Abstract This paper explores the utilization of carbon-based nanomaterials to enhance cementitious matrices for multifunctional applications. Insights into the significance of improving cementitious matrices and the role of nanomaterials in this context are followed by a comprehensive overview of carbon-based nanomaterials. Specific types of nanomaterials, including carbon nanotubes (CNTs), graphene, graphene oxide (GO), and carbon nanofibers (CNFs), are analyzed, detailing their synthesis, dispersion techniques, and impacts on mechanical, electrical, and thermal properties. Furthermore, this paper examines the integration of carbon-based nanocomposites for self-healing capabilities in cementitious matrices, as well as their diverse applications in structural, functional, and environmental domains. Challenges such as dispersion issues and long-term durability concerns are highlighted alongside future research directions. Key findings are summarized, emphasizing the promising prospects of carbon-based nanomaterials in advancing cementitious systems.
Abstract Structural health monitoring of reinforced concrete elements increasingly requires nondestructive techniques capable of assessing the internal condition of embedded reinforcement. This study investigates the feasibility of using the passive magnetic response of reinforcing steel as an indicator of strain when subjected to uniaxial tensile loading. The experimental program evaluates three key aspects: (1) the correlation between surface magnetic field intensity and strain, (2) the attenuation of the magnetic signal as a function of concrete cover thickness, and (3) the evolution of the magnetic response during the transition from elastic to plastic behavior of the steel. Tensile tests were conducted on reinforced concrete specimens with cover thicknesses ranging from 20 to 75 mm, while measuring magnetic field and strain simultaneously. The results demonstrated a strong and consistent linear correlation between magnetic field and strain in the elastic range, a predictable attenuation trend governed by magnetostatic dispersion through concrete, and a clear magnetic signature associated with yield and plasticity. Despite signal reduction, the magnetic response remained detectable and informative up to the maximum cover thickness prescribed by structural design codes (75 mm). These findings confirm the potential of passive magnetic monitoring as a noninvasive and effective technique for assessing the mechanical condition of embedded reinforcement in concrete structures.
Abstract Accurately predicting the compressive strength of ultrahigh performance concrete (UHPC) is challenging due to the nonlinear and coupled effects of its compositional variables. This study proposes a hybrid modeling framework that combines deep neural networks (DNNs) with traditional machine learning regressors (XGBoost, Random Forest, and SVR) to achieve both high prediction accuracy and interpretability. A data set comprising 810 UHPC mix designs was used, including 13 input variables such as cement, fiber, water–binder ratio, and curing age. The DNN was trained to extract deep nonlinear features, which were then fed into ensemble regressors. Among all models, DNN-XGBoost achieved the best performance with R 2 = 0.9872 , RMSE = 7.74 MPa , and an a20-index of 95.82%. External validation on 1,031 samples confirmed strong generalization ( R 2 = 0.8956 ). Model interpretability was explored using SHAP and partial dependence plots, revealing critical variables and nonlinear thresholds. For instance, fiber content improved strength up to 50 kg / m 3 , beyond which strength declined due to agglomeration. Neuron activation analysis further showed that the DNN learned physically meaningful patterns aligned with hydration and packing mechanisms. This hybrid framework provides a robust, interpretable, and scalable approach for UHPC strength prediction. It supports data-driven mix design optimization while maintaining alignment with engineering principles.
