Fiber Reinforced Cement Composites Research Articles

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.

Special Issue on Advanced Fiber-Reinforced Cementitious Composites

Fiber-reinforced cementitious composites (FRCC) have emerged as a promising alternative to traditional cementitious materials due to their enhanced mechanical properties and durability [...]

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.

Multiphysics processes in the interfacial transition zone of fiber-reinforced cementitious composites under induced curing pressure and implications for mine backfill materials: A critical review

Multiphysics processes in the interfacial transition zone of fiber-reinforced cementitious composites under induced curing pressure and implications for mine backfill materials: A critical review

Effect of micro steel fibre contents on compressive and self-sensing properties of polyethylene fibre-reinforced cement composite (PE-FRCC) in cyclic compression

This study is conducted to develop a cement-based strain-detecting sensor with high cost-effectivity, large strain measuring range and good compatibility with concrete infrastructures. The paper describes experimental results on the compressive properties and piezoresistive behaviour of polyethylene(PE) fibre-reinforced cement composite(PE-FRCC) with different contents of micro steel fibres (SFs) under cyclic compression. The synthetic PE fibres were added into cement-based mortar to improve the strain capacity in compression and micro SFs at 0.25-1.5% by volume fraction of cement were incorporated to improve the compressive properties and electrical conductivity. Test results show that for the PE-FRCC with compressive strength of 32MPa, the increase in the micro SF content to 0.5% increased about 45% in the compressive strength compared to PE-FRCC without SFs. The addition of micro SFs into PE-FRCC improved the compressive properties, such as modulus of elasticity and lateral confinement. The incorporation of micro SFs is also effective to reduce the signal noise in the relationship between fractional change in resistance (FCR) and axial strain of PE-FRCC. PE-FRCC sensor with more 1.0% micro SF (PE0.75+SF1.00 composite) possess a strong linear relationship between FCR and axial strain during repeated compression at different stress amplitudes.

State-of-the-art review of physical and mechanical properties of natural fibre-reinforced cementitious matrix composite

State-of-the-art review of physical and mechanical properties of natural fibre-reinforced cementitious matrix composite

Flexural Behavior of PVA Fiber Reinforced Cement Composites Modified by Graphene Oxide Nanoflake by DIC Technique

Flexural Behavior of PVA Fiber Reinforced Cement Composites Modified by Graphene Oxide Nanoflake by DIC Technique

The influence of water-cement ratios and alumino-silicate based accelerator on the properties of fiber-reinforced cement composites

Due to more strict environmental protection and greenhouse gas reduction, it is very important for all industries to appropriately manage their energy consumption. Fiber- reinforced cement composites are the popular building materials which consume enormous energy to intensify its chemical reaction during the autoclave steam curing process. Utilization of chemical admixture to replace the conventional energy-driven autoclave steam curing process will support the fiber- reinforced cement composites industry to develop sustainable building materials. In this research, typical and mechanical properties of the air-cured fiber- reinforced cement composites incorporated with alumino-silicate based accelerator were investigated. The results show an excellent positive correlation between the water-cement ratio of the mix design and the mechanical strength which is the optimum water-cement ratio for this FRCC are 0.53. Moreover, the properties of fiber- reinforced cement composites cured by either the autoclave steam curing process or air-curing process are comparable.

Crack propagation analysis and mechanical properties of basalt fiber reinforced cement composites with changing fiber surface characteristics

The large-scale application of basalt fiber reinforced cement composites (BFRCC) is due to the relatively high performance and decreased CO2 footprint of basalt fiber. Still, the ultimate tensile strain of BFRCC is always difficult to exceed 1%, hindering its popularity. Chemical grafting on the basalt fiber surface is a promising way to deal with the such drawback. The crack propagation mechanism of BFRCC is also unclear. Thus, the influence of fiber interface characteristics on the tensile failure mechanism of BFRCC is analyzed. The main work of this study is to achieve ultra-high toughness BFRCC with ultimate tensile strain exceeding 2% through chemical modification of fiber surface. The decrease in bonding strength has little effect on the water absorption of BFRCC but can improve its compressive and tensile properties to 1.88 times and 1.95 times. The crack resistance mechanism of modified BFRCC was revealed. The results showed that the average crack propagation speed of modified BFRCC was one order of magnitude lower, and the initiation energy threshold and crack propagation energy were higher. Proper interfacial bonding strength and high sliding friction coefficient can suppress the cracking width and fiber breaking rate.

