural Color Electronic Skins

AbstractOrganisms possess remarkably adaptive ability to complex environments. For example, chameleons can alter their skin color to adapt to varying environments, which has inspired significant advances in bioinspired soft electronic skins (E‐skins), and their wide applications in wearable sensors, intelligent robots, and health monitoring. However, current bioinspired E‐skins face challenges in ultra‐stretchability, high sensitivity, and long‐term stability owing to the intrinsic limitations associated with their mismatched interface between soft matrix and hard conductive fillers, hindering their practical applications. Here, it is reported that bioinspired structural color electronic skins (SC E‐skins) that consist of liquid metal particles (LMPs), periodical ordered colloidal crystal arrays, and ultra‐stretchable hydrogel, imparting synergistic and durable electrical–optical sensing capabilities. Such SC E‐skins demonstrate outstanding performances including superior flexibility (elongation at break > 1100%), high sensitivity (gauge factor = 3.26), fast synergetic electric–optical response time (≈100 ms), outstanding durability (over 1500 cycles), and high accuracy (R2 > 99.5%). These bioinspired SC E‐skins with excellent capability of converting mechanical signals into synergetic electrical–optical outputs hold great promise for smart wearable devices, affording a new horizon in developing advanced health monitoring technologies.

Futher Operations on Neutrosophic Hypersoft Matrices and Application in Decision Making

The main objective of this paper is to extend the concept of Neutrosophic Hypersoft Matrix theory. Neutrosophic soft matrix parametrically evaluates the attributes chosen whereas Neutrosophic hypersoft matrix can parametrically evaluate the sub-attributes of the attributes chosen. Some notions and operations related to Neutrosophic Hypersoft matrices (NHSMs) such as Row-NHSM, Column-NHSM, Diagonal-NHSM, Proper-NHS submatrix, Disjoint NHSM, Extended union (NHSM), Extended intersection (NHSM), addition, subtraction, AND-product and OR-product on NHSM have been introduced with examples. Further a new NHSM-algorithm has been developed based on value matrix, grace matrix and mean matrix to solve Neutrosophic Hypersoft Set based decision-making problems.

Stromal softness confines pancreatic cancer growth through lysosomal-cathepsin mediated YAP1 degradation

The progression and malignancy of many tumors are associated with increased tissue stiffness. Conversely, the oncogenically transformed cells can be confined in soft stroma. Yet, the underlying mechanisms by which soft matrix confines tumorigenesis and metastasis remain elusive. Here, we show that pancreatic cancer cells are suppressed in the soft extracellular matrix, which is associated with YAP1 degradation through autophagic-lysosomal pathway rather than Hippo signal mediated proteasome pathway. In the soft stroma, PTEN is upregulated and activated, which consequently promotes lysosomal biogenesis, leading to the activation of cysteine-cathepsins for YAP1 degradation. In vitro, purified cathepsin L can directly digest YAP1 under acidic conditions. Lysosomal stress, either caused by chloroquine or overexpression of cystatin A/B, results in YAP1 accumulation and malignant transformation. Likewise, liver fibrosis induced stiffness can promote malignant potential in mice. Clinical data show that down-regulation of lysosomal biogenesis is associated with pancreatic fibrosis and stiffness, YAP1 accumulation, and poor prognosis in PDAC patients. Together, our findings suggest that soft stroma triggers lysosomal flux-mediated YAP1 degradation and induces cancer cell dormancy.Graphical

Acute contact with profibrotic macrophages mechanically activates fibroblasts via αvβ3 integrin-mediated engagement of Piezo1.

