The coarse aggregate is the strongest and the least porous component of concrete. It is also a chemically stable material. Presence of coarse aggregate reduces the drying shrinkage and other dimensional changes occurring on account of movement of moisture. Coarse aggregate contributes to impermeability in concrete provided that it is properly and the mix is suitably designed. Coarse aggregate in cement and there is a weak interface between cement matrix and aggregate surface in cement concrete. These two factors result in lower strength of cement concrete. But in high strength concrete, by restricting the maximum size of aggregate and also by making the transition zone stronger by usage of mineral admixtures, the cement concrete becomes more homogenous and there is a marked enhancement in the strength properties as well as durability characteristics of concrete.
The main objective of this experimental work is to investigate the behaviour of basalt fiber (chopped strand) reinforcedconcrete with replacing GGBS by fine aggregate compressive strength, tensile strength, flexural strength of concrete using basalt fiber and GGBS and identify the use of these two materials in regular construction. To study the strength characteristics of concrete are compared with the reference mix (M40 concrete without fiber and GGBS) and possible use of basalt fiber and GGBS.
This paper presents an experimentalstudy on the effect of hybridfibre addition to M40 concrete mix using the steel-nylon hybridfibrereinforced system. The study is done by comparing the flexuralbehaviour of reinforcedconcrete beams without fibres, with steel fibres, with nylon fibres and with hybridfibre combination of steel and nylon. M40 grade concrete was designed as the control mix. The main variables considered were the volume fraction of crimped steel fibres and nylon fibres. The mechanical properties of the mono fibrereinforced cast specimens were tested at four different volume fractions of fibre content i.e., 0.5%, 1.0%, 1.5% and 2.0%. The optimum volume fraction of steel fibre addition was obtained as 1.5% and that of nylon fibre addition was obtained as 1%. Hybrid combinations of 1.5% by volume of steel fibre along with various volume fractions of nylon fibre, such as 0.1%. 0.15%, 0.2%, 0.25% and 0.3%, were cast in order to find the optimum percentage of the hybrid steel-nylon fibre combination. An optimum of hybrid combination of 1.5% steel with 0.2% of nylon was obtained. A total of 12 reinforcedconcrete beams were cast and tested. After conducting flexural strength test on the beams, the first crack load, deflection pattern, crack development pattern and ultimate load carrying capacity of the beams were studied and compared.
The main objective of this project is to study the different strength parameters like compressive, tensile, flexural, impact strength of hybridfibrereinforcedconcrete with different mix proportion of fibres for M25 grade concrete and comparing with the conventional concrete and to know the optimum percentage of addition of fibres to concrete and finding maximum hybrid ratio and to determine workability of HFRC and to study the durability properties.
The promotion of steel fibrereinforcedconcrete (SFRC) as a construction material for tunnel linings has prompted a number of researchers to focus on methods of evaluating their flexural strength and stiffness. This thesis presents the results of an experimental and numerical investigation of the flexuralbehaviour of full-scale steel fibrereinforcedconcrete tunnel lining segments. A series of a three-point flexure tests were performed to evaluate the maximum load carrying capacity, the load-deformation behaviour and crack propagation characteristics of these segments. The material properties of the steel fibrereinforcedconcrete were also studied, using both destructive and non-destructive methods. Element compression and tension tests were conducted to characterize the compressive and tensile strength properties of the SFRC. Additionally, computed tomographic scanning was conducted to analyse and estimate the density fraction and fibre orientation of the fibres in SFRC cores. Three-dimensional finite element analyses were conducted to calibrate a concrete damage plasticity constitutive model and provide better understanding of the segment flexuralbehaviour. The experimental program indicated that the variation in structural performance of the segments was likely due to an inhomogeneity of fibre distribution and orientation. Modifying the numerical model to account for these variations resulted in a more accurate analysis. Furthermore, from the numerical finite element analysis it was found that the non-linear elasto-plastic concrete damage plasticity model in the crack zone of the beam was mesh dependent. Parametric analyses also revealed that the model was particularly sensitive to small changes to the tensile material property input parameters.
steel, carbon and polymer (Guneyisi. E. et al., 2013). Among the various types of fibers, steel fiber is the most commonly used for most structural and non- structural purposes (Bolat,H et al,2014).In this research steel fiber have been used. The application of the steel fiber is mostly utilized in construction due to its ability in resisting the formation and growing of cracking, abrasion and enhances the flexural strength, fatigue strength of reinforcedconcrete (Altun. F. et al,, 2012). From the study, the tensile and flexural strength of concrete enhanced significantly due to addition of steel fiber (Shahiron.S.,2009). In this study, the behaviour of reinforcedconcrete beam with different aspect ratio of steel fiber added into mixture was focused. According to the ACI 544, 3R-08, aspect ratio is referred to the ratio of fiber length over the diameter. Normal range of aspect ratio for steel fiber is from 20-100mm. Aspect ratio of steel fiber greater than 100mm is not recommended because it will cause inadequate workability, formation of mat in the mix and also non uniform distributed.