Crack detection and classification of repaired concrete beams by acoustic emission monitoring

In this study, acoustic emission (AE) monitoring was used to investigate the cracking behavior of normal concrete beams repaired with fiber-reinforced cementitious composites (FRCC). The investigated beams were strengthened at two locations: tension side and compression side of the beam. Two different fibers were used in FRCC strengthening material: steel fibers and polyvinyl alcohol fibers. One normal concrete beam and two fully cast FRCC beams were also tested for comparison. All beams were tested under four-point loading until failure. The investigation considered the variations in several AE parameters such as number of hits, cumulative signal strength, signal amplitude, peak frequency, absolute energy, and b-value analysis. In addition, rise time/amplitude analysis was successfully utilized in this study to classify the failure modes (flexural or shear/debonding failure between the repair layer and existing beam) for all beams. The impact of the fiber type, strengthening location, and sensor location on the aforementioned parameters was clearly highlighted. Varying the fiber type of the FRCC or changing the repair location of the beam seemed to have a significant impact on the resulting AE parameters. A good correlation was found in repaired and unrepaired beams between AE parameters and the progression of cracks beyond the first crack until failure. The results also indicated that the AE analysis carried out in this study led to the identification of the first crack in repaired and unrepaired beams.

Enhancing thermoelectric performance in carbon fiber-reinforced cement composites through boron doping

Although carbon fiber-reinforced cements (CFRCs) have the potential for ambient energy harvesting, their low thermoelectric performance restricts their practical application in construction. In this study, we investigate the possibility of using boron doped carbon fibers to improve the thermoelectric performance of cement composites. The electrical conductivity of a single carbon fiber was significantly enhanced, reaching a value of 272.1 × 102 S/cm despite the limited amount of boron doping. This was due to the formation of highly aligned, dense, thin, and long domains within the carbon fibers, which facilitated electron flow. The pristine carbon fiber's hydrophilic surface retarded the hydration reaction, while the boron-doped carbon fiber's hydrophobic surface had a diminished impact on the hydration products. The highest power factor of 0.02 μW/mK2 in cement composites was attained by incorporating boron doped carbon fibers, which exhibit outstanding electrical conductivity, into the cement matrix.

Graphene and its application: A review

The extraordinary properties of graphene have been acknowledged as an efficient reinforcement for cementitious composites, enabling the construction of more clever, durable, and long-lasting building materials. Graphene-based reinforcing fillers, however, are unable to be directly included into cementitious composites for industrial manufacture due to dispersion problems and high prices. Therefore, it seems that commercialising graphene for cementitious materials may be more feasible if it were combined with ordinary fibres to reinforce cement. Recent research findings on the use of graphene in fiber-reinforced cementitious composites were evaluated critically and synthetically in this review study. First, the processes for producing and describing hybrid graphene-fiber fillers are discussed. Then, a summary of mechanical reinforcing mechanisms is presented, emphasising the significant contributions made by the nucleation effect, filling effect, interfacial bonding effect, and toughening effect. The study continues by describing in detail the enhancements made to the mechanical, electrical conductivity, electromagnetic interference shielding, and multifunctional interfacial properties of graphene-fiber reinforced cementitious composites. Finally, key challenges likely consequences are examined in order to provide useful recommendations and provide guidance for applicable future studies.

Multifunctional properties of carbon fiber integrated cement composite – A review and insights

This article examines the strength characteristics of carbon fiber-reinforced cement composite (CFRCC). The research explores the residual mechanical characteristics and microstructure of concrete reinforced with carbon fiber. The review also focused on the determination of the effect of CFRCC on the improvement of strength, microstructure, crystalline phase shift, and hydration products of the cement composites. The review indicates that the inclusion of carbon fibers can intensify the flexural and splitting strengths of CFRCC, but the compressive strength is magnified to a lesser extent. In addition to the initial elastic modulus and peak stress of carbon fiber-reinforced cement composite, a discernible strain-rate hardening effect was also observed. This indicates that carbon fiber-reinforced cement composite has a promising future as cement composite reinforcements. The review of the characteristics of the composites also suggests their applicability in tunnel building in the cement composite. It is determined that carbon fiber-reinforced cement composite has a stronger capacity to withstand impact loads, and further information about its features will be supplied. The scanning electron microscopy (SEM) result demonstrates that the single and most significant failure mode under stress is carbon fiber breaking and the pull-out of carbon fibers. Thus, the review reveals that carbon fibers have a limited but positive act on enhancing the mechanical properties of cement composites.

Modelling Fibre-Reinforced Concrete for Predicting Optimal Mechanical Properties.

