Reduced Crack Widths Research Articles

Self-healing performance of engineered geopolymer composites subjected to sodium sulphate

Engineered geopolymer composites (EGCs) have self-healing potential due to their multiple fine-cracking features. However, water immersion, as a self-healing condition for fibre-reinforced cement-based composites, may limit the self-healing ability of EGCs due to water would not directly participate in the precipitation reaction. By contrast, sodium sulphate is proved as an effective activator to promote the geopolymerisation process, while the self-healing performance of EGCs exposed to sodium sulphate has not been comprehensively demonstrated in the literature. Therefore, this paper investigates the self-healing performance of the EGCs subjected to sodium sulphate (Na2SO4) under wet-dry cycles. The results show that the EGCs preloaded at 3 days attain a higher increment of C-(A)-S-H gels at the cracks than those preloaded at 28 days, indicating the EGCs cracked at the early age have better self-healing performance under sulphate exposure. Besides, ettringite and calcium carbonate are detected as the self-healing products in the EGCs preloaded at 3 days, while the ettringite cannot be found in the EGCs preloaded at 28 days. The EGCs exposed to 5 % Na2SO4 solution and wet-dry cycles can achieve self-healing by forming more CaCO3. Increasing the Na2SO4 concentration to 10 % can accomplish self-healing by facilitating the C-(A)-S-H and CaCO3 formation, enhancing the tensile stiffness recovery and crack width reduction ratios for the EGCs with tensile strains of 2 % and 4 % at 3 days. Decreasing the preloading level also improves the tensile stiffness recovery and crack width reduction ratios regardless of the Na2SO4 concentration and preloading age, since the self-healing products are easier to fill the small cracks. Through a combination of Na2SO4 solution and wet-dry cycles, this study develops a new strategy for the accomplishment of self-healing of EGCs.

Effects of Macro Fibers on Crack Opening Reduction in Fiber Reinforced Concrete Overlays.

Macro fibers have been extensively used in the construction of various concrete structures, including bridges, dams, tunnels, industrial floors, and pavements. However, their effectiveness in reducing crack opening widths in concrete pavements has not been fully explored. This study aims to delineate the role of fibers by identifying the optimal types and volumes for effectively controlling cracks in concrete pavement structures, particularly in thin overlays. The research investigates how different fiber types, such as synthetic and steel, and their respective volumes can mitigate crack propagation in concrete overlays. Additionally, it evaluates the performance of fiber-reinforced concrete overlays compared to conventional dowel bar systems in terms of crack width reduction and overall pavement durability. The findings aim to provide specific design criteria for incorporating macro fibers in concrete overlays to enhance structural integrity and longevity.

Study on the effect of deformation and strength characteristics of microencapsulated phase change materials on modified silty clay under dry and wet cycles

To prevent the cracking of silty clay under cyclic wet-dry cycling (W-D), which leads to the increase of deformation and strength attenuation of silty clay, microencapsulated phase change material (mPCM) was used to improve it. The deformation and strength characteristics of silt with different dosages (1 %, 2 % and 4 %) of mPCM and their changing patterns were analyzed and studied by indoor compaction test, crack observation test, consolidation test and straight shear test, and compared with silt without modifier. The results showed that with the increase of mPCM dosage, the optimum water content of silt and the maximum dry density decreased. A 2 % dosage of mPCM inhibited the development of silty clay cracks, reduced crack width and deformation, and increased the compression modulus of the soil samples by nearly 2.3 times. Under dry and wet cycling conditions, the cohesion decay of silty clay is greater than the angle of internal friction. The addition of 2 % mPCM significantly increased the shear strength of silty clay, cohesion by nearly 2.1 times, and internal friction angle by 1.4 times. The mPCM inhibits crack development mainly by regulating the internal temperature field of soil samples, thus improving soil strength. This study provides a reference for inhibiting soil cracking from a new temperature perspective.

