Adding an expansive agent to increase the toughness of steel fibre reinforced concrete

2019 ◽  
Vol 26 (4) ◽  
pp. 197-208
Author(s):  
Leo Gu Li ◽  
Albert Kwok Hung Kwan

Previous research studies have indicated that using fibres to improve crack resistance and applying expansive agent (EA) to compensate shrinkage are both effective methods to mitigate shrinkage cracking of concrete, and the additions of both fibres and EA can enhance the other performance attributes of concrete. In this study, an EA was added to fibre reinforced concrete (FRC) to produce concrete mixes with various water/binder (W/B) ratios, steel fibre (SF) contents and EA contents for testing of their workability and compressive properties. The test results showed that adding EA would slightly increase the superplasticiser (SP) demand and decrease the compressive strength, Young’s modulus and Poisson’s ratio, but significantly improve the toughness and specific toughness of the steel FRC produced. Such improvement in toughness may be attributed to the pre-stress of the concrete matrix and the confinement effect of the SFs due to the expansion of the concrete and the restraint of the SFs against such expansion.

2017 ◽  
Vol 23 (6) ◽  
pp. 806-813 ◽  
Author(s):  
Inmaculada MARTÍNEZ-PÉREZ ◽  
Juozas VALIVONIS ◽  
Remigijus ŠALNA ◽  
Alfonso COBO-ESCAMILLA

The building of structures from steel fibre reinforced concrete (SFRC) in the external and conventional rein­forced concrete (RC) in the internal layer represents an economical alternative of structures effectively using SFRC. The paper presents test results of flexural behaviour of layered beams with SFRC external layers and RC internal layer. The behaviour of these beams is compared to test results of SFRC and conventional RC beams. The test results show, that the flexural load capacity for all series of beams is nearly similar, but the deflections of layered beams are less comparing to monolithic ones. It also been shown that the equations indicated in the Eurocode 2 can be used to design the flexural reinforcement in layered SFRC beams.


The present investigation is carried out to study the strength and durability characteristics of steel fibre reinforced concrete, by replacing Ordinary Portland cement with Fly Ash, Ground Granulated Blast Furnace Slag (GGBS) and Metakaolin. In this study, cement is replaced by 30% and 40% with Fly Ash, GGBS and Metakaolin for M30 and M35 grades of concrete. Steel fibres @ 1% by weight of binder is used in all the mixes. Strength characteristics like compressive strength and split tensile strength are tested at 7 days and 28 days age. Additionally, durability tests such as water absorption and Sorptivity tests are conducted after 28days curing. The test results have shown that 30% replacement is optimum for strength criteria. And when metakaolin is used with fly ash, durability properties were improved and workability reduced.


1990 ◽  
Vol 211 ◽  
Author(s):  
X. Destree ◽  
M. Sahloul

Steel fibre reinforced concrete is a composite material consisting of a brittle matrix reinforced and randomly oriented fibres. The concrete matrix is brittle and the engineered steel fibres are ductile (elasto-plastic). When these two materials are mixed, the importance of the bond between the steel fibres and concrete becomes obvious.


10.14311/1823 ◽  
2013 ◽  
Vol 53 (4) ◽  
Author(s):  
Jaroslav Beňo ◽  
Matouš Hilar

The use of precast steel fibre reinforced concrete (SFRC) for tunnel segments is a relatively new application of this material. It was first applied in Italy in the 1980s. However, it did not begin to be widely applied until after 2000. The Czech Technical University in Prague (CTU), together with Metrostav, carried out a study to evaluate the use of this new technology for tunnels in the Czech Republic. The first tests were carried out on small samples (beams and cubes) produced from SFRC to find an appropriate type and an appropriate dosage of fibres. The tests were also used to verify other factors affecting the final product (e.g. production technology). Afterwards, SFRC segments were produced and then tested at the Klokner Institute of CTU. Successful test results confirmed that it was possible to use SFRC segments for Czech transport tunnels. Consequently a 15 m-long section of segmental lining generated from SFRC without steel rebars was constructed as part of line A of the Prague metro.


