scholarly journals Non-Destructive Multi-Method Assessment of Steel Fiber Orientation in Concrete

2022 ◽  
Vol 12 (2) ◽  
pp. 697
Author(s):  
Sabine Kruschwitz ◽  
Tyler Oesch ◽  
Frank Mielentz ◽  
Dietmar Meinel ◽  
Panagiotis Spyridis
Keyword(s):  
Fiber Orientation ◽  
Steel Fiber ◽  
Fiber Reinforcement ◽  
Cementitious Materials ◽  
Fiber Reinforced Concrete ◽  
Material Behavior ◽  
Environmental Benefits ◽  
Future Research ◽  
Hardened Concrete ◽  
Non Destructive

Integration of fiber reinforcement in high-performance cementitious materials has become widely applied in many fields of construction. One of the most investigated advantages of steel fiber reinforced concrete (SFRC) is the deceleration of crack growth and hence its improved sustainability. Additional benefits are associated with its structural properties, as fibers can significantly increase the ductility and the tensile strength of concrete. In some applications it is even possible to entirely replace the conventional reinforcement, leading to significant logistical and environmental benefits. Fiber reinforcement can, however, have critical disadvantages and even hinder the performance of concrete, since it can induce an anisotropic material behavior of the mixture if the fibers are not appropriately oriented. For a safe use of SFRC in the future, reliable non-destructive testing (NDT) methods need to be identified to assess the fibers’ orientation in hardened concrete. In this study, ultrasonic material testing, electrical impedance testing, and X-ray computed tomography have been investigated for this purpose using specially produced samples with biased or random fiber orientations. We demonstrate the capabilities of each of these NDT techniques for fiber orientation measurements and draw conclusions based on these results about the most promising areas for future research and development.

scholarly journals Effects of Steel Fiber Percentage and Aspect Ratios on Fresh and Harden Properties of Ultra-High Performance Fiber

2021 ◽  
Vol 2 (3) ◽  
pp. 501-515
Author(s):  
Rajib Kumar Biswas ◽  
Farabi Bin Ahmed ◽  
Md. Ehsanul Haque ◽  
Afra Anam Provasha ◽  
Zahid Hasan ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Aspect Ratio ◽  
High Performance ◽  
Steel Fiber ◽  
Setting Time ◽  
Fiber Reinforced Concrete ◽  
Future Research ◽  
Manufacturing Cost ◽  
Aspect Ratios ◽  
High Performance Fiber

Steel fibers and their aspect ratios are important parameters that have significant influence on the mechanical properties of ultrahigh-performance fiber-reinforced concrete (UHPFRC). Steel fiber dosage also significantly contributes to the initial manufacturing cost of UHPFRC. This study presents a comprehensive literature review of the effects of steel fiber percentages and aspect ratios on the setting time, workability, and mechanical properties of UHPFRC. It was evident that (1) an increase in steel fiber dosage and aspect ratio negatively impacted workability, owing to the interlocking between fibers; (2) compressive strength was positively influenced by the steel fiber dosage and aspect ratio; and (3) a faster loading rate significantly improved the mechanical properties. There were also some shortcomings in the measurement method for setting time. Lastly, this research highlights current issues for future research. The findings of the study are useful for practicing engineers to understand the distinctive characteristics of UHPFRC.

scholarly journals Shrinkage and Mechanical Properties of Self-Compacting SFRC With Calcium-Sulfoaluminate Expansive Agent

Materials ◽  
2020 ◽  
Vol 13 (3) ◽  
pp. 588 ◽  
Author(s):  
Changyong Li ◽  
Pengran Shang ◽  
Fenglan Li ◽  
Meng Feng ◽  
Shunbo Zhao
Keyword(s):  
Mechanical Properties ◽  
Steel Fiber ◽  
Volume Fraction ◽  
Cementitious Materials ◽  
Fiber Reinforced Concrete ◽  
Steel Fibers ◽  
Steel Fiber Reinforced Concrete ◽  
Volume Stability ◽  
Calcium Sulfoaluminate ◽  
Expansive Agent

With the premise of ensuring workability on a fresh mixture, the volume stability of hardened self-compacting steel fiber reinforced concrete (SFRC) becomes an issue due to the content of cementitious materials increased with the volume fraction of steel fiber. By using the expansive agent to reduce the shrinkage deformation of self-compacting SFRC, the strength reduction of hardened self-compacting SFRC is another issue. To solve these issues, this paper performed an experimental investigation on the workability, shrinkage, and mechanical properties of self-compacting SFRC compared to the self-compacting concrete (SCC) with or without an expansive agent. The calcium-sulfoaluminate expansive agent with content optimized to be 10% mass of binders and the steel fiber with a varying volume fraction from 0.4% to 1.2% were selected as the main parameters. The mix proportion of self-compacting SFRC with expansive agent was designed by the direct absolute volume method, of which the steel fibers are considered to be the distributed coarse aggregates. Results showed that rational high filling and passing ability of fresh self-compacting SFRC was ensured by increasing the binder to coarse-aggregate ratio and the sand ratio in the mix proportions; the autogenous and drying shrinkages of hardened self-compacting SFRC reduced by 22.2% to 3.2% and by 18.5% to 7.3% compared to those of the SCC without expansive agent at a curing age of 180 d, although the expansion effect of expansive agent decreased with the increasing volume fraction of steel fiber; the mechanical properties, including the compressive strength, the splitting tensile strength, and the modulus of elasticity increased with the incorporation of an expansive agent and steel fibers, which met the design requirements.