Fibrosis-excessive scarring after injury-causes >40% of disease-related deaths worldwide. In this misguided repair process, activated fibroblasts drive the destruction of organ architecture by accumulating and contracting extracellular matrix. The resulting stiff scar tissue, in turn, enhances fibroblast contraction-bearing the question of how this positive feedback loop begins. We show that direct contact with profibrotic but not proinflammatory macrophages triggers acute fibroblast contractions. The contractile response depends on αvβ3 integrin expression on macrophages and Piezo1 expression on fibroblasts. The touch of macrophages elevates fibroblast cytosolic calcium within seconds, followed by translocation of the transcription cofactors nuclear factor of activated T cells 1 and Yes-associated protein, which drive fibroblast activation within hours. Intriguingly, macrophages induce mechanical stress in fibroblasts on soft matrix that alone suppresses their spontaneous activation. We propose that acute contact with suitable macrophages mechanically kick-starts fibroblast activation in an otherwise nonpermissive soft environment. The molecular components mediating macrophage-fibroblast mechanotransduction are potential targets for antifibrosis strategies.

Highly Stretchable Sensitive Multiscale Hydrogel Inspired by Biological Muscles for Wearing Sensors.

Hydrogels have attracted substantial research interest for application in wearable electronics due to their stretchability, elasticity, and compliance. However, most hydrogels could not satisfy the application requirements for high-performance wearable sensors due to their poor sensitivity, low mechanical properties, and sensing detection range until this day. Inspired by the fascia in biological muscles, we propose a strategy to form entangled "clusters" through the dense entanglement between highly cross-linked elastic hydrogel microspheres and polymer segments, and prepared a multiscale hydrogel with high sensitivity and mechanical toughness. This strategy embedded highly swollen hydrogel microspheres (with different pore sizes) to act as the microregions of dense entanglement in the soft matrix to adjust the microstructure of multiscale gel. When pressure was applied, this structure could provide a fast response due to the stack layer formed by microspheres and soft matrix produced effective stress distribution, resulting in the outstanding sensitivity of the multiscale hydrogel (S = 1.1 kPa-1) in the pressure range of 0-50 kPa. The distinct microspheres functioning as microscale joint areas significantly augment energy dissipation, culminating in exceptional mechanical stability, ultrastretchability (≈1050%), and high strength of the multiscale hydrogel. The most notable progress was that the synthesized multiscale hydrogel not only combined the above advantages but also simultaneously solved multiple dilemmas of tedious synthesis steps, high cost, and poor durability. Besides, the multiscale hydrogel also had excellent antibacterial properties and biocompatibility, which enabled them to have large-scale application potential in wearable and implantable electronic devices. Our research could provide a universal approach to the creation of robust, flexible, wearable, and sensitive sensors, significantly increasing the uses of stress sensors in wearable technology.

Heterogeneous phase deformation in a dual-phase tungsten alloy mediated by the tungsten/matrix interface: insights from compression experiments and crystal plasticity modeling

Tungsten heavy alloy (WHA) is a typical multiphase alloy material consisting of hard tungsten (W) and soft matrix (γ) phases. When loaded, the two phases deform quite differently due to the large difference in their mechanical properties. At present, our understanding of phase deformation and behavior in the multiphase context is relatively poor compared to the single phase case. Such insight is necessary, however, for the design of multiphase alloys having optimal phase microstructure and corresponding material behavior. By combining mechanical testing and crystal plasticity modeling, the relationship between phase microstructure and multiphase alloy deformation behavior is systematically investigated in this work. The results demonstrate that deformation in the W and γ phases is quite different and related to the contrast in material properties between the two phases. Deformation heterogeneity in the multiphase alloy is characterized by the strain gradient near/across the W/γ interface and differences in phase deformation states in relation to the contrast in phase material properties and phase volume fraction. It is found that dislocation pile-up and twinning are the main mechanisms mediating heterogeneous deformation in the region around W/γ interfaces. Based on this insight, a novel design strategy for multiphase alloys is proposed based on optimization of the contrast in phase mechanical properties and the phase volume fractions. This strategy can be employed to design new tungsten alloys and other multi-phase alloys.

Matrix Stiffness of GelMA Hydrogels Regulates Lymphatic Endothelial Cells toward Enhanced Lymphangiogenesis.