Pseudo strain-hardening alkali-activated composites with up to 100 % rubber aggregate: Static mechanical properties analysis and constitutive model development

Strain-hardening alkali-activated materials (SHAAM) provide a sustainable alternative to conventional strain-hardening cementitious composites (SHCC), offering significant environmental and economic benefits. This study examines the effects of various rubber powder (RP) volume replacement ratios (0 %, 25 %, 50 %, 75 %, and 100 %) on the properties of Rubber Powder Modified Strain-Hardening Alkali-Activated Composite Material (R-SHAAM), assessing workability, uniaxial compressive behavior, and uniaxial tensile behavior. The findings reveal that R-SHAAM with 100 % RP aggregate significantly enhances durability, achieving a 50.7 % reduction in crack width. Optimal axial tensile performance is observed at a 25 % replacement ratio, where R-SHAAM shows an 8.1 % increase in tensile strength and a 4.1 % increase in ultimate tensile strain. The robust multi-dimensional performance of R-SHAAM across different RP replacement ratios suggests its potential for diverse applications including pavement, marine structures, and explosive engineering, thereby offering valuable insights into sustainable material design and the effective recycling of waste materials in construction.

Experimental investigation of bond behavior with lap splice for CFRP-steel composite bars in coral sea-sand aggregate seawater concrete

The pull-out tests on a total of 81 lap-spliced specimens in 27 groups were conducted to investigate the lap-spliced behavior and the appropriate splice length for CFRP-steel composite bars (C-FSCB) in coral sea-sand aggregate seawater concrete (CSSC). The test variables included the C-FSCB diameter (dc), splice length, concrete cover thickness, concrete strength, lap spacing, stirrup ratio, and materials type. Then, the influence of various test variables on the lap-spliced behavior of C-FSCB in CSSC was analyzed. The results showed that when the splice length was less than 17dc, the specimens exhibited pull-out and concrete splitting failure, while C-FSCB fracture failure occurred when the splice length exceeded 17dc. Severe shear damage was observed on the C-FSCB surface in the case of pull-out and concrete splitting failure. When the splice length was less than 14dc, the bond strength of the specimens was approximately 7.2 MPa. As the splice length increased beyond 14dc, the bond strength gradually decreased. After the cover thickness was greater than 4dc or the compressive strength of CSSC was greater than 30 MPa, the variation in bond strength of the specimens can be negligible. Increasing the stirrup ratio led to an increase in bond strength and a significant reduction in crack width. Compared to specimens with steel bars, the bond strength reduction for specimens with C-FSCB exceeded 25%. Based on the test results, calculation formulas for the bond strength and splice length of C-FSCB in CSSC were established. Furthermore, referring to the approach in the Chinese code GB 50010–2010, a simplified calculation formula for splice length was proposed.

Self-healing efficiency of later-age cracked microbial mortar embedded with unencapsulated microorganisms under long-term water and ambient exposure conditions

To ensure the long-term self-healing ability of concrete structures throughout their lifespan is a crucial requirement for Microbially Induced Carbonate Precipitation (MICP) technology. In this study, unencapsulated microbial cells were directly mixed into the fresh mortar as a component to investigate their efficiency in repairing later-age cracks, respectively exposed to long-term water environment and ambient conditions. The crack width repair ratio for samples with cracks initially created by splitting tests was calculated at healing intervals of 6 and 12 days, revealing a sixfold higher repair ratio in 150-day samples with initial widths below 200 μm than those cases with 500 μm-wide cracks. The 26.3 % reduction in water absorption content after a 12-day healing period reflected an effective healing result for cracks and capillary pores. The microbially induced calcite precipitations were confirmed through SEM, XRD, and EDS analysis, with complete crack closure observed for 150-day samples with widths less than 200 μm. However, it was also found that the self-healing efficiency decreased with increasing crack width due to the limited availability of healing agents, with the maximum completely healed crack width of 507.8 μm. Despite prolonged exposure, no further reduction in crack width and sorptivity was observed, highlighting the challenges in achieving a complete healing effect. Surface images obtained from microscopes revealed the enduring presence of unencapsulated microorganisms, corroborating their role in continuous calcite precipitation and crack filling.

