Fiber Reinforced Concrete

Ultra-high performance fiber-reinforced concrete (UHPFRC) is a new class of concrete that has been developed in recent years. UHPFRC results from the addition of either short discrete fibers or continuous long fibers to the cement based matrix. When UHPFRC compared with high performance concrete (HPC), UHPFRC exhibits superior properties in terms of compressive behavior, tensile behavior, workability, toughness, ductility and durability. UHPFRC has exceptional mechanical and transport properties including a very high tensile strength, strain hardening, and a density leading to a very low permeability. In this research, tests were carried out on twelve ultra high performance reinforced concrete beams with 100 mm × 200 mm cross section, 1600 mm total length to study the effects of adding steel fibers on flexural behavior of UHPC beams. The major parameters included in this research were the amount of internal steel reinforcement and the volume fraction of fibers. The test results showed that adding steel fibers to UHPC beams led to an increase in both load-carrying capacity and flexural ductility, also the concrete strain reaches to high percentage of its ultimate value that taking full advantage of the improved properties of UHPFRC, Furthermore adding steel fiber to UHPC beams can change the crack patterns, delay the crack appearance and restrain the crack expansion in concrete specimen. Ultra-haute performance béton fibré (BFUP) est une nouvelle classe de béton qui a été développé ces dernières années. BFUP résultats de l'addition de fibres courtes soit discret ou continu des fibres longues à la matrice à base de ciment. Lorsque BFUP par rapport au béton haute performance (HPC), BFUP présente des propriétés supérieures en termes de comportement en compression, comportement à la traction, la maniabilité, la résistance, de ductilité et de longévité. BFUP a exceptionnelles propriétés mécaniques et de transport, notamment une résistance à la traction très élevée, d'écrouissage, et une densité conduisant à une très faible perméabilité. Dans cette recherche, les tests ont été effectués sur douze ultra haute performance poutres en béton armé de 100 mm × 200 mm de section, 1600 mm de longueur totale pour étudier les effets de l'ajout de fibres d'acier sur le comportement en flexion de poutres BFUP. Les principaux paramètres inclus dans cette étude étaient la quantité d'armature en acier interne et la fraction volumique de fibres. Les résultats des tests ont montré que l'ajout de fibres d'acier à poutres BFUP ont conduit à une augmentation de la capacité de charge et la ductilité en flexion, également la souche béton atteint à fort pourcentage de sa valeur ultime en tirant pleinement parti des propriétés améliorées de BFUP, outre ajoutant fibres d'acier à poutres BFUP pouvez modifier les modèles de crack, de retarder l'apparition des fissures et limiter l'expansion fissure dans éprouvette de béton.

This paper presents the development of simple semi-empirical formulae for the analysis of nominal flexural strength of high strength steel fiber reinforced concrete (HSFRC) beams. Such developed formulae were based on strain compatibility and equilibrium conditions for fully and partially HSFRC sections in joint with suitable idealized compression and tension stress blocks. The stress blocks were given by suitable empirical functions for the compressive and post-cracking strengths of HSFRC. The enhancement in compressive strength due to fibers inclusion is proposed as a function of concrete matrix strength and fiber reinforcing index. To account for the pullout resistance of fibers in tension, the post-cracking strength was evaluated as a function of fiber reinforcing index and bond strength. The fiber reinforcing index was considered as a function of volume content, aspect ratio, orientation and length efficiency factors of the fibers. In view of the degenerative nature of the pullout resistance of the fibers with the increase of crack width, a limit was placed on the useful tensile strain extent; depending on fiber length and crack spacing. It was found that there is a good agreement between the flexural strengths for HSFRC beams predicted by the proposed formulae and the experimental results reported in the literature, while the predicted flexural strengths as computed by ACI Committee (544) were very conservative. The parametric studies indicate that the nominal moment section capacity increases with the increase of fiber content and fiber aspect ratio.

This paper investigates the applicability of artificial neural network model for strength prediction of fibers' self-compacting concrete under compression. The available 99 experimental data samples of fibers self-compacting concrete were used in this research work. In this paper, computational-based research is carried for predicting the strength of concrete under compression and model was developed using ANN with five input nodes and feed-forward three-layer back-propagation neural networks with ten hidden nodes were examined using learning algorithm. ANN model proposed analytically was verified, and it gives more compatible results. Hence, the ANN model is proposed to predict the strength of fibrous self-compacting concrete under compression.

