Fiber Reinforced Cement Composites Research Articles

Study On Axial Stretching Mechanical Property Of Plant Fiber Reinforced Cementitious Composites

This paper aims to explore the tensile properties of plant fiber-reinforced cementitious composites (PFRCCs). An axial tensile numerical-simulation and test study of PFRCC panels with four thicknesses was performed to analyze their tensile properties, providing a relevant basis for the engineering application of PFRCC panels. The results show that the peak load of uniaxial tensile failure of PFRCC panels with thicknesses of 8 mm, 12 mm, 15 mm and 18 mm is 424.0 N, 664.8 N, 825.0 N and 986.4 N, respectively. The bearing capacity of the panels gradually increases with the increase of the thickness. The peak tensile strain is about 0.044%, 2.93 times that of the cement matrix and the tensile strength is about 2.73 MPa. It is proved that adding plant fiber can increase the toughness of the cement matrix and increasing PFRCC panel thickness can improve its tensile bearing capacity without affecting its tensile-strength. KEYWORDS: Composite materials, Cement matrix, Plant fiber, Axial tension.

Enhancing mechanical performance of green fiber cement composites: Role of eco-friendly alkyl ketene dimer on surfaces of hemp fibers

Fiber composites reinforced natural fibers have attracted more attention in sustainable building materials due to the high Young's modulus, availability, and biodegradability. However, poor interfacial bonding of the fiber-reinforced cement composites attributed to the intrinsically swelling-shrinkage behavior of the hydrophilic natural fibers, seriously limits the strength development of the composite. Here, an eco-friendly and low-cost surface treatment agent, alkyl ketene dimer (AKD), is innovatively introduced for reinforcing the combined effect of hemp fiber (HF)/cement matrix. The experimental approach includes the chemical modification of hemp fibers, followed by the direct preparation of fiber cement composites. Fourier transformation infrared spectroscopy (FTIR) and water absorption test analyses confirmed that the modified HF surface was successfully grafted with AKD, leading to superior hydrophobic characterization and reduced swelling-shrinking behavior. Adding the modified HF to the cement composites effectively enhanced their mechanical properties and toughness capacity by strengthening the interfacial bond of modified HF/Mortar. The modified fiber-reinforced mortar has the highest increment (28 % in compressive strength and 24 % in flexural strength, respectively) from 7 d to 28 d among all investigated mortars. Furthermore, the micro-observation of fractured mortar composites supports the strengthened interface of the modified fibers/cement matrix. The study provides a feasible and practical approach to improving the comprehensive strength properties of hemp fiber-reinforced cement composites. It benefits the practical industrial-scale application of biomaterials in low-cost housing, thus enhancing sustainability.

Optimization of the Shape of Hooked-End Steel Fiber Based on Pulling Out and Reinforcing Cementitious Composites.

Efficient steel fiber-reinforced cementitious composites (SFRCC) should improve not only the ultimate tensile strength but also the residual tensile strength (post-cracking tensile strength) of the SFRCC matrix. The degradation of the post-cracking tensile strength of SFRCC depends on the pullout properties of the steel fibers from the cementitious matrix. When the straight steel fiber was pulled out from the matrix, the pullout resistance was affected by the actions of bonding and friction. After debonding, the load was transferred only by friction, and the pullout resistance decreased rapidly, resulting in a weak reinforcing effect. In addition, changing the fiber shape can effectively slow down the decreasing rate of the pullout resistance of the steel fibers, thus improving their reinforcing effects. In this study, the shape of the steel fibers was optimized to slow down the decrease in the pullout resistance of the steel fibers from the cementitious matrix, thus achieving better tensile properties of SFRCC. First, a calculation model for the steel fiber pullout resistance was established. On this basis, a method to optimize the shape of the steel fibers was proposed. Finally, the pulling out behavior of steel fibers with different end hook shapes was tested, and the influence of the steel fiber shape on the decreasing rate of the residual pullout resistance was analyzed. The results showed that the optimized hooked-end steel fibers had better pullout resistance than ordinary hooked end steel fibers of the same diameter, tensile strength, and matrix.