2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
Sivakumar Anandan ◽  
Sounthararajan Vallarasu Manoharan ◽  
Thirumurugan Sengottian

Corrosion in steel can be detrimental in any steel rebar reinforced concrete as well as in the case of steel fibre reinforced concrete. The process of corrosion occurring in steel fibre incorporated concrete subjected to corrosive environment was systematically evaluated in this study. Concrete specimens were prepared with steel fibre inclusions at 1.5%Vf(volume fraction) of concrete and were added in slag based concrete (containing manufactured sand) and replaced with cement at 20%, 40%, and 60% of total binder. Accelerated corrosion studies were carried out using alternate wetting and drying cycle accompanied with initial stress at 40% and 60% of ultimate stress. Concrete specimens were then immersed in chloride-free water and sodium chloride solution (3.5%) after subjecting to initial stress. The alternate wetting and drying process of different concrete mixes was continued for longer exposure (6 months). Later, the strength degradation during the accelerated corrosion process was then assessed in compressive and flexural tests. Test results indicated that the strength degradation was marginal in the case of steel fibre reinforced concrete containing higher slag content and for the concretes containing corrosion inhibitors. The maximum strength reduction was noticed in the case of plain concrete containing steel fibres and, with the slag addition, a considerable reduction in corrosion potential was noticed. Also, with the increase in slag replacement up to 60%, a significant increase in strength was noticed in flexural test. Experimental test results also showed that the corrosion process in steel fibre reinforced concrete can be controlled with the incorporation of corrosion inhibitors in cementitious system.


2014 ◽  
Vol 5 (2) ◽  
pp. 119-125
Author(s):  
I. Kovács

The present paper of a series deals with the experimental characterisation of flexural toughness properties of structural concrete containing different volume of hooked-end steel fibre reinforcement (75 kg/m3, 150 kg/m3). Third-point flexural tests were carried out on steel fibre reinforced concrete beams having a cross-section of 80 mm × 85 mm with the span of 765 mm, hence the shear span to depth ratio was 3. Beams were sawn out of steel fibre reinforced slab elements (see Part I) in order to take into consideration the introduced privilege fibre orientation (I and II) and the position of the beam (Ba-a, Ba-b, Ba-c) before sawing (see Part I). Flexural toughness properties were determined considering different standard specifications, namely the method of the ASTM (American Standards for Testing Materials), the process of the JSCE (Japan Society of Civil Engineering), and the final proposal of Banthia and Trottier for the post cracking strength. Consequently, behaviour of steel fibre reinforced concrete was examined in bending taking into consideration different experimental parameters such as fibre content, concrete mix proportions, fibre orientation, positions of test specimens in the formwork, while experimental constants were the size of specimens, the type of fibre used and the test set-up and test arrangement.


2018 ◽  
Vol 15 (1) ◽  
pp. 15
Author(s):  
AMIR SYAFIQ SAMSUDIN ◽  
MOHD HISBANY MOHD HASHIM ◽  
SITI HAWA HAMZAH ◽  
AFIDAH ABU BAKAR

Nowadays, demands in the application of fibre in concrete increase gradually as an engineering material. Rapid cost increment of material causes the increase in demand of new technology that provides safe, efficient and economical design for the present and future application. The introduction of ribbed slab reduces concrete materials and thus the cost, but the strength of the structure also reduces due to the reducing of material. Steel fibre reinforced concrete (SFRC) has the ability to maintain a part of its tensile strength prior to crack in order to resist more loading compared to conventional concrete. Meanwhile, the ribbed slab can help in material reduction. This research investigated on the bending strength of 2-ribbed and 3-ribbed concrete slab with steel fibre reinforcement under static loading with a span of 1500 mm and 1000 mm x 75 mm in cross section. An amount of 40 kg/m steel fibre of all total concrete volume was used as reinforcement instead of conventional bars with concrete grade 30 N/mm2. The slab was tested under three-point bending. Load versus deflection curve was plotted to illustrate the result and to compare the deflection between control and ribbed slab. This research shows that SFRC Ribbed Slab capable to withstand the same amount of load as normal slab structure, although the concrete volume reduces up to 20%.


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