This paper summarizes flexural modeling and design procedures for strain softening fiber reinforced concrete. Closed form solutions for calculating neutral axis, moment and curvature are presented and used to study the effect of post crack tensile strength and compressive to tensile strength ratio. With simplification to the closed form solutions, a single equation to predict moment capacity of a flexural member is obtained. To avoid sudden failure in flexural loading and to control crack width caused by shrinkage and temperature, the minimum post crack tensile strength for each case is proposed. A design example of slab on grade is employed to illustrate the calculation steps. Once the design part is finished, the specified post crack tensile strength for the slab must be verified by material testing.

An experimental program has been carried out to evaluate the performance of plain concrete and fiber-reinforced concrete under compressive fatigue loading. Two types of hooked-end steel fibers (30 mm length and 60 mm length) have been tested and their performance compared. The displacements and the acting load were measured during the tests so that several material parameters could be identified and assessed. W€ o ohler diagrams were determined, cyclic creep curves were plotted and the evolution of the secant stiffness was also appraised for the tested materials. The correlation between the secondary creep rate and the fatigue life was investigated. The monotonic stress-strain envelope was compared with fatigue deformations at failure and a good agreement was found between them. Ó

Effect of superelastic SMA fibers end-shape on pullout resistance was investigated. Four end-shapes: straight end, L-shaped N-shaped, and crimped end were considered. Pullout test was done by displacement control to obtain hysteretic pullout behavior. Four cycling loadings were applied to each specimen during pullout test. a b s t r a c t This study investigated the effects of superelastic shape memory alloy (SMA) fibers end-shape on pullout resistance through hysteretic pullout testing. Superelastic NiTi SMA wire of 1.0 mm diameter was employed in manufacturing short fibers. SMAs were fabricated with four end-shapes: 1) prismatic and straight end, 2) L-shaped end, 3) N-shaped end, and 4) crimped end with a spearhead. The embedded length of a fiber into the mortar matrix having compressive strength of 50.0 MPa was 18.0 mm, except for the N-shaped end fiber for which the embedded length was 21.0 mm. The pullout test was conducted with displacement control to obtain hysteretic pullout behavior by four cycling loadings. The results showed that crimped-end fibers considerably magnified the pullout strength, and the deformation was recovered by their superelastic behavior. As N-shaped end fibers could not show flag-shaped behavior, another test was performed through which fibers were annealed to induce superelasticity, so, a perfect strain recovery was obtained. Results showed that additional annealing of the N-shaped fibers after the manufacturing improved superelastic behavior at the bended part.

In the present paper, a numerical and experimental study about creep and shrinkage behavior of a high strength self-compacting concrete is performed. Two new creep and shrinkage prediction models based on the comprehensive analysis on the available models of both conventional concrete and self-compacting concrete are proposed for high strength self-compacting concrete structures. In order to evaluate the predictability of the proposed models, an experimental program was carried out. A concrete which develops 60 MPa within 24 h was used to obtain experimental results. Several specimens were loaded: (i) at different ages and (ii) with different stress-to-strength ratios. Deformation in non-loaded specimens was also measured to assess shrinkage. All specimens were kept under constant stress during at least 600 days in a climatic chamber with temperature and relative humidity of 208C and 50%, respectively. Results showed that the new models were able to predict deformations with good ac...

This paper presents the results of a research work aimed to determine the efficiency of using different materials to increase the punching shear strength of slab-column connections. These materials are steel bars, and glass or carbon fiber reinforced polymers as shear reinforcement stirrups. Openings in reinforced concrete (RC) slabs are not commonly prescribed in design codes. Even when they are, they raise concerns regards to the size of the openings and the location of the applied loads. There are many developments in concrete technologies that have major impacts on structural systems. The main conclusions obtained from previous researches are also included in this paper.

Carrier compounds besides the type of bacteria for microbial induced calcite precipitation are equally important in self-healing concrete. This study investigates the potential utilization of natural fibers namely, coir, flax, and jute fibers to carry bacterial spores for self-healing in concrete. The comparison is drawn for introducing calcite precipitation bacteria namely Bacillus subtilis KCTC-3135T, Bacillus cohnii NCCP-666, and Bacillus sphaericus NCCP-313 in concrete along with calcium lactate pentahydrate and urea as organic nutrients. The findings from visual, microstructural, and mechanical properties of selfhealing concrete suggest that natural fibers were capable of substantial immobilization potential for bacterial spores. Flax fibers provided better protection to bacteria with improved crack-healing and regain in compressive strength, whereas coir fibers resulted in higher compressive strength. It is also observed that B. sphaericus NCCP-313 precipitated more calcium carbonate as a healing product with uniform healing in the entire length of cracks in concrete. Consequently, approximately 75–85% and 60–65% healing rates were attained by fiber immobilized bacteria in 7 days and 28 days pre-cracked specimens, respectively.

