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The prevalent overreliance on silica sand within strain-hardening cement-based composites (SHCC) underscores the urgency to address the depletion of natural resource. To address this concern, a novel approach involving the utilization of waste marine clay (WMC), an underutilized construction waste residue, is explored. This study marks the first application of high-volume calcined WMC as a substitute for silica sand within sustainable and cost-effective strain-hardening cement-based composites (SC-SHCC). The investigation encompasses a comprehensive analysis of SC-SHCC, covering mechanical properties, hydration, shrinkage, and cost. The results showed that the integration of calcined WMC instead of silica sand had noticeable improvements in the mechanical properties of SC-SHCC due to the notable pozzolanic activity and filling effect of calcined WMC. The developed SC-SHCC replacing two-thirds of the silica sand with calcined WMC exhibited a compressive strength of 76.34 MPa, a tensile strength of 14.63 MPa, and a tensile strain capacity of 5.99%, which successfully pushed the performance of conventional SHCC. Key indicators such as compressive strength, flexural strength, and tensile strength exhibited promising enhancements as calcined WMC dosage increased. The incorporation of calcined WMC contributed to heightened ettringite formation, thereby improving the tensile strength, and tensile strain energy of SC-SHCC. Besides, SC-SHCC exhibited pronounced drying shrinkage, primarily attributable to the free water evaporation and capillary pore development associated with calcined WMC. Furthermore, substituting calcined WMC for silica sand led to reducing the costs within SC-SHCC production. Therefore, the findings of this study hold promise for advancing the field of SHCC while promoting the environmentally friendly utilization of waste materials. • Calcined waste marine clay (WMC) is used as fine aggregates in strain-hardening cement composites (SHCC). • SHCC containing calcined WMC exhibits excellent mechanical performance. • Bond between fibers and SHCC matrix is enhanced. • The enhanced performance can be attributed to filler effect and pozzolanic activity of calcined WMC. [ABSTRACT FROM AUTHOR]

• The macroscopic mechanical properties of SBFRCC decrease with temperature. • The pore structure is "coarsened" significantly with the increasing temperature. • The index with the highest correlation to uniaxial compressive strength at high temperatures is porosity. • Gel pore directly affects the generation of cracks while large pore affects the propagation of cracks. Steel-basalt hybrid fibers reinforced cementitious composites (SBFRCC) have excellent mechanical properties, and current studies mainly focused on the macroscopic or microscopic properties of SBFRCC at room temperature separately. However, the macroscopic and microscopic properties of SBFRCC subjected to elevated temperatures, especially their correlation relationships are still unclear. Hence, this study aims to investigate the macroscopic and microscopic properties and their correlation relationships of SBFRCC subjected to elevated temperatures. Firest, the mass loss rate, three-point bending, uniaxial compressive, mercury intrusion porosimetry (MIP) and scanning electron microscopy (SEM) tests were conducted subjected to elevated temperatures. Then, the correlations between mass loss rate, fracture, uniaxial compressive behavior and pore structure were analyzed based on a correlation analysis approach. The results show that steel fiber and basalt fiber can effectively restrict crack initiation and propagation subjected to elevated temperatures. Uniaxial compressive strength and elastic modulus decrease with temperature while peak strain increases below 600 °C and drops after 600 °C. With the increase of temperature, the gel pore and transitional pore decrease, the large pores increase, the porosity increases, and the pore structure is "coarsened" significantly. The correlation coefficient between uniaxial compression strength and porosity is the highest, and it is reasonable to use porosity to characterize the changes of uniaxial compressive strength subjected to elevated temperatures. Gel pore has the highest correlation with initiation fracture toughness while large pore has the highest correlation with mass loss rate, unstable fracture toughness, fracture energy, and elastic modulus. Gel pore directly affects the generation of cracks while large pore directly affects the propagation of cracks. [ABSTRACT FROM AUTHOR]

