Slurry Infiltrated Fiber Concrete Research Articles

Blast Resistance of Slurry Infiltrated Fibre Concrete with Waste Steel Fibres from Tires

The utilization of waste steel fibres (coming from the recycling process of the old tires) in production of blast resistant cement based panels was assessed. Waste fibres were incorporated in slurry infiltrated fibre concrete (SIFCON), which is a special type of ultra-highperformance fibre reinforced concrete with high fibre content. The technological feasibility (i.e. suitability of the waste fibres for SIFCON technology) was assessed using homogeneity test. Test specimens were prepared with three volume fractions (5; 7.5 and 10 % by vol.) of waste unclassified fibres. SIFCON with industrial steel fibres (10% by vol.) and ultra-highperformance fibre concrete with industrial fibres were also cast and tested for comparison purposes. Quasi-static mechanical properties were determined. Real blast tests were performed on the slab specimens (500x500x40 mm) according to the modified methodology M-T0-VTU0 10/09. Damage of the slab, the change of the ultrasound wave velocity propagation in the slab specimen before and after the blast load in certain measurement points, the weight of fragments and their damage potential were evaluated and compared. Realized tests confirmed the possibility of using the waste fibres for SIFCON technology. The obtained results indicate, that the usage of waste fibres does not significantly reduce the values of SIFCON flexural and compressive strength at quasi-static load - the values were comparable to the specimens with industrially produced fibres. With increasing fibre content, the mechanical parameters are increasing as well. Using of the waste fibres reduces fragmentation of SIFCON at blast load due to the fibre size parameters. Using of low diameter fibres means more fibres in the matrix and thus better homogeneity of the whole composite with less unreinforced areas. Regarding the blast tests, the specimen with waste steel fibres showed the best resistance and outperformed also the specimen with commercial fibres. Using of waste fibres in SIFCON technology can reduce the price of this composite by 70 % by keeping the original SIFCON extraordinary properties, which makes it very competitive material in the concrete area.

Fresh and some mechanical properties of sifcon containing silica fume

Slurry infiltrated fiber concrete (SIFCON) is one of the recently developed construction material. SIFCON could be considered as a special type of fiber concrete with high fiber content. The matrix of SIFCON consists of flowing cement mortar or cement slurry. SIFCON has a very good potential for application in area where resistance to impact and high ductility are needed especially in designing the seismic retrofit, in the structures under impact and explosive effects and repair of structural reinforced concrete element. The main objective of this paper is to determine the effect of steel fiber content and silica fume (SF) cement replacement on the mechanical properties of SIFCON concrete. The percentage of SF replacement was 10% by weight of cement in SIFCON slurry, and three different volume fractions of hooked ended steel fiber (6, 8.5, and 11) % were used. The tested properties of SIFCON were compressive strength and splitting tensile strength which were carried out on standard size of cubes and cylinders respectively at the age of 7and 28 days. It was observed that the mechanical properties of SIFCON were affected in a positive manner by using silica fume as a partial replacement of cement and by adding steel fiber reinforcement in different percentages. The compressive and splitting tensile strength up to 83.7 MPa and 17.3MPa, respectively were obtained at the age of 28 days.

Effect of steel fiber volume fraction and aspect ratio type on the mechanical properties of SIFCON-based HPFRCC

Plain concrete is a brittle material with a very low tensile strength compared to compressive strength and critical tensile strain. This study analyzed the dynamic characteristics of high-performance fiber-reinforced cementitious composites based on slurry-infiltrated fiber concrete (SIFCON-based HPFRCC), which maximizes the steel–fiber volume fraction and uses high-strength mortar to increase resistance to loads, such as explosion and impact, with a very short acting time. For major experimental variables, three levels of fiber aspect ratio and five levels of fiber volume fraction between 6.0% and 8.0% were considered, and the flexural strength and toughness characteristics were analyzed according to these variables. Furthermore, three levels of the aspect ratio of used steel fibers were considered. The highest flexural strength of 65.0 MPa was shown at the fiber aspect ratio of 80 and the fiber volume fraction of 7.0%, and the flexural strength and toughness increased proportionally to the fiber volume fraction. The test results according to fiber aspect ratio and fiber volume fraction revealed that after the initial crack, the load of the SIFCON-based HPFRCC continuously increased because of the high fiber volume fraction. In addition, sufficient residual strength was achieved after the maximum strength; this achievement will bring about positive effects on the brittle fracture of structures when an unexpected load, such as explosion or impact, is applied.