Lymphatic vessel regeneration is crucial for various tissue engineering strategies, particularly in resolving inflammation and restoring tissue homeostasis. In our study, we focused on investigating how hydrogel matrix stiffness influences lymphatic endothelial cells (LECs) in promoting lymphatic vessel regeneration. Gelatin methacrylate (GelMA) was chosen as our biomaterial due to its versatility in tissue engineering and biofabrication. We fabricated GelMA hydrogels at concentrations of 5, 7.5, and 15% (w/v) with corresponding Young's modulus values of 1.55 kPa (soft matrix), 12.02 kPa (medium matrix), and 48.50 kPa (stiff matrix). Among these, the 7.5% GelMA hydrogel exhibited optimal stiffness for promoting lymphangiogenesis. LECs seeded either on the hydrogel surface or within spontaneously formed a more stable lymphatic capillary network compared with other GelMA formulations. Furthermore, we investigated the enhancement of lymphangiogenesis by incorporating VEGF-C into the GelMA hydrogel, leveraging the synergistic effects of mechanical and chemical cues. Our results underscored the critical role of FAK-phosphorylation in this process; treatment with an FAK-specific inhibitor prevented the formation of tube-like structures by LECs and attenuated the expression of lymphatic markers. Overall, our findings highlight how the mechanical and chemical cues provided by GelMA hydrogels can effectively regulate LEC behavior toward enhanced lymphangiogenesis via the integrin/FAK mechanotransduction pathway. This study proposes a promising strategy for developing hydrogel-based scaffolds or bioinks tailored to promote lymphatic vessel regeneration in therapeutic applications.

Innovative Soft Cryptosystem for Encrypting and Decrypting Messages with IDEA

This paper introduces an advanced cryptosystem for message encryption and decryption, integrating the International Data Encryption Algorithm (IDEA) with soft set and soft matrix principles. Soft sets, conceptualized by Molodtsov, are adept at managing uncertainty, making them ideal for cryptographic frameworks. Our approach utilizes inverse and characteristic products of soft sets and matrices, combined with the robust IDEA algorithm, to significantly enhance security. The IDEA algorithm operates on 64 -bit data blocks with a 128 -bit key, ensuring strong encryption. Additionally, we incorporate the symmetric to introduce complex permutations, further strengthening the cryptographic process by ensuring unique encryptions for identical plaintexts. This layered approach drastically improves resilience against unauthorized decryption. Practical applications demonstrate the system's efficacy, highlighting its superior security and reliability for data transmission in environments with high uncertainty. This innovative cryptosystem provides a formidable solution for contemporary encryption challenges.

Unusual deformation mechanisms evoked by hetero-zone interaction in a heterostructured FCC high-entropy alloy

Understanding the synergistic mechanical effects of heterostructured materials remains challenging due to the complexities in the underlying deformation mechanisms, which are usually diverse, activated at different length scales and possibly interacting. Here, we unravel a deformation fundamental for heterostructures: in addition to the direct contribution on strength, hetero-zone interaction and the development of long-range internal stress could assist in evoking extra plastic mechanisms that are difficult to activate in their homogeneous counterparts. Specifically, the deformation of a heterostructure in Al0.1CoCrFeNi alloy, featuring nanostructured hard lamellae embedded in fine-grained soft matrix, is taken as an example for study. Drawing from experimental insights, the long-range internal stress buildup at elastoplastic transition stage due to intense dislocation pile-ups against hetero-zone boundary, which increases yield strength significantly, is theoretically analyzed. At the plastic stage, the high internal stress helps to activate phase transformation in the fine-grained zones, and the inter-zone constraint leads to form dispersed stable strain bands in the nanostructured zones. These extra mechanisms, together with enhanced deformation twinning, facilitate work hardening and coordinate the strain partitioning between zones, imparting improved ductility at high flow stress. These findings indicate a principle for heterostructural design: introducing strong hetero-zone interaction to enhance internal stress and thereby invoke new deformation mechanisms.