Bond and Cracking Characteristics of PVA-Fiber-Reinforced Cementitious Composite Reinforced with Braided AFRP Bars

Easy maintenance and high durability are expected in structures made with fiber-reinforced cementitious composite (FRCC) reinforced with fiber-reinforced polymer (FRP) bars. In this study, we focused on the bond and cracking characteristics of polyvinyl alcohol (PVA)-FRCC reinforced with braided AFRP bars (AFRP/PVA-FRCC). Pullout tests on specimens with varying bond lengths were conducted. Beam specimens were also subjected to four-point bending tests. In the pullout tests, experimental parameters included the cross-sectional dimensions and the fiber volume fractions of PVA-FRCC. A trilinear model for the bond constitutive law (bond stress–loaded-end slip relationship) was proposed. In the pullout bond test with specimens of long bond length, bond strength was found to increase with increases in both the fiber volume fraction and the cross-sectional dimension of the specimens. Bond behavior in specimens of long bond length was analyzed numerically using the proposed bond constitutive law. The calculated average bond stress–loaded-end slip relationships favorably fitted the test results. In bending tests with AFRP/PVA-FRCC beam specimens, high ductility was indicated by the bridging effect of fibers. The number of cracks increased with increases in the fiber volume fraction of PVA-FRCC. In specimens with a fiber volume fraction of 2%, the load reached its maximum value due to compression fracture of the FRCC. The crack width in PVA-FRCC calculated by the predicted formula, considering the bond constitutive law and the fiber bridging law, showed good agreement with the reinforcement strain–crack width relationship obtained from the tests.

Providing a strategy to restore damaged RC beam-column joints with the combination of CFRP and HPFRCC

This paper endeavors to assess the seismic performance of 3D reinforced concrete (RC) beam-column joints situated on the exterior of buildings, but lacking special ductility requirements. The joints have been rehabilitated by High-Performance Fiber-Reinforced Cement Composites (HPFRCC) and retrofitted using Carbon Fiber Reinforced Polymer (CFRP) wrap methodology. In this context, five beam-column joints located on the exterior of a structure have been subjected to cyclic lateral loading, while being scaled down to half their original size. The present study entailed an investigation into the cyclic behavior of three control specimens in its initial stage. Following the initial examination, it was observed that the control specimens, lacking any designated ductility standards, experienced significant core damage. During the subsequent phase of experimentation, the impaired concrete sections of the control samples were remediated through substitution with HPFRCC matter. Additionally, CFRP sheets were implemented for retrofit purposes. The modified specimens were then exposed to comparable cycles of loading. An analysis is conducted on the empirical findings of the specimens under investigation. The findings of this study indicate that the utilization of HPFRCC materials and CFRP sheets in the restoration and enhancement of deteriorated joints has led to a notable enhancement of their strength and displacement capacity. Specifically, this approach has facilitated the creation of a flexural plastic hinge and impeded the occurrence of shear failure within the core, leading to an improved overall behavior of the repaired damaged joint, which is comparable to that of undamaged seismic joints. The application of this technique demonstrates a high degree of efficacy in the rehabilitation and enhancement of edifices with deficient seismic details that have sustained damage subsequent to an earthquake event.

Phase Segmentation of PVA Fiber-Reinforced Cementitious Composites Using U-net Deep Learning Approach

Phase Segmentation of PVA Fiber-Reinforced Cementitious Composites Using U-net Deep Learning Approach

Enhancement of in-plane shear performance in masonry walls strengthened with high-performance fiber-reinforced cementitious composites

This study aims to design a high-performance fiber-reinforced cementitious composite (HPFRCC) material for reinforcing masonry walls and assess its impact on in-plane shear performance. Different specimens were compared, including an unreinforced one, a conventional mortar-reinforced one, and HPFRCC-reinforced specimens of varying thicknesses ranging from 10 mm to 20 mm. Aspects such as failure modes, shear stress–strain curves, pseudo-ductility, and energy dissipation were evaluated. Test results indicated that the unreinforced and mortar-reinforced masonry walls demonstrated brittle failure with wide cracks on both sides, whereas HPFRCC-reinforced walls exhibited ductile failure with controlled crack propagation owing to the excellent mechanical properties of HPFRCC, such as an average tensile strength of 7.32 MPa and a tensile strain capacity of 4.60 %. The HPFRCC significantly enhanced the shear strength and modulus of the masonry walls. The wall reinforced with 20 mm-thick HPFRCC showed a remarkable 26-fold increase in the energy dissipation capacity compared to the unreinforced one, and the 10-mm-thick and 15 mm-thick strengthening demonstrated 4.0- and 5.7-times improvement, respectively. The ideal HPFRCC overlay thickness was found to be between 15 mm and 20 mm. Beyond this thickness, gravitational flow and stiffness asymmetry negatively impacted shear performance.