Concrete is most commonly used construction material in the world. Concrete is an artificial rock made from cement, sand and aggregate. The voids in between the aggregates are filled by sand and the cement paste glues the aggregates together when water is added to cement, a chemical process called hydration starts and continues as long as water is available. This process gives strength to concrete. In this present times it is not uncommon to use another ingredient called admixture. Concrete has some inherently brittle nature and have some disadvantages such as poor deformability and weak crack re- sistance in practical usage. Concrete made with Portland ce- ment is relatively strong in compression but weak in tension. Also, there tensile and flexural strength is relatively low com- pared to their compressive strength. To overcome this defect fibrereinforcedconcrete is used. Fibrereinforcedconcrete is Portland cement concretereinforced with more or less ran- domly distributed fibres. In FRC, thousands of small fibres are dispersed and distributed randomly in the concrete during mix- ing and thus there is improvement in concrete properties in all directions. Fibrereinforcedconcrete gives excellent flexural and tensile strength, resistance to splitting, impact resistance and excellent permeability, crack and frost resistance. In this present experimental work study is carried on Steel fibre (Bind- ing wire), Glass fibre and Polyproplene fibre to know the flex- ural strength. Steel fibres has higher Crack resistance and improves toughness characteristics of hardened concrete and it has relatively low cost. Whereas Polypropylene fibres are a synthetic carbon polymer, is produced as continuous filaments, with circular cross section that can be chopped to required length and section. PP fibres are advantages in many ways as it improves bleeding, plastic settlement, thermal and shrinkage resistance of concrete resistance.
Abstract: Steel fiber reinforcedconcrete (S.F.R.C) is distinguished from plain concrete by its ability to absorb large amount of energy and to withstand large deformations prior to failure. The preceding characteristics are referred to as toughness. Flexural toughness can be measured by taking the useful area under the load-deflection curve in flexure. Detailed experimental investigation was carried out to determine flexural toughness and toughness indices of SFRC the variables used in investigation were: reinforcement, steel fiber percentage by volume. The aim of this project is to present the findings of the investigation and equations obtained for predicting the desired flexural toughness and in turn the toughness indices for SFRC. These equations are dependent on the ultimate flexural strength, first crack multiple deflections and concrete specimen size. They are independent of the concrete matrix composition.
ABSTRACT: An experimental investigation was made by the partial replacement of fine aggregates with hemp and steel fibres in concrete. HybridFibreReinforcedConcrete (HFRC) can be defined as concrete that is reinforced by two or more types of fibres. Partial replacement was done for mono fibre(hemp) and hybridfibre (hemp and steel) concrete. The above fibres were cut into fine pieces. Steel and hemp fibres were partially replaced by the weight of cement in various proportions of 0.5%,1%,1.5% respectively in the concrete mixture. Concrete having compressive strength of 25 N/mm 2 (M25) was used. Test were carried out for each mix in fresh state to test the workability of concrete. In addition, compressive strength, flexure strength and split tensile strength were carried out and compared with conventional concrete. The test conducted reveals that mono fibres(hemp) shows higher strength when compared with hybrid and conventional concrete in compressive and flexural nature but decreases in tensile nature.