The Static and Dynamic Properties of Slurry Infiltrated Fibre Concrete with Waste Steel Fibres from Tires

The Static and Dynamic Properties of Slurry Infiltrated Fibre Concrete with Waste Steel Fibres from Tires

Comparison of tensile behaviour of polypropylene, aramid and carbon fibre reinforced cementitious composite at high strain rate loading

This paper presents an experimental study on uniaxial mechanical properties of polypropylene, aramid and carbon micro-fibre reinforced high performance cementitious composite subjected to both static and high strain rate tensile loading. This cementitious composite is intended to be used as a matrix for slurry infiltrated fibre concrete, which is being developed to be used for elements and structures for blast, ballistic and other impact protection. Cylindrical specimens of 30 mm diameter and 15 mm thickness were subjected to the indirect tensile (Brazilian) test at loading rate about 5.10-5 GPa.s-1 (quasi-static load regime) and 2.103 GPa.s-1 (high strain rate load regime). Specimens were tested using servo hydraulic press machine and 15 mm diameter Split Hopkinson pressure bar. Dynamic strength increase factor and fibre reinforcement factor have been studied versus both strain-rate and fibre type. Indirect tensile strength and post peak behaviour vary for specimens with different micro-fibre reinforcement, which allows to find the optimal reinforcement for high strain rate impacted concrete structures.

Predicting the strength properties of slurry infiltrated fibrous concrete using artificial neural network

This paper is aimed at adapting Artificial Neural Networks (ANN) to predict the strength properties of SIFCON containing different minerals admixture. The investigations were done on 84 SIFCON mixes, and specimens were cast and tested after 28 days curing. The obtained experimental data are trained using ANN which consists of 4 input parameters like Percentage of fiber (PF), Aspect Ratio (AR), Type of admixture (TA) and Percentage of admixture (PA). The corresponding output parameters are compressive strength, tensile strength and flexural strength. The predicted values obtained using ANN show a good correlation between the experimental data. The performance of the 4-14-3 architecture was better than other architectures. It is concluded that ANN is a highly powerful tool suitable for assessing the strength characteristics of SIFCON.

On low-velocity impact response of SIFCON slabs under drop hammer impact loading

The response of thin slabs of Slurry-Infiltrated Fibrous Concrete (SIFCON) with and without reinforcement under low velocity impacts is explored via drop-hammer impact experiments. For comparison purpose, plain cement concrete (PCC) and reinforced cement concrete (RCC) slabs were also cast and tested. To produce SIFCON slabs made with binary cementitious materials, the pre-determined concrete mixtures were designed with 15% of silica fume, 30% of blast furnace as a partial substitute of cement along with a constant 10% of hooked end steel fibres by volume fraction. The replication of a low-velocity impact on slab was achieved by dropping a steel ball (weighing 4.5 kg), with fall height of 457 mm, via the utilization of a self-fabricated drop-hammer impact test device. The parameters like first crack and ultimate failure energy absorption capacity, ultimate crack resistance, crack resistance ratio, ductility indices, and failure pattern were examined. The test results reported that the incorporation of binary blends of silica fume and slag in SIFCON matrix shows better performance in terms of strength and durability characteristics.