Considerable amount of energy is spent in the manufacturing processes and transportation
of various building materials. Conservation of energy becomes important in the context of limiting of
greenhouse gases emission into the atmosphere and reducing costs of materials. The paper is focused
around some issues pertaining to embodied energy in buildings particularly in the Indian context.
Energy consumption in the production of basic building materials (such as cement, steel, etc.) and
different types of materials used for construction has been discussed. Energy spent in transportation
of various building materials is presented. A comparison of energy in different types of masonry has
been made. Energy in different types of alternative roofing systems has been discussed and
compared with the energy of conventional reinforced concrete (RC) slab roof. Total embodied
energy of a multi-storeyed building, a load bearing brickwork building and a soil–cement block
building using alternative building materials has been compared. It has been shown that total
embodied energy of load bearing masonry buildings can be reduced by 50% when energy
efficient/alternative building materials are used.

Aim of study is examine the effect on compressive strength of concrete by use of waste plastic and human hair as composite fiber reinforced material. The above plastic waste and human hair are mixed with cement concrete in various proportions (0.1%to 2%) and test specimens were casted (cubes and prisms) the study the behavior of plastic mixed concrete in axial compression. Study of human hair and plastic fiber is taken because of its excellent attributes which are available in low cost as compare to other fiber. At 5% optimum modifier content, the strength of the modified concrete was found to be 1.2 times greater than the plain concrete. By using Plastic waste and human hair as modifier, we can reduce the quantity of cement and sand by their weight, hence decreasing the overall cost of construction. The experimental finding in all tested sample will encourage the future researches in direction of long term of performance to extending thick chip for economical type of fiber use n structural application and reduced the environmental problem. By testing we found that there is an increment in the various properties and strength of concrete by the addition of human hair as fiber reinforcement which makes it suitable for an alternative additive for concrete to enhance its mechanical properties.

Fiber Reinforced Concrete (FRC) is a composite material consisting of cement based matrix with an ordered or random distribution of fiber which can be steel, nylon, polythene etc. The addition of steel fibre increases the properties of concrete, viz., flexural strength, impact strength and shrinkage properties to name a few. A number of papers have already been published on the use of steel fibres in concrete and a considerable amount of research has been directed towards studying the various properties of concrete as well as reinforced concrete due to the addition of steel fibres. Hence, an attempt has been made in the present investigations to study the influence of addition of polythene fibers (domestic waste plastics) at a dosage of 0.5% by weight of cement. The properties studied include compressive strength and flexural strength. The studies were conducted on a M20 mix and tests have been carried out as per recommended procedures of relevant codes. The results are compared and conclusions are made.

Fibers and bacterial additives in concrete have achieved significant success as a construction material. This paper presents the field of concrete self-repairing by introducing both Bacillus subtilis bacteria and polyethylene fiber as a dual-components. The main research goal is to reveal the principles of concrete self-repairing. At first, the research investigates the fiber-reinforced-concrete behavior, the concrete self-repairing process with the Bacillus subtilis bacteria for forming bacterial-concrete. And then, the study highlights the damage-repairing numerical simulation of fiber-reinforced-bacterial-concrete. The research shows the bacterial-concrete benefits to durability and mechanical properties besides to the polyethylene fiber assistance to enhance post-cracking tensile resistance and the pre-peak elastic modulus of concrete. The novelty of the fiber-reinforced-bacterial-concrete is the matrix combined improvement of both basic material properties and the post-cracking deflection capacity.

El hormigón es el material de construcción más ampliamente utilizado por sus
múltiples propiedades.
Sin embargo, a pesar de sus propiedades reconocidas, tiene sus puntos débiles
que es necesario fortalecer.
Conocemos su buen comportamiento a los esfuerzos de compresión, pero
también sus bajas prestaciones a los esfuerzos de tracción y de flexión, generalmente,
presentes en sus diversas aplicaciones en la industria de la construcción.
Por otra parte, los materiales compuestos de matriz cementícea, están sujetos al
desarrollo de una microfisuración intrínseca que se genera durante el proceso de
hidratación de las partículas constituyentes del cemento y de otros procesos
fisicoquímicos, que pueden producirse a lo largo del tiempo con la formación de
materiales expansivos que inducen una fisuración adicional.
Estos procesos de fisuración reducen sus propiedades resistentes e incrementan
su vulnerabilidad al ataque químico de diversos iones, que atacan los álcalis del
cemento y reducen su vida útil, es decir, su durabilidad.
Estos puntos débiles inciden muy notablemente en el coste de las obras construidas
con hormigón, en el mantenimiento, y, finalmente, en su demolición y reposición.
Debe ser un objetivo prioritario de las nuevas tecnologías fabricar hormigones
más resistentes y tenaces, mucho más resistentes a la fisuración, con la adición de
fibras y, por consiguiente, con una mayor durabilidad que prolongue su vida útil.
El objetivo de esta publicación técnica, es presentar líneas de actuación,
encaminadas a eliminar o reducir muy notablemente la fisuración autógena de los
compuestos cementíceos y a modificar su comportamiento durante la rotura,
haciéndolos más tenaces y dúctiles, con la utilización adecuada de las fibras como
elementos de refuerzo.
La incorporación de nanopartículas y nanofibras como refuerzo de la matriz
cementícea producirá materiales cementíceos de propiedades muy superiores a las
de los materiales que ahora se están utilizando en la industria de la construcción

