Polypropylene Fiber Reinforced Concrete Research Articles

Post‐cracking behavior of polypropylene fiber reinforced concrete under bending and uniaxial tensile tests

The post‐cracking tensile behavior of polypropylene fiber reinforced concrete (PFRC) was investigated through an experimental study; special attention was devoted to the effects of fiber distribution and orientation on samples performance. In this regard, an experimental campaign based on uniaxial tensile tests (UTTs) on notched cylinders as well as three‐point bending tests (3PBTs) on notched beams was carried out. Uniaxial post‐cracking tensile laws retrieved both directly (UTTs) and indirectly (3PBTs) were compared. In the latter case, the fracture energy was higher because of the strongly dependency between PFRC post‐cracking performance and fiber distribution and orientation. In addition to cast cylindrical samples, core samples were directly drilled from the beams and tested under UTTs in order to compare their post‐cracking performance with that obtained by flexural standard tests on notched beams.

Shaking table tests on seismic behavior of polypropylene fiber reinforced concrete tunnel lining

Fiber reinforced concrete has been a widely applied durable material in ground structures or as the primary support in underground structures in the form of shotcrete. Whereas, fiber reinforced concrete was seldom utilized as secondary lining in underground structures, much less the polypropylene fiber reinforced concrete. Currently, many researches about fiber reinforced concrete have attempted to study tunnel linings behavior mostly in static state but fiber reinforced concrete has more advantages in seismic dynamic circumstance. A shaking table-based method to determine the behavior of polypropylene fiber reinforced concrete as tunnel lining can be the ideal method to study its response mechanism in seismic dynamic states. This paper presents results from a series shaking table tests on scaled tunnel models with the plain concrete (PC), steel reinforced concrete (RC) and polypropylene fiber reinforced concrete (PFRC) under increasing seismic intensities excitations. This research aims to explore the polypropylene fiber reinforced concrete as secondary lining reducing the seismic response intensity of tunnel structure. The comparison demonstrates that low tensile strength and brittle behavior at low strain are the two significant shortcomings of plain concrete. Concrete destruction, mortar destruction and cement pastes destruction are the three levels can describe the damage process of plain concrete. The three main roles of polypropylene fiber in concrete lie in polypropylene fiber strength, toughness and resistance to split. Polypropylene fiber changes the brittle behavior of PC and the damage patterns of RC along with the distribute paths of cracks. Besides, polypropylene fiber is able to effectively minimize the amount of initial micro cracks, postpone the appearance of new cracks, prevent the propagation of macro cracks and relieve the stress concentration at the ends of fibers. Polypropylene fiber allows tunnel lining to generate smaller deformations and strains to resist deformations of surrounding rock, which is more suitable to be applied in the large deformation sections of tunnel lining in soft surrounding rock. It is important to choose the suitable lining materials in terms of seismic intensity to take full advantage of the aseismic performance. The above research results can provide reference for polypropylene fiber reinforced concrete design and further research as tunnel lining.

A Review: Performance of Polypropylene Fiber Reinforced Concrete

Plain concrete has low strain capacity due to which crack occur on the outer layer of the concrete structures. The fibers are incorporated in concrete to prevent the crack formation and enhance the tensile strength of the mix. Polypropylene fiber reinforced concrete (PPFRC) is a composite material that contains short discrete randomly distributed fibers. PP fibers in concrete shows promising results while enhancing the mechanical properties, stiffness and durability. This paper presents a review of properties of PPFRC based on various research works.