Post-fire curing and autogenous self-healing in alkali-activated slag: Microstructures and healing mechanisms

Among various ways to counter the effects of cracking and damage induced by exposure to elevated temperatures, self-healing appears to be a promising technique for maintaining construction materials' structural integrity and longevity. This research investigates the effectiveness and potential of autogenous self-healing for alkali-activated concrete performance recovery after exposure to elevated temperatures up to 800 °C. Two post-fire curing methods were examined: exposure to ambient air and immersion in sodium hydroxide (NaOH), to assess their effectiveness in promoting self-healing in AAS. To achieve better understanding of the mechanisms behind post-fire AAS's self-healing, a comprehensive evaluation of crack healing, microstructural changes, and the durability of the treated materials was conducted through a combination of visual inspection, ultrasonic pulse velocity, water sorptivity, rapid chloride permeability tests, scanning electron microscopy-energy dispersive X-ray, and X-ray diffraction. Findings reveal that NaOH immersion significantly enhances self-healing, evidenced by reduced crack widths and improved material properties. Changes in the amount of hydration products and various shapes of self-healing product crystals, such as trigonal, cubical, and rectangular, were detected. However, the dominant healing product was calcium carbonate (CaCO3), which precipitates through a combination of hydration reactions and carbonation processes, crucially contributing to the closure of microcracks and the restoration of the material's integrity. This process underscores the critical role of chemical reactions in AAS's self-healing mechanism, offering insights into its potential for enhancing the durability and resilience of construction materials. This emphasized the potential for leveraging AAS properties by self-healing and mitigating fire damage, thus extending the lifespan of structures and reducing maintenance costs.

Thermomechanical behavior of textile-reinforced geopolymer concrete based on mineral-impregnated carbon-fibers (MCFs) composites

State-of-the-art textile reinforcements are well employed to strengthen, rehabilitate or build new structures, whilst polymeric impregnation degrades considerably in elevated temperatures or aggressive environments. Herein, mineral-based matrices are regarded as a viable and novel technique. This study introduces a methodology to manufacture 2D-textile reinforcements using mineral-impregnated carbon fiber (MCF) automatically via a pultrusion and robotic–based structuring process. The reinforcing ability of MCF textiles without and with surface modification in geopolymer (GP) concrete was compared to commercial epoxy-impregnated textiles. After thermally stimulated rapid solidification, the resulting grid-like structures were incorporated into the concrete matrix. The MCF-GP-concrete composites were evaluated regarding their load-bearing capacity from 20 °C to 200 °C. Digital Image Correlation (DIC) and μCT analysis were used to study damage processes and interphase adhesion. The results demonstrated that GP concrete components with MCF textiles exhibited superior thermal resistance and a bi-linear stress-strain behavior compared to polymer matrix composite. Dilatometry and TGA measurements provided shrinkage and dehydration evidence for the thermally induced strength decrease. The enhanced chemical compatibility achieved via GP impregnation facilitates the formation of finely distributed crack patterns with reduced crack widths, contributing to improved durability scenarios and failure behavior of textile-reinforced concrete (TRC).