Maximization of strength–ductility balance of dual-phase steels using generative adversarial networks and Bayesian optimization

Dual-phase (DP) steels with a soft ferrite matrix and hard martensite islands exhibit an excellent combination of strength and ductility. However, further improvement of the strength–ductility balance is desirable for automotive applications, and the optimization of the DP microstructure is crucial for enhancing mechanical properties. This study aimed to maximize the strength–ductility balance of DP steel using an integrated computational framework comprised by generative adversarial networks (GAN), finite element method (FEM), and Bayesian optimization. GAN was trained on the microstructures of real DP steels to generate synthetic microstructure images randomly mapped from latent variable vectors, and the tensile properties of the generated microstructures were evaluated using FEM. Bayesian optimization was then employed to identify latent variables yielding microstructures with the highest tensile strength (TS), uniform elongation (uEL), or strength–ductility balance (TS × uEL). The optimized microstructures of DP steels were then quantitatively analyzed to elucidate the relationship between the microstructural morphology and tensile properties. The optimal synthetic DP microstructure exhibited a TS × uEL value higher by 4027 MPa% than the highest value shown by real DP steels. Thus, the proposed integrated optimization framework enables efficient computational design of various material microstructures for maximizing desired mechanical properties.

Comparison of Bioengineered Scaffolds for the Induction of Osteochondrogenic Differentiation of Human Adipose-Derived Stem Cells.

Osteochondral lesions may be due to trauma or congenital conditions. In both cases, therapy is limited because of the difficulty of tissue repair. Tissue engineering is a promising approach that relies on designed scaffolds with variable mechanical attributes to favor cell attachment and differentiation. Human adipose-derived stem cells (hASCs) are a very promising cell source in regenerative medicine with osteochondrogenic potential. Based on the assumption that stiffness influences cell commitment, we investigated three different scaffolds: a semisynthetic animal-derived GelMA hydrogel, a combined scaffold made of rigid PEGDA coated with a thin GelMA layer and a decellularized plant-based scaffold. We investigated the role of different biomechanical stimulations in the scaffold-induced osteochondral differentiation of hASCs. We demonstrated that all scaffolds support cell viability and spontaneous osteochondral differentiation without any exogenous factors. In particular, we observed mainly osteogenic commitment in higher stiffness microenvironments, as in the plant-based one, whereas in a dense and softer matrix, such as in GelMA hydrogel or GelMA-coated-PEGDA scaffold, chondrogenesis prevailed. We can induce a specific cell commitment by combining hASCs and scaffolds with particular mechanical attributes. However, in vivo studies are needed to fully elucidate the regenerative process and to eventually suggest it as a potential approach for regenerative medicine.

Influence of Ni content on electrochemical corrosion and tribological behavior of Cu-10Sn coatings by laser cladding

In this work, Cu-10Sn-xNi (x = 0, 3, 6, 9, and 12 wt%) alloy coatings were prepared using laser cladding technology. The influence of Ni content on the phase composition, microstructure, crystallographic characteristics, microhardness, electrochemical corrosion, dry sliding wear and corrosive wear behavior of the coatings were studied. The results indicated that the coatings formed good metallurgical bond with the substrate. The coatings were composed primarily of the α-Cu matrix and small γ precipitates. The Ni element effectively reduced component segregation, and with the increased of Ni content, the grain size in the coating was significantly refined, resulting in fine equiaxed grains. Under the effect of fine grain strengthening, the Cu-10Sn-12Ni (C12NS) coating achieved a higher microhardness of approximately 222.9 ± 5.3 HV0.2. In the electrochemical corrosion test, the increased in the number of grain boundaries significantly reduced the corrosion resistance of the Cu-10Sn-xNi coatings. The Cu-10Sn-6Ni (C6NS) coating exhibited excellent corrosion resistance, with an Icorr of only 1.37 μA/cm2. The results of the dry sliding wear test showed that under the influence of the hardness gradient between the hard precipitate phase and the soft matrix of the coating, the C6NS coating achieved satisfactory wear resistance with a specific wear rate of 3.30 × 104 μm3/Nm. Meanwhile, due to the good corrosive resistance, the C6NS coating showed the best tribological performance in 3.5 wt% NaCl environment, and the specific wear rate was 1.58 × 104 μm3/Nm.