Analysis of probable consequences of cement composite frost destruction

The article presents an analysis of variations in the internal resistance of standard and fiberreinforced cement composites under non-stationary low-temperature and humidity effects. Various aspects of the response kinetics of prismatic samples in the monotonous compression mode are considered. The sample set included control samples and those subjected to cyclic freezing and thawing according to their standard frost resistance. Test samples (100 × 100 × 400 mm) were made of conventional (B series) and fiber-reinforced (FB, polypropylene fibers df = 0.8 mm, lf = 40 mm, µf = 1.5 vol%) concrete with a component ratio of cement: sand: crushed stone: water = 1:1.42:3.57:0.55. The accepted base of T-W cycles corresponded to the standard concrete grade in terms of frost resistance, established in control tests (F200). Static tests of composites were preceded by low-temperature exposures according to an accelerated method for assessing frost resistance with a temperature decrease down to minus 35℃ and thawing in a 5% NaCl solution. Samples were automatically loaded (Instron 5989 test complex) according to a special program with a constant deformation rate of 5·10-5 mm/s and continuous recording of deformations. Significant differences were observed in the strength kinetics, magnitude and structure of deformations, along with a high sensitivity and quantitative informativeness of the significant parameters of the strength kinetic concept for solid bodies. The expediency of a differentiated approach to the selection of calculation models and criteria for the temperature and humidity transformations of cement-matrix composites, which takes operational requirements into account, is substantiated.

Repair, flexural upgrading and seismic retrofit of RC columns with reinforced FRCC light jacket

An innovative repair, flexural upgrading and seismic retrofit solution consisting of a reinforced light jacket (i.e., 3–4 cm) made of Fibre Reinforced Cement Composites, FRCC coupled with a High-Performance steel reinforcement is proposed for existing reinforced concrete (RC) columns. The proposed solution consists in a FRCC light jacketing coupled with a High-Performance steel reinforcement that works both as anchorage system for the jacket and as additional transverse reinforcement (Reinforced FRCC light jacketing or RFRCC). The goal of the solution is to improve the columns resistance against the migration of aggressive agents and at the same time to increase its flexural capacity. The potential of the proposed solution is demonstrated on 6 full-scale RC columns experimentally tested under quasi-static cyclic loading. The RC columns under investigation are subjected to a seismic pre-damage before the application of the RFRCC jacket. Square and rectangular columns with smooth and deformed rebars are tested to assess the feasibility of the technique for the repair and flexural strengthening of existing deficient RC columns. The experimental results attest the high potential of the proposed technique in recovering and enhancing the flexural capacity, ductility and energy dissipation of seismically pre-damaged RC columns.

Multi-performance experimental assessment of autogenous and crystalline admixture-stimulated self-healing in UHPFRCCs: Validation and reliability analysis through an inter-laboratory study

The huge benefits brought by the use of Ultra High-Performance Fibre-Reinforced Cementitious Composites (UHPFRCCs) include their high “intrinsic” durability, which is guaranteed by (1) the compact microstructure and (2) the positive interaction between stable multiple-cracking response and autogenous self-healing capability. Hence, self-healing capability must be properly characterized addressing different performances, thus providing all the tools for completely exploiting such large potential. Within this context, the need is clear for a well-established protocol for self-healing characterization. To this end, in the framework of the Cost Action CA15202 SARCOS, six Round Robin Tests involving 30 partners all around Europe were launched addressing different materials, spanning from ordinary concrete to UHPFRCC, and employing different self-healing technologies. In this paper, the tailored experimental methodology is presented and discussed for the specific case of autogenous and crystalline-admixture stimulated healing of UHPFRCC, starting from the comparison of the results from seven different laboratories. The methodology is based on chloride penetration and water permeability tests in cracked disks together with flexural tests on small beams. The latter ones are specifically aimed at assessing the flexural performance recovery of UHPFRCCs, which stands as their signature design “parameter” according to the most recent internationally recognized design approaches. This multi-fold test approach allows to address both inherent durability properties, such as through-crack chloride penetration and apparent water permeability, and more structural/mechanical aspects, such as flexural strength and stiffness.