Slurry Infiltrated Fibre Concrete with Waste Steel Fibres from Tires - The Behaviour under Static and Dynamic Load

Waste fibres coming from the recycling process of the old tires were incorporated in slurry infiltrated fibre concrete (SIFCON), which is a special type of high performance fibre reinforced concrete with high fibre content. The technological feasibility (i.e. suitability of the waste fibres for SIFCON technology) was assessed using infiltration test and homogeneity test. Test specimens were prepared with three volume fractions (5; 7.5 and 10% by vol.) of waste unclassified fibres. SIFCON with industrial steel fibres (10% by vol.) and high performance fibre concrete with industrial fibres were also cast and tested for comparison purposes. Quasi-static mechanical properties were determined. The impact test was carried out by using an in-house manufactured impact testing machine based on drop test principle. Realized tests confirmed the possibility of using the waste fibres for SIFCON technology. The obtained results indicate, that the usage of waste fibres does not significantly reduce the values of SIFCON flexural and compressive strength at quasi-static load and energy absorption at dynamic load, the values were comparable to the specimens with industrially produced fibres. With increasing fibre content, the mechanical parameters and energy-absorption characteristics at dynamic load are increasing as well.

Performance analysis of Levenberg-Marquardt and Steepest Descent algorithms based ANN to predict compressive strength of SIFCON using manufactured sand

The advent of rapid industrialization and urbanization all over the world has led to the depletion of sand, the key structural material in the concrete structures and there is an urgent need of an alternative to the natural sand. In this paper, investigations are carried out for assessing the strength of Slurry Infiltrated Fibrous Concrete (SIFCON) with different percentage fibre fractions using manufactured sand in place of natural sand by experimental method and prediction models. SIFCON is a special type of new steel fibre reinforced concrete structure and is considered as a relatively high performance concrete. An important mechanical property of the concrete is the compressive strength, which can be measured after curing the concrete specimens for a standard curing period of 7, 28 and 56days. The application of artificial neural network (ANN) models to predict the highly desirable compressive strength of SIFCON has great potential in arriving at solution to inverse problems that are non linear in nature and proves advantageous over the conventional methods. In this study, Levenberg-Marquardt (LM) Algorithm and Steepest Descent (SD) Algorithm based ANN models are used in predicting the compressive strength of SIFCON concrete that contains cement, manufactured sand and various percentage fibre fractions, at different curing times. A total of 15 ANN architectures are implemented and 2-4-14-1 architecture is proved to be the best possible architecture in the case of LM and 2-2-15-1 architecture in the case of SD algorithm. The optimized configuration provides a lower Root Mean Squares (RMS) Error. The LM requires less number of iterations compared to SD, apart from high accuracy (95%), and fast convergence. The proposed ANN methods demonstrate that they are practical and beneficial to predict strength of concrete. The results reveal that although SD algorithm was accurate in predicting the compressive strength of SIFCON, yet LM algorithm was more accurate than SD algorithm.

Effects of slag on flexural strength of slurry infiltrated fibrous concrete

Slurry infiltrated fibrous concrete is one of the new advanced concrete composite which differs from method of fabrication and composition of the matrix. Extensive research is being carried out on alternative binders or supplements to cement aiming to reduce environmental impact. However, little has been published to investigate the structural behaviour of SIFCON incorporating with mineral admixtures, particularly as regards its ultrahigh ductility, which may alter the mode of failure from brittle to the more desirable ductile. An experimental study was carried out to investigate the flexural behavior of SIFCON containing three different percentage of fibre content 6%,8% &10% with incorporation of optimum dosage of blast furnace slag replaced by cement. Strength characteristics such as Compressive strength and splitting tensile strength test were carry out for SIFCON incorporating 10% of fibre content and different percentage of slag (0, 15, 30, 45, 60%&75%) to optimize the replacement level. The test results found that the maximum strengths were attained at 30% of blast furnace slag replaced by cement. To study the flexural behavior of SIFCON beam of size 1.2x0.1x0.2m containing different percentages (6%, 8% & 10%) fibre content incorporating with and without the optimum percentage of slag were cast and tested. Both flexural strength and Load displacement characteristics of the specimens were studied under flexure. The outcomespresentedfromtest resultshave been compared. The test results reveals that the flexural strength, toughness, ductility and stiffness characteristics were significantly improved due to incorporation of optimum dosage of slag enhancing when compared to without mineral admixtures also compared to conventional concrete(RCC). Major conclusions were drawn from the investigations which are presented.