Preparation and performance study of silicon modified polyurethane-based magnetorheological elastomeric polishing pad

Abstract By employing Magnetorheological Elastomers (MREs) as polishing pads for chemical mechanical polishing (CMP), the magnetorheological properties are utilized to effectively control the flexible removal of materials in CMP. This study presents a method for preparing a Silicon modified Polyurethane (SPU)-based MRE polishing pad, aimed at demonstrating improved magnetorheological properties while preserving mechanical properties. The SPU-based MRE polishing pad was synthesized through the copolymerization of hydroxypropyl silicone oil and polyurethane prepolymers, with subsequent evaluation of its mechanical properties and polishing performance. Fourier Transform Infrared (FTIR) analysis confirmed the successful incorporation of the soft polydimethylsiloxane main chain from organosilicon into the polyurethane main chain, forming a soft segment that intertwines with the polyurethane main chain to create a soft-hard segment crosslinked structure. Comparison to Polyurethane (PU)-based MRE, SPU exhibits significantly reduced hardness but improved wear resistance, as well as enhanced resistance to acid and alkali corrosion. Due to the presence of a soft matrix, SPU shows better magnetorheological effects than PU-based MRE. Under a magnetic field intensity of 845 mT, the magnetorheological effect of PU-based MRE is only 18%, while Si-15.96 and Si-16.79 SPU-based MREs can reach 84% and 110%, respectively. Although the Material Removal Rate (MRR) of single-crystal SiC decreases after polishing with SPU compared to PU-based MRE, a higher surface quality is achieved, and the glazing degree of the polishing pad is significantly reduced. In the magnetic field-assisted polishing of single crystal SiC, the MRR increased by 38.4% when polished with an SPU-based MRE polishing pad, whereas the MRR was only 8.7% when polished with a PU-based MRE polishing pad. This study provides further evidence for the development and application of MRE in CMP.

Molecular and spatial signatures of human and rat corpus cavernosum physiopathological processes at single-cell resolution

The composition and cellular heterogeneity of the corpus cavernosum (CC) microenvironment have been characterized, but the spatial heterogeneity at the molecular level remains unexplored. In this study, we integrate single-cell RNA sequencing (scRNA-seq) and spatial transcriptome sequencing to comprehensively chart the spatial cellular landscape of the human and rat CC under normal and disease conditions. We observe differences in the proportions of cell subtypes and marker genes between humans and rats. Based on the analysis of the fibroblast (FB) niche, we also find that the enrichment scores of mechanical force signaling vary across different regions and correlate with the spatial distribution of FB subtypes. Invitro, the soft and hard extracellular matrix (ECM) induces the differentiation of FBs into apolipoprotein (APO)+ FBs and cartilage oligomeric matrix protein (COMP)+ FBs, respectively. In summary, our study provides a cross-species and physiopathological transcriptomic atlas of the CC, contributing to a further understanding of the molecular anatomy and regulation of penile erection.

Low-Hysteresis and Tough Ionogels via Low-Energy-Dissipating Cross-Linking.