An Experimental Investigation on The Mechanical Behaviour of Polypropylene Fibre Reinforced Concrete Using Ferrous Slag as A Partial Replacement of Fine Aggregate

Globally construction industry has enormous growth year by year. This leads to increase the need for construction materials. We are taking the materials from natural resources because of this natural resource depletion occurs at a faster rate. Also, this affects the environment. Cement production leads to higher amount of CO2 emission similarly depletion in river sand leads to ground water problems. So we have to find some alternate materials to conserve the earth for next generation. The faster industrial growth generates large amount of industrial wastes. Industrial waste material management is such a challenging area. Handling and disposal of industrial waste is a big issue for every country around the world. Ferrous slag is considered as an industrial waste which is obtained from iron smelting process. To minimize the environmental problems ferrous slag is used in concrete as a partial replacement of fine aggregate. Concrete is strong in compression and weak in tension. Using Polypropylene fibre we can increase the tensile strength of concrete. Mainly polypropylene fibre resists the micro plastic shrinkage cracks. Here polypropylene fibres added as micro reinforcement. But not much research has been carried out to study the combined behaviour of ferrous slag and Polypropylene fibre. The percentages of replacements of sand by granulated ferrous slag are 0%, 20%, & 50% and also the fibre dosage is maintained as constant 0.5% of cement. This research focused on the combined behaviour of ferrous slag and polypropylene fibre in study strength and transport properties.

Behavior of earthquake-resistant structure elements using polypropylene fiber and high strength reinforcing bars

The use of high strength reinforcing bars has becoming an interesting and cost-efficient option in construction industry recently. However, their use is limited due to their low deformability which might induce a brittle collapse in the structures. Also, longer development length is needed to transfer stress from reinforcing bars to the surrounding concrete. This paper focuses on investigating the influence of fibrous concrete and high-strength reinforcing bars on the behavior of structural elements. Five half-scaled specimens of interior joints using plain or fibrous concrete, reinforced with conventional 420 MPa or high strength reinforcing bar of 520 Mpa were experimentally tested. The two specimens of plain concrete, reinforced longitudinally with 16 mm and 19 mm reinforcing bars are defined as control specimens. The other test specimens were casted with Polypropylene fiber reinforced concrete (PFRC) with 16 mm and 19 mm longitudinal reinforcing bar. Loading protocol of all test specimens is defined according to ACI 374.2. The structure behavior, such as dissipated energy, bond between reinforcing bars and surrounding concrete, and stiffness degradation of the four specimens were evaluated and compared. The results obtained shows that the use of fiber increase the dissipated energy up to 27.5 % compared to specimens with plain concrete. Moreover, the peak strength of PFRC specimens was slightly increased (3% - 7%) compared to that of specimens with plain concrete. Moreover, there is an increase in peak-to-peak stiffness at elastic range loading with the addition of fiber, while no significant difference after the yields of longitudinal reinforcing bars.

Microscopic Texture of Polypropylene Fiber‐Reinforced Concrete with X‐Ray Computed Tomography

Polypropylene fiber‐reinforced concrete (PFRC) is a cement‐based composite material with short‐cut fibers which has been utilized to provide multidimensional reinforcement and enhance toughness of concrete. However, this improvement is closely related to the microstructural morphology of the concrete. A nondestructive technique using X‐ray computed tomography (CT) was therefore used to grasp the microscopic texture of PFRC samples. The results showed that the orientation of microcracks, which appear in the interfacial transition zone, are along the surface of the coarse aggregate. The range of distribution of fibers is proportional to fiber volume fraction. The coarse aggregate influence distribution and orientation of polypropylene fibers whose shape are mainly fold line and curve. The dispersion of pores with small volume is uniform, and the distance between the pores with larger volume is short. The proportion of pores with the diameter in the range 0∼199 μm exceeds 70%, of which the sum of volume exceeds a half of total volume with the amount being about 1% of total amount.