Role of fiber dosages and lengths on the mechanical strength, shrinkage, and pore structure of CO2-cured amorphous metallic-fiber-reinforced belite-rich cement composites

The impact of varying dosages and lengths of amorphous metallic fiber (AMF) on the mechanical strength, shrinkage, and pore structure of fiber-reinforced cementitious composites cured in water and in a carbonation chamber were assessed. This study evaluated fourteen mortar mixes, i.e., seven mixes for traditional water curing and seven for CO2-curing (60% relative humidity, 20 °C, and 10% CO2 concentration). The outcomes reveal that the compressive and flexural strength are significantly augmented for the mixes reinforced with AMFs as compared to the control mix (fiber-free mix), and this behavior is more pronounced with increased dosages and lengths of the AMF. Furthermore, compared to the control mix, significant mitigation in the development and magnitude of shrinkage was recorded with increased dosages and lengths of the AMF. The porosity and voids were all increased in the samples with AMF as compared to the control mix. The carbonation-cured specimens exhibited significantly higher mechanical strength, fewer voids, and higher shrinkage than those cured in water. Based on the experimental findings, it is recommended to use 0.50% volume of AMF and a length of 20 mm to produce fiber-reinforced cement composites, as this combination provides outstanding performance among all mixes tested here.

The early-age shrinkage cracking and late-age fracture properties of fiber-reinforced cementitious composites

In this research, the shrinkage cracking and fracture properties of fiber-reinforced cementitious composites (FRCC) are investigated using eccentric ring test and three-point bending test. In the eccentric ring test, the concept of the equivalent crack width (weq) is proposed based on the morphology and number of cracks of FRCC. A function considering curing time and fiber volume fraction is established to calculate the equivalent crack width of FRCC. The initial and complete-through cracking times of FRCC were measured to explain the effect of the fibers. In the three-point bending test, the crack initiation in FRCC is determined based on the average transverse force. The initial and unstable fracture toughnesses, as well as the fracture energy, have been calculated. The experimental results indicate that an increase in polyvinyl alcohol (PVA) fiber content can reduce the crack width and prolong the initial and complete-through cracking times induced by shrinkage. The unstable fracture toughness and fracture energy increase with the increase in the PVA fiber content. The results of the eccentric ring test and three-point bending test demonstrate that the primary role of PVA fibers is to extend the intermediate stage of cementitious materials from initial cracking to unstable cracking. Additionally, PVA fibers delay the energy release rate during the failure process.

Experimental and numerical investigations on the stress waves propagation in strain-hardening fiber-reinforced cementitious composites: Stochastic analysis using polynomial chaos expansions

The propagation of stress waves can result in spalling fractures in materials, which poses a threat to the safety of engineering structures. Hence, in-depth studies are necessary to mitigate such risks. Ultra-high toughness cementitious composites (UHTCC) with significant tensile strain-hardening properties are advanced engineering materials with great potential for impact engineering. The study used a combination of experimental and numerical methods to analyse the propagation and attenuation behaviour of stress waves in the UHTCC. The numerical model was developed using the Smooth Particle Galerkin (SPG) method and the Karagozian & Case concrete/cementitious (KCC) material constitutive model. Additionally, a quantitative global sensitivity analysis (GSA) using a polynomial chaos expansion (PCE) surrogate model and Sobol's method was conducted to analyse the stochastic input parameters of the numerical model. Results show that compressive stress waves undergo significant attenuation during propagation in UHTCC, and the developed numerical model accurately simulated the stress wave propagation process Furthermore, the PCE-Sobol GSA revealed that the selected stress wave propagation responses are most sensitive to the tensile strength of UHTCC. This study is expected to deepen the understanding of the propagation behaviour of stress waves in UHTCC and pave the way for promising applications of UHTCC in impact engineering.

User-friendly end-to-end fiber identification for fiber-reinforced cementitious composites (FRCC) through deep learning

Authentic fiber distribution and orientation in fiber-reinforced cementitious composites (FRCC) is vital in study of cracking mechanism and tensile mechanics model. Existing analytical methods based on fluorescent microscopes or CT are complex, time-consuming and labor-intensive. This study presents a general and user-friendly end-to-end fiber identification method for FRCC through deep learning, which accomplished greatly accurate semantic segmentation of fibers (>100 μm) with an ordinary SLR camera. The optimal model achieved MIoU of 98.93% and class accuracy of 99.998% for fiber. Specifically, the effect of pore, which is the possible interference to fiber identification in the cross-sections, was analyzed and the extracted multidimensional features were visualized and discussed. Furthermore, a case study on fiber distribution and orientation based on the proposed method was carried out. The results show that new advances are made in terms of the simplicity of modeling process, the accuracy and intuitiveness of results, and the user experience.