Low-hysteresis merits can help polymeric gel materials survive from consecutive loading cycles and promote life span in many burgeoning areas. However, it is a big challenge to design low-hysteresis and tough polymeric gel materials, especially for ionogels. This can be attributed to the fact that higher viscosities of ionic liquids (ILs) would increase chain friction of polymeric gels and eventually dissipate large amounts of energy under deformation. Herein, a chemical design of ionogels is proposed to achieve low-hysteresis characteristics in both mechanical and electric aspects via hierarchical aggregates formed by supramolecular self-assembly of quadruple H-bonds in a soft IL-rich polymeric matrix. These self-assembled nanoaggregates not only can greatly reinforce the polymeric matrix and enhance resilience, but also exhibit low-energy-dissipating features under stress conditions, simultaneously benefiting for low-hysteresis properties. These aggregates can also promote toughness and subsequent anti-fatigue properties in response to external cyclic mechanical stimuli. More importantly, these ionogels are presented as a model system to elucidate the underlying mechanism of the low hysteresis and fatigue resistance. Based on these findings, it is further demonstrated that the supramolecular low-hysteresis strategy is universal.

Elastomer-based soft syntactic foam with broadly tunable mechanical properties and shapability

Fabrication of lightweight composites using thermally responsive expandable microspheres (EM) embedded in an elastomeric matrix to form syntactic foams offers significant opportunities to create functional and structural composites for diverse applications. The morphology of the EM-elastomer composite on the micro- and macro-scales is significantly influenced by the fabrication sequence and parameters (composition, expansion time/temperature, etc.). Herein, we report the morphological evolution of an EM-elastomer composite through the fabrication processes and elucidate the interaction of relevant fabrication parameters. Unlike the majority of published reports on hard EM composites, the in-situ expansion of the closed-cell foam structure within a soft matrix leads to larger void sizes, and the concomitant expansive force of the EM impacts the polymer chain mobility within the soft composite. At the same time, higher EM loading improves the mechanical properties; the evolved microstructure leads to a lightweight but stiff structure. For the first time the report details the thermal expansion of EM under applied pretension, leading to irreversible prestrain-dependent morphological changes toward anisotropic mechanical properties. Additionally, the composites are shaped under constrained expansion. The study provides a comprehensive guide and expands the pathways for the practical application of EM-embedded soft syntactic foams in aerospace, electronics, wearables, robotics, etc.

Scalable Synthesis and Electrochemical Study of Ceramic-Polymer Nanocomposite Solid Electrolytes for Solid-State Battery Manufacturing

Solid-state lithium batteries (SSBs) have the potential to achieve high energy and power densities due to the use of solid electrolytes (SEs) that are compatible with lithium metal or silicon-based anodes. However, fabrication of SEs with good ionic conductivity, mechanical strength, electrochemical stability, and interfacial contact with solid electrodes have been challenging. One promising approach is to combine ceramic lithium conductors that is expected to show a relatively high room-temperature Li-ion conductivity and a soft polymer matrix that facilitates mechanical integrity at the electrode-electrolyte interface during charge-discharge cycling. In this study, we report a scalable synthesis of Al0.25Li6.25La3Zr2O12 (LLZO) nanofibers and polyethylene oxide (PEO) composite SEs using roll-to-roll manufacturing. Our LLZO fibers showed 0.3 mS/cm conductivity at room temperature and the LLZO-PEO composites showed three times higher critical current density than a single PEO polymer electrolyte. Microstructural and electrochemical properties of the composite electrolytes will be discussed.

Matrix stiffness regulates the triad communication of adipocytes/macrophages/endothelial cells through CXCL13

Adipose tissue remodeling and plasticity are dynamically regulated by the coordinated functions of adipocytes, macrophages, and endothelial cells and extracellular matrix (ECM) that provides stiffness networks in adipose tissue component cells. Inflammation and fibrosis are crucial exogenous factors that dysregulate adipose tissue functions and drastically change the mechanical properties of the ECM. Therefore, communication among the ECM and adipose tissue component cells is necessary to understand the multifaceted functions of adipose tissues. To obtain in vivo stiffness, we used genipin as a crosslinker for collagen gels. Meanwhile, we isolated primary adipocytes, macrophages, and endothelial cells from C57BL/6J mice and incubated these cells in the differentiation media on temperature-responsive culture dishes. After the differentiation, these cell sheets were transferred onto genipin-crosslinked collagen gels with varying matrix stiffness. We found that inflammatory gene expressions were induced by hard matrix, whereas antiinflammatory gene expressions were promoted by soft matrix in all three types of cells. Interestingly, the coculture experiments of adipocytes, macrophages, and endothelial cells showed that the effects of soft or hard matrix stiffness stimulation on adipocytes were transmitted to the distant adipose tissue component cells, altering their gene expression profiles under normal matrix conditions. Finally, we identified that a hard matrix induces the secretion of CXCL13 from adipocytes, and CXCL13 is one of the important transmitters for stiffness communication with macrophages and endothelial cells. These findings provide insight into the mechanotransmission into distant cells and the application of stiffness control for chronic inflammation in adipose tissues with metabolic dysregulation.