Enhancing durability and sustainability in concrete with fibre-reinforced composites

This paper presents a study focused on two pivotal innovations in the field of fibre-reinforced concrete (FRC) to significantly enhance its durability and sustainability in construction. First, our research investigates the application of advanced self-healing mechanisms in FRC. By embedding microcapsules containing healing agents within the concrete matrix, we achieved a remarkable reduction in crack propagation and improved structural integrity. Our results demonstrate that the self-healing FRC exhibited a 30% increase in compressive strength and a 40% reduction in crack width, leading to a longer service life for concrete structures. Second, we explore the integration of sustainable materials in FRC production. By incorporating locally sourced and recycled materials, we successfully reduced the environmental impact associated with FRC manufacturing. Our findings reveal a substantial reduction in carbon emissions, with a 25% decrease in the overall carbon footprint of FRC production. This innovation not only contributes to a greener construction industry but also aligns with sustainability goals and regulations. This research underscores the transformative potential of self-healing mechanisms and sustainable material integration in FRC, offering tangible results in terms of increased durability and reduced environmental impact. These innovations promise to reshape the construction landscape, aligning it with the principles of sustainability and long-term structural resilience.

Experimental study on the seismic performance of GFRP reinforced concrete columns actively confined by AFRP strips

This paper proposes a new type of concrete columns, which are reinforced with GFRP bars and actively confined by Aramid Fiber-Reinforced Polymer (AFRP) strips. FRP reinforcement is a non-corrosive material and has the advantages of having lighter weight, higher tensile strength, and long-term durability as compared to steel reinforcement. Active confinement has advantages over non-confined concrete columns and it is expected that the active confinement in the critical area increases the adhesion between the concrete and the rebars, strengthens the concrete cover portion of the rebars, and increases the shear capacity of the column. The literature does not show a comprehensive examination of the actively confined concrete columns that are reinforced by polymer and steel bars. Six reinforced concrete columns were cast, loaded, and tested under simultaneous application of axial and cyclic loads. Four columns were actively confined by AFRP strips at 10% and 30% of the AFRP ultimate strain in the critical area. Two columns were reinforced with steel bars, and the other two were reinforced with GFRP bars. Also, two columns with steel bars and GFRP bars, but without confinement, were utilized as the control specimens. Experimental results showed that the strain in the cover portion of the actively confined columns was reduced due to the effect of active confinement, and the strength of the concrete core increased. The active confinement increased the adhesion between the concrete and the bars and also reduced crack width, which ultimately resulted in increasing concrete strength, ductility, and energy absorption.

Effect of macro-synthetic and hybrid fibres on the behaviour of square concrete columns reinforced with GFRP rebars under eccentric compression

GFRP rebars have emerged as a suitable alternative for steel rebars to tackle corrosion-related issues. However, the abrupt failure of GFRP-reinforced concrete (RC) elements due to the brittle behaviour of GFRP rebars is a significant concern. Fibre reinforced concrete (FRC) reduces brittleness by providing pseudo-ductility to GFRP RC members failing in compression. Moreover, fibre addition helps reduce crack widths by bridging them when subjected to tensile stresses. The current study aims to understand the influence of adding macro-synthetic Polyolefin (PO) and a hybrid mix of steel and PO fibres (HB) on the behaviour of GFRP-RC columns. Twenty-six square columns reinforced with GFRP rebars and discrete fibres are tested. A low-eccentricity to-width ratio (e/d of 0.2) and a high-eccentricity to-width ratio (e/d of 0.4) are chosen as loading parameters. The test matrix includes the following specimens: i) control with no fibres, ii) only PO fibres, and iii) a hybrid mix of steel and PO fibres. Test results show that specimens reinforced with hybrid fibres outperformed macro-synthetic fibres in energy absorption and strength improvement. They also had better post-peak behaviour under eccentric compression. Fibre addition increased the load resistance contribution of GFRP rebars and prevented the complete spalling of concrete cover. It also improved the deformabilty factors when compared to control columns with no fibres under eccentric compression.