Behaviour of reinforced concrete beams with SIFCON at various locations in the beam

This paper reports the flexural behaviour of conventional reinforced concrete beams with Slurry Infiltrated Fibrous Concrete (SIFCON) at various locations in the beam. Composite beams are cast with a layer of SIFCON at various locations of the conventional RC beam. Beams made entirely with RC, Fibre Reinforced Concrete (FRC) and SIFCON are also investigated for comparison. A total number of twenty one specimens corresponding to seven test series are cast and tested under two point flexural forward cyclic loading system. The parameters like load carrying capacity, stiffness degradation, ductility and energy absorption capacity are assessed. The concrete mix for RC beams are designed to obtain a concrete grade of M30. For SIFCON, the fibre volume fraction is 9%. The steel fibers used in the study are round crimped fibers having 0.5 mm diameter and aspect ratio of 60. Results indicate that the use of SIFCON in conventional RC beams have enhanced the cracking behavior in terms of considerable increase in the first crack load and in the formation of larger number of finer cracks. The ultimate load carrying capacity, stiffness, ductility and energy absorption capacity are increased to a greater extent for composite beams compared with that of conventional RC beams.

Influence of Fibre Type and Fibre Volume Fraction on Dynamic Properties of Slurry Infiltrated Fibre Concrete

The effect of fibre type and fibre amount on physico-mechanical properties of slurry infiltrated fibre concrete (SIFCON) at both quasi-static and dynamic load was evaluated experimentally. SIFCON is a special type of cement-based composite with high fibre volume fraction, extremely strong and ductile. Test specimens were prepared with 7 types of steel fibres (with different shape and mechanical parameters) in four volume fractions (7.5-15 vol. %). High performance fibre-reinforced concrete (HPFRC) has also been cast and tested for comparison purposes. The impact test has been carried out by using an in-house manufactured impact testing machine based on drop test principle. The test results revealed that SIFCON slab with 15 vol. % fibre content exhibits superior energy-absorption characteristics when compared to other slab specimens. Diameter of the fibres plays an important role for both strength and energy absorption capacity of SIFCON - using of low-diameter fibres with higher aspect ratio leads to the best results.

EXPERIMENTAL INVESTIGATION OF PRECAST WALL JOINTS BY USING SIFCON

In India, the construction field streams towards the hike with the advent of new innovative technologies. The increase in the quantity of construction seeks the superior quality from the researchers in terms of effective methodologies which reduce the requirement of manpower and material with increased efficiency and pace of construction. One of the most promising solutions for this issue suggested by the researchers is the precast construction. Precast construction entirely restructures the conventional construction process to improve the quality and pace of the construction. The predicaments with precast construction are shrinkage of filling material between the wall which leads to crack formation and also cause leakage of water. The occurrence of shrinkage is initiated and leaded by the compacting or filling problem in filling materials up to ground level due to the use of coarse aggregate and the usage of non flexible and improper bonding of sealant in the wall joints. In order to reduce these structural problems, we investigated the method of SIFCON (slurry infiltrated fibre concrete) with varies mix proportion 1: 1, 1:1.5 and 1:2 with the replacement of coarse aggregate by perlite. The sealant we used is poly sulphide sealant and the watercement ratio of the filling material varies between 0.3 and 0.4. Even though the conventional practical way of using fibres in SIFCON is limited up to 12%, we investigated the usage of fibres up to 20% in this experiment. The results obtained from the experiment shows that the filling material with the cement mortar ratio of 1:1.5 with 5% glass fibre applied in the method of Slurry Infiltrated Fibre Concrete successfully arrests the leakage of water between the wall joints.

Study on exterior RC beam-column joints upgrade with SIFCON in joint core under reversed cyclic loading

