New Procedure to Evaluate the Post-Crack Behavior of Fiber-Reinforced Concrete (original) (raw)
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Evaluation of post-cracking behavior of fiber reinforced concrete using indirect tension test
Construction and Building Materials, 2019
h i g h l i g h t s The DEWS test is a reliable instrument for structural parameterization of the FRC. The simplified DEWS test was able to identify the anisotropy of the FRC. The DEWS test was suitable to evaluate synthetic and steel fibers with low content. The susceptibility of the DEWS test to post-peak instability was evaluated.
Investigation of Fiber-Reinforced Concrete for Use in Transportation Structures
Transportation Research Record: Journal of the Transportation Research Board, 1997
Results are presented of a laboratory investigation to determine the properties of fiber-reinforced concretes (FRCs) with steel (hooked-end), polypropylene (monofilament and fibrillated), and the recently introduced polyolefin fibers (monofilament) for application in pavements and bridge deck overlays. Concrete properties in the unhardened and hardened states were evaluated and compared. Although the ultimate splitting tensile strength, compressive strength, and first-crack strength were higher in most of the FRCs, when strength values were adjusted for changes in air content, only a few batches had higher strengths. The addition of fibers resulted in great improvements in flexural toughness and impact resistance. Three FRC pavement overlays were applied in Virginia in 1995. The FRCs used in the projects were similar to those used in the laboratory investigation, with similar fiber volumes, types, and sizes. To implement the findings of the study successfully, the performance of the...
Influence of Fibre Reinforcement on the Long-Term Behaviour of Cracked Concrete
RILEM Bookseries, 2016
The influence of fibre reinforcement on the long-term behaviour of cracked concrete is analysed in this work by means of a creep test. Nine concrete mixes were prepared (7 SFRCs and 2 conventional RCs) based on two basic mix designs. Concretes type I were conceived for structural precast applications and concretes type II reproduce a general purpose. Fibre dosages and conventional reinforcements were varied to represent a wide spectrum of post-peak flexural responses. In all cases with fibre reinforcement steel fibres were used. Conventional RC specimens were reinforced with two steel rebars. In addition to the variables of mix design of concrete, there are two significant variables related to the creep test: the pre-crack opening level (CMODpn) and the stress level (Ic) sustained during the test. Creep tests were performed by applying a constant flexural load on notched pre-cracked specimens and controlling crack opening evolution. Some of the specimens developed a sudden increase of crack opening deformations during the creep test. Creep coefficients and Crack Opening Rates were calculated and analysed. Creep coefficients show significant dependence on the analysed variables. The results of this experimental campaign show that creep of SFRC specimens may be similar to a traditional RC.
Comparison of Performance Engineered and Fiber Reinforced Concrete Mixtures
2020
A challenging objective for the concrete industry, in using structural fibers in concrete pavements and overlays while moving towards the implementation of the Performance Engineered Mixture (PEM) design, is to understand the influence of fibers on tests performed in the PEM design procedure. The goal of the PEM design procedure is to produce concretes that resist climate and material related distresses, such as durability cracks and concrete-degradation due to chloride-ion penetration. The addition of fibers in a concrete mixture also increases concrete durability by enhancing post- cracking performance. Using PEM procedure for fiber reinforced concrete (FRC) pavements will produce durable concrete pavements that resist environmental- and material- driven distresses as well as possess an improved post-crack performance. The objective of this research is to study the relationship between different fresh concrete properties and their influence on the hardened concrete behavior and durability. The materials used in this study includes two types of coarse aggregates, fine aggregate, two types of fiber, cement, fly ash and admixtures. Two different fiber types (twisted and embossed geometries) and two fiber dosages (4 lb/ yd3 and 7.6 lb/ yd3) were considered in this study. Fresh and Hardened concrete test results for all the FRC mixes were compared to results of the control plain concrete mixes. Fresh concrete tests such as slump, air content, super air meter number (SAM), Box, and V-Kelly tests were conducted. Hardened concrete properties such as compressive strength, modulus of elasticity, beam flexural strength, resistance to distresses caused by multiple freeze-thaw cycles, and surface/electrical resistivity was determined. Based on the results of this study, it was found that fiber dosages and types significantly influence the V-Kelly index, while moderately influence SAM number and box test rating. The fibers used in this study had significant influence on the post-crack behavior of concrete. The freeze-thaw durability and surface resistivity test results indicated that fibers have less influence on the concrete resistance to freeze-thaw durability issues.