Developing countries like Iraq suffers from high quantities of solid waste such as empty beverage plastic bottles. This type of waste forms one of the serious environmental pollution resources. The main aim of this research is to study the effect of adding Waste Plastic Fibers (WPF) on the mechanical properties of ferrocement mortar. Waste plastic resulting from cutting plastic beverage Polyethylene Terephthalate (PET) bottles by electrical shredder machine, which is used to cut paper, was added with different volume ratios of fibers to cement mortar, and these percentages were (0.5%, 1.0%, 1.5%). Reference mix was made for comparative reason. The following tests were made to investigate ferro-cement mortars mechanical properties as followed: compressive strength, flexural strength and density.
      Results showed that, the compressive strength decreased slightly with the increase in WPF content. The lowest value of compressive strength in (14, 28 and 56) days was (37.1 MPa) for (Vf=1.5%) at (14) days test age. Decrease ranged was between (1.1-12.2) percent with respect the reference mix. Flexural strength increased with increased of the waste plastic fibers volume. The highest value of flexural strength in (14, 28 and 56) days was (8.22 MPa) for (Vf=1.5%) for (56) days age. The increase in the flexural strength in (14, 28 and 56) days ranged between (2.27-16.67) % with respect to reference mix.

El shotcrete convencional, tal como lo conocemos, requiere una planta dosificadora, un equipo de transporte de la mezcla y un lanzador robótico. Este es el sistema de sostenimiento con shotcrete utilizado por la mayoría de las minas subterráneas en todo el mundo en la actualidad. La minería subterránea constantemente incrementa los niveles de profundización del minado lo cual requiere la aplicación de shotcrete de mayores espesores. Los volúmenes de material requeridos también se incrementan, así como la distancias que se tienen que recorrer aumentado los costos y disminuyendo la productividad.

Con estos desafíos que enfrentan las minas, hemos desarrollado un nuevo shotcrete vía húmeda denominado MineCreteS3 (MineCrete S3) Shotcrete Híbrido, el primero en su tipo. Es una mezcla de 3 partes que consta de cemento, agregado y agua. Ya no se necesitan aditivos adicionales como retardadores, aceleradores, plastificantes, antiespumantes, cenizas volcánicas y humo de sílice. MineCrete S3 se entrega en forma de polvo que incluye todos los aditivos requeridos ya mezclados y combinados con la opción de incluir también la fibra de refuerzo.

¿Por qué lo llamamos al MineCrete S3 un "Shotcrete Híbrido"?, Lo denominamos así, porque hemos combinado las ventajas de un TSL (Thin Spray-On Liners, Revestimientos de espesores delgados) y las ventajas del shotcrete vía húmeda. Los TSL utilizan polímeros para incrementar la resistencia a la adherencia, tracción y corte, y que son altamente superiores al shotcrete convencional. El shotcrete convencional utiliza principalmente la resistencia a la compresión y la absorción de energía para desarrollar un sistema de soporte estructural que puede trabajar de forma segura en cualquier tipo de roca, especialmente en condiciones de terrenos de muy mala calidad geotécnica, altas deformaciones y presencia de agua.