Experimental Investigation on Damage Behavior of Polypropylene Fiber Reinforced Concrete under Compression

This paper presents an experimental investigation on the stress–strain behavior and the damage mechanism of polypropylene fiber reinforced concrete (PFRC) under monotonic and cyclic compression. Fifty-four specimens for different fiber volume fractions and aspect ratios were tested. Acoustic emission (AE) technique was used to monitor the damage progression. The damage mechanism of concrete was analyzed based on the AE parametric analysis. The results show that the incorporation of polypropylene fiber (PF) has a positive effect on the monotonic and cyclic behaviors of concrete, especially for the post-cracking branch. The toughness and ultimate strain are enhanced and the performance degradation in terms of elastic stiffness and strength is alleviated by the addition of PF. However, PF has little influences on the plastic strain, and the damage process of concrete is mainly driven by the envelope strain. The effect of fiber volume fraction on the cyclic behavior of concrete shows more pronounced than that of aspect ratio. In addition, it is found from AE results that the damage, closely related to AE events, has a quick evolution just after the peak stress, with the AE hits having a concentrated release. The total amount of AE hits increases with increasing fiber volume fraction due to fiber pullout and sliding, while the concrete with fiber aspect ratio of 280 reaches the largest amount. Meanwhile, as substantiated by AE, the failure of PFRC shows an obvious shear mode, with shear cracks dominating the damage progression. Finally, a damage elasto-plastic model is developed to predict the monotonic and cyclic responses of PFRC and the prediction yields a fairly close estimation with experimental results.

An Experimental Investigation on the Properties and Effects of Polypropylene Fibre Reinforced Concrete

An Experimental Investigation on the Properties and Effects of Polypropylene Fibre Reinforced Concrete

Research on compressive impact dynamic behavior and constitutive model of polypropylene fiber reinforced concrete

The latest experimental studies indicate that polypropylene fiber is able to remarkably enhance the ability of concrete to resist impact loading and crack. This paper further studies the dynamic behavior and constitutive model of polypropylene fiber reinforced concrete (PFRC) at high strain rate. PFRC specimens with various polypropylene fiber content (0, 0.8, 1.2, 1.6, 2.0, 5.0 kg/m3) are tested by utilizing the Split Hopkinson Pressure Bar (SHPB). Both the quasi-static tests and the SHPB tests were performed to study the effect of fiber content, strain rate and water-cement (w/c) ratio on the dynamic mechanical properties of PFRC. Test results indicate that the dynamic mechanical properties of PFRC such as dynamic strength, dynamic increase factor, peak and ultimate strain, peak and ultimate toughness, are positively affected by strain rate. Polypropylene fiber can improve the impact toughness and crack resistance of concrete and it is more suitable for concrete material with a higher w/c ratio. Finally, the experimental stress-strain curves obtained in SHPB test were fitted by a damage dynamic constitutive model of PFRC on the basis of ZWT constitutive model. The great fitting results prove that the modified model can well describe the dynamic behavior of PFRC.

Behavior of High-Strength Polypropylene Fiber-Reinforced Self-Compacting Concrete Exposed to High Temperatures

AbstractIn this study we analyzed the use of high-performance structural concrete reinforced with polypropylene fibers in applications requiring long exposure times to high temperatures, such as th...

Impact characterization and modelling of basalt‒polypropylene fibre-reinforced concrete containing mineral admixtures

The impact-resistance behaviour of basalt‒polypropylene fibre-reinforced concrete containing the mineral admixture (BPFRC) was experimentally investigated under impact loading using a ϕ75 mm split-Hopkinson pressure bar. The results showed that the dynamic compressive strength, dynamic elastic modulus and critical strain of BPFRC increased with increasing strain rate. The addition of basalt fibre (BF) and polypropylene fibre (PF) yielded significant increases in the strain rate effect of the dynamic compressive strength and dynamic elastic modulus of concrete and improved the deformation capacity of concrete. The influence of PF on the strain rate effect of dynamic compressive strength of concrete was greater than that of BF. However, there was no clear difference between the influences of BF and PF on the strain rate effect of the dynamic elastic modulus of concrete. There was a significant positive correlation between the hybrid volume of fibre and the strain rate effect of the dynamic compressive mechanical behaviour of BPFRC. The proposed viscoelastic damage constitutive model in this study can be used to accurately describe the dynamic mechanical behaviour of BPFRC.