Interaction Mechanism of Cementitious Composites Containing Different Twisted PVA Fiber Bundles

Fiber-reinforced cementitious composites (FRCCs) have made significant progress in improving the tensile and flexural properties of concrete members. Studies have shown that polyvinyl alcohol (PVA) fibers can effectively enhance the toughness of FRCCs, but the haphazard distribution of short-cut fibers makes it difficult to give full play to the high tensile strength of the fibers, and it is difficult for bundled fibers to effectively bond with the concrete substrate, which has become a challenge in the study of changing materials. Twisting the fibers by a physical process to improve the bonding performance of PVA fibers with FRCC substrate is a safe and feasible solution. However, research on silicate cementitious composites reinforced with twisted PVA fibers is limited. In this study, the interaction mechanism of through-length twisted PVA FRCCs with different twist factors and fiber bundle numbers was investigated. A concrete matrix material configured from silicate cement, fly ash, silica fume, and medium sand, in which PVA fibers with different twist factors were pre-incorporated, was used for the tests. Three-point bending tests were carried out on specimens with different twist factors (0, 50, 100, and 150 twists per meter) and fiber bundle numbers 1, 2, and 3. Compared to the untwisted PVA fiber specimens, the twist factor of 100 and the single fiber bundle specimens showed significant improvements in the bending properties, including a 36% increase in deflection, a 68% increase in the equivalent bending stress, and a 119% increase in energy consumption. Micro-X-ray computed tomography scans showed improved bending properties and energy consumption capabilities due to enhanced bonding properties as a result of the increased fiber–matrix interaction area and surface toughness.

Optimisation of the Mechanical Properties and Mix Proportion of Multiscale-Fibre-Reinforced Engineered Cementitious Composites.

Engineered cementitious composites (ECCs) are cement-based composite materials with strain-hardening and multiple-cracking characteristics. ECCs have multiscale defects, including nanoscale hydrated silicate gels, micron-scale capillary pores, and millimetre-scale cracks. By using millimetre-scale polyethylene (PE) fibres, microscale calcium carbonate whiskers (CWs), and nanoscale carbon nanotubes (CNTs) as exo-doped fibres, a multiscale enhancement system was formed, and the effects of multiscale fibres on the mechanical properties of ECCs were tested. The Box-Behnken experimental design method, which is a response surface methodology, was used to construct a quadratic polynomial regression equation to optimise ECC design and provide an optimisation of ECC mix proportions. The results of this study showed that a multiscale reinforcement system consisting of PE fibres, CWs, and CNTs enhanced the mechanical properties of ECCs. CWs had the greatest effect on the compressive strengths of highly ductile-fibre-reinforced cementitious composites, followed by CNTs and PE fibres. PE fibres had the greatest effect on the flexural and tensile strengths of high-ductility fibre-reinforced cementitious composites, followed by CWs and CNTs. The final optimisation results showed that when the ECC matrix was doped with 1.55% PE fibres, 2.17% CWs, and 0.154% CNTs, the compressive strength, flexural strength, and tensile strength of the matrix were optimal.

High volume fly ash and basalt-polypropylene fibres as performance enhancers of novel fire-resistant fibre reinforced cementitious composites

This study attempts to address the fire resistance of fibre reinforced cementitious composite (FRCC) while considering sustainability. Sustainable FRCC mixes were developed by varying the contents of silica fume and high-volume fly ash (up to 60% by wt.), along with a hybrid combination of basalt and polypropylene fibres. The FRCC was exposed to temperatures up to 800 °C, and its appearance, mass loss, and compressive properties were analysed. Exceptional performance in terms of resistance to cracking and strength retention was observed. The relative residual compressive strength of one of flyash based mixes was found to be 93.46%, 117.48%, 102.03% and 38.48% between 200 and 800 °C. Also, fly ash enhanced the mass retention properties especially with higher replacement levels and at higher temperatures. The influence of temperature on hydration products in the system has been explained using scanning electron microscope, X-ray diffraction, and thermogravimetric analysis. Furthermore, the improvement in thermal performance is demonstrated as a novel incentive for addition of fly ash in high volumes.