Effect of Fibers on Durability of Concrete: A Practical Review
Materials, 2020
This article reviews the literature related to the performance of fiber reinforced concrete (FRC) in the context of the durability of concrete infrastructures. The durability of a concrete infrastructure is defined by its ability to sustain reliable levels of serviceability and structural integrity in environmental exposure which may be harsh without any major need for repair intervention throughout the design service life. Conventional concrete has relatively low tensile capacity and ductility, and thus is susceptible to cracking. Cracks are considered to be pathways for gases, liquids, and deleterious solutes entering the concrete, which lead to the early onset of deterioration processes in the concrete or reinforcing steel. Chloride aqueous solution may reach the embedded steel quickly after cracked regions are exposed to de-icing salt or spray in coastal regions, which de-passivates the protective film, whereby corrosion initiation occurs decades earlier than when chlorides woul...
Post-Cracking Behaviour Of High Strength Fiber Concrete Prediction And Validation
2011
Fracture process in mechanically loaded steel fiber reinforced high-strength (SFRHSC) concrete is characterized by fibers bridging the crack providing resistance to its opening. Structural SFRHSC fracture model was created; material fracture process was modeled, based on single fiber pull-out laws, which were determined experimentally (for straight fibers, fibers with end hooks (Dramix), and corrugated fibers (Tabix)) as well as obtained numerically ( using FEM simulations). For this purpose experimental program was realized and pull-out force versus pull-out fiber length was obtained (for fibers embedded into concrete at different depth and under different angle). Model predictions were validated by 15x15x60cm prisms 4 point bending tests. Fracture surfaces analysis was realized for broken prisms with the goal to improve elaborated model assumptions. Optimal SFRHSC structures were recognized.
GRD Journals, 2019
Fibers used to enhance the brittleness property of steel reinforced concrete and plain concrete, and modify the tensile strength by increasing work of fracture. Thus, the toughness measurements are valuable for assessing the post crack performance of fiber reinforced concrete (FRC). There are many international standard around the world, but this paper are focuses on review the American standard specifications via exclusive ASTM. The review involve the flexural strength testing methods and toughness testing methods for FRC. For flexural strength test, the ASTM C 78 and ASTM C 293 reviewed and compared between both, while for toughness the ASTM C 1018, ASTM C 1609, ASTM C 1399 and ASTM C 1550 reviewed. This paper also describes concisely the method for each testing and considerable advantages of these methods. Beside, abridged some limitation of these methods. All figures have been redrawn with inserted more details to be most obvious and more rich.
Durability, physical and mechanical properties of fiber-reinforced concretes at low-volume fraction
Construction and Building Materials, 2014
Steel, polypropylene, and glass fiber concretes at low-volume fractions, which have been successfully used for crack control in many structural applications, were tested for different properties including water absorption, electrical resistivity, sorptivity, depth of chloride penetration, chloride profiles, rebar corrosion half-cell potential, and corrosion current density. Compressive strength and splitting tensile strength, flexural strength, and fracture toughness were also determined. Two different water-cement ratios and two curing types were used in the study. Fibers caused physical changes in concrete, which were reflected to the tested properties. The effect on durability was more significant in longer-term tests like corrosion. Moist curing was found to be more effective in fiber concrete for mechanical properties.
This work proposes a novel methodology for the complete characterization of fiber reinforced concrete (FRC). The method includes bending tests of prismatic notched specimens, based on the Standards for FRC, tensile and pure shear tests. The values adopted by the standards for designing FRC are the obtained from bending tests, typically fR3, even for shear and pure tension loading. This paper shows that the remaining strength of FRC, supplied by the fibers, depends on the type of loading. In the case of shear and tensile loading the prescriptions of the standards may be unsafe. In this work, the remaining halves of specimens subjected to bending test are prepared and used for shear and tension tests. This means significant savings in specimen preparation and a greater amount of information for structural use of FRC. The results provide relevant information for the design of structural elements of FRC compared with the only use of data supplied by bending tests. In addition, a video-e...
Fiber reinforced concrete: from flexural tests to solid slabs
Proceedings of the 10th International Conference on Fracture Mechanics of Concrete and Concrete Structures, 2019
Tensile behavior of fibre reinforced concrete is assessed based on flexural tests where specifically the post cracking strength values are of interest. However, the residual tensile strength values obtained based on such characterization test exhibit a very high scatter which is mainly due to the variation of number and orientation of fibres at the fracture plane. This rather unrepeatable behavior may cast doubt on the overall performance of a structure reinforced only with fibres and may question the validity of estimated tensile strength parameters that are used in the design of such from one specimen to another structures. While there is evidence that fibre reinforced concrete structures show a behavior that can be predicted by the average material properties, no strong proof is yet available. If so, then the low characteristic value of residual strength values may be a very conservative starting point for design of such structures To validate the reliability of design approach proposed for fibre reinforced concrete structures, twelve nominally identical fibre reinforced concrete slabs sized 2000×2000×150 mm, and twelve notched specimens sized 150×150×600 mm are tested, and the results are compared. Further, a yield line method is employed to predict the ultimate load bearing capacity of the slabs based on the tensile parameters obtained from the characterization tests. The results show that the average material properties can satisfactorily predict the bearing capacity of the slabs. FraMCoS X Conference.