• Increasing fly ash properly can reduce the rate of strength degradation, but will reduce the compressive strength and increase the explosive spalling rates. • Hybrid fibers can significantly improve the explosive spalling behavior, flexural and splitting tensile strength. • The microstructures become loose and the porosities increase after exposure to high temperatures. The excellent performance of steel and basalt fiber at room and high temperatures makes steel-basalt hybrid fibers reinforced cementitious composites (SBFRCC) a promising solution for engineering structures with fire risk. In this study, the morphology, explosive spalling behavior, flexural, compressive and splitting tensile strength, and uniaxial tensile properties of SBFRCC with different substitution rates of fly ash after exposure to high temperatures were studied. In addition, the effects of high temperature on the microstructures of SBFRCC were investigated by the scanning electron microscopy (SEM), energy dispersive X-ray (EDX), and X-ray computed tomography (XCT) tests. The results show that the incorporation of steel fiber and basalt fiber can significantly improve the explosive spalling behavior, flexural and splitting tensile strength. After exposure to high temperatures, increasing the substitution rate of fly ash properly can reduce the rate of strength degradation to some extent, but will reduce the compressive strength and increase the explosive spalling rates. The microstructures of SBFRCC become loose and the porosities of SBFRCC increase under the combined effect of the decomposition of hydration products, the melting of fly ash, and the deterioration of steel fiber and basalt fiber. [ABSTRACT FROM AUTHOR]

• Steel-basalt hybrid fibers significantly improves flexural and splitting tensile strength. • Compressive, flexural and splitting tensile strength essentially decrease with temperature. • Hybrid fibers can effectively inhibit cracks generation and propagation up to 900°C. Steel-basalt hybrid fibers reinforced cement-based composites (SBFRCC) have excellent mechanical properties at ambient temperature. Conducting research on the behavior of SBFRCC at high temperatures is beneficial for applications in structures which may be exposed to fires. In this study, the physical properties of fibers and mechanical properties of SBFRCC exposed to high temperatures were assessed through appearance, mass loss, and compressive, flexural, and splitting tensile strength tests. The deterioration mechanism was studied by X-ray diffraction (XRD), simultaneous thermal analysis (STA), and scanning electron microscopy (SEM). The results show that the color and mass of steel and basalt fiber change significantly with temperature. The addition of steel fiber and basalt fiber can improve residual flexural strength and splitting tensile strength. High basalt fiber content is harmful for compressive strength. The compressive, flexural, and splitting tensile strength of SBFRCC essentially decreases with temperature. Models were established to describe the quantitative relationship between relative strength and fiber content, temperature. The addition of steel fiber and basalt fiber can effectively inhibit cracks generation and propagation by multi-stage cracking resistance. High temperature deterioration of hybrid fibers can only reduce the reinforcement, but steel fiber and basalt fiber can still play a role in bridging cracks at 900°C. [ABSTRACT FROM AUTHOR]

• Develop a new approach to measure internal stress in asphalt binder. • Use EBM approach to characterize healing properties of asphalt binder. • Use healing kinetics method to calculate healing activation energy. • Use healing activation energy to quantify healing capability of asphalt binder. • Quantify relation of healing ability and damage level from causal mechanics. Self-healing capability is one of the most important characteristics of asphalt binder, which has a significant influence on field performance of asphalt pavements. Although the internal stress has been proven to be the driving force of healing, limited studies have been conducted for this part. As a result, this study aims at proposing a new approach to measure the internal stress and quantify the relationship between healing capability and damage levels of asphalt binder from its causal relationship based on healing kinetics. Specifically, a new approach called creep and zero-strain-rate recovery (CZSR) test to measure the internal stress is proposed. The accuracy of this new approach is verified in both undamaged and damaged asphalt binder. Then, the application of this new approach is expanded from creep-recovery condition to multiple-cyclic-loading-recovery condition. This action not only expands the application fields of this proposed new approach, but also provides a bridge to evaluate the relationship between healing capability and damage levels from its causal relationship. After that, the healing-kinetics method is used to characterize the healing capability of asphalt binder under different damage levels on the basis of energy-based mechanistic (EBM) approach. Moreover, the healing capability and damage level of asphalt binder are expressed as healing activation energy and crack length, respectively. Final results indicate that the healing activation energy increases with the growth of crack length, and there is a negative relationship between healing capability and damage levels of asphalt binder. [ABSTRACT FROM AUTHOR]