Abstract The compression casting process improves pore structure and mechanical performance in cementitious systems. However, in alkali-activated materials (AAMs), the effects of activator loss during compression casting on reaction behavior remain poorly understood. This study investigates the mechanical performance of AAM via compression casting. Response surface methodology was used to analyze the effects of precompression rest time, casting pressure, alkali equivalent, and liquid-to-solid (L/S) ratio on compressive strength in compression casting AAM. A method was proposed to evaluate retained alkali equivalent during compression casting and its role. The experimental results demonstrate that compression casting reduces AAM porosity and optimizes pore size distribution by increasing gel and transition pores, enhancing strength through physical densification. Microstructural analyses revealed elements enrichment and increased Ca/Si, Al/Si, and Na/Si ratios in compression casting AAMs, accompanied by enhanced gel polymerization and reduced bound-water loss, collectively contributing to the improvement of compressive strength. At 5% alkali equivalent, compression casting effectiveness improves with increasing L/S ratio and precompression rest time. At 7% alkali equivalent, strength enhancement reaches saturation. Casting pressure effects depend on initial alkali content and precursor development, showing both positive and negative impacts during activation. Compression casting improves alkali utilization efficiency, and despite pressure reducing alkali equivalents, higher retained alkali levels produce superior enhancement effects.
Abstract With global wind power capacity exceeding 1.021 billion kW, decommissioned carbon/glass fiber blades create a major disposal challenge. This study aims to effectively dispose of and utilize discarded wind turbine blades by developing a technology for preparing geopolymers using blade glass fiber–reinforced polymer (GFRP) as a raw material, and to investigate mechanical activation methods for enhancing the reactivity of the GFRP. The effects of ball-milling speed, ball-milling time, and alkali activators on the particle size of the GFRP powder, pozzolanic activity, and properties of the reaction products are investigated. The results confirmed that the particle size of the GFRP powder decreases with an increase in the ball-milling speed and milling time, and the particle-size distribution becomes narrower in this case. The GFRP undergoes a geopolymerization reaction to form a hardened paste under the action of alkali activators. The smaller the particle size of the GFRP, the higher the compressive strength of the geopolymer. The compressive strength of the GFRP geopolymer initially increases and subsequently decreases when the modulus of the alkali activator increases from 1.0 to 1.8, and the water-to-binder ratio rises from 0.33 to 0.42. However, the strength of the GFRP geopolymer consistently increased with an increase in alkali content in the paste. The ball-milled GFRP-based geopolymer specimens with a size of 20 × 20 × 20 mm 3 exhibited a 28-day compressive strength of 42.1 MPa, which is three times that of their non-ball-milled counterparts. The potential application of the GFRP-based geopolymer could be the prefabricated components, such as drainage pipes and bricks. This significant enhancement in mechanical properties was achieved with a grinding energy consumption of approximately 1,125 kWh per ton of GFRP. Furthermore, the resulting geopolymer has a carbon footprint of about 1, 392.99 kg · CO 2 - e / m 3 , substantially lower than the 1,800 kg · CO 2 - e / m 3 associated with traditional cement.
Abstract Geotextiles are widely used in geotechnical engineering to reinforce soil and enhance the stability of various structures. This study investigates the effectiveness of different treatments in improving the sand–geotextile interface. A series of direct shear tests were conducted on the sand–woven geotextile interface to evaluate three treatment methods: (1) cement slurry (CS)-treated geotextile, (2) polyvinyl alcohol (PVA)-treated geotextile, and (3) polyurethane foam adhesive (PFA)-treated geotextile. Various parameters, including binder dosage, curing time, moisture content, and geotextile type, were considered to assess their impact on mobilized shear strength at the interface. The results demonstrate that these treatment methods significantly improved the interaction between sand and geotextiles, with the PFA treatment proving to be the most effective. PFA-treated geotextiles exhibited the highest mobilized shear strength in a short time, creating adhesion at the interface—an effect not observed in the PVA and CS treatments—while also enhancing the friction angle. For a given binder dosage and curing time, the PFA treatment resulted in significantly higher mobilized shear strength compared with the PVA and CS treatments, with CS yielding the lowest values. The mobilized shear strength of the PFA-treated interface was approximately 80% to 290% higher than that of the other treatments, depending on curing time and normal stress. Adhesion at the interface increased significantly by approximately 77% for the PFA treatment when the curing time was extended from 1 to 28 days, whereas curing time had a minimal effect on the friction angle. The influence of moisture content on mobilized shear strength was complex and highly dependent on the treatment method. Additionally, the effect of geotextile type in the PFA treatment was primarily significant at low PFA content. These findings highlight the potential of PFA treatment as a promising technique for enhancing geotextile performance in geotechnical applications.