Based on the present experimental program and the analysis of test results, it is observed that as the percentage of steel fibre increases the workability of FRC decreases. This is due to the fact that the added fibre will obstruct the flow and hence affect the workability of concrete. In comparison with conventional concrete, there was a slump drop of 3.15% for combined 0.5% steel and 0.1% PP fibre content. For the same steel fibre content of 0.5%, when PP fibre content was increased to 0.2 % & 0.3 %, slump drop was observed to be of 2.08 % & 1.03% respectively as compared to conventional concrete. This shows that workability of concrete increases due to addition of fibrillated PP fiber in it. This is due to good mixability of PP fibre. A mix with steel fiber content of 1.4% and PP fiber content of 0.3% , shows slump drop of 24.05%. in comparison with conventional concrete. It was observed that as the percentage of steel fiber is increased, there is decrease in workability of the concrete. Fig. 5 shows variation in the slump values with different percentages of steel and polypropylene fibers
The use of UHPFRC for repair and strengthening applications has been investigated in a limited number of experimental, analytical and numerical studies. Habel et al.  conducted an extensive analytical investigation on the performance of composite UHPFRC-concrete elements under the assumption of perfect bond between the old and the new element where the efficiency of this technique was highlighted. Numerical study has been presented by Lampropoulos et al.  where the structural performance of beams strengthened with UHPFRC layers has been studied through Finite Element Analysis and comparisons with conventional methods have also been presented. Bruhwiler and Denarie  presented a realistic application of the UHPFRC for the rehabilitation of RC structures, such as a road bridge, a bridge pier and an industrial floor, and the benefits of the application of UHPFRC for the rehabilitation of concrete structures were highlighted. Safdar et al. , investigated the application of UHPFRC as a repair material and the flexural response of composite UHPFRC- RC elements was examined. The experimental results indicated that the use of UHPFRC layers increased the stiffness and the resistance of the elements. Talayeh and Bruhwiler  investigated the performance of reinforced UHPFRC beams subjected to bending and shear in a cantilever beam setup and they found that most of the specimens failed due to a flexural failure at a force of 2 to 2.8 higher than the resistance of the control specimens.
being exposed to accelerated conditioning environments. Cory High et al. (2015) investigated the use of basalt fiber bars as flexural reinforcement for concrete members and the use of chopped basalt fibers as an additive to enhance the mechanical properties of concrete. Chaohua Jiang et al. (2014) studied the effects of the volume fraction and length of basalt fiber (BF) on the mechanical properties of FRC. Coupling with the scanning electron microscope (SEM) and mercury intrusion porosimeter (MIP), the microstructure of BF concrete was also studied. Fathima Irine et al. (2014) investigated the mechanical properties of Basalt fiber concrete and compare the compressive, flexural and splitting tensile strength of basalt fiber reinforcedconcrete with plain M30 grade concrete. Jon sung Sim et al. (2005) investigated the applicability of the basalt fiber as a strengthening material for structural concrete members through various experimental work for durability, mechanical properties and flexural strengthening. Kunal Singha (2012) presented a short review on basalt fiber. Mehmet Emin Arslan (2016) investigated the fracture behaviour of basalt fiber reinforcedconcrete (BFRC) and glass fibrereinforcedconcrete (GFRC). In the experimentalstudy three-point bending tests were carried out on notched beams produced using BFRC and GFRC.Gore Ketan et al. (2013) evaluated the performance of high strength concrete (HSC) containing supplementary cementations materials. Concrete had a good future and is unlikely to get replaced by any other material on account of its ease to produce, infinite variability, uniformity, durability and economy with using of basalt fiber in high strength concrete. Nasir Shafiq et al. (2016) presentenced the flexural test results of 21 fiber reinforcedconcrete (FRC) beams containing Poly vinyl alchol (PVA) and basalt fibers (1-3% by volume) Fiber reinforcedconcrete was made of three different binders. Experimental results showed that the addition of PVA fibers significantly improved the post-cracking flexural response compared to that of the basalt fibers. Amuthakkannan et al. (2013) focused on the effect of fibre length and fibre content of basalt fiber on mechanical properties of the fabricated composites. TianyuXie and Togay Ozbakkaloglu (2016) conducted experimentalstudy on the axial compressive behavior of concrete filled FRP tubes (CFFTs), prepared using different amounts of recycled concrete aggregate (RCA).