Özet: Bu çalışmada, polipropilen, cam ve çelik lifli betonların dona dayanıklılıkları araştırılmıştır. Deneyler için, lifsiz, polipropilen, cam, çelik ve karışık lifli 12 farklı beton üretilmiştir. Beton karışımında mikro yapılı çapı 50 µ, boyut oranı 400 polipropilen ve çapı 14 µ, boyut oranı 857 olan cam lifler ile makro yapılı çapı 0.75 mm, boyut oranı 80 olan çelik lifler kullanıldı. %0.5, 0.75 ve %1 hacimsel oranında çelik lifler, beton içinde %0.1 hacimsel oranında polipropilen ve cam liflerle karışık ve ayrı ayrı kullanıldı. Deneyler ASTM C 666 standardından havada hızlı donma-çözülme koşulları dikkate alınarak yapılmıştır. 30 donma-çözülme çevrimi sonucunda hazırlanan numuneler üzerinde ağırlık kaybı, ultrases geçiş hızı ve dayanıklılık faktörü değerleri belirlenmiştir. Deney sonuçları, betonda kullanılan lif tipine göre değerler arasında önemli farklılıklar olduğunu göstermiştir.

In conventional concrete, micro-cracks develop before structure is loaded because of drying shrinkage and other causes of volume change. When the structure is loaded, the micro cracks open up and propagate because of development of such micro-cracks, results in inelastic deformation in concrete. Fibre reinforced concrete (FRC) is cementing concrete reinforced mixture with more or less randomly distributed small fibres. In the FRC, a numbers of small fibres are dispersed and distributed randomly in the concrete at the time of mixing, and thus improve concrete properties in all directions. The fibers help to transfer load to the internal micro cracks. FRC is cement based composite material that has been developed in recent years. It has been successfully used in construction with its excellent flexural-tensile strength, resistance to spitting, impact resistance and excellent permeability and frost resistance. It is an effective way to increase toughness, shock resistance and resistance to plastic shrinkage cracking of the mortar. These fibers have many benefits. Steel fibers can improve the structural strength to reduce in the heavy steel reinforcement requirement. Freeze thaw resistance of the concrete is improved. Durability of the concrete is improved to reduce in the crack widths. Polypropylene and Nylon fibers are used to improve the impact resistance. Many developments have been made in the fiber reinforced concrete.

Fibres have been used in construction materials for a very long time. Through previous research and investigations, the use of natural and synthetic fibres have shown promising results, as their presence has demonstrated significant benefits in terms of the overall physical and mechanical properties of the composite material. When comparing fibre reinforcement to traditional reinforcement, the ratio of fibre required is significantly less, making fibre reinforcement both energy and economically efficient. More recently, waste fibres have been studied for their potential as reinforcement in construction materials. The build-up of waste materials all around the world is a known issue, as landfill space is limited, and the incineration process requires considerable energy and produces unwanted emissions. The utilisation of waste fibres in construction materials can alleviate these issues and promote environmentally friendly and sustainable solutions that work in the industry. This study reviews the types, properties, and applications of different fibres used in a wide range of materials in the construction industry, including concrete, asphalt concrete, soil, earth materials, blocks and bricks, composites, and other applications.

Concrete exhibits brittle nature it is not strong enough to resist tension. Fibers are used to enhance tensile strength to the concrete. They also increase many engineering properties of concrete. They are very helpful in controlling micro cracks and restricts crack propagation. The critical parameter we need to consider while describing fiber is "Aspect Ratio". It is defined as the ratio of length to diameter of the fiber. Mechanical properties of Fiber Reinforced Concrete (FRC) are very much got affected by the fiber type and its aspect ratio. Fly ash is broadly utilized as predominant alternative for Portland cement in construction sector. At the point when added to concrete, fly ash improves workability, strength, freeze thaw resistance, and reduce permeability. These advantages of fly ash over Portland cement make it a favored material for construction activities. The results clarified that utilization of fly ash in fiber reinforced concrete (FRC) impacts the both physical and mechanical properties of concrete.

Bu çalışmada, bükülebilir betonun deneysel olarak hazırlanması ve kullanım alanlarını araştırmak amacıyla bir literatür çalışması yapılmıştır. Bükülebilir betonu geleneksel beton ile kıyaslayarak malzeme içeriğinin davranışı nasıl etkilediği, bükülebilir betonun davranış prensibi ve bükülebilir beton ile yapılmış farklı deneysel çalışmalar incelenmiştir.

Many construction buildings and Structural barrier members that was built before 90s in USA, they weren't designed for Seismic resistance until Federal Emergency Management Agency FEMA started to do seismic evaluation and rehabilitation and suggested reinforcement methods. In this article we evaluate FRP sheet reinforcement.