scholarly journals Green and Durable Lightweight Aggregate Concrete: The Role of Waste and Recycled Materials

Materials ◽  
2020 ◽  
Vol 13 (13) ◽  
pp. 3041 ◽  
Author(s):  
Jiyu Wang ◽  
Kai Zheng ◽  
Na Cui ◽  
Xin Cheng ◽  
Kai Ren ◽  
...  
Keyword(s):  
Solid Waste ◽  
Negative Impact ◽  
Lightweight Aggregate ◽  
Cementitious Materials ◽  
Environmental Benefits ◽  
Industrial Wastes ◽  
Lightweight Aggregate Concrete ◽  
Future Research ◽  
Aggregate Concrete ◽  
By Products

Lightweight aggregate concrete manufactured by solid waste or recycled by-products is a burgeoning topic in construction and building materials. It has significant merits in mitigating the negative impact on the environment during the manufacturing of Portland cement and reduces the consumption of natural resources. In this review article, the agricultural and industrial wastes and by-products, which were used as cementitious materials and artificial lightweight aggregate concrete, are summarized. Besides, the mechanical properties, durability, and a few advanced microstructure characterization methods were reviewed as well. This review also provides a look to the future research trends that may help address the challenges or further enhance the environmental benefits of lightweight aggregate concrete manufactured with solid waste and recycled by-products.

scholarly journals Implementation of natural and artificial materials in Portland cement

2020 ◽  
Vol 74 (3) ◽  
pp. 147-161
Author(s):  
Pero Dabic ◽  
Damir Barbir
Keyword(s):  
Portland Cement ◽  
Cementitious Materials ◽  
Environmental Benefits ◽  
Supplementary Cementitious Materials ◽  
Hardened Concrete ◽  
Cement Composites ◽  
Artificial Materials ◽  
Waste Container ◽  
Almost All ◽  
The Impact

For the preparation of modern cement and concrete, supplementary cementitious materials (SCM) have become essential ingredients. The technical, economic and environmental advantages of using SCM have become unquestionable. The main technical reasons for their use are the improvement of the workability of fresh concrete and durability of hardened concrete. Actually, SCM affect almost all concrete properties, while environmental and economic reasons may be more significant than technical reasons. These ingredients can reduce the amount of Portland cement used in cement composites, resulting in economic and environmental benefits. In addition, many of the SCM are industrial by-products, which can otherwise be considered as waste. This paper presents a literature review of the present knowledge on the impact of natural zeolite, waste construction brick and waste container glass on physical, chemical and mechanical properties of Portland cement as the most commonly used cement in the world.

scholarly journals Testing an Impedance Non-destructive Method to Evaluate Steel-Fiber Concrete Samples

2018 ◽  
Vol 18 (1) ◽  
pp. 35-40 ◽  
Author(s):  
Tereza Komarkova ◽  
Pavel Fiala ◽  
Miloslav Steinbauer ◽  
Zdenek Roubal
Keyword(s):  
Composite Material ◽  
Steel Fiber ◽  
Fiber Composite ◽  
Fiber Reinforced Concrete ◽  
Steel Fiber Reinforced Concrete ◽  
Measuring Device ◽  
Steel Fiber Concrete ◽  
Measured Sample ◽  
Non Destructive ◽  
Sample Set

Abstract Steel-fiber reinforced concrete is a composite material characterized by outstanding tensile properties and resistance to the development of cracks. The concrete, however, exhibits such characteristics only on the condition that the steel fibers in the final, hardened composite have been distributed evenly. The current methods to evaluate the distribution and concentration of a fiber composite are either destructive or exhibit a limited capability of evaluating the concentration and orientation of the fibers. In this context, the paper discusses tests related to the evaluation of the density and orientation of fibers in a composite material. Compared to the approaches used to date, the proposed technique is based on the evaluation of the electrical impedance Z in the band close to the resonance of the sensor–sample configuration. Using analytically expressed equations, we can evaluate the monitored part of the composite and its density at various depths of the tested sample. The method employs test blocks of composites, utilizing the resonance of the measuring device and the measured sample set; the desired state occurs within the interval of between f=3 kHz and 400 kHz.

