High-performance Fiber-reinforced Cementitious Composites Research Articles

An Analytical Study of the Out-of-plane Seismic Performance of Masonry Walls Reinforced with High-Performance Fiber-Reinforced Cementitious Composites

Frequent earthquake occurrences in various regions of Korea have highlighted the urgent need that exists for the seismic retrofitting of unreinforced masonry buildings, which are particularly vulnerable to lateral forces. In this study, the out-of-plane seismic performance of masonry walls reinforced with high-performance fiber-reinforced cementitious composites (HPFRCCs) was evaluated using finite element analysis. ABAQUS was used to establish the analysis model, and the reliability of the model was validated by comparing the model results with shaking table test results. A parametric study of the reinforced masonry walls was thereafter conducted using the parameters of the reinforced sides of the walls (unilateral and bilateral) and thicknesses (10 and 20 mm). The analysis of the acceleration and displacement of the masonry walls revealed the beneficial effects of HPFRCCs on the out-of-plane seismic performance of the walls. The seismic performance of the walls was significantly enhanced when the HPFRCCs were applied to both sides of the walls.

Projecting the resiliency of nano-modified cementitious composites with hybrid BFP/PVA fibers in shear key joints

Effective bond strength at the interface between conventional concrete (CC) and high-performance fiber-reinforced cementitious composites (HPFRCC) is vital for applications like shear key for bridge joints. This study investigated the suitability of HPFRCC incorporating various constituents (cement, slag, as well as nano-silica), with only basalt fiber pellets (macro-BFP) or hybrid fiber systems including macro-BFP and micro-polyvinyl alcohol (PVA) fibers. BFP is a new emerging class of basalt fiber strands protected by a polymer coat. Experimental results (slant shear, pure shear, rebar pull-out, etc.) were used to develop modeling [homogenization/finite element modeling (FEM)] components to evaluate the effect of HPFRCC mixture design parameters on the mode of failure and bonding capacity with CC and steel rebar. After verification, these model components were integrated in a full-scale shear key joint model to project the field performance of the developed HPFRCC. The results revealed that nano-silica had a significant effect at improving the HPFRCC bonding strength capacity with CC and steel reinforcement. Whilst increasing BFP dosage (4.5%) in the nano-modified composites resulted in reduction of the interfacial bonding with CC, it significantly improved the rebar interfacial bonding and ultimate shear key capacity of the joint. Comparatively, the inclusion of 1% micro-PVA fibers in the nano-modified composites comprising macro-BFP resulted in the highest increase in shear resistance force, interfacial bonding with precast CC and shear reinforcement dowels, and ductility which suggests their promising potential to be employed in shear key jointing applications.

Recent studies on the mechanical properties of Engineered Cementitious Composite

Engineered Cementitious Composite (ECC) is a type of High-Performance Fiber-Reinforced Cementitious Composite (HPFRCC) that has emerged as a promising material for use in construction and engineering. ECC is designed based on micromechanical theory, resulting in a remarkable tensile strain capacity of over 6%, while maintaining a low fiber volume fraction of no more than 2%. The material’s high flexibility enables it to be molded into various shapes, and it exhibits excellent mechanical properties, making it suitable for field applications such as the construction of joint-less deck slabs, link slabs, and retrofitting of critical structures like dams and tunnels. However, the accurate characterization of ECC’s properties requires the use of appropriate testing methods, particularly regarding its mechanical characteristics, including compressive strength, flexural strength, and direct and indirect tensile strength. This review highlights the significance of understanding ECC’s mechanical properties and emphasizes the importance of using appropriate testing techniques to evaluate the material’s properties and structural behavior.