Abstract Bio-based resins have demonstrated to be a technically viable solution to reduce crude-oil dependency in fiber-reinforced polymer (FRP) composites. However, their long-term performance, particularly their durability under harsh conditions, is still mostly unknown. The study presented in this paper investigates the performance of three types of FRP composites, with different fibers and thermoset bio-based resins, under thermal cycling. E-glass, basalt, and carbon fiber composites, produced by vacuum infusion with respectively two compositions of bio-based unsaturated polyester resin (developed in-house) and a bio-based epoxy resin, were considered in this study. In parallel, conventional, fully oil-based counterparts incorporating similar fibers and layups have also been considered as benchmark. The composites were exposed to 100, 200, and 300 thermal cycles, each cycle comprising a segment at –20°C (5 h), a segment at 50°C (5 h), and 2 h of heating and cooling in between temperature plateaus (total cycle duration of 12 h). Mechanical (tension, compression, in-plane shear, and interlaminar shear) and thermomechanical (dynamic mechanical analysis) testing of the composites was performed after each set of cycles. The results of those tests show that the performance of the bio-composites is comparable to their oil-based counterparts. Thermal cycling produced low to moderate effects in the polymer composites, with property reductions ranging between 5% and 30% in more extreme cases. The results were compared to those available in the literature regarding thermal cycling durability of conventional FRP composites, demonstrating a good agreement with data from previous studies.
Abstract In response to the high environmental load and dependence on natural aggregates in traditional 3D-printed cement-based mortars, this study develops an alkali-activated 3D-printing mortar using industrial solid wastes such as ground granulated blast-furnace slag (GGBS), fly ash (FA), and steel slag sand as raw materials, aiming to promote the sustainable utilization of green building materials. The study systematically tests the working performance (flowability, shape retention, extrudability, buildability), mechanical properties (cube compressive strength and anisotropy), and combines X-ray diffraction and scanning electron microscopy analyses to reveal the hydration products and microstructural characteristics. The results indicate that the FA content and activator modulus significantly affect the mortar flowability, with the best shape retention and buildability at a flowability range of 170–220 mm. The cube compressive strength of the steel slag sand mortar increases with the GGBS content, reaching a maximum strength of 67.94 MPa at 28 days. Microstructural analysis shows the formation of C─(A)─S─H gel and the reinforcing effect at the interface of steel slag sand. This study provides a theoretical basis for applying 3D-printing materials entirely composed of industrial solid wastes in engineering, thereby advancing the synergistic combination of green building materials and sustainable construction practices.
Abstract Geopolymer mortar (GM) is a sustainable alternative to cement with a low carbon footprint and excellent mechanical performance. However, its reliance on ground granulated blast-furnace slag (GGBFS) and natural sand, along with significant drying shrinkage, limits its sustainability and durability. In this study, peanut husk ash (PHA), an agricultural by-product, was utilized as a dual replacement material to partially replace GGBFS and natural sand in GM, thereby developing a novel green building mortar. A total of 17 mortar mixtures, prepared by employing PHA as a dual replacement material to partially replace GGBFS (0%–15% by weight) and natural sand (0%–30% by weight), respectively, were systematically investigated for properties including fresh state behavior, mechanical strength, drying shrinkage, and microstructure versus cement mortar (CM). The experimental results show that the volcanic ash effect and the microaggregate filling effect of PHA work synergistically to enhance the matrix performance. Compared with the reference group, when the total replacement rate was 20% by weight, the 28-day compressive strength of mortar increased by 21.7%, the 90-day drying shrinkage reduced by 31.2%, and the working performance met the construction requirements. Microstructural analysis reveals that highly active SiO 2 in PHA reacts with Ca ( OH ) 2 generated by GGBFS hydration to form gels, which improves the pore structure. This study offers new insights into using agricultural wastes efficiently in geopolymers, providing theoretical and engineering support for sustainable building materials.
