High-performance Fiber-reinforced Cementitious Composites Research Articles

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.

Impact simulations for high-performance fiber-reinforced cement composites using a coupled finite element and smoothed particle Galerkin method

This paper presents a projectile impact analysis of high-performance fiber-reinforced cement composite (HPFRCC) structures based on the coupling of the finite element method (FEM) and the smoothed particle Galerkin (SPG) model in the LS-DYNA program. The K&C material model is calibrated for the HPFRCC. Through a quasi-static analysis using the calibrated model, the criteria for the element size of a FEM and the nodal particle distance of the SPG model are determined. Numerical simulations of the coupled SPG-FEM model are conducted to predict the structural responses of HPFRCC structures subjected to high impact velocities ranging from 342 m/s to 808 m/s. The results for the coupled model are compared with experimental data as well as numerical results for a pure FEM model to determine the relative accuracy and efficiency of a coupled FEM and SPG model for the large deformation problem. The convergence of the numerical results is also investigated in terms of the residual velocity and penetration depth. Moreover, the effects of various parameters on the models are discussed through a sensitivity analysis, and suitable parameter ranges that improve the accuracy of the numerical results are suggested.

Seismic behavior of high-performance fiber reinforced cementitious composites columns with limited reinforcement details

Many older reinforced concrete (RC) buildings were designed considering only gravity loads. The column members in such buildings could be vulnerable to earthquakes, as they have limited reinforcement details. The aim of this study was to enhance the cyclic behavior of older RC columns using high-performance fiber reinforced cementitious composites (HPFRCCs) comprising polyvinyl alcohol (PVA) fibers. Six–full scale column specimens were constructed and tested. The use of the HPFRCC improved the seismic behavior of columns and also delayed the onset of damage stares and of lap–splice failure.

Robustness assessment of RC frame buildings with HPFRCC subjected to progressive collapse

Beam-column joints are one of the most critical components of RC structures, affecting the structure's performance under different types of loads. In recent years, some researchers have considered high-performance fiber-reinforced cementitious composites (HPFRCCs) as an alternative to conventional concrete for improving the performance of beam-column joints. The effects of HPFRCC materials on the robustness of reinforced concrete structures subjected to progressive collapse were investigated in this study. To this end, the method proposed by Fascetti et al. was utilized to assess the robustness of three five-story RC buildings with a moment-resisting frame system. The buildings were designed as special moment frames (SMF), intermediate moment frames (IMF), and intermediate moment frames with HPFRCC at joints (IMF-H) per ACI 318–14. The OpenSees finite element platform has been widely used for 3D buildings simulation and nonlinear analysis. In this study, the analyses and calculated robustness indices indicated that using HPFRCCs materials in beam-column joints significantly improved the robustness of concrete moment frames subject to progressive collapse. Furthermore, the damage distribution based on plastic rotation results confirmed that the robustness of concrete moment frames with HPFRCC joints subjected to progressive collapse was significantly improved.

Validated Uniaxial Stress–Strain Model for Cyclic Analysis of High-Performance Fiber-Reinforced Cementitious Composites

Validated Uniaxial Stress–Strain Model for Cyclic Analysis of High-Performance Fiber-Reinforced Cementitious Composites

Effect of Twisted and Coiled Polymer Actuator (TCPA) on Crack Dispersion Properties of HPFRCC.

To achieve high durability and excellent mechanical performances of cementitious materials, research on fiber-reinforced cementitious composites (FRCC) containing various fibers has been actively conducted. On the other hand, in robotics and other fields, research on artificial muscles using Twisted and Coiled Polymer Actuator (TCPA), which have similar functions to human muscle fibers, has attracted much attention. In this study, use of this TCPA as a reinforcing fiber in high performance FRCC (HPFRCC) was proposed. The employed TCPA has a structure of coiled nylon fibers with wrapping stainless-steel fibers. The effect of the TCPA and its shrinkage motion on the crack dispersion properties of HPFRCC was investigated. The experimental results showed that the strain-hardening with multiple cracks in HPFRCC continued up to more than 7% of the ultimate strain when the TCPA was electrically stimulated to shrinkage motion. This information indicates that the TCPA has high potential to further improve HPFRCC performance.

Effect of crack width on electromagnetic interference shielding effectiveness of high-performance cementitious composites containing steel and carbon fibers

In this study, the effects of carbon fibers and crack widths on the electromagnetic interference (EMI) shielding effectiveness of high-performance fiber-reinforced cementitious composites (HPFRCCs) with 2 vol.% straight steel fibers were evaluated. To this end, 0.2 vol.% carbon fibers were added and four penetrated pre-crack widths ranging from 0.02 to 0.2 mm were applied under tension. The tensile strength and electrical resistance of the composites were also investigated. The test results indicated that adding 0.2% carbon fibers effectively enhanced the tensile strength, electrical conductivity, and shielding effectiveness of the HPFRCC. Furthermore, the electrical conductivity was improved by 224%, and a 27% higher shielding effectiveness was achieved. A shielding effectiveness of 48.5 dB at 1 GHz was achieved with a specimen thickness of 25 mm. Tiny cracks with a width of 20 μm significantly reduced the EMI shielding effectiveness of the HPFRCC by approximately 40%. For the plain HPFRCC, the shielding effectiveness was not significantly affected by the crack width, as it was thoroughly cracked. The benefits of adding carbon fibers for improving the shielding effectiveness disappeared at crack widths greater than 0.1 mm. Thus, the addition of carbon fibers was effective only for HPFRCCs without cracks or with very tiny cracks of less than 40 μm.

