COMPOSITE MATERIALS - INTRODUCTION (original) (raw)
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Rosario Natuzzi, 2023
Applications of composite materials in the civil construction sector have had to wait several decades, starting with their first demonstrations in the sector aviation, before arousing real practical interest. Fiber-reinforced composite systems are increasingly used in the applications of civil engineering for the reinforcement and rehabilitation of reinforcement structures in reinforced concrete, allowing an extension of the original service life. Recently, FRCM composites are spreading. This article discusses composite materials.
Polymer Composite Materials Fiber-Reinforced for the Reinforcement/Repair of Concrete Structures
MDPI, 2020
The present paper deals with the use of polymeric matrix composite materials reinforced with carbon fiber as concrete shear reinforcement materials. Accordingly, cement specimens were manufactured and coated with various types of carbon fabrics and epoxy resin in liquid and solid form (paste). Additionally, composite materials of epoxy resin matrix reinforced with carbon fiber fabrics were manufactured. In all the specimens, the mechanical properties were estimated; the cement samples coated with composite materials of epoxy resin matrix reinforced with carbon fiber fabrics were tested for compressive strength, while the other specimens were tested for shear and bending strength. The specimens were subjected to artificial aging through heat treatment for 8, 12 and 16 days. During the process of artificial aging, the temperature in the chamber reached the range of 65–75 °C. These composite materials exhibited high mechanical properties combined with adaptability. Both an external deterioration of the materials as well as a reduction in mechanical properties during their artificial aging heat treatment were observed. This was shown in the specimens that were not subjected to artificial aging, with an applied compression strength of 74 MPa, and after the artificial aging, there was a decrease of ~7%, with the compression strength being reduced to 68 MPa
Chapter 45 Composites in Construction
2 CONSTRUCTION APPLICATIONS OF COMPOSITES 1370 2.1 Aggressive Environments 1370 2.2 Repair and Retrofit Infrastructure Systems 1371 2.3 Internal Reinforcement of Concrete Members Using FRP Composites 1399 2.4 All-Composites Structural Applications 1401 3 DEVELOPMENT OF CODES AND STANDARDS 1416 4 NEW STRATEGY AND RECOMMENDATIONS 1418 BIBLIOGRAPHY 1420 ƒ Volume of composite Volume of matrix V ϭ (2) m Volume of composite Knowing the ratios, V ƒ and V m , the void volume ratio can be calculated as:
Durability of Fabric-Reinforced Cementitious Matrix (FRCM) Composites: A Review
Applied Sciences
Strengthening and rehabilitation of masonry and concrete structures by means of externally bonded fabric-reinforced cementitious matrix (FRCM) (also referred to as textile reinforced mortar (TRM)) composites was proposed as an alternative to the use of fiber-reinforced polymer (FRP) composites due to their good mechanical properties and compatibility with the substrate. However, quite limited studies are available in the literature regarding the long-term behavior of FRCM composites with respect to different environmental conditions. This paper presents a thorough review of the available researches on the long-term behavior of FRCM composites. Namely, (i) test set-ups employed to study the FRCM durability, (ii) conditioning environments adopted, and (iii) long-term performance of FRCM and its component materials (mortar and fiber textile) subjected to direct tensile and bond tests, are presented and discussed. Based on the available results, some open issues that need to be covered ...
Application of Composites in Infrastructure - Part III (a brief report on research and development)
Composites have been in application for the past 3 -4 decades, but only in the last decade that engineers have been given any serious consideration for its application in civil Infrastructure: such as bridges, roads, earthquake retrofitting of buildings etc. In this paper the growth of application of composites in civil infrastructures and some of its implications are discussed. This paper is divided into 3 parts: Part-I) Materials aspect -fundamentals of composite materials, the matrix and fibers used, Part-II) Composites industry viewpoint: outlook of an engineer of the Australian branch of a worldwide composites manufacturing company towards infrastructure applications (part-I and part-II are in the previous paper), and Part-III) a Structural engineer's observation on the increased application of composites in civil infrastructure.