Ti3C2Tx MXene modified polyethylene fibers for enhancing interface properties of strain-hardening cementitious composites

MXene is a new two-dimensional transition metal carbide/nitride with remarkable hydrophilicity, which has been widely applied in multifunctional coatings. In this study, Ti3C2Tx MXene was synthesized by LiF/HCl solution etching of Ti3AlC2 and used to modify the surface of polyethylene (PE) fiber, enhancing the interfacial properties between fiber and matrix and further improving the tensile properties of strain hardening cementitious composites (SHCC). The tensile stress and strain of SHCC incorporating the MXene-coated PE (MXene@PE) fiber increased by 18.73 % and 93.60 %, respectively, accompanied by reduced crack width and crack spacing. Single fiber pullout results showed that the frictional bond strength increased by 71.35 % due to the strong chemical bond between fiber and matrix. The microstructure of MXene@PE fiber and bonding properties were characterized by SEM/EDS, FTIR, and XPS. The MXene was proved to have a dual effect of bonding to PE fiber and to C–S–H via covalent and hydrogen bonds.

Tailoring crack width control of LC3-based engineered cementitious composites (ECC) via fiber hybridization: From micromechanics design to macro investigation

As a class of strain-hardening cement-based material, Engineered Cementitious Composites (ECC) feature high tensile ductility and multiple cracking. However, ECCs reinforced with hydrophobic fibers attain high ductility but also exhibit larger crack widths caused by the weak bonding of the fiber/matrix interface, attenuating the durability potential of resulting infrastructures. This research aims at tailoring the crack width control ability of ECC through hybridizing hydrophilic PVA and hydrophobic PP fiber. A systematic design procedure was proposed based on the micromechanical analysis with a multi-scale investigation. Experimental results verified the hypothesized composite ductility enhancement by PP fiber and strength enhancement and crack width reduction by PVA fiber. Tight crack width of 50 μm at 2 % tensile strain can be achieved by a fiber hybridization ratio of 1:1 to ensure extreme durability. Changes in the microstructure of the matrix, associated with fresh property alteration due to fiber hybridization, were captured by micro CT scanning. Finally, the trade-off between mechanical performance, durability, and material sustainability was investigated for optimal material design. This research demonstrates that hybridizing PVA fiber with PP fiber holds promise to enhance material sustainability while maintaining the advantageous characteristics of ductile ECC and tight crack width for extreme durability.

Studies of the formation and distribution of cracks and various defects on the heated tungsten plate surface during pulsed plasma flux impact

In this work, cracking of the surface of a tungsten plate was studied using a PW-7 pulsed plasma accelerator. The surface of the tungsten plate was exposed at an energy density and plasma flux duration of 1.1 MJ/m2 and 200 μs, respectively. Before each shot, the base of the tungsten plate was heated to a temperature of 823 K. Heating of the base of the tungsten plate above the ductile–brittle transition temperature made it possible to control the temperature gradient on its surface under pulsed plasma exposure. In other words, the temperature gradient of the tungsten plate before and after exposure to the plasma flux decreased. Compared to the data at room temperature, the results of heating of the tungsten plate to the tungsten ductile–brittle transition temperature of 823 K showed a reduction in crack width to several hundred nanometers under the influence of plasma. It should be noted that heating of the plate did not completely eliminate cracking of the surface of the tungsten plate. However, this significantly minimizes the emission of dust from the surface of the tungsten plate under the influence of the plasma flux (barely no dust was observed).

Performance Improvement and Microstructure Characterization of Cement-Stabilized Roadbase Materials Containing Phosphogypsum/Recycled Concrete Aggregate.