Abstract Asphalt binder and mineral filler are key components that significantly affect the properties of mastic asphalt (MA) mixtures. Asphalt mastic, formed by mixing mineral filler and asphalt binder, offers an effective way to study their roles within the MA system. This study focuses on mineral filler and asphalt binder, using asphalt mastic as the entry point to thoroughly investigate their functions in MA concrete. Rheological experiments and the discrete element method (DEM) were combined to analyze and validate the interaction between mineral filler and asphalt binder. The Hirsch model was used to quantitatively assess their mechanical interaction in the MA system. Results indicate that increasing both Trinidad Lake asphalt (TLA) and mineral filler content raises the complex modulus and reduces the phase angle of asphalt mastic. The Hirsch model shows that TLA content mainly affects high-temperature properties, while filler content has a greater impact on low-temperature properties. Mineral fillers contribute more than half of the resistance to external loads, with their effect increasing as filler content rises. Simulations reveal that although the asphalt binder bears larger forces, the filler ultimately withstands more force under external loading. The binder primarily distributes the force to the filler, ensuring uniform stress. This comprehensive investigation clarifies the interaction mechanism between asphalt binder and mineral filler in MA concrete through experiments, modeling, and simulations.
Abstract Precuring stage is a pivotal period for the strength formation of ultrahigh performance concrete (UHPC), while the traditional one-day precuring duration decreases the turnover rate with low construction efficiency. This study synergistically utilized carbon nanofibers (CNFs) and ohmic heating (OH) precuring to enable rapid and low-carbon fabrication of CNF-reinforced UHPC (CNF-UHPC). Traditional room temperature (RT) curing was replaced by OH curing within 24 h, and enhanced electrical-thermal-mechanical properties were found in OH precured CNF-UHPC. Specifically, the terminal electrical resistivity was decreased from 2.51 to 1.01 k Ω · cm as CNFs increased from 0 to 0.9 vol%. Similarly, the peak temperature, heating rate, and temperature stability during OH precuring were increased to 135.6°C, 11.35 ° C / min , and 75%, respectively. Moreover, the highest one-day compressive strength of 82.4 MPa was observed in 2 h OH precured CNF0.9-UHPC, which was comparable to that of seven-day RT cured sample. The enhanced effects of CNFs and OH precuring were elucidated by microstructural tests. Hydration degree and pore structure analysis indicated that CNFs and OH precuring accelerated cement hydration, promoted the formation of hydration products, and refined the pore structure of CNF-UHPC. The conductive mechanism of CNF-UHPC during OH curing was clarified through electrochemical impedance spectroscopy analysis, 0.9 vol% CNFs plays a crucial role in stabilizing the conductive network. Further, OH precuring demonstrated superior energy efficiency and lower carbon emissions compared to the RT curing taking the strength as the indicator. This research brings innovative insights into the efficient fabrication of UHPC with modified precuring regime and advanced composites system.
Abstract The use of marginal granular materials (MGM), defined here as those that do not fully meet the quality specifications for road construction granular materials, represents an option for constructing low-volume traffic roads (LVTR). This study focuses on assessing the performance of MGM in terms of two indices, stiffness and permanent deformation, to validate their potential use in pavement structures for LVTR. The study included materials with plasticity indices (PI) of 8%, 12%, 16%, and 20% and a fines content (passing sieve No. 200) of 20%, exceeding the current specification for granular subbases of the Instituto Nacional de Vias (INVIAS) in Colombia. After fabricating the specimens by gyratory compaction, they were subjected to dynamic triaxial testing in accordance with American and European test procedures. The results suggest that: (1) the MGM assessed have adequate performance indices for possible use as granular subbase in pavements for LVTR, (2) there is no conclusive influence of the PI and dry unit weight on the performance of MGM, and (3) the European protocol led to higher resilient modulus values, up to 26%, than the American protocol. These results encourage the assessment of additional sources of MGM to promote further material characterization and application, which will benefit cost reduction and carbon footprint. However, future research should focus on assessing the effect of hydraulic conditions, including changes in performance related to successive drying-wetting paths.