Testing the anti-explosion protection of HPFRCC for ready-mixed concrete system based on fiber selection and resistance to live explosives

The aim of the research is to evaluate the anti-explosion protecting performance with proper workability of high-performance fiber-reinforced cementitious composites (HPFRCCs) with combined fibers when exposed to live explosives such as those used in warfare and terrorist attacks. Various types of fiber-reinforced cementitious composites with high-energy absorption have been studied and determined resistant to explosions. However, because of difficulty of executing in-field tests using live explosives, the experimental data regarding these types of tests are difficult to be obtained and they are reported insufficiently. The data provided in this research regarding HPFRCC resistance to live explosives, is based on explosion tests conducted to test HPFRCC with various fiber combinations and contents. Binary fibers of long steel and organic fibers achieved desirable anti-explosion protection with synergetic effects from two different fibers with relatively less adverse effects on fundamental performances of fluidity, air content, and compressive strength. This research is expected to contribute on providing the explosion test data for combined fiber HPFRCC under conditions that can assist in providing both a sufficient protection for concrete structures under wide ranged explosions not only military and terrorist attacks, but also industrial accidents, and an enough workability to use with ready-mixed concrete system.

Optimum percentage of steel fibres of HPFRCC for reduction of transverse reinforcement in beam–column joints

Reinforcement congestion causes problems during construction, including improper concrete pouring and concrete vibration. In this study, the replacement of normal concrete by high-performance fibre-reinforced cementitious composites (HPFRCC) has been investigated in order to reduce the amount of transverse reinforcement and prevent reinforcement congestion in beam–column joints. Uniaxial compression and tension tests were used to determine the mechanical properties of HPFRCC materials. In order to investigate the effects of HPFRCC on improving and upgrading the joint strength, five half-scale exterior beam–column joint connections were tested under incremental cyclic lateral loading. The tested specimens consisted of two normal concrete control specimens with and without specific seismic details and three specimens of HPFRCC with different percentages of steel fibres. The cracking patterns, hysteresis behavior, bearing capacity, energy absorption and damping percentage of all test specimens were analysed and compared with the response of normal concrete specimens. Results show that the use of HPFRCC materials in the joint area improves seismic behavior and significantly increases load-bearing capacity, energy absorption and ductility. Moreover, it prevents the shear failure of the joint and the formation of the flexural plastic hinge in the beam.

Improving the tensile resistance at high strain rates of high-performance fiber-reinforced cementitious composite with twisted fibers by modification of twist ratio

This study aims to examine effects of twist ratio on the tensile resistance at high strain rates and strain rate sensitivity of high-performance fiber-reinforced cementitious composites (HPFRCCs) with a small amount of twisted fibers. Two types of twisted steel fibers with different twist ratios, T3-fibers (3 twists/30 mm) and T9-fibers (9 twists/30 mm), were incorporated at 1% by volume into two matrices with different matrix strengths, M1 (56 MPa) and M2 (84 MPa). The direct tensile test results indicated that HPFRCCs with 1% twisted fibers generated not only high tensile resistance at high strain rates but also great rate sensitivity by maintaining tensile strain hardening accumulated with multiple micro cracks at high strain rates. T9-fibers produced the highest tensile resistance at high strain rates in M1 whereas T3-fibers did in M2. In addition, T9-fibers exhibited lower rate sensitivity than T3-fibers in all matrices. Theoretical models have been used successfully to predict dynamic post cracking strength of HPFRCCs with twisted fibers considering number of twists and the predicted results showed good agreements compared to the experimental results.

Rheological and Mechanical Properties of High-Performance Fiber-Reinforced Cement Composites with a Low Water-Cement Ratio.

High-performance fiber-reinforced cement composites (HPFRCCs) have been widely used in structural engineering due to their excellent performance. With the trend of lightweight construction, these materials, which can be used in prefabricated components, are becoming more and more important. This study investigated the influence of the water–cement (w/c) ratio, within the 0.19–0.28 range, on the rheological and mechanical properties of HPFRCCs; the pore structure and microstructure were observed to evaluate its effect. An elastic modulus test showed that a smaller w/c ratio would result in a higher rigidity of the material. Both the yield shear stress and plastic viscosity decreased to significantly different degrees with an increasing w/c ratio; a decrease in the yield shear stress and plastic viscosity was conducive to air discharge from the composite and, hence, reduced the air content. Most of the internal pores had a diameter of 20–100 nm or larger than 200 nm, while the proportion of those with a diameter of 100–200 nm was relatively low. When the w/c ratio was below 0.22, the flexural and compressive strengths barely increased due to an increment in the number of larger pores (i.e., diameter >200 nm). The results showed that the yield shear stress, plastic viscosity, pore uniformity, and the number of pores with a diameter above 200 nm are the dominant factors affecting the HPFRCC performance at a low w/c ratio.