• A method for evaluating the hydration degree of blended cement which can consider the influence of temperature was proposed. • A hydration kinetic model of nonevaporable water (NEW) was recommended to predict the ultimate NEW of blended cement. • The hydration process of RHA blended cement was analyzed by this assessment method. • The addition of RHA could reduce the apparent activation energy (Ea) of blended cement. Rice husk ash (RHA) has been considered as a suitable cement mineral additive. A key issue in the study of RHA blended cement is to evaluate the contribution of RHA to hydration kinetics. Although numerous methods have been given to assess the hydration degree of blended cement, there are still some controversial aspects, such as the effect of temperature is not well considered. Therefore, this study aims at developing a method for evaluating the hydration degree of blended cement which can consider the influence of temperature. The key of this method is to adopt a hydration kinetic model of nonevaporable water (NEW) to determine the ultimate NEW content of blended cement when it is completely hydrated. In the hydration kinetic model, the Arrhenius equation is introduced to reflect the relationship between hydration rate and temperature, and the inversion phenomenon between ultimate NEW and temperature is considered simultaneously. Furthermore, the hydration process of portland cement pastes containing RHA (two types of RHA: RHA-1 from the factory and RHA-2 by controlled combustion) is analyzed by this assessment method. It is found that the effect of temperature on RHA cement is similar to that of ordinary Portland cement (OPC), which has an inversion phenomenon between hydration degree and temperature. Under the same temperature, the hydration degree of RHA cements is lower than that of OPC, while the difference in hydration degree gradually decreases with the progress of hydration. Moreover, according to the fitting results of the model when m = 3, the addition of RHA could reduce the apparent activation energy (Ea) of blended cement, the Ea values of OPC, RHA-1 cement and RHA-2 cement are 37.64 kJ/mol, 35.39 kJ/mol and 34.18 kJ/mol, respectively. [ABSTRACT FROM AUTHOR]

• Some properties of lightweight cement-based composites with high toughness were investigated. • The effect of cenosphere content on the tensile ductility of the composites was analyzed based on the micromechanical design theory. • The incorporation of cenosphere could effectively reduce the shrinkage of the cement-based composites. • Lightweight cement-based composites with excellent mechanical properties can help mitigate environmental costs of construction. Cenosphere is an industrial waste residue used as lightweight aggregate in cement-based composites. In this work, we investigated the influences of cenosphere on the properties and applicability of cement-based composites. The compressive and flexural strength, bending toughness, tensile ductility, and shrinkage of the composites were measured. Meanwhile, the environmental and economic benefits of cenosphere were analyzed. Our results showed that cenosphere-added lightweight cement-based composites exhibited a density of 1477.52–1734.23 kg/m3, compressive strength of 63.94–70.69 MPa, and flexural strength of 9.50–14.71 MPa, depending on the cenosphere content. The calculated fracture energy of the matrix notably dropped with increasing cenosphere content due to the weak interface transition zone between the aggregate and cement paste. Moreover, the incorporation of cenosphere had a negative effect on the tensile strain capacity and tensile strength of composites. The high bridging stress of the fibers ensured the tensile ductility and bending properties of the cement-based composites. Due to internal curing effect of cenosphere, the shrinkage of lightweight toughness cement-based composites was effectively reduced with increasing cenosphere content. Compared with the control group, the embodied energy of the cement-based composites containing 30% cenosphere was reduced from 10.12 to 7.20 GJ/m3, while the global warming intensity was reduced by 37.85%. Therefore, developing eco-friendly cement-based composites with cenosphere is viable approach to mitigate the environmental costs of construction. [ABSTRACT FROM AUTHOR]