Minor defect correlation with dynamic elastic properties of polypropylene fiber-reinforced concrete

The efficient rehabilitation of aging civil infrastructure requires innovative and emerging materials along with the proper implementation of structural health monitoring (SHM). Prior to identifying a strategic SHM technique, the understanding of defects in structures is vital. Common defects in concrete include consolidation problems and the development of microcracks during consolidation or stress induction. Monitoring the dynamic characteristics of concrete can play an essential role in detecting real-time and early stages of deterioration. Much research is focused on detecting large defects; however, not much information is available on the detection of minor defects in composites such as fiber-reinforced concrete. This study focuses on testing and monitoring of the dynamic elastic behavior of concrete using a non-destructive resonant frequency approach. The change in dynamic elastic properties of normal concrete under flexural and compression loading is analyzed. Moreover, an initial attempt to monitor the change in the elastic behavior when polypropylene fibers are added as reinforcement is also investigated. Experimental results show a decrease in the dynamic modulus of elasticity when minor defects are present and when polypropylene fibers are added to plain concrete mixture.

Effectiveness of Polypropylene Fiber Reinforced Concrete in Enhancement of Long-Term Durability of Hydraulic Structures

The long-term durability of concrete hydraulic structures can be improved by controlling their rate of water absorption and linear shrinkage. Incorporation of fibers in concrete composites has the potential to improve these properties of concrete. Artificial fibers are commonly used in concrete due to its durable nature for long serviceable life. So, the overall aim of this research program is to study the effectiveness of artificial fibers for improvement of long-term durability of concrete hydraulic structures. To start with, polypropylene fibers are considered. The polypropylene fibers (PPF) have the unique properties of chemically inertness and low cost raw materials. The pilot study presents the experimental evaluation of water absorption and linear shrinkage of polypropylene fiber reinforced concrete (PPFRC) in comparison to that of plain concrete (PC). The mix design proportion of 1:3:1.5:0.7 (cement:sand:aggregates:water) is used in preparation of PC and PPFRC. For PPFRC, the fiber length of 50 mm and content of 5% by mass of cement are added. All tests are performed as per ASTM standard. Discussions on the considered properties of PC and PPFRC are made. As per expected outcomes PPFRC showed less water absorption and less linear shrinkage as compared to that of PC. Because of this possible attribute, the PPFRC can be used in hydraulic structures.

An Investigation on Shear Behavior of Prestressed Concrete Beams Cast by Fiber Reinforced Concrete

Failure due to shear is brittle in nature, and inherent lesser concrete tensile strength is a main contributing factor. During loading before the shear reinforcement could start functioning, cracking in concrete starts. Use of fibers in concrete had proven improved impact on tensile strength of concrete. Active reinforcement role initiates after concrete cracking starts. This paper investigates into the shear behavior of fiber reinforced, pretensioned concrete I-section beam specimens. A total of six beam specimens were cast. Two types of fibers, steel fibers and polypropylene fibers were used in five different proportions. For comparison, one control specimen was also cast without inclusions of fibers in concrete. Concrete mix ratio, prestress force, shear span-to-depth ratio and shear and flexural reinforcement details were kept constant in all specimens. Specimens were subjected to four-point loading to ensure that all specimens fail due to excessive shear force. During tests, deflections and strains were also measured. It was concluded that shear strength of beams was improved using steel fiber reinforced concrete (SFRC) as compared to polypropylene fiber reinforced concrete (PPFRC). SFRC beam containing 0.65% fiber depicted 50.71% improvement in ultimate failure load, 67% improvement in first cracking load and 36% improvement in ultimate deflection as compared to control beam.