Cyclic behavior of existing RC bridge piers strengthened by exterior ECC and BFRP/ECC composite jacketing at pier base

Engineered cementitious composites (ECC) are a class of high-performance fiber-reinforced cementitious composites. This study proposes using ECC and BFRP grid-reinforced ECC (BFRP/ECC) as external jackets at the base of existing RC bridge piers to enhance seismic performance. Seven 1/5-scale RC bridge piers were tested under reversed cyclic loading, including one unmodified pier as reference and six reinforced piers with varying jacket thickness, height, interface, and BFRP grid mesh size. The test results demonstrate that both ECC and BFRP/ECC composite jacketing effectively enhance ductility. The hysteretic response of the reinforced piers with different interfacial properties, however, varied significantly. The piers with interfacial shear keys exhibited enhanced flexural strength, ductility, and energy dissipation capacity but sustained severe damage as jacketing thickness and height increased. Conversely, the piers with smooth interfaces showed insignificant improvements in flexural strength but significant enhancement in ductility with marginal damage. This behavior can be attributed to the fact that the exterior jacketing in specimens with interfacial shear keys was under bi-axial tension-compression stress state due to flexural compression and lateral expansion of the plastic hinge, while the jacket in specimens with smooth interfaces acted solely as lateral confinement.

Effect of conductive surface-coated polyethylene fiber on the electrical and mechanical properties of high-performance fiber-reinforced cementitious composites

This study investigated the electrical conductivity and mechanical properties of high-performance fiber-reinforced cementitious composites (HPFRCC) with conductive coated ultra-high-molecular-weight (UHMW) polyethylene (PE) fibers. The silver nanoparticles with spherical shape were coated most evenly. Despite some parts of the fiber surface being less coated with carbon nanotube (CNT) and graphite nanofiber (GNF) compared to the silver nanoparticles, they effectively increased electrical conductivity of the plain PE fiber. Both the coating degree and conductivity of the coating material affect the conductivity of PE fiber. The compressive strength of HPFRCC was not affected by conductive coating. The electrical conductivity of HPFRCC improved by 18.7%–45.1% than the control specimen, and the highest electrical conductivity was achieved when coated with silver nanoparticles. Incorporating conductive coating fibers had a negative effect on tensile strengths (18.9–23.5% decreases) but a positive effect on the ductility. The GNF-coated PE fibers led to the strain capacity and energy absorption capacity improved by 69.4 and 44.8%, respectively. Therefore, given the increase in deformation performance outweighs the decrease in tensile strength, engineered, conductive coating fibers can be used as novel reinforcement in HPFRCC to attain additional functionalities related to electrical capabilities.

Strain Softening of High-Performance Fiber-Reinforced Cementitious Composites in Uniaxial Compression

This study investigates the strain softening behavior of high-performance fiber-reinforced cementitious composites (HPFRCCs) under uniaxial compression. HPFRCC mixtures with different compressive strengths ranged from 120 to 170 MPa were prepared. The measurement method of feedback control on loading rate based transverse displacement was applied. Stress–strain and stress−inelastic displacement curves were plotted and analyzed with the results in the literature. It was found that the post-peak energy absorption of HPFRCC considering inelastic deformation was about 3–7 times higher than conventional concrete. Based on the experimental results in the present work, fitting models on post-peak stress–strain/−displacement curves were considering for different aspect ratios proposed.

Assessment of Different Methods for Enhancing Progressive Collapse Resistance of Irregular Reinforced Concrete Buildings Using Pushdown Analysis