• Permanent deformation of asphalt mixture was reduced by adding graphene oxide (GO). • Inclusion of GO in HMA enhances its resilient modulus and moisture stability. • Inclusion of GO improves the fracture resistance of the asphalt mixture. The use of nanomaterials to modify the asphalt mixture to enhance its performance has become an area of growing interest. Graphene oxide (GO) has recently been found to be the potential nanomaterial for improving the performance of asphalt binder due to its advantageous properties and dispersion ability in different matrixes. In this study, GO modified asphalt binder was employed in hot mix asphalt to assess its influence on the engineering characteristics of hot mix asphalt (HMA). A base asphalt binder with 60/70 penetration grade was first mixed with GO at different concentrations using a high shear mixing equipment and then employed to prepare the asphalt mixtures. A series of performance tests, e.g., resilient modulus, dynamic creep, freeze–thaw splitting, Marshall immersion and semi-circular bending (SCB) fracture were conducted to investigate the rutting and fatigue performance, moisture stability and fracture resistance of the GO-modified HMA mixtures. Results suggest that significant improvement in mechanics behavior of HMA may be achieved by incorporating GO compared to the conventional mixture. [ABSTRACT FROM AUTHOR]

• Develop a kinetic model for recovery of asphalt mixtures using internal stress. • Propose healing activation energy to quantity healing ability of asphalt mixtures. • Use generalized Maxwell model to characterize the change of recovery modulus. • Propose a model to characterize pseudo strain and damage density. • Verify the accuracy of the mechanical and kinetic recovery model. The recovery of asphalt mixtures during rest periods is a key factor that affects the performance and service life of asphalt pavements in addition to the loading period. However, much less attention has been paid to the unloading periods in terms of laboratory characterization and numerical modeling. Thus, this study is intended to develop a coupled mechanical and kinetic approach to accurately characterize and simulate the recovery phase of asphalt mixtures. For the unloading period, a kinetics-based recovery model is proposed, which consists of two periods (fast-rate period and constant-rate period) with the kinetic parameters like the recovery activation energy and pre-exponential factors. In addition, a generalized Maxwell model is proposed to characterize the change of the recovery modulus predicted by the kinetics-based recovery model, which would facilitate the implementation in the numerical simulation process. For the loading period, an improved constitutive model is developed for the damage process of asphalt mixtures based on the relation between the pseudo strain and damage density. The proposed models are then applied to laboratory tests and finite element modeling on different asphalt mixtures with two types of binders, three aging periods, two air void contents, and nondestructive and destructive loading conditions. The laboratory results show that the kinetic parameters like the recovery/healing activation energy are good indictors of recovery/healing capacity of asphalt mixtures. The numerical simulations demonstrate that the output responses match very well with the measured values under both the nondestructive and destructive loading conditions, which verify the accuracy of the proposed approaches. [ABSTRACT FROM AUTHOR]

• The feasibility of cost-effective fiber in functional cementitious composites is investigated. • The rank of three factors' significance for sorpotivity coefficient is fly ash > silica fume > fiber. • Response surface methodology is used to obtain the minimum sorptivity coefficient of fuctional cementitious composites. • New functional cementitious composite reduces equivalent carbon emission by 26.2% and 7.3% compared to the typical ECC M45 and high volumes fly ash ECC. The disease of the operating tunnel lining has seriously threatened traffic safety and needs to be cured urgently. Engineered Cementitious Composite (ECC), due to its excellent deformation ability and high damage tolerance, has the potential to retrofit the linings, but the quite high cost of raw material, mainly involving PVA fiber, has limited the broader application of ECC in the civil infrastructure. This paper proposed a practical design method of integrating four parts: engineering requirements, economical cost, matrix design and environmental assessment. A novel type of cementitious composites with low water absorption, moderate flexibility and light-weigh, named functional cementitious composite (FCC), was exploited to handle the common diseases of tunnel lining economically and environmentally. The results indicated that the cost-effective fiber is available to prepare the FCC, which shows great performance of cost-saving and functional properties. Besides, the functional characteristics, including low water sorptivity, light density and moderate flexibility, were optimized by response surface methodology (RSM) and subsequently the optimized results were proven by the test results. Finally, the environmental assessment emphasized an excellent material greenness of FCC with reduction of 26.9% embodied energy consumption and 26.2% carbon equivalent emission compared to the ECC (M45). [ABSTRACT FROM AUTHOR]