Dynamic compressive mechanical behaviour and modelling of basalt–polypropylene fibre-reinforced concrete

Dynamic compressive behaviour of basalt–polypropylene fibre-reinforced concrete (BPFRC) was experimentally investigated using a 75-mm-diameter split-Hopkinson pressure bar. The results showed that the addition of basalt fibre (BF) and polypropylene fibre (PF) is effective at improving the impact-resistance behaviour of concrete. The dynamic compressive strength, critical strain, and energy absorption capacity of BPFRC increased with increasing strain rate. At strain rates of 20–140s−1, the addition of BF and PF significantly increased the dynamic compressive strength, critical strain, and energy absorption capacity of concrete. The dynamic increase factor of BPFRC increased linearly with the decimal logarithm of strain rate. The hybrid addition of BF and PF significantly improved the strain rate effect of the dynamic compressive strength. The strengthening and toughening mechanisms of BF and PF are discussed in detail. The proposed dynamic damage constitutive model can be used to accurately describe the dynamic stress–strain relationship of BPFRC.

Effect of Polypropylene Fibers on Self-Healing and Dynamic Modulus of Elasticity Recovery of Fiber Reinforced Concrete

This study aims to evaluate self-healing properties and recovered dynamic moduli of engineered polypropylene fiber reinforced concrete using non-destructive resonant frequency testing. Two types of polypropylene fibers (0.3% micro and 0.6% macro) and two curing conditions have been investigated: Water curing (at ~25 Celsius) and air curing. The Impact Resonance Method (IRM) has been conducted in both transverse and longitudinal modes on concrete cylinders prior/post crack induction and post healing of cracks. Specimens were pre-cracked at 14 days, obtaining values of crack width in the range of 0.10–0.50 mm. Addition of polypropylene fibers improved the dynamic response of concrete post-cracking by maintaining a fraction of the original resonant frequency and elastic properties. Macro fibers showed better improvement in crack bridging while micro fiber showed a significant recovery of the elastic properties. The results also indicated that air-cured Polypropylene Fiber Reinforced Concrete (PFRC) cylinders produced ~300 Hz lower resonant frequencies when compared to water-cured cylinders. The analyses showed that those specimens with micro fibers exhibited a higher recovery of dynamic elastic moduli.

Uniaxial tensile creep of a cracked polypropylene fiber reinforced concrete

This paper details and discusses the results of an experimental campaign into the uniaxial tensile creep behavior of a polypropylene fiber reinforced concrete (PFRC). In total, 16 FRC prisms are cast and tested according to the European Standard EN 14651. Cylindrical cores, taken from the prisms, are notched and are then used to identify the uniaxial tensile behavior of the FRC. The notched cores are also precracked and subjected to creep loading to study the time-dependent crack width growth at two different load ratios, 30 and 45% of the residual capacity. The results show that the load ratio has an important influence on the long-term tensile behavior of cracked FRC. For the samples subjected to 45%, the crack width exceeds the precrack width within hours, while the average crack width for the 30% samples remained below the initial crack width after 180 days under load. Based on the creep rate and crack width recovery upon unloading, it is shown that the 45% loaded samples exhibited plastic deformations, attributed to the onset of plasticity in the fibers. Furthermore, in terms of structural design, it is found that the residual post-creep capacity of the 30% samples was similar to that of undamaged cores, but significant differences were found for the higher loaded samples. For these samples, the average tensile capacity of the post-creep cores is 40% lower than that of the undamaged specimens. A comparison with steel FRC yielded that the time-dependent crack widening is similar, contrary to results in literature.

Development of sandwich panels combining Sisal Fiber-Cement Composites and Fiber-Reinforced Lightweight Concrete