Fibre-reinforced cementitious composites are highly effective for construction due to their enhanced mechanical properties. The selection of fibre material for this reinforcement is always challenging as it is mainly dominated by the properties required at the construction site. Materials like steel and plastic fibres have been rigorously used for their good mechanical properties. Academic researchers have comprehensively discussed the impact and challenges of fibre reinforcement to obtain optimal properties of resultant concrete. However, most of this research concludes its analysis without considering the collective influence of key fibre parameters such as its shape, type, length, and percentage. There is still a need for a model that can consider these key parameters as input, provide the properties of reinforced concrete as output, and facilitate the user to analyse the optimal fibre addition per the construction requirement. Thus, the current work proposes a Khan Khalel model that can predict the desirable compressive and flexural strengths for any given values of key fibre parameters. The accuracy of the numerical model in this study, the flexural strength of SFRC, had the lowest and most significant errors, and the MSE was between 0.121% and 0.926%. Statistical tools are used to develop and validate the model with numerical results. The proposed model is easy to use but predicts compressive and flexural strengths with errors under 6% and 15%, respectively. This error primarily represents the assumption made for the input of fibre material during model development. It is based on the material's elastic modulus and hence neglects the plastic behaviour of the fibre. A possible modification in the model for considering the plastic behaviour of the fibre will be considered as future work.

On crack healing in fiber-reinforced cementitious composites incorporating mineral-based healing agent and superabsorbent polymer: Evaluation using modified permeability test method

In this study, the crack healing properties of fiber-reinforced engineered cementitious composites (ECCs) under incremental strains, various fiber contents, and incorporation of a mineral-based self-healing agent (SHA) and a superabsorbent polymer (SAP) were evaluated. A permeability test setup applicable to plain mortar samples was modified to evaluate the fiber-reinforced ECC samples under several strains and crack widths. Supplementary self-healing tests—resonant frequency (RF) recovery, stiffness recovery, and crack image inspection—were also conducted. Changes in the permeability, RF, stiffness, and crack images were monitored for 28 days after sample cracking, to evaluate self-healing. The findings showed that the permeability reduction of the ECCs was significantly influenced by the fiber content instead of by the addition of the SHA and the SAP. In addition, the SAP particles were observed to improve the self-healing properties of the ECC samples.

Application of fiber reinforced cement composites in rigid pavements: A review

Concrete that has been reinforced with fibers has more structural integrity. It has uniformly distributed, short discrete fibers that are randomly orientated. The volume of fibers, the aspect ratio of the fibers, and other variables all have an impact on the flexural strength of FRC. In this essay, each of the criteria is covered. Carbon dioxide pollution in the atmosphere is attributed to cement manufacture. According to studies, producing one ton of cement results in the release of nearly half a ton of CO2 into the environment. In order to lower carbon footprints and create sustainable pavements, the cement content must be decreased. Due to the enormous design thickness required by conventional plain cement concrete, it is necessary to increase the flexural strength of concrete to reduce pavement thickness. Concrete's flexural strength is increased by the addition of fibers, and pavement design thickness is decreased. Cement use and CO2 emissions will decrease with a reduced design thickness. As a result, the application of FRC can significantly lower the carbon emissions of pavement per unit area linked to the manufacture of materials. Calculations of the cost of paving per unit area reveal that Glass Fibers, Polypropylene Fibers, and Hooked Steel Fibers are more cost-effective reinforcement options. The paper reviews the academic literature on fiber-reinforced concrete through a methodical literature study A keywords analysis is done to find out the most focused fiber. This study describes several fiber kinds and their impact on the mechanical characteristics of concrete. The characteristics of steel, plastic, synthetic, recycled, and natural fibers are widely covered in this essay. A comparative examination of several fiber kinds at various replacement percentages is carried out. The economic and environmental advantages of FRC in rigid pavements are discussed.

Self-healing capacity of ultra-rapid-hardening fiber-reinforced cementitious composites under tension

This study investigates the self-healing capacity of ultra-rapid-hardening fiber-reinforced cementitious composites. For this purpose, polyethylene (PE) fibers with three different lengths (6, 9, and 12 mm) were incorporated with different volume fractions of 1.0, 1.5, and 2.0%. All test series were pre-damaged with 0.5 and 1.0% pre-strains and re-tested after 30 wet-dry healing cycles. The fiber reinforcing index was proportional to the tensile performance regardless of the pre-strain and the length of the PE fiber was more dominant than the volume fraction. The case in which self-healing occurred most appropriately was for specimens that incorporated 2% of medium-length (9 mm) fibers. Thirty wet-dry cycles improved the tensile strength by up to 47.5% compared to the conventional one, while the strain capacity was reduced, resulting in a recovery ratio of only 74.5%. The energy absorption capacity was sufficiently recovered to be comparable to that of the control specimen and excellent strain-hardening behavior was obtained with a sufficient number of additional microcracks. Microcracks with widths of less than 50 μm were filled significantly with the formation of CaCO3 crystals, which was verified by scanning electron microscopy and energy dispersive X-ray spectroscopy.