Effect of Fibers In Concrete Composites
Fiber Reinforced Concrete (FRC) is a concrete containing fibrous material which increases its structural integrity. It contains short discrete fibers that are uniformly distributed and randomly oriented. Fibers include steel fibers, glass fibers, synthetic fibers and natural fibers – each of which lend varying properties to the concrete. In addition, the character of fiber-reinforced concrete changes with varying concretes, fiber materials, geometries, distribution, orientation, and densities. Fibers are used in concrete to control cracking due to plastic shrinkage and to drying shrinkage. They also reduce the permeability of concrete. Some types of fibers produce greater impact–, abrasion–, and shatter–resistance in concrete. Generally, fibers do not increase the flexural strength of concrete, and so cannot replace moment–resisting or structural steel reinforcement. Indeed, some fibers actually reduce the strength of concrete. The amount of fibers added to a concrete mix is expressed as a percentage of the total volume of the composite (concrete and fibers), termed "volume fraction" (Vf). Vf typically ranges from 0.1 to 3%. The aspect ratio (l/d) is calculated by dividing fiber length (l) by its diameter (d). Fibers with a non-circular cross section use an equivalent diameter for the calculation of aspect ratio. If the fiber's modulus of elasticity is higher than the matrix (concrete or mortar binder), they help to carry the load by increasing the tensile strength of the material. Increasing the aspect ratio of the fiber usually segments the flexural strength and toughness of the matrix. However, fibers that are too long tend to "ball" in the mix and create workability problems. The weak matrix in concrete, when reinforced with steel fibers, uniformly distributed across its entire mass, gets strengthened enormously, thereby rendering the matrix to behave as a composite material with properties significantly different from conventional concrete. Because of the vast improvements achieved by the addition of fibers to concrete, there are several applications where Fiber Reinforced Concrete (FRC) can be intelligently and beneficially used (ACI Committee 1996). Fibrous concrete was described at a meso-scale as a three-phase material composing of aggregate, cement matrix, steel fibers and interfacial zones between cement matrix and aggregate, and between cement matrix and steel fibers. The effect of the fiber interface strength, fiber volume, fiber orientation, fiber length and specimen size on the concrete behavior was investigated (Kozicki and Tejchman 2010). Addition of fibers to concrete enhances its toughness and strain at peak stress, but can slightly reduce the Young's modulus. Simple expressions are proposed to estimate the Young's modulus and the strain at peak stress, from the compressive strength results, knowing fiber volume, length and diameter (Neves and Fernandes de Almeida 2005). Key words: Concrete, Aggregates, bond, cement matrix, Fiber reinforced concrete, Steel fibers, Glass fibers Introduction Because of the vast improvements achieved by the addition of fibers to concrete, there are several applications where Fiber Reinforced Concrete (FRC) can be intelligently and beneficially used. These fibers have already been used in many large projects involving the construction of industrial floors, pavements, highway-overlays, etc., in India. The principal fibers in common commercial use for civil engineering applications include steel, glass, carbon and aramid. These fibers are also used in the production of continuous fibers and are used as a replacement to reinforcing steel. High percentages of steel fibers are used extensively in pavements and in tunneling. This invention uses Slurry Infiltrated Fiber Concrete (SIFCON). Fibers in the form of mat are also being used in the development of high performance structural composite. The usefulness of FRC in various civil engineering applications is indisputable. Fiber reinforced concrete has so far been successfully used in slabs on grade, shotcrete, architectural panels, precast products, offshore structures, structures in seismic regions, thin and thick repairs, crash barriers, footings, hydraulic structures and many other applications. Compared to other building materials such as metals and polymers, concrete is significantly more brittle and exhibits a poor tensile strength. Based on fracture toughness values, steel is at least 100 times more resistant to crack growth than concrete. Concrete in service thus cracks easily, and this cracking creates easy access routes for deleterious agents resulting in early saturation, freeze-thaw damage, scaling, discoloration and steel corrosion. The concerns with the inferior fracture toughness of concrete are alleviated to a large extent by reinforcing it with fibers of various materials. The resulting material with a random distribution of short, discontinuous fibers is termed fiber reinforced concrete (FRC) and is slowly becoming a well accepted mainstream construction material (Banthia 1991). The weak matrix in concrete, when reinforced with discrete steel fibers, uniformly distributed across its entire mass, gets strengthened enormously, thereby rendering the matrix to behave as a composite material with properties significantly different from conventional concrete. Research explores the relationship between permeability and crack width in cracked, steel fiber–reinforced concrete. In addition, it inspects the influence of steel fiber reinforcement on concrete permeability. The feedback–controlled splitting tension test (also known as the Brazilian test) is used to induce cracks of up to 500 microns in concrete specimens without reinforcement, and with steel fiber reinforcement volumes of both 0.5% and 1%. The cracks relax after they are induced. The steel fibers decrease permeability of specimens with relaxed cracks larger than 100 microns (Rapoport et al. 2001). This paper presents a brief state-of-the-art report on mechanical properties and durability of different types of fiber reinforced concretes.