Autogenous self-healing of polypropylene fiber reinforced ettringite-based composite

This study intends to advance the poor knowledge on the ability of an ettringite-based binder to obtain autogenous self-healing and its relevant mechanism. We developed a high-performance polypropylene fiber-reinforced cementitious composite using a slag-based ettringite binder and investigated its autogenous healing property under water-saturated conditions. Cracks were created via four-point bending loads on prismatic specimens at different crack opening displacements (i.e., 0.5, 1, and 2 mm in total crack opening). After curing times, the mechanical retention and recovery of the damaged composite were compared with the sound sample. We found that the material effectively heals micro cracks (i.e., under 100 μm) after 1 month of aging, while larger cracks could not completely close during the total curing times (up to 3 months). The healing products were mainly CaCO3 and ettringite observed through both experiments and thermodynamic modelling. These crystals mainly formed from the carbonation of ettringite and other AFm phases in aqueous conditions. The strength retention slightly reduced (about 10%) after healing, however, the composite still exhibited deflection-hardening behavior. Findings show the high potential of ettringite-based binder to be a matrix for self-healing cementitious composites. Further improvements, nevertheless, are needed to increase the healing rate and strength recovery of the composite.

Mechanical properties and cracking behaviour of lightweight engineered geopolymer composites with fly ash cenospheres

Engineered geopolymer composites (EGCs) are known for their superior tensile performance and multiple cracking characteristics. The development of lightweight EGCs is crucial for applications in structural strengthening and repair. However, the addition of lightweight aggregates often compromises the mechanical properties of these composites. Fly ash cenosphere (FAC) has demonstrated its effectiveness as an aluminosilicate precursor in geopolymers and as a crack width controller in fibre-reinforced cementitious composites, thus showcasing significant potential for the advancement of high-performance lightweight EGCs. This study investigates the effects of FAC incorporation on the properties of lightweight EGCs. The results of this study confirmed the benefits of using FACs in terms of reducing the density of the composites while maintaining satisfactory compressive strength. With increasing the FAC replacement ratio, the tensile strength decreases; however, increasing the FACs/binder ratio preserves the tensile strength of the EGCs. Moreover, the utilisation of FACs preserves the high tensile strain capacity of lightweight EGCs, reaching approximately 9 %. Furthermore, the presence of fractured unreacted FACs, partially hollow reacted FACs, and a weak FAC/geopolymer interface act as artificial flaws, thereby enhancing the crack control ability of EGCs with higher FAC replacement or FACs/binder ratios. Moreover, the inclusion of FACs does not alter the main reaction products of EGCs, providing an attractive avenue for achieving lightweight EGCs with exceptional tensile strain capacity.

Durability and microstructure of cementitious composites under the complex environment: Synergistic effects of nano-SiO2 and polyvinyl alcohol fiber

As the most commonly used construction material for marine buildings, cementitious composites are exposed to a complex environment of coupled action of relative humidity, temperature, and chloride salts erosion, which severely impacts the safety and longevity of marine buildings. The effect of nano-SiO2 dosage on the durability of polyvinyl alcohol fiber-reinforced cementitious composites (PVAF-RCC) for the preparation of marine buildings under the complex environment was investigated in this work. The complex environment with the temperature of 50 °C, relative humidity of 100%, and chloride salt concentration of 5% was simulated by the environment chamber. The cementitious composites exposed to the complex environment for 30 d were tested for anti-permeability, anti-chloride ion penetration, frost resistance, and chloride salt erosion resistance. Furthermore, the pore characteristics of the cementitious composites and the micromorphology of nano-SiO2, matrix, and fibers were characterized and analyzed by the combination of scanning electron microscope and mercury intrusion porosimetry tests. Results revealed that the durability of cementitious composites improved initially and subsequently decreased with rising the dose of nano-SiO2 under the complex environment. PVAF-RCC consisting of 1.5% nano-SiO2 obtained the best durability. As the nano-SiO2 dosage increased, the total porosity and cumulative porosity of PVAF-RCC decreased first and subsequently increased. Nano-SiO2 refined and improved the pore structure of PVAF-RCC and the interface between matrix and PVA fibers through its filling effect and participation in the hydration reaction to generate C-S-H gels with filling effect to convert more harmful and harmful pores into less harmful or harmless pores, thus enhancing the compactness and durability of cementitious composites under the complex environment.