In the present era, a number of researchers are using either industrial or agricultural priceless products as a basic source of raw materials for the construction industry. ese waste products are economical and helpful in producing a sustainable environment and reducing environmental pollution, which is called handling waste products. However, this research work was conducted on concrete containing 0.25%, 0.50%, 0.75%, and 1% of jute fiber as reinforcement material and 10%, 20%, 30%, and 40% of wheat straw ash (WSA) as replacement for fine aggregates. Moreover, the separate and combined effect of jute fiber and WSA as a replacement for sand ingredient in concrete is to determine the fresh and hardened properties of concrete. In this research, a number of concrete samples were prepared with 1 : 1.5 : 3 mix proportion at 0.54 water-cement ratio and cured at 28 days. e experimental outcomes displayed that the compressive, splitting tensile, and flexural strengths improved by 32.88 MPa, 3.80 MPa, and 5.30 MPa at 0.50% of jute fiber along with 30% of WSA at 28 days consistently. Similarly, the modulus of elasticity was developed while the dosages of jute fiber and WSA increased together in concrete. Moreover, the permeability and workability of concrete were reduced while utilized jute fiber and WSA increased together in concrete.

The secondary spiral and skin reinforcement in the anchorage zone of prestressed post-tensioned girders cause congestion and poses difficulty in the placement of concrete. It is also labor intensive to produce and place the secondary anchorage reinforcement. The objectives of this study was to determine the feasibility of reducing the secondary reinforcement with fibers for post-tensioned anchor zones, because of the expected improvement in mechanical properties of fiber reinforced concrete (FRC) over non-fibrous concrete. The first phase of the test program involved the determination of split tensile strength, compressive strength and flexural toughness of FRC and non-fibrous concrete. Two steel fibers and one synthetic fiber with various amounts were utilized. Steel fibers enhanced the properties of concrete, whereas the role of synthetic fiber was not encouraging. In the second phase, AASHTO Special Anchorage Device Acceptance Test was performed. Variations of spiral and skin reinforcement, with two levels of concrete strengths, were utilized to investigate the performance of the two types and various amounts of steel fibers. The experimental results indicated that 1% steel fiber could be used to replace all the secondary reinforcement for minimum concrete strength of 5900 psi (40.7 MPa), and could reduce a maximum of 79% of the secondary reinforcement for a minimum concrete strength of 4710 psi (32.5 MPa). Lower volumes of steel fibers may also result in reduction of secondary reinforcements. A finite element model of AASHTO test block was also developed to validate the experimental results. Good agreement was found between theoretical and experimental strain values. Usage of steel fiber reinforced concrete in the anchorage zones will result in negligible change in the girder costs.

Strengthening of reinforced concrete (RC) structures using fiber-reinforced polymers (FRP) has emerged as a potential solution to the problems associated with civil infrastructures. FRP is made of high tensile strength fibers such as carbon, glass, and aramid. FRPs are corrosion-resistant, which increase the service life of structures by reducing the concrete deterioration significantly. In general, FRP offers high strength-to-weight ratio, good fatigue behavior, low relaxation, and easy handling and installation.
Consequently, many researchers have reported significant increase in strength and stiffness of the FRP-strengthened concrete structures. Nevertheless, possible brittle failures could limit the use of the full efficiency of the FRP-retrofitted system. Among these brittle failures, the premature debonding of FRP, which could occur at load levels significantly less than the capacity of the FRP material employed in the strengthening technique.
Several types of debonding may dominate the failure mode, when strengthening RC beams in flexure with externally bonded FRP laminates. Debonding failures are classified into: i) plate end (PE) debonding; debonding occurs at or near the end of the FRP plate, and ii) intermediate crack (IC) induced debonding; debonding occurs under the flexural or flexural-shear cracks. Therefore, there is a crucial need for an improved understanding of debonding failure mechanism of the FRP-strengthened concrete beams as a basis for a reliable retrofit design.
The work reported in this thesis aims to evaluate and characterize the bond and the load transfer mechanisms between the FRP material and concrete, and investigate the influence of various parameters on the debonding process.
A comprehensive investigation is conducted in four phases. The first phase includes collection and compiling of existing experimental data, creating broad-spectrum databases of simply supported RC beams strengthened in flexure with externally bonded FRP laminates and encountered either PE or IC debonding failure. Two databases are constructed: PE database of 149 beams that experienced PE debonding and IC database of 197 beams exhibited IC debonding. The second phase introduces the existing different design methodologies developed for the evaluation of the FRP bond strength: empirical formulas, mechanics of materials models, fracture mechanics approaches, and design guidelines. The third phase comprises a non-linear finite element (FE) analysis to predict the debonding failure loads of the beams enclosed in the assembled experimental databases. The fourth phase presents a parametric study of 38 simply supported RC beams strengthened with externally bonded FRP sheets with variable parameters and analyzed using the non-linear FE program.
Finally, a comparison is held among the experimental data, the current analytical models, the design formulas in several design guidelines, and the non-linear FE results through an extensive statistical study. Based on the statistical analysis outcomes, the American design guideline (ACI Committee 440-2008) is considered the least scattered and the most efficient model for predicting debonding failure loads, but with un-conservative nature.
The design recommendations and guidelines are presented based on the results of both the statistical analysis and the parametric study. According to the research findings, the strain level at which debonding may occur has been identified through a proposed analytical expression. The model is introduced to predict the behavior of RC beams strengthened in flexure with externally bonded FRP laminates and verified with the gathered databases.
With the formula presented in this thesis, the risk of premature debonding failure of RC beams strengthened with externally FRP plates bonded to their soffits can be estimated.