AbstractEnsuring structures meet rigorous structural requirements is paramount in mitigating progressive collapse risk. In this comprehensive investigation, we scrutinize the impact of four distinct mitigation techniques on the propensity for progressive collapse in a six-story building featuring irregular structural attributes. The study adheres to the concrete building construction code ACI 318-14 and evaluates methods that include: (a) reinforcing the reinforced concrete (RC) slab with high-performance fiber-reinforced cementitious composites (HPFRCCs), (b) enhancing the RC slab with carbon fiber-reinforced polymers (CFRPs), (c) incorporating steel plate shear wall (SPSW) within specific columns, and (d) introducing an innovative approach named as the steel belt strip (SBS). In the context of 10 independent column loss scenarios conducted on the first floor, the nonlinear dynamic analysis reveals that HPFRCC effectively reduces vertical displacement under the removed column by up to 99.89% in certain scenarios. Meanwhile, the use of CFRP layers leads to reductions of up to 95% in vertical displacement, but with variations in effectiveness across scenarios. Notably, the SBS technique demonstrates remarkable potential by reducing vertical displacement by 97%, 89%, and 25.9% in different scenarios. This reduction, in conjunction with the mitigation of axial load on adjacent columns, makes the SBS a standout performer. Moreover, pushdown analysis indicates that, with the employment of these mitigation methods, the maximum loading factor can be increased up to 2.14 times in specific scenarios, significantly enhancing the structure’s resistance to progressive collapse. This pioneering research not only bolsters the resilience of irregular RC buildings but also holds profound implications for industry standards, risk assessment, and construction technology innovation.

Seismic rehabilitation of existing RC school buildings with under-designed joints by means of reinforced jacketing of high performance fiber reinforced cementitious composite (HP-FRCC)

Seismic rehabilitation of existing RC school buildings with under-designed joints by means of reinforced jacketing of high performance fiber reinforced cementitious composite (HP-FRCC)

Cementitious Composites with Cellulose Nanomaterials and Basalt Fiber Pellets: Experimental and Statistical Modeling

The production of high-performance fiber-reinforced cementitious composites (HPFRCCs) as a durable construction material using different types of fibers and nanomaterials critically relies on the synergic effects of the two materials as well as the cementitious composite mixes. In this study, novel HPFRCCs were developed, which comprised high content (50%) slag by mass of the base binder as well as nano-silica (NS) or nano-crystalline cellulose (NCC). In addition, nano-fibrillated cellulose (NFC), and basalt fiber pellets (BFP), representing nano-/micro- and macro-fibers, respectively, were incorporated into the composites. The response surface method was used in this study’s statistical modeling part to evaluate the impact of key factors (NS, NCC, NFC, BFP) on the performance of 15 mixtures. The composites were assessed in terms of setting times, early- and late-age compressive strength, flexural performance, and resistance to freezing-thawing cycles, and the bulk trends were corroborated by fluid absorption, thermogravimetry, and microscopy tests. Incorporating NS/NCC in the slag-based binders catalyzed the reactivity of cement and slag with time, thus maintaining the setting times within an acceptable range (maximum 9 h), achieving high early- (above 33 MPa at 3 days) and later-age (above 70 MPa at 28 days) strength, and resistance to fluid absorption (less than 2.5%) and frost action (DF above 90%) of the composites. In addition, all nano-modified composites with multi-scale fibers showed notable improvement in terms of post-cracking flexural performance (Residual Strength Index above 40%), which qualify them for multiple infrastructure applications (i.e., shear key bridge joints) requiring a balance between high-strength properties, ductility, and durability.

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.

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.

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.

Investigation of constitutive models of HPFRCC subjected to static and dynamic loadings

High-performance fiber-reinforced cement composite (HPFRCC), an advanced construction material, has superior material properties than normal concrete. As concrete constitutive models, such as the Karagozian & Case (K&C) and continuous surface cap (CSC) models, are utilized in various numerical analyses of HPFRCC structures under static and dynamic loadings, here, calibration methods for these two constitutive models are suggested to describe the material behaviors of HPFRCC more precisely based on uniaxial and triaxial test data. Multi-element analysis of laboratory material tests is performed on the calibrated models with four different element sizes not only to examine their reliability but also to investigate their mesh-size dependency. Moreover, the differences in the performance of these models are analyzed in terms of their theoretical background, and numerical simulations are performed on the HPFRCC structures subjected to a low-velocity impact as well as near-field blast tests. By comparing the numerical and experimental results, the CSC model is found to exhibit strength for simulating crack distribution at low strain rates, whereas the K&C model shows reasonable predictions of the failure behavior of HPFRCC structures at high strain rates.