Abstract To address the shortage of natural sand resources and environmental issues, the industry has shifted to using manufactured sand as a substitute. Flocculants are often used to treat sand washing wastewater in wet production processes, which can lead to excessive flocculant residues in mechanized sand, negatively affecting the performance of shotcrete. In this study, the influences of polyacrylamide (PAM) on the workability, mechanical properties, and microstructural development of shotcrete were investigated by simulating different residual PAM levels in manufactured sand. The addition of PAM resulted in a significant loss of mortar workability and a shortening of the net mortar setting time. PAM adsorbs Ca 2+ to occupy adsorption sites, thereby inhibiting the formation of [ Al ( OH ) 4 ] − generated in an alkaline environment from participating in AFt formation, thus slowing down the hydration of C 3 A . By weakening the adsorption of AFt, it promotes the hydration of C 3 S to form more C─S─H gel and CH structures. As the reaction progresses, the AFt structure formed by the hydration of C 3 A also exerts an adsorption effect on C 3 S , causing the hydration rate of C 3 S to slow down again. As a result, the maximum decrease in mortar strength after 6 h was 19.4%, and the maximum increase in mortar strength after 24 h was 8.7%. Through this study, we hope to provide guidance on the control of PAM residue in mechanized sand used in shotcrete and provide a theoretical basis for the preparation of high-quality mechanized sand shotcrete.
Abstract In seasonally frozen regions, asphalt pavements are prone to cracking and freeze–thaw damage, while high-temperature deformation is relatively minor. Developing an asphalt system suitable for such regions can maximize material performance and reduce costs. In this study, a composite modified asphalt was prepared using the plasticizer diisononyl adipate (DINA) and polyphosphoric acid (PPA) to enhance overall thermal performance. The study employed macroscopic tests, microstructural analysis, and molecular dynamics simulations to evaluate its performance and mechanisms. The results indicated that PPA effectively compensated for the high-temperature performance loss caused by the plasticizer. The formulation containing 3.5% DINA and 1% PPA (D3.5P1) exhibited high-temperature deformation resistance comparable to the base asphalt, and its fatigue life was 1,110 times greater, demonstrating strong applicability for heavy-load traffic. DINA significantly improved low-temperature flexibility, with the maximum bending strain of D3.5P1 increasing by 39%. The composite system also enhanced moisture resistance, with a TSR 4.5% higher than that of the base asphalt. Fourier transform infrared spectroscopy and fluorescence imaging confirmed that DINA modified asphalt through physical interaction, whereas PPA induced chemical reactions, locally altering the spatial distribution of DINA. Simulations revealed that plasticizer molecules acted as lubricants within the polar fractions, with PPA interacting with asphaltenes and redistributing plasticizer molecules toward nonpolar regions. This composite system provides enhanced low-temperature properties with adequate high-temperature stability, demonstrating strong potential for cold-region pavement applications.
Abstract This study investigated the influence of cellulose nanomaterials (CNMs) on the strength performance of supersulfated cement (SSC) with high phosphogypsum (PG) content. Cotton-based CNMs, particularly sulfated cellulose nanocrystals (S-CNCs) at a dosage of 0.05%, exhibited superior strength enhancement effects at 28 days compared with carboxylated cellulose nanocrystals (C-CNCs), despite a slight reduction in early-age strength. In contrast, wood pulp–based CNMs negatively affected strength performance across all ages. C-CNCs and S-CNCs inhibit hydration and alter the structure of the main hydration product, C─(A)─S─H gel, resulting in shorter silicate chains and reduced cross-linking. Furthermore, adding these CNMs mitigates the excessive formation of ettringite (AFt), a common issue in high-gypsum blended systems. Despite the inhibition of hydration, C-CNCs and S-CNCs refine the pore structure of SSC through the physical filling effect of CNC particles, counteracting the negative impact of loosely dispersed unreacted gypsum particles on porosity.