Techniques of Non-Destructive Testing of Steel Fiber Reinforced Concrete

2017 ◽  
Vol 755 ◽  
pp. 153-158 ◽  
Author(s):  
Eva Zezulová ◽  
Tereza Komárková
Keyword(s):  
Reinforced Concrete ◽  
Large Scale ◽  
Steel Fiber ◽  
Fiber Reinforced Concrete ◽  
Non Destructive Testing ◽  
Fiber Reinforced ◽  
Steel Fiber Reinforced Concrete ◽  
Destructive Testing ◽  
Measurement Devices ◽  
Non Destructive

Non-destructive testing (NDT) is seeing increasingly frequent use in civil engineering thanks to the fact that the tests are repeatable and do not cause serious damage to the material. The requirements for the development and modernization of available testing devices and methodologies are ever increasing and the testing of existing structures often requires the use of NDT. Unfortunately, every measurement and methodology has its limits and the measurement devices for the evaluation of steel fiber reinforced concrete (SFRC) are no exception. In recent decades there has been an effort to modernize and develop existing measurement devices for SFRC testing. This building material is commonly used especially in large-scale structures. Nevertheless, the technology of SFRC could seem complicated when compared with ordinary concrete and the very nature of this composite material could lead to SFRC inhomogeneity during construction. This paper describes the assessment of SFRC by more or less available methodologies and measurements utilizing non-destructive principles.

scholarly journals Hysteretic Behavior of Reinforced Concrete Coupling Beams According to Volume Fraction of Steel Fiber

2020 ◽  
Vol 13 (1) ◽  
pp. 182
Author(s):  
Joo-Hong Chung ◽  
Dong-Hee Son ◽  
Su-Yong Kim ◽  
Baek-Il Bae ◽  
Chang-Sik Choi
Keyword(s):  
Reinforced Concrete ◽  
Steel Fiber ◽  
Volume Fraction ◽  
Fiber Reinforcement ◽  
Fiber Reinforced Concrete ◽  
Steel Fibers ◽  
Hysteretic Behavior ◽  
Steel Fiber Reinforced Concrete ◽  
Coupling Beams ◽  
Cyclic Loading Tests

The purpose of this study was to evaluate the structural performance of steel fiber reinforced concrete (SFRC) coupling beams. Reversed cyclic loading tests were performed with full-scale specimens. The main variable for the tests was the volume fraction ratio of the steel fibers. The results showed that the maximum strength was increased by about 11% with 1% of steel fibers incorporated, and about 24% when the ratio of mixed fibers was doubled to 2%. Because numerous microcracks occurred, decreased crack width due to the bridge effect was observed with the steel fiber reinforcement. Increased diagonal tension crack angles and energy dissipation also appeared as the volume fraction of steel fibers increased. The contribution of shear to the total deformation was decreased while the contribution of rocking was increased as steel fibers were added. Considering the results of these experiments, it can be concluded that steel fiber reinforcement affects the deformation of coupling beams in various ways, and should be considered when estimating the effective stiffness of such beams when SFRC is introduced.

scholarly journals LABORATORY TESTING OF STEEL FIBER CONCRETE PRISM FOR TENSION IN BENDING

2020 ◽  
pp. 105-113
Author(s):  
M.G. Surianinov ◽  
◽  
S.P. Neutov ◽  
I.B. Korneeva ◽  
I.K. Kalchev ◽  
...  
Keyword(s):  
Crack Resistance ◽  
Bearing Capacity ◽  
Steel Fiber ◽  
Fiber Reinforcement ◽  
Fiber Reinforced Concrete ◽  
Steel Fiber Reinforced Concrete ◽  
Load Bearing Capacity ◽  
Load Bearing ◽  
Fiber Concrete ◽  
Steel Fiber Concrete

Abstract. Laboratory bending tests of concrete and steel-fiber-concrete prisms were carried out. The concrete matrix for all prisms is made of a concrete mixture of the same composition with a coarse aggregate size up to 10 mm and a water-cement ratio that allows correct mixing of the ready mixture with fiber, so that the latter is evenly distributed over the sample volume. Fiber reinforcement is 1% for all three types of fiber, a fiber made of the same steel with an ultimate strength of 1335 MPa, fiber length 50 mm, diameter 1 mm is used. Fibers differ only in shape, which makes it possible to compare test results across series without correction factors. Concrete samples without fiber are considered as control samples. As a result of laboratory tests, data sets were obtained and analyzed, which are presented in the form of diagrams. Different types of steel fiber show different increases in the load at the beginning of cracking and load-bearing capacity. The most profitable from this point of view is the addition of anchor fiber to concrete, the least – wave fiber. However, the presence of any of the considered steel fibers in the mixture significantly increases the load-bearing capacity of the sample. In addition, the type of destruction of such a sample changes from brittle to viscous. We also studied the deformability of samples with different fiber reinforcement and plotted the dependence of the relative longitudinal strain on the load. Before the crack formation begins, there is a direct proportionality between the load and the strain with the appearance of cracks, the slope of the graphs changes sharply. When the load-bearing capacity is lost, steel fiber-reinforced concrete samples are restrained from final destruction. The use of steel fiber in concrete on average increases the crack resistance by 40%, and the load-bearing capacity by 64%. Compared with samples without fiber reinforcement, samples with anchor fiber show an increase in load-bearing capacity by 89%, and crack resistance by 61%. When using flattened fiber, these values are 56% and 32%, and for wave fiber – 47% and 25%, respectively. The use of steel fiber in the manufacture of concrete mix avoids the brittle nature of destruction.

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