Blast Resistance Capacities of Structural Panels Subjected to Shock-Tube Testing with ANFO Explosive.

This study presents a series of shock-tube tests conducted on structural panels using ammonium nitrate fuel oil (ANFO) as the explosive. The characteristics of the blast waves propagating through the shock tube were analyzed by measuring the pressure generated at specific locations inside the shock tube. The extent of differences in blast pressure generated in a confined space, such as the shock tube, was compared to that predicted by the proposed method in the Unified Facilities Criteria 3-340-02 report. The target specimens of this study were plain reinforced concrete (RC), high-performance fiber-reinforced cementitious composites (HPFRCCs), and composite panels. Polyurea-coated RC panels and steel plate grid structure-attached RC panels were used as composite panels to evaluate the effectiveness of the coating and structural damping methods on the enhancement of structural blast resistance. The tests were conducted with different ANFO charges, and the crack patterns and lengths on the rear surface of each panel were measured. Based on the measured results, discussions regarding the blast resistance capacities of each panel type are provided.

Experimental Research on Axial Compression Performance of High-Performance-Fiber-Reinforced-Cement-Composite-Prefabricated Monolithic Composite Columns

In order to improve the mechanical properties of prefabricated monolithic composite columns, high-performance fiber-reinforced cement composite (HPFRCC) material was used to prefabricate mold shells and form a composite column with post-cast ordinary concrete. Axial compression tests were conducted on five HPFRCC-prefabricated shell composite columns and one RC prefabricated shell composite column to study the mechanical performances of prefabricated monolithic composite columns. The influences of the volume stirrup ratio, the longitudinal reinforcement ratio, and the shell material on axial compression performance were also studied. The results showed that using HPFRCC-prefabricated shells could improve the deformation performance of the composite column. The compressive strain corresponding to the yielding load of the HPFRCC-prefabricated formwork column was 23.85% higher than that of the RC-prefabricated shell composite column, and the compressive strain corresponding to the peak load increased by 26.72%. The longitudinal reinforcement ratio slightly affected the axial compression bearing capacity of the prefabricated shell composite column. Compared with ECCT−01, the peak load of ECCT−04 increased by 0.6%, and the peak load of ECCT−05 increased by 1.4%. As the volume stirrup ratio increased, the deformation performance of the HPFRCC-prefabricated composite column improved. Compared with ECCT−01, the compressive strain corresponding to the yield load and peak load of ECCT−02 increased by 24.21% and 7.33%, respectively. The compressive strain values corresponding to the yield load and peak load of ECCT−03 decreased by 25.58% and 24.01%, respectively.

Crack width prediction of self-healing engineered cementitious composite using multi-expression programming

Concrete structures are prone to cracking due to environmental damage and/or tensile strain. Self-healing concrete has garnered scientific interest in recent years as it addresses the cracking problem and extends the service life of concrete structures. Engineered cementitious composite (ECC), a high-performance fiber-reinforced cement composite, is known to have some self-healing characteristics. However, the self-healing capability of ECC is characterized by the type and content of input parameters and is difficult to predict. This investigation utilised a multi-expression programming algorithm for the prediction of self-healing characteristics of ECC containing various admixtures. The database, containing 619 points, was extracted from literature containing crack width before self-healing (CB), limestone powder (LP), silica fume (SF), and fly ash (FA) as input parameters and crack width after self-healing as an output parameter. The performance of the developed model was evaluated based on various statistical indices and parametric analysis. The results showed that the developed model is robust and efficient in predicting the self-healing behavior of ECC containing various admixtures. Parametric and sensitivity analysis revealed that among the admixtures used, fly ash had the least impact and limestone powder had the highest impact on the self-healing capacity of ECC.