Abstract Ultrafine CEM-I portland cement with high-purity clinker has high strength, and it is widely used in reinforcing microfractures and very small voids. Existing studies on rheological properties have been focused on composite or blended cements without exact content of each component. It is difficult to accurately obtain the influence of mineral admixture content and to guarantee grouting effectiveness. Currently, rheological parameters and correlations of ultrafine CEM-I cement composite grouting material, especially with ultrafine fly ash and silica fume, are still insufficiently studied. This study systematically investigated rheological properties of ultrafine CEM-I cement grouts (UICGs) influenced by ultrafine fly ash (UFA), silica fume (SF), and polycarboxylate superplasticizer (PCE). Results indicated that at a water-to-binder ratio ( W / B ) of 0.8–2.0, increasing UFA content (0%–40%) and decreasing SF content (0%–15%) led to progressive reductions in plastic viscosity, hysteresis area, and yield stress. Synergistic interactions of UFA, SF, and PCE effectively counteracted the adverse rheological effects of SF. When the W / B was 0.8–1.2, the rheological model of UICG with UFA (10%–40%) followed the modified-Bingham model, and the Herschel-Bulkley model was more suitable for UICGs with UFA and SF (5%–15%). For UICGs with UFA, interrelationships among plastic viscosity, yield stress, and hysteresis area generally followed modified linear trends, and SF transformed this relationship into linear trends. At a W / B of 1.0–1.5, favorable rheological performance was achieved as the amounts of UFA, SF and PCE were 30%–40%, 5%–10%, and 0.3%–0.4%, respectively. These findings have provided theoretical bases for workability and injectability design of UICGs in civil engineering.
Abstract Ultrahigh performance fiber-reinforced concrete (UHPFRC) is a promising composite material, exhibiting compressive strength of around 150 MPa and flexural strength of up to 45 MPa. Despite its impressive properties, the characteristics of the interfacial transition zone (ITZ) between the fiber and the cementitious matrix, which are similar to those in conventional fiber reinforced concrete, significantly influence the behavior of the composite. Since the fiber surface is in direct contact with the ITZ, modifying this interface presents a promising technique to enhance the performance of the composite. In this context, silanes can be used as coupling agents to improve fiber–matrix interactions. This study investigates UHPFRC with the fibers’ surface functionalized using tetraethoxysilane (TEOS) at different proportions: 0.1, 0.5, and 1.0% silane in surface treatments. The analysis was conducted on both fresh and hardened states, evaluating workability and hydration through calorimetry, and flexural and compressive strength through mechanical testing. The results demonstrated that the addition of 0.5% of TEOS improved workability and hydration, showing 7% more heat released in the acceleration period in comparison to the reference (REF) series. The bending results indicated that the sample with 0.5% TEOS in the treatment resulted in an improvement in strength indices up 15% on maximum load, and a 28-day equivalent compressive strength was achieved.