The proper reutilization of the phosphogypsum (PG) by-product derived from the production of phosphoric acid and recycled concrete aggregate (RCA) from waste concrete in roadbase materials is of great necessity and importance. This investigation tried seeking a new approach to reuse them to high quality, including turning PG into calcinated PG (CPG) via washing and calcination, as well as adopting sodium metasilicate nonahydrate (SMN) to strengthen the roadbase materials of cement-stabilized CPG and RCA. Upon the mix design, with a series of experiments including unconfined compressive strength, the wet-dry cycle, freeze-thaw cycle, and scanning electron microscopy, the comprehensive effects of PG treatment, the CPG to RCA mix ratio, SMN dosage, wet-dry cycle and freeze-thaw cycle on the road performance of roadbase materials were well evaluated, and the traffic bearing capacity and microstructure characteristics were also analyzed. The results demonstrate that the 7 d unconfined compressive strength of CPG/RCA roadbase materials can reach 5.34 MPa as the CPG and SMN dosage are 20% and 11%, respectively, which meets the requirements of an extremely and very heavy traffic grade. After five wet-dry cycles and freeze-thaw cycles, the resistance of the CPG/RCA roadbase materials to moisture and frost was significantly improved as 11% SMN was added. Meanwhile, SMN contributes to the reduction in crack width and densifies the microstructure of CPG/RCA roadbase materials. The research results can be used to provide new guidance for building more durable roadbase materials.

Rubber particle bridging effect on crack width control of low carbon Engineered Cementitious Composites (ECC)

Engineered Cementitious Composites (ECC) exhibit high tensile ductility and multiple cracking behaviors. The weak bonding between hydrophobic fiber and matrix tends to enlarge the crack width of ECC. This paper investigated recycled crumb rubber (CR) to tailor the crack width control of ECC as an artificial flaw. The experimental results show that CR can enhance the multiple cracking and reduce the crack width of ECC, which can be attributed to the CR weakened matrix and particle bridging effect. Micro-CT scanning revealed how CR influences the initiation and propagation of microcracks qualitatively. A constitutive model of CR particle bridging was developed to evaluate the quantitative contribution of CR particle bridging to the crack width reduction of ECC. Although the effect of bridging on crack width reduction is not as strong as that of the weakened matrix, the combined effect is consistent with the experimental magnitude of crack width reduction. Further parametric analysis indicates that small particle size, higher content, and narrower size distribution range of CR are preferred for better crack width control of ECC. The insights gained provide guidance on ECC composite design for a tight crack width with better durability properties.

Using Jute Fiber to Improve Fresh and Hardened Properties of Concrete

ABSTRACT The brittle nature of concrete sometimes makes it challenging for many critical applications. Research has indicated that including discrete short-length, closely spaced fibers in concrete could improve its ductility and act as a crack arrester. As Bangladesh is the prime producer of natural fiber jute, this research aimed to improve the concrete property with this biomaterial. Laboratory work evaluated the mechanical property and shrinkage cracking resistance of jute fiber reinforced concrete with different fiber fractions (viz. 0.1%, 0.2%, 0.3%, and 0.4% by concrete volume) and lengths. The fibers were designated J20 and J25 for 20 and 25-mm lengths, respectively. A portion of the fiber was treated with alkali before using in concrete to improve its property. Jute Fiber Reinforced Concrete (JFRC) was analyzed qualitatively, semi-quantitatively, and quantitatively for compressive, splitting tensile strength, and plastic shrinkage cracking. It was found that the compressive and splitting tensile strengths can be improved by 7% and 25%, respectively. Furthermore, the bio-fiber had a significant influence on shrinkage crack control. In a controlled environment, up to 61% crack area and 62% maximum crack width reduction were achieved. Overall, jute fiber was found to be a sustainable biomaterial for concrete construction in an arid region.

An influence of finishing procedures and protective coating on the ultrastructure of conventional and hybrid glass ionomer cement restorations