Interfacial Bonding between Basalt Fiber/Polymer Pellets and Various Nano-Modified Cementitious Matrices

In fiber-reinforced cementitious composites, the fiber/matrix interfacial bonding is a governing factor for bridging cracks, load transfer, and toughening mechanisms. Basalt fiber pellets (BFP) are a novel form of macrofibers consisting of basalt fiber strands encapsulated by a polymeric resin, with textured microgrooves, which can be used to produce high-performance fiber-reinforced cementitious composites (HPFRCC). Hence, the current study focused on the synergetic evaluation of the flexural performance and single pellet pull-out of BFP in homogenized nano-modified [nano-silica (NS); nano-crystalline cellulose (NCC)] cementitious matrices, without/with micro [polyvinyl alcohol fibers (PVA)], or nano-fibers [nano-fibrillated cellulose (NFC)]. Integrated experimental and modeling studies were conducted to evaluate the effect of BFP interfacial bonding with various nano-modified cementitious matrices. Key results showed that NS-modified matrices led to improvement by 17% and 5%, respectively, in terms of bonding strength with BFP and debonding energy, compared with matrices comprising NCC. Reduction of BFP interfacial bond strength and debonding energy by 11% and 10% was observed for cementitious matrices comprising NCC and reinforced with NFC, relative to mixture G-NCC. Conversely, using PVA fibers in matrices comprising NS led to noticeable enhancement of bonding with BFP (highest bonding strength and debonding energy), which suggests their promising potential for field applications requiring HPFRCC.

Dynamic structural responses of high-performance fiber-reinforced cement composites panels subjected to high-velocity projectile impact loadings

Dynamic structural responses of high-performance fiber-reinforced cement composites panels subjected to high-velocity projectile impact loadings

Progressive collapse assessment of reinforced concrete (RC) buildings with high-performance fiber-reinforced cementitious composites (HPFRCC)

The susceptibility of concrete beam-column joints in reinforced concrete (RC) frame structures to progressive collapse can result in severe damage or collapse. High-performance fiber-reinforced cementitious composites (HPFRCCs), as a strain-hardening material, can be used instead of ordinary concrete to improve RC frame buildings' performance. This study evaluates the effects of using HPFRCC in beam-column joints on the behavior of RC frame structures subjected to progressive collapse. Five RC buildings with moment-resisting frame systems were studied for this purpose, one with ordinary concrete beam-column joints and the others with HPFRCC beam-column joints and varying quantities of reinforcement on beams and columns. The buildings were evaluated using 3D modeling with OpenSees finite element software and removing a corner column using the alternative load path method (ALP) per GSA regulations. The results show that using HPFRCC in beam-column joints can improve the robustness of RC frame buildings to progressive collapse by increasing beam-column joint stiffness, load-bearing capacity, and the ability to withstand large deformations. Furthermore, damages caused by the sudden removal of corner columns in buildings reveal that the use of HPFRCC in beam-column joints results in a reduction in damages, even in buildings with a reduced quantity of reinforcements (buildings H1 and H2), even though a significant decrease in the number of longitudinal reinforcements of beams and columns in the building with HPFRCC beam-column joints (building H3) can result in severe damage to the connections.

A framework for improving bridge resilience and sustainability through optimizing high-performance fiber-reinforced cementitious composites

High-performance fiber-reinforced cementitious composites (HPFRCC) exhibit benefits in improving infrastructure resilience but often compromise sustainability due to the higher upfront cost and carbon footprint compared with conventional concrete. This paper presents a framework to improve bridge resilience and sustainability through optimizing HPFRCC. This research considers ultra-high-performance concrete and strain-hardening cementitious composite, both featuring high mechanical strengths, ductility, and damage tolerance. This paper establishes links between bridge resilience, bridge sustainability, mechanical properties of HPFRCC, and mixture design. The investigated mechanical properties include the first crack stress, the ultimate tensile strength, and the ultimate tensile strain. With the established links, sustainability is maximized while resilience is retained by optimizing HPFRCC mixtures. The framework is implemented into a case study of a bridge that collapsed during construction. Results show that use of HPFRCC enhances resilience, and HPFRCC mixtures can be engineered to minimize the material cost and carbon footprint while retaining high resilience.