Journal of Composites for Construction, 2013
The repair and retrofit/rehabilitation of existing concrete and masonry structures have traditionally been accomplished with externally bonded fiber-reinforced polymer (FRP) systems, steel plates, reinforced concrete (RC) overlays, and posttensioning, just to name some of the many techniques presently available. Fabric-reinforced cementitious-matrix (FRCM) composites have recently emerged as an additional strengthening technology. FRCM is a composite material consisting of a sequence of one or more layers of cement-based matrix reinforced with dry-fiber fabric. This paper has three objectives: (1) to review existing guidelines for tensile testing and calculation of FRCM material properties to be used in analysis;
APPLICATIONS OF FIBRE REINFORCED COMPOSITE POLYMER IN CONSTRUCTIONS
1 (MTECH (SE) student department of civil engineering Usha Rama college of engineering and technology) 2 (ASSISTANT PROFESSOR department of civil engineering Usha Rama college of engineering and technology) 3 (PROFESSOR & HEAD OF THE Department of civil engineering Usha Rama college of engineering and technology) ABSTRACT: fibrere in forced polymer composites, developed primarily for the aerospace and defence industries, are a class of materials with great potential to use in civil infrastructure. Since the construction of the first all-composite bridge superstructure in Miyun, China, in 1982, they have been gradually gaining acceptance from civil engineers as a new construction material. During these 30 years, their proved to be useful in a few areas of application: mostly in form of sheets and strips for strengthening existing bridge structures, and to some extent, as reinforcing bars substituting steel as concrete reinforcement. Also, a number of constructions have built, in which FRP composites replaced traditional materials for structural elements (girders, bridge decks, stay cables). Among these constructions there is a relatively big amount of hybrid bridge structures, where only a part of the superstructure is made of FRP composites, and a much smaller amount of all-composite bridge structures, with superstructures made exclusively of this material. The purpose of this paper is to present the state of the art in the use of FRP composites in bridge engineering with the focus on hybrid and all-composite structures. Firstly, the paper will present the basic information about FRP composites, including the definition, description of the components, mechanical properties and general areas of application. Then, it will focus on FRP composites as the material of which structural elements are made, describing manufacturing processes relevant to civil engineering applications, assortment of structural profiles, cables, tendons and bridge deck systems, presenting the problem of codes and design guidelines that refer to the use FRP composites as the construction material, and methods of joining structural elements. Thirdly, it will compare the properties of FRP composites with those of traditional materials. Finally, there are presented some examples of hybrid and all composite bridge structures and a list of 355 constructions made of this material around the world, with basic data and references providing more information.
A critical study of composite fibre reinforced concrete
Concrete is a most versatile material it can be used in typical environmental condition like extreme cold & hot weather, under any chemically surcharged and atomic reactor. Concrete possess very good compressive strength but have very low tensile strength, that cannot be neglected also limited ductility and little resistance to cracking. Internal microcracking is inherently present in concrete and the poor tensile strength of concrete is due to propagation of these microcracks and that leads to brittle fracture of concrete. In a Composite Fiber Reinforced Concrete (CFRC), two or more different types of fibers are rationally combined and added to the concrete produce a composite material that derives benefits from each of the individual fibers and show evidence of a synergistic response. The foremost aim of the present experimental investigation is to use different fractions of coconut coir and galvanized steel fibers to produce HFRC and thus to evaluate its performance under compression and flexure strength. Samples were prepared with 10 % replacement of ordinary Portland cement with fly ash and various proportions of these two fibers. The amount of fiber is kept upto 3% by the weight of cement. Six samples are prepared with the ratio of S0C0, S3C0, S2C1, S1.5C1.5, S1C2, & S0C3. The strength of each specimen is investigated to determine the optimum result of sample.
The usefulness of fiber reinforced concrete (FRC) in various civil engineering applications is indisputable. Fiber reinforced concrete has so far been successfully used in slabs on grade, shotcrete, architectural panels, precast products, offshore structures, structures in seismic regions, thin and thick repairs, crash barriers, footings, hydraulic structures and many other applications. This paper presents a brief state-of-the-art report on mechanical properties and durability of fiber reinforced concrete. In particular, issues related to fiber-matrix interaction, reinforcement mechanisms, standardized testing, resistance to dynamic loads, and transport properties are discussed.