Beam-column joint is a key component of a Reinforced Concrete (RC) moment resisting frame and should be designed and detailed properly, particularly when the frame is subjected to earthquake seismic forces. Failure of beam-column joints is governed by bond and shear failure mechanism which are brittle in nature. Therefore, all international codes insist sufficient anchorage to longitudinal bars and confinement of core concrete in resisting shear. In this paper, the behavior of exterior RC beam-column joints with Slurry Infiltrated Fibrous Concrete (SIFCON) in the joint core under reversed cyclic loading is presented. Beam-column joints made entirely with RC, Fibre Reinforced Concrete (FRC) and SIFCON are also investigated for comparison. A total number of ten specimens corresponding to five test series are cast and tested under reversed cyclic loading to study the load deformation behavior, ductility associated parameters, ultimate load carrying capacity and failure characteristics. A nonlinear finite element model is also developed using FEA software ANSYS to validate the experimental results such as load-deflection response and the corresponding failure modes. From the test results, it is observed that the ultimate load carrying capacity, stiffness, ductility and energy dissipation capacity are improved to a greater extent for beam-column joints with SIFCON when compared with that of conventional RC beamcolumn joints.

EFFECTS OF REPLACEMENT OF METAKAOLIN WITH CEMENT ON THE MECHANICAL PROPERTIES OF SIFCON

Slurry Infiltrated Fibrous CONcrete (SIFCON) is unique type of concrete invented by Lankard in 1979, containing high percentage of fiber about 6% to 20% by volume of concrete. SIFCON possesses high strength as well as large ductility and for excellent potential for structural application. Metakaolin (MK) is a pozzolanic material, which improves the durabilityand strength of concrete. In this study the test programs were carried out with 2%, 3% and 4% of fiber content by volume of concrete with replacement of cement by Metakaolin at 5% and 7.5% by weight of cement. The aim of work is to optimize the percentage of fiber content and to minimize the cement usage by replacing it by Metakaolin. It also gives way to effective disposal of industrial waste to avoid global problem and protect environment. The main objective of this work was to determine the effect of replacement of cement with Metakaolin on mechanical property of SIFCON mortar. For that purpose compressive strength, flexural strength and Split tension strength of SIFCON specimen were tested after 7 and 28 days of curing, yielding positive results. In this study, we found that 2% fiber replacement by volume of concrete and Metakaolin at7.5% by weight of cement yields best and economical results.

Flexural performance of SIFCON composites subjected to high temperature

High temperature resistance is one of the most important parameters which affects the durability and service life of materials. Due to synergistic interaction of different mechanisms, mechanical performance can be lowered especially for the multi-component composite materials exposed to high temperature. Standard or steam cured slurry infiltrated fiber concrete (SIFCON) and slurry specimens were subjected to 300, 600, 750 and 900°C in the scope of present study. Exposing the specimens to 300°C enhanced the mechanical performance, while higher temperatures have detrimental effects on the SIFCON composites such as the loss in the cross section of steel fibers and the destruction of C–S–H structure. Mechanical test results were in accordance with micro-structural and thermal analyses.

Use Of precast SIFCON Laminates For Strengthening of RC Beams

Slurry infiltrated fibrous concrete (SIFCON) is a novel type of high performance fibre reinforced concrete made by infiltrating steel fibre bed with a specially designed cement based slurry. Laboratory experiments have shown that SIFCON is an innovative construction material possessing both high strength and large ductility. In the present study, the use of SIFCON has been investigated as an externally bonded strengthening material on reinforced concrete beams The experimental programme has been carried out to study the behaviour of flexural RC beams with precast SIFCON laminates. A total number of twenty one specimens of size 150mm x 300mm x1800mm corresponding to four test series are cast and tested under static loading to study the load deformation behaviour and ductility associated parameters. The concrete beams has been designed to obtain a concrete grade of M20.For laminates the fibre volume fraction was 7% and 10%. The steel fibres used in the study were hooked end steel fibres having 0.6mm diameter and aspect ratio of 50. Previous results indicate that the strengthening of RC beams with SIFCON laminates has significantly improved the cracking behaviour in terms of significant increase in first crack load and the formation of larger number of finer cracks. The stiffness, ductility and energy absorption are found to be increase to a great extent when the beams are strengthened by three face confinement ( bottom & side faces ).