In the recent years, the basalt fiber (BF) reinforced polymer composites were introduced to retrofit the structural elements. However, on the contrary, the studies on the use of BF in concrete are very limited. This study addresses experimentally to
find out the performance of BF as an alternative to glass fibers for the usability in fiber reinforced cement composites (e.g. façade panels). BF have some advantages such as fire resistance and alkaline resistance higher than those of glass fibers. The research was especially carried out to achieve the variation of the flexural strength in the extreme conditions that only cement was used as binder material. The heat rain test was conducted to observe durability of BF as well. The experimental results indicated that the flexural strain capacity of BF is sensitive to stress accumulation due to the cement hydration products in the matrix-fibre interface. This sensitivity especially increased during heat-rain durability test, however any sign of chemical attack in the alkaline environment was not observed in SEM images.

Plain cement concrete has inferior performance in tension and a very high carbon footprint. These issues can be minimized by simultaneous incorporation of fibers and recycled aggregates in concrete. This research paper investigates the influence of glass fiber (GF) reinforcement on mechanical and durability performance of concrete made with recycled coarse aggregate (RCA). In this study, three types of concrete mixes are produced using 0% RCA, 50% RCA, and 100% RCA, and in each of these three mixes, 0%, 0.25%, 0.5%, 0.75%, and 1% volume fractions of GF are used. Mechanical performance of concrete mixtures is evaluated on the basis of compressive strength, split tensile strength and flexural strength. Durability performance is evaluated on the basis of porosity, sorptivity coefficient, and chloride penetration. The results of testing show that 50% RCA concrete outperforms the plain natural coarse aggregate (NCA) concrete at 0.5% GF in overall mechanical performance (compressive, split tensile, and flexural strength). Whereas, both 50% RCA and 100% RCA concrete with 0.25% GF perform better than plain NCA concrete in split tensile and flexural strength. All permeability-based durability properties are negatively influenced by increasing RCA and GF content. Higher dosages (>0.5%) of GF are more detrimental to the durability of concrete than the lower dosages of GF (<0.5%).

Fibre reinforced concrete is of high strength compared to normal concrete and also reduces the cracks due to shrinkage. In this investigation, Recron fibre is added to concrete in the proportion of 0%, 0.25%, 0.50%, and 1% by the weight of cement. This investigation is done in 4 different grades of concrete such as M20, M25, M30 and M35. For strength parameters, each grade of concrete for each proportion, cubes are casted for 7 days, 14 days and 28 days and prisms and cylinders are casted for 28 days. The compressive strength, flexural strength and split tensile strength are found and compared.

In the present paper, a numerical and experimental study about creep and shrinkage behavior of a high strength self-compacting concrete is performed. Two new creep and shrinkage prediction models based on the comprehensive analysis on the available models of both conventional concrete and self-compacting concrete are proposed for high strength self-compacting concrete structures. In order to evaluate the predictability of the proposed models, an experimental program was carried out. A concrete which develops 60 MPa within 24 h was used to obtain experimental results. Several specimens were loaded: (i) at different ages and (ii) with different stress-to-strength ratios. Deformation in non-loaded specimens was also measured to assess shrinkage. All specimens were kept under constant stress during at least 600 days in a climatic chamber with temperature and relative humidity of 208C and 50%, respectively. Results showed that the new models were able to predict deformations with good ac...

Macrosynthetic fiber–reinforced concrete (MSFRC) has reached maturity as an engineering material and is widely being used in some civil engineering applications. However, design approaches for MSFRC are not as well developed as for steel fibers, and there is a need for further research on this new material in order to further help the development of guidelines and increase the practical applications. The main objective of this study is to critically review the present state of knowledge and applications of MSFRC and to study the effect of these fibers on fresh-and hardened-state performance of different concrete mixtures. Seven groups of concrete mixtures were produced with different volume fractions of steel fibers, fly ash, macrosynthetic fibers, and chemical admixture. Mini slump, compression, and flexural tests were conducted on the specimens for evaluating their mechanical performance, and water absorption and sorptivity tests were also conducted for measuring the permeability of these different concrete mix groups. Therefore, with this comprehensive study, a detailed understanding is gained about the present state of applications of macrosynthetic fibers and their potential for being used as a fiber-reinforcement mechanism in concrete elements.