Heat treatments effects on Wear performance of Laser based Powder Bed Fusion fabricated Inconel 718 alloy

Among the AM processes Laser based Powder Bed Fusion (LPBF) technique offers precise and complex geometric fabrication. However, the microstructural and mechanical properties obtained from LPBF process requires further investigation, especially for IN718 superalloys. In this study, various heat treatments were applied to LPBFed Inconel 718 specimens to examine their effects on microstructure, microhardness and wear behavior. Three different heat treatments, each involving varied solutionizing and ageing steps were incorporated. As-printed specimens exhibited distinct fish scale structures with columnar dendrites. Heat treatments effectively dissolved the Laves phase and precipitated strengthening phases like γ′′ and γ′. Microhardness increased significantly after heat treatments, correlating with the formation of strengthening precipitates. Friction and wear tests showed as-printed specimens exhibited higher wear loss (922 ± 13 μm) and coefficient of friction (COF) (0.511 ± 0.07) due to the presence of Laves phase and softer matrix. Heat-treated specimens demonstrated significantly reduced wear loss (262 ± 5 μm) and COF (0.368 ± 0.01), with HT2 showing the best wear resistance attributed to a homogeneous microstructure. SEM analysis of worn surfaces confirmed abrasive and adhesive wear mechanisms in as-printed specimens, while heat-treated specimens exhibited reduced wear with smoother surfaces.

Visco-plastic deformation characteristics of accelerated-aging asphalt mixture containing reclaimed asphalt pavement regenerated with crumb rubber based on Hamburg Wheel-Track test

The regeneration of the reclaimed asphalt pavement (RAP) with incorporation of crumb rubber was a cleaner alternative for reducing the fossil and ore resources consumption. For the desert area like Egypt, the rut of reclaimed pavement was principal contradiction during a long service. This work mainly characterized the visco-plastic deformation of accelerated-aging rubberized reclaimed asphalt mixture based on Hamburg Wheel-Track test. Four mixtures were designed by two contents of RAP (15% and 30%), two contents of crumb rubber (5% and 15%), and two asphalts (pen-#70 and pen-#90). Specifically, this work focused on the determination of accelerated aging effect, and analysis of rutting deformation fitting including overall deformation and visco-plastic deformation. Then, effect of accelerated aging time and material compositions on visco-plastic deformation was analyzed. In addition, the correlation analysis among indicators evaluating rutting deformation of mixture was conducted, and the correlation analysis between rutting deformation of mixture and average recovery rate at 3.2 kPa of extracted bitumen was completed. The results demonstrated that the accelerated aging equivalent factor of sunlight was approximately 6, meaning that one day of accelerated aging was equivalent to six days of natural aging in Cairo. With the accelerated aging time increased, resistance to rutting deformation of rubberized reclaimed asphalt mixture was promoted with the incorporation of RAP, crumb rubber and soft matrix binder. Meanwhile, dynamic stability, derived from fitting curve of visco-plastic deformation, was positively correlated with accelerated aging time, and it could accurately evaluate visco-plastic deformation characteristics of reclaimed mixture. Finally, visco-plastic deformation characteristics of reclaimed mixture was closely related to the permanent deformation resistance of binder at high temperature.