Experimental determination of sectional forces in impact tests: Application to composite RC-HPFRCC beams

The impact response of concrete structures differs significantly from the quasi-static behaviour due to strain rate influence on mechanical properties, formation of inertia forces and local damaging mechanisms. The time-variable acceleration of the impacted element leads to inertia forces which produce a time-dependent distribution of shear forces and bending moments. The failure mode of impacted elements is significantly affected by the distribution of sectional forces and a detailed study of such forces is therefore convenient for a full understanding of impact mechanics. One of the most extended approaches to study experimentally the impact behaviour of reinforced concrete (RC) beams is with the help of instrumented drop weight testing machines. Such facilities usually incorporate dynamic load cells to measure the support reactions and the impact force. Though the resulting inertia force can be derived by difference of reactions and impact force, its distribution cannot be determined, which is necessary for the estimation of sectional forces. In the present paper, an experimental methodology based on digital image correlation (DIC) supported by a high-speed and high-resolution camera is presented. The proposed methodology provides an accurate estimation of inertia forces which allows deriving the time-dependent evolution of shear forces and bending moments. The methodology is applied to an experimental campaign consisting of RC beams strengthened with a thin layer of high-performance fiber-reinforced cement composite (HPFRCC). The impact response of composite RC-HPFRCC elements is analyzed by examining the shear forces and bending moments at the critical sections. The implemented DIC-based methodology allows understanding the critical instants of the tests which lead to shear cracking. Moreover, a shear strength model is presented to estimate the capacity of studied RC-HPFRCC elements.

A Comparative Study on the Shear Behavior of UHPC Beams with Macro Hooked-End Steel Fibers and PVA Fibers.

Structural members made of ultra-high-performance concrete (UHPC) have been attractive to engineers and researchers due to their superior mechanical properties and durability. However, existing studies were focused on the behavior of UHPC members reinforced with micro straight steel fibers at a volume fraction between 1 and 3%. There is a lack of studies on the influence of different types and amounts of fibers on the shear behavior of UHPC structural members. The objective of the study was to experimentally investigate the shear behavior of UHPC beams with macro hooked-end steel (MHS) fibers and polyvinyl alcohol (PVA) fibers, which are two of the most used fibers for high-performance fiber-reinforced cementitious composites. The shear behavior of ten large-scale non-prestressed UHPC beams was studied. The experimental parameters included the shear span-to-effective depth ratio, the fiber volume fraction, and the type of fibers. It was found that both MHS fibers and PVA fibers were effective in enhancing the shear performance of the UHPC beams whether the shear transfer mechanism was governed by arch action or beam action. Moreover, the measurement results of the average crack spacing imply the distinct difference in the fiber bridging effects of the MHS fibers and PVA fibers in the UHPC beams.

Efficiency of high performance fiber reinforced cementitious composites as a retrofit material for fire-damaged concrete

In this paper, high performance fiber reinforced cementitious composites (HPFRCC) confinement jackets were proposed to investigate its effectiveness in retrofitting and strengthening fire-damaged concrete (FDC) cylinders. Sixteen normal strength concrete (NSC) cylinders were heated at 600 °C for 2 h. Six mixtures, three with different water-binder (w/b) ratios and three with varying fiber contents by volume, were engineered to provide 40 mm HPFRCC jackets round the FDC specimens and examined under axial compression load. The laboratory findings show that the w/b ratio and fiber content significantly affect the strength restoration of retrofitted specimens. It was observed that the specimens with the highest fiber content and lowest w/b obtained the maximum restoration capacity by 335% and with better ductility performance in all retrofitted specimens. It was also observed that the core FDC lateral strain decreased with increment in volume of steel fiber at the same axial strain level, suggesting increased deformability with energy absorption of retrofitted specimens. The study observation indicates the tremendous promise of using HPFRCC as a retrofit material for structural members, particularly columns damaged by fire.

Summary of findings on magnetic orientation of fibers in cement composites

This article summarizes the findings in newly developed technology – Magnetic Orientation of Fibers (MOF). New incoming technology MOF can easily and effectively reinforce concrete elements in a specific direction with ferromagnetic fibers using a magnetic field. Using this technology, it is possible to provide the required orientation of steel ferromagnetic fibers in a fresh mixture of High-Performance Fiber Reinforced Cementitious Composite (HPFRC) with the help of a magnetic field. This article aims to inform about the existing research that deals with this technology. It summarizes the experiments performed, the development of magnetic field generation devices and fiber alignment measurement equipment.