The world's population growth and the increasing demand for new infrastructure facilities and buildings present us with the vision of a higher resources consumption, specially in the form of more durable concrete such as High Performance Concrete (HPC). Moreover , the growth of the world pollution by plastic waste has been tremendous. The aim of the research is to investigate the change in mechanical properties of HPC with the addition of plastics in concrete. For this purpose 2.5%, 5% and 7.5% in volume of natural fine aggregate in the HPC mixes were replaced by an equal volume of Polyethylene Terephthalate (PET) waste , get by shredded PET bottles. The mechanical properties (compressive, splitting tensile, and flexural strength ) evaluated  at the ages of (7 ,28, 56 and 91) days while the static modulus of elasticity tested at (28 and 91) days . The results indicated that HPC containing PET-aggregate presented lower compressive strength and static elasticity . The  splitting strength display an arising trend at the initial stages, however, they have a tendency to decrease after a while. On the other hand, flexural strength results gives better modulus of rapture at all ages of curing , as compared with reference concrete specimens.

This paper presents the comparative study of effect basalt, glass and steel fiber on compressive and flexural strength of M40 grade concrete. For flexural and compressive strengthening of reinforced concrete, total thirty-nine cubes and thirty-nine beams were cast and beams were tested over an effective span of 900 mm up to failure of the beam under two-point loading. The beams were designed as balance-section. The fibers were placed in concrete randomly by (0.25%, 0.5%, 0.75%, 1%) of its total volume of concrete. For each percentage of fiber total three cubes and three beams were casted to take average results. Finally comparative results are shown for each percentage and for these three fibers.

The primary objective of this study to investigate the strength of cement mortar. Cement is part replaced by Rice Husk Ash up to 30%. Jute fiber were added in the percentage of 0.5%, 1%, 1.5%, and 2% by total weight of cement mortar. Jute fiber enhances the mechanical properties of cement mortar and also avoid crack propagation. The mixed specimen is cured for 7, and 28 days for observing compressive strength test results. Addition of small closely spaced, uniformly distributed fibers act as crack arrester, substantially increase static and dynamic properties with increasing water content. This paper results in the experimental study on the behavior of plain and fiber reinforced cement mortars with jute fiber. It has been resulted that the tested fiber reinforced mortars had no greater static and impact strength compared to plain mortar.

This paper investigates on analyzing the effects of use of fibers and mineral admixtures in the mechanical properties of high strength concrete. This study involves the use of different mineral admixtures like fly ash, ground granulated blast furnace slag, silica fume along with steel fibers. It also includes determination of mix proportioning with different mineral admixtures and steel fibers, determination of water binder ratio, determination of basic properties of concrete such as tensile strength, compressive strength, flexural strength and water permeability. One of the main tasks of the construction industry is to increase the strength and reliability of structures while reducing construction costs. Effective use of fiber reinforced concrete is likely to lead to reduction in reinforcement. In the previous studies, very less research is carried out on use of fibers with a combination of two or more admixtures. Hence, it is felt that there is a need to explore the feasibility of arriving at an optimum mix using a combination of fibers with two or more mineral admixtures, so as to increase the properties at minimum cost.

A detailed description of the instrumented dropweight impact machine is presented. The instrumentation, the calibration, the inertial loading correction, and the dynamic analysis of a concrete beam specimen undergoing three-point impact flexural loading are described. Some results, using such an impact testing machine, obtained from tests done on plain concrete, fiber-reinforced concrete, and conventionally reinforced concrete are presented. It is concluded that the use of such a testing machine may be successfully made in order to test cementitious materials under)mpact.

A theoretical study was performed to investigate the punching shear strength of interior slab-column connections made of steel fiber reinforced concrete (FRC). In the steel FRC slab-column connection, the shear force applied to the critical section is resisted by both the compression zone and the tension zone at the critical section. The shear capacity of the compression zone was defined by considering the interaction between the shear and the normal stresses developed at the critical section. The shear capacity of the tension zone was defined by considering the post-cracking tensile strength of FRC. By using the shear capacity, a new strength model for the punching shear strength of steel FRC slab-column connections was developed. The proposed strength model was verified using existing test results and showed very good accuracy. For convenience in design, a simplified design equation was also developed.