Abstract The transition to low - CO 2 steelmaking via hydrogen-based direct reduced iron (DRI) processes is increasing the generation of electric arc furnace slags (EAFS), yet their utilization remains limited due to poor hydraulic and pozzolanic reactivity. This study explores the potential of DRI-EAFS as carbon-negative cementitious materials through carbonation-hydration under simulated flue gas conditions (20% CO 2 , 50°C, ambient pressure, 95% relative humidity). High- and low-basicity slags were tested for reactivity, phase evolution, and strength development using selective dissolution, X-ray diffraction–Rietveld refinement, Fourier-transform infrared, thermogravimetric analysis, and scanning electron microscopy–energy-/wavelength-dispersive spectroscopy (SEM-EDS/WDS) mapping. Both slags exhibited strength gain upon carbonation but followed distinct reaction mechanisms. Low-basicity (LB) slag underwent rapid surface carbonation, forming a calcite-rich shell and achieving ∼ 95 % of its 7-day strength within 24 h. In contrast, high-basicity (HB) slag exhibited a two-step kinetic response: initial fast carbonation, followed by sustained strength development driven by hydration and subsequent carbonation of residual larnite. Aragonite, absent in LB slag, was identified only in HB slag, likely stabilized through interaction with calcium silicate (C─S─H) gels. Microstructural analyses revealed thin surface layers in LB slag versus multizonal reaction rims with multiple C─S─H gel types in HB slag. These results highlight slag basicity as a key factor controlling carbonation pathways and binder performance, supporting the valorization of EAFS under flue gas curing as a practical route to low-energy, CO 2 -sequestering construction materials.
Abstract The widespread use of carbon fiber–reinforced polymer (CFRP) has resulted in a substantial increase in waste CFRP materials, presenting a significant global environmental challenge regarding their disposal. Recycling these waste CFRP materials would be an environmentally sustainable solution, but the diminished mechanical properties of recycled carbon fiber (rCF) restrict the utilization of rCF in high-precision industries. To address the potential to recycle rCF, this study incorporated rCF into bitumen to determine if rCF could enhance bitumen’s mechanical performance. A comprehensive evaluation of the effect of rCF on bitumen’s durability measured high-temperature performance, resistance to fatigue, and low-temperature performance. The enhancement mechanisms were determined by analyzing the thermodynamic properties and microstructural characteristics of base bitumen and bitumen with rCF. The results demonstrated that the incorporation of rCF increased the rutting resistance and fatigue resistance of bitumen, especially for rCF with a diameters ranging from 0.5 to 1.0 mm and a length of 10 mm. The rCF with a diameters ranging from 0.2 to 0.5 mm and a length of 5 mm was more beneficial for improving the low-temperature cracking resistance of bitumen. The rCF with lower specific heat capacity enhanced heat absorption, thereby improving the high-temperature resistance of the bitumen. In addition, the rCFs formed a three-dimensional network structure in bitumen; this structure restricted bitumen flow and reinforced the bitumen, thereby enhancing the low-temperature cracking resistance of the bitumen. This study highlights the promising feasibility of integrating rCF into bitumen as an economically and environmentally sustainable solution for recycling waste CFRP materials.
Abstract The development of self-healing polymers has primarily focused on enabling healing functionality, while comparatively little attention has been paid to meeting specific performance criteria. Without performance benchmarks, it is difficult to guide material design toward practical use. This study investigates a self-healing sealant for concrete pavement joints that incorporates dynamic disulfide bonds. The sealant—prepared from commercially available thiol-terminated polysulfides (LP55) and bisphenol-A epoxy resin—was evaluated under environmental and load conditions typical for concrete pavements. Static displacement was applied to assess self-healing and bond durability under freeze–thaw cycling. Two tertiary amines, 2,4,6-tris(dimethylaminomethyl)phenol (DMP) and triethylamine (TEA), were tested as initiators to study their effect on polymer curing. Fourier transform infrared analysis confirmed complete curing under ambient conditions within 3 weeks. The cured polymer exhibited a low glass transition temperature ( − 35 ° C ), favorable for flexibility in cold climates. Tensile tests showed higher strength for the TEA-cured sample (465 kPa) compared to the one cured with DMP (190 kPa). The thiol–epoxy sealant demonstrated stronger adhesion to concrete than a commercial silicone. Self-healing efficiency improved in some formulations when joint displacement increased from 1 mm to 2 mm. Overall, the results demonstrate that thiol–epoxy sealants with dynamic bonding can meet key performance requirements for pavement applications. They also highlight the need for further investigation into the effects of initiator chemistry on polymer performance and strategies to reduce residual deformation under low-rate loading.