This research proposes the development of an innovative structural panels based on the use of thin outer layers of Sisal Fiber-Cement Composites (SiFCC) together with a core layer of Polypropylene Fiber-Reinforced Lightweight Concrete (PFRLC).The influence of sisal fibers was studied in two different ways, short sisal fibers (50 mm) randomly distributed in the matrix, and long unidirectional aligned sisal fibers (700 mm) applied by a cast hand layup technique. Lightweight aggregates and polypropylene fibers were used in the concrete layer forming the panel's core in order to reduce its density and improve its post-cracking tensile strength and energy absorption capacity.The behavior of the sandwich panels in four-point bending test is described, and the various failure mechanisms are reported. Mechanical properties of both SiFCC and PFRLC were obtained, which were also used in the numerical simulations. Pull-off tests were performed to evaluate the bond strength between the outer SiFCC layers and the core PFRLC. The results revealed that the long sisal fibers were more effective in terms of providing to the panel higher flexural capacity than when using short sisal fibers, long fibers ensured the development of a deflection hardening behavior followed by the formation of multiple cracks, while short sisal fibers promoted a softening response after cracking.

Behavior of fiber reinforced concrete for controlling the rate of cracking in canal-lining

Seepage is a major water loss (20–30%) from the canal as compared to the other forms of water losses. Concrete is commonly used for canal-lining to reduce the seepage loss. Considerable seepage (15–20%) has been observed even in the cement–concrete conventional sections. The performance of canals decreases with an increase in the rate of cracking in concrete canal-lining. The rate of cracking in canal-lining can be reduced by improving the flexure, compressive, and splitting-tensile strengths of concrete. Out of these, splitting-tensile strength of concrete plays a vital role in controlling cracks. The use of fibers for characteristics improvement of concrete is very ancient. Natural fibers include many benefits, like low cost due to its abundance, least health hazards, and flexibility. The use of synthetic fibers as reinforcement in matrix has also attained intentness by reasons of its high strength, less water absorption, and low density in nature. The overall aim of the research program is to explore materials for better performance of canal-lining in terms of reduced water losses by controlling its rate of cracking due to alternate wetting and drying, and due to differential settlement, etc. The purpose of this work is to examine experimental behaviors of jute fiber reinforced concrete (JFRC), nylon fiber reinforced concrete (NFRC), and polypropylene fiber reinforced concrete (PPFRC) for controlling the rate of cracking in canal-lining. For this purpose, the mechanical properties (compressive, splitting-tensile, and flexure strengths, energies, and toughness indices), water absorption, and linear shrinkage of JFRC, NFRC, and PPFRC are determined experimentally as per ASTM standards. The properties of plain concrete (PC) are used as reference. The proportion of 1:3:1.5:0.7 (cement: sand: aggregate: water) is used for PC mix. The mixes of JFRC, NFRC, and PPFRC are manufactured by adding the jute fibers, nylon fibers, and polypropylene fibers, respectively, in the same mix design as that of PC. For production of each type of fiber reinforced composite (FRC), fibers having length of 50mm are added in concrete by an amount of 5% (by mass of cement). A reduction in compressive properties, and an improvement in splitting-tensile and flexural strengths, water absorption and linear shrinkage is exhibited by FRCs over that of PC. Among the tested FRCs, PPFRC shows better performance. This may ensure to control the rate of cracking in canal-lining, ultimately improving its performance.

The influence of elevated temperatures on the mechanical properties of polypropylene fiber reinforced concrete

This paper describes the strength of Polypropylene Fiber Reinforced Concrete (PFRC) exposed to the elevated temperatures. In the study, control specimens without any fibers and the concrete specimens with the ratios of 0.30, 0.60, 0.90 and 1.20 kg/m³ polypropylene fibers both in woolen and bar shape fiber have been produced. The specimens have been kept in the laboratory conditions for 28 days. Shortly after the curing period was completed, every group was heated at 23, 150, 300, 450, 600 and 750°C for two hours then the compressive strengths of them were determined. The maximum compressive strength was obtained by the specimens including 0.30 kg/m³ woolen polypropylene. For this group, the compressive strength increase was 8% according to the control specimens. The compressive strengths of bar polypropylene fiber concrete were higher than the wool fibers under elevated temperatures. On the other hand, more compressive strength values are obtained from the control specimens than fiber groups at 600°C temperature. Melting the polypropylene fiber at 500°C formed some pore spaces in concrete and caused reduction of the compressive strength.