An Overview of the Application of Fiber-Reinforced Cementitious Composites in Spray Repair of Drainage Pipes

The structural performance of buried drainage pipes is gradually deteriorating under the influence of external loads and chemical and microbial corrosion. It is crucial to reinforce them and improve their bearing capacity for safe use. One of the important technologies used to extend the service life of deteriorated pipes is the use of fiber-reinforced cementitious composites (FRCC) for spray repair. Combined with the current situation of drainage pipes, this article introduces the basic properties of FRCC, briefly describes the requirements for material performance for drainage pipe spraying rehabilitation, reviews the structural bearing capacity of drainage pipes repaired by spraying with FRCC, and discusses the relevant research and engineering applications of the spraying method. Studies show that FRCC has high strength and corrosion resistance, and excellent sprayability. The structural performance of the host pipe is significantly improved after repair, but measures should be taken to enhance the interfacial bonding performance during the repair. In the design of the liner wall thickness, there is no unified calculation theory, and the existing methods have not considered the influence of secondary load on the structure. It is recommended to combine the type of pipe defects and the degree of deterioration in further study.

A Comparative Study on Electrical Resistivity and Compressive Strength Properties of Cement Composites Incorporating Conductive Materials

Conductive cement composites have attracted high attention in recent years due to the possibility of achieving multifunctional materials. The usual approach has been to incorporate steel fiber, carbon fiber, graphite, and carbon nanotube/or carbon nanofiber into the cement matrix. In this article, an experimental comparative study was conducted on the electrical resistivity and compressive strength properties of cement composites incorporating carbon fiber (CF) and steel fiber (SF), which are conductive materials. The electrical resistivity of the conductive fiber-reinforced cement composites (FRCCs) was measured using the four-probe method, and compressive strength was conducted based on the KS L ISO 679 and ASTMC109/C109M test methods. Their performance was compared and analyzed with plain cement composites (PCCs). Afterwards, the fracture surfaces of the conductive SFRCCs (steel fiber-reinforced cement composites) and CFRCCs (carbon fiber-reinforced cement composites) were also analyzed using a scanning electron microscope (SEM). The experimental results showed that, in all specimens, the electrical resistivity gradually increased as the curing ages elapsed, while the electrical resistivity decreased significantly as the fiber volume fractions increased. Overall, the addition of SF up to a fiber volume fraction of 1.25% did not significantly affect the electrical resistivity of cement composites. In contrast, however, the electrical resistivity of CF decreased slightly even at a low dosage (i.e., 0.1–0.3%), and thereafter, it was significantly decreased. The percolation threshold of the conductive CFRCC incorporating CF used in this experiment was 0.4%, and this seemed to be the optimal CF dosage that can greatly improve the conductive cement composites while maintaining the maximum performance of compressive strength. In addition, the compressive strength of conductive SFRCC was higher than that of PCC, whereas in the case of conductive CFRCC, it showed a greater tendency to decrease significantly as the fiber volume fractions increased. We expect the results of SEM image analysis to be useful as basic data for establishing microstructure mechanisms of reinforcement fibers in the cement matrix.

Effect of Elevated Temperature on the Behavior of Amorphous Metallic Fibre-Reinforced Cement and Geopolymer Composites

To improve the tensile, flexural, and ductility properties of geopolymer composites, amorphous metallic fibres (AMF) are used to reinforce these composites, and the behavior of these composites at elevated temperatures has been assessed in this study. Four types of composites, i.e., cement, reinforced cement, geopolymer, and reinforced geopolymer composites have been prepared. The composites have been reinforced using AMF with a fibre volume fraction of 0.75%. The composites have been assessed for change in mass loss, cracking, compressive strength, and flexural strength at four elevated temperatures of 200 °C, 400 °C, 600 °C, and 800 °C, and conclusions have been drawn concerning these composites. The results have shown that an increase in temperature has an adverse effect on these composites, and geopolymer composites exhibit higher performance than their counterpart cement composites at elevated temperatures. The mass loss and surface cracking were significantly lower in geopolymer composites, and the fibre reinforcement had a negligible effect on mass loss. Also, the residual compressive and flexural strength of reinforced geopolymer composites was significantly higher than that of the reinforced cement composites. In addition, scanning electron microscopic images also showed that even at higher temperatures, the geopolymer matrix is present on the AMF fibre, which results in higher residual strength than the cement composites in which a negligible amount of matrix is present on the fibres.