ÇELİK VE POLİPROPİLEN LİFLERİN YALIN VE KOMBİNASYONLU OLARAK KULLANILMASININ SİFCON'UN MEKANİK VE FİZİKSEL ÖZELLİKLERE ETKİSİ

Cimento bulamaci infiltre edilmis lifli beton (SIFCON) ile ilgili farkli calismalar bulunmasina ragmen normal betonlara gore oldukca az oldugu gorulmektedir. Dunyada ozellikle de Avrupa’da konuyla ilgi yapilan calismalar ulkemize gore fazla yapilmakta ve gun gectikce artmaktadir. Geleneksel betonlara gore, ustun mekanik ve durabilite ozellikleri, farkli bilesenleri ve uretim teknigiyle one cikmaktadir. Bu haliyle SIFCON, gunumuz icin hala guncel bir calisma konusu olarak ortaya cikmaktadir.Bu calismada SIFCON'da genel olarak kullanilan iki ucu kancali liften farkli olarak, farkli geometriye ve malzeme yapisina sahip liflerin, SIFCON’nun mekanik ve fiziksel ozelliklerine etkisi incelenmistir. Bu amac icin numuneler uzerinde basinc ve egilme dayanimi, kirilma toklugu, ultrases gecis hizi, schimdt test cekici deneyleri yapilmistir. Sonuc olarak, mekanik ozellikler uzerinde celik liflerin polipropilen liflere gore daha iyi oldugu, birim dayanim maliyet yonunden incelendiginde ise dalgali geometriye sahip celik lifin daha ekonomik oldugu gorulmustur. Korozyon riskinin yuksek oldugu yerlerde ise daha dusuk dayanima sahip olmasina ragmen polipropilen liflerin kullanimini uygun olacagi sonucuna varilmistir.

Behavior of steel fiber-reinforced high-strength concrete-filled FRP tube columns under axial compression

This paper presents the results of the first-ever experimental study on the axial compressive behavior of steel fiber reinforced high-strength concrete (SFRHSC)-filled FRP tubes. A total of 27 circular unreinforced and steel fiber reinforced high-strength concrete FRP tubes (SFRHSCFFTs) were tested under axial compression. The effects of steel fiber parameters, including fiber shape, fiber aspect ratio and fiber volume fraction were examined. Concrete type was also investigated as a parameter, where two different types of concrete, including a conventional HSC and slurry infiltrated fiber concrete (SIFCON) were considered. The results indicate that both SFRHSCFFTs and SIFCON-filled FRP tubes (SIFCONFFTs) exhibit highly ductile compressive behavior. The results also indicate that the axial stress–strain behavior of CFFTs is influenced by the presence and amount of internal steel fibers, with particularly significant influences noted on the FRP hoop rupture strains and post-peak strength losses. It is found that fiber volume fraction significantly affects the compressive behavior of CFFTs. Concrete type, fiber shape and fiber aspect ratio also have some, but less significant, influence on the behavior of CFFTs. It is observed that the compressive strength and ultimate strain of CFFTs increases with an increase in fiber volume fraction or a decrease in fiber aspect ratio. It is also observed that CFFTs reinforced with hooked end steel fibers exhibit improved compressive behavior compared to the companion CFFTs reinforced with crimped fibers.

Effect of pre-setting pressure applied flexure strength and fracture toughness of new SIFCON + RPC composite during setting phase

Reactive powder concrete (RPC) and Slurry Infiltrated Fiber Concrete (SIFCON) are steel fiber-reinforced cement composites which have superior mechanical properties such as compressive, tensile, shear and flexural strength with extraordinary toughness values. Manufacturing of a new composite material was intended by using superior performance of SIFCON in terms of flexural strength as well as superior performance of RPC in terms of compressive strength. For this reason, fresh SIFCON was filled into the bottom portion of mold by means of specially-designed molds and pre-setting pressure was applied by filling reactive powder concrete on it. For RPC and SIFCON in mold, pre-setting pressure was applied in six different pressures (0, 3, 6, 9, 12, 15MPa). Test results indicated that maximum flexure strength was obtained as 69.70MPa under 15MPa pre-setting pressure. According to control-without pressure, flexure strength was improved by 43.21% with 15MPa pre-setting pressure. Also fracture toughness was increased about 32.03% with 12MPa pre-setting pressure. Prefabricated structural elements can be produced with the composite material, which is built via SIFCON+RPC composite, without needing a steel reinforcement.