Introduction. In addition to the advantages of glass ionomer cements that have led to their wide application, hybrid glass ionomer cements have been developed to overcome the shortcomings in mechanical resistance. The aim of the study was to perform an ultrastructural analysis of restorations made from conventional and hybrid glass ionomer cements after recommended finishing procedures and application of a protective coating. Materials and Methods. This study analyzed 30 samples of conventional glass ionomer cement Fuji IX? and 30 samples of hybrid glass ionomer cement EQUIA Forte HT Fil?. The samples were prepared in cylindrical molds and divided into the three groups. The first group of samples, after adaptation, was left untreated and served as a control group. The second group consisted of samples that were finished with a cylindrical diamond bur with water cooling. The samples in the third group were finished and protected with appropriate coatings (G-COAT PLUS? and EQUIA Forte Coat?). The samples were analyzed using scanning electron microscopy. Results. The finishing procedures of Fuji IX? samples significantly reduced crack width (t = 3.42, p < 0.005; Z = 3.25, p = 0.001). Similarly, the crack width in EQUIA Forte HT Fil? samples was also significantly smaller in treated samples (t = 4.78, p < 0.001; Z = 4.28, p < 0.001). Ultrastructural analysis of both materials showed the complete absence of cracks in finished samples protected by coatings. Conclusion. Finishing of conventional and hybrid glass ionomer cements results in a reduction in the number of cracks as well as a decrease in their widths, and the protective coatings completely cover remaining cracks.

Experimental and numerical analysis of concrete slabs reinforced with rebar and recycled steel fibers from waste car tyres

AbstractIn light of various initiatives taken around the world to convert waste materials into new products, the objective of this paper is to promote the use of steel fibers from recycled car tyres in the concrete industry. Hybrid steel fiber reinforced concrete (HSFRC) is a material that combines two or more types of steel fibers, in this case: manufactured steel fibers and recycled steel fibers from waste car tyres in equal proportions. The main objective of the presented research was to investigate the possible application of HSFRC in structural elements with conventional reinforcing bars in order to improve the flexural behavior and to investigate the possibility of partially replacing the conventional reinforcement with steel fibers in terms of service performance. For this purpose, eight slab specimens with different reinforcement ratios were subjected to a four‐point bending test to measure displacements, strength, and crack widths. The addition of a hybrid fiber mix to a conventionally reinforced concrete slab significantly reduced crack widths by up to 53%. The addition of fibers compensated for a conventional reinforcement reduction of 20% by reducing crack widths by up to 38%. It was observed that slightly more cracks opened with smaller widths and at smaller distances from each other in these slab types than in the conventionally reinforced reference slabs. Slabs with hybrid fiber mix and 44% reinforcement reduction showed no improvement in crack control compared to the conventionally reinforced concrete reference slabs. Using numerical models in ABAQUS simulating the flexural test on notched prismatic specimens, a calibration of the material models of plain concrete, and HSFRC was performed based on the test results. These validated material models were used for numerical modeling of slabs. The results of the analyses compared with the experimental results showed good agreement and confirmed the ability of the proposed material model of HSFRC to predict the flexural behavior of slabs with conventional reinforcement.

Cyclic behavior of GFRP-reinforced concrete one-way slabs with synthetic fibers

This paper investigates the cyclic behavior of one-way glass fiber-reinforced polymer (GFRP)-reinforced concrete (GFRP-RC) slabs incorporating synthetic fibers. The study aims at improving the performance of GFRP-RC slabs both at serviceability (SLS) and ultimate limit states (ULS). A total of 8 slabs were tested under cyclic bending and the effect of fiber type (polypropylene (PP) and polyvinyl alcohol (PVA)), fiber dosage (0, 0.5%, and 1.0%), and the type of reinforcement (steel and GFRP) was investigated. The comparison and evaluation of the slabs’ behavior was made in terms of crack width and deflection performance, ductility, failure mode, and overall load and deflection capacity. The results showed that the effect of fibers was more pronounced in GFRP-RC slabs compared to steel-RC slabs, both at the SLS and ULS. This is due to their reduced neutral axis depth as a result of the lower elastic modulus GFRP bars. Moreover, the fibers were found to reduce crack widths and deflections and enhanced the energy absorption; however, they did not significantly enhance the ductility of the slabs. The addition of fibers also resulted in an elastic response with most of the total applied deflection recovered at the end of each cycle of loading. Compared with steel-RC members, the cost of repair of GFRP-RC members seems to be relatively lower because of the reduced permanent deflection of the slab.