Fuat Ko Ksal et al (2007) experimentally investigated on the mechanical properties of concrete specimens produced by using silica fume and steel fibre. The main objective of this work was to obtain a more ductile high strength concrete produced by using both silica fume and steel fibre. Two types of steel fibre with aspect ratios (fibre length/fibre diameter) of 65 and 80 were used in the experiments and volume fractions of steel fibre were 0.5% and 1%. Additions of silica fume into the concrete were 0%, 5%, 10% and 15% by weight of cement content. Water/cement ratio was 0.38 and the reference slump was 120 ± 20 mm. Slump test for workability, air content and unit weight tests were performed on fresh concretes. Compressive strength, splitting tensile strength and flexural strength tests were made on hardened concrete specimens. Load–deflection curves and toughness of the specimens were also obtained by flexural test performed according to ASTM C1018 standards. Flexural tests on beam specimens were achieved using a closed loop deflection-controlled testing machine. The use of silica fume increased both the mechanical strength and the modulus of elasticity of concrete. On the other hand, the addition of steel fibre into concrete improves toughness of high strength concrete significantly. As the steel fibre volume fraction increases, the toughness increases, and high values of aspect ratios give higher toughness. The toughness of
FRC is very widely used and the principal applications are beams on grade, shortcrete, and precast members, as well as a number of specialty applications. Until now, most of the production of FRC has been for non-structural applications, with the fibres added primarily for control of cracking due to plastic or drying shrinkage. However for any reinforcement to be effective, it must be stiffer than the concrete matrix that is reinforcing. Generally the less stiff fibres only offer benefits in improving the tensile strength of plastic and semi-hardened concrete and are therefore mainly used to reduce plastic shrinkage and plastic settlement cracking. The stiffer fibres improve both the tensile strength and the toughness of harden concrete.
Abstract: This paper discusses the experimental results on the mechanical properties of hybridfibrereinforced composite concrete (HyFRCC) containing different proportions of steel fibre (SF) and polypropylene fibre (PPF). The mechanical properties include compressive strength, tensile strength, and flexural strength. SF is known to enhance the flexural and tensile strengths, and at the same time is able to resist the formation of macro cracking. Meanwhile, PPF contributes to the tensile strain capacity and compressive strength, and also delay the formation of micro cracks. Hooked-end deformed type SF fibre with 60 mm length and fibrillated virgin type PPF fibre with 19 mm length are used in this study.
steel fibre content increased from 1.5 % to 2%, the toughness index reduced from 2.89 to 2.545. But in case of Basalt fibrereinforcedconcrete beams, the toughness index increased from 2.155 to 2.517. In case of a hybridfibre content of 2 %, the toughness index first decreased from 3.913 to 3.55 and then increased to 3.72. The maximum value of toughness index was obtained for the Hybridfibrereinforcedconcrete beam at a fibre content of 2% consisting of 60 % steel fibre and 40 % basalt fibre. The reason could be attributed to the increased strength and ductility as a result of hybridizing steel and basalt fibres. Also, both macro and micro cracks of the concrete are arrested ensuring proper toughness.
performance of hybridfibrereinforcedconcrete. The influence of fibre content on the strength and ductility performance of hybridfibrereinforcedconcrete specimens having different proportions of steel (S) and polyester (P) fibres was investigated. The parameters of investigation included modulus of rupture, ultimate load, service load, ultimate and service load deflection, crack width, energy ductility and deflection ductility. 100 x 100 x 500 mm prisms were tested to study the above parameters. The specimens incorporated 1.0% fibre volume fraction of steel and polyester fibres in different proportions. The strength and ductility performance of hybridfibrereinforcedconcrete specimens was compared with that of plain concrete. The test results show that a proportion of S60P40 hybrid fibres improve the performances appreciably.
Using the data obtained from the experiment, load deflection plots were drawn and comparison of these plots is shown Fig.4.4. All the plots show linear behavior till the formation of first crack. This could be termed as pre-cracking stage. Beyond this stage, the slope of the curve decreases. This indicate the formation of multiple cracks and hence reduction in flexural rigidity of the beam specimens. In this stage, deflection increases nonlinearly with the load. Beyond this stage, plots became more or less flat and the specimens without fibres showed a sudden drop in the load beyond the peak load. On the other hand F&GHGPC with fibre exhibits more or less flat descending portion, which indicate improvement in ductility due to the fibres and enhancement of stiffing
Modeling of the beam was done for the dimensions similar to that of the specimens cast. Materials used for analysis includes concrete and steel reinforcement bars. Constitutive models for both steel reinforcement and concrete are available in the ABAQUS material library. Beam was modeled as a three dimensional solid continuum element (C2D8R) which can be called as a brick element or hexahedron and was used for analysis of behavior of fibrereinforcedconcrete. The elements consisted of eight nodes and each node has three degrees of freedom i.e., translations in x, y and z directions. For the modeling of steel reinforcing bars, a two dimensional truss element was used (T3D2) with two nodes. Each node has three degrees of freedom same as that of the beam element. The properties given for steel reinforcing bars include an average value of yield stress of 500 MPa, Young’s Modulus of 210 GPa and Poisson’s ratio of 0.3. The properties of concrete input were Young’s modulus of 2000 MPa for plain concrete and for other beam models this value varied. The compressive strength, tensile strength and Poisson’s ratio varies with each beam model.