AIM: The aim of this topic is to define fiber reinforced concrete and its application, it important properties as well as it superior resistance to cracking. As a result of the ability of fiber to arrest cracks, the composites of fiber possesses an increased in tensile strength both at the first crack and at ultimate, especially under flexural loading, and the fibers can still hold the matrix together even after a lot of cracking.
Introduction
Concrete is a structural material that is weak in tension and they also have brittle properties with a low tensile strength and strain capacity. Fiber reinforced concrete is known as one of the fastest segments in concrete which contain fibrous materials which increase the structural integrity. Fiber reinforced concrete can also be defined as a composite materials which is compose of aggregate, cement and discrete discontinuous fibers. Fibers include natural fibers, glass fibers, synthetic fibers and steel fibers. Fiber is developed recently in the early sixties and when it is added to concrete makes it to be consistent and isotropic in nature. The mode of failure of fiber reinforced concrete is either by bond failure between fiber and matrix or failure of the materials.
The application area of fiber reinforced concrete is an old form of method which helps to improve the characteristics of construction materials. The recent applications include the addition of horse hair to reinforce plaster, asbestos to reinforce pottery and straw to mud bricks.
The role of fibers in concrete is to bridge across the cracks that develop some post cracking ductility and to increase it toughness and types of loading. The uses of reinforced concrete help to increase the strength and ductility but it req...
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...forced concrete beams up to 100 percent.
Column: The use of fibers help in reducing the types of explosives failure for columns and an increase of fiber content slightly increases the ductility of axially loaded strength.
Applications of Fiber Reinforced Concrete: The application of fibers in concrete industries depends on the designer and the builder. The main area where fiber reinforced concrete are applied is as follows:
Runway, Aircraft Parking, and pavements
Tunnel Lining and Slope Stabilization.
Blast Resistant Structures.
Thin Shell, Walls, Pipes and Manholes.
Dams and Hydraulics Structures
Conclusions: From my understanding, it shows that Fiber Reinforced Concrete is a promising material to be used because of it good properties, no workability problem , it helps to control cracks in concrete and it is long lasting in concrete structures.
It has also been discovered that the components of Kevlar fiber, have a radial orientation that is in a crystal. Crystal-like regularity is the largest contributing factor in the strength of Kevlar fiber. PROPERTIES It is five times stronger, yet the same weight as steel. Kevlar Aramid fiber is an improved material, which is an extremely lightweight, man-made organic fiber. Kevlar fiber has a combination of properties, which makes Kevlar a very useful material.
Carbon fiber as a building material: in the case of building and construction for many centuries humans have always looked towards natural resources in providing its populations with various building materials, some examples of these materials includes steel from large scale mining and bricks from clay sands. But this has proven to be deadly to our environment, through modern research we have come to understand that the uses of these natural resources have created greater environmental vulnerability. The heavy production of timber creates silt which has been polluting our water systems, and also the mass collection of clay sands and limestone for bricking and concreting purposes has caused top soil erosions which make the environment more susceptible to flooding and landslides. ...
Checking the opening of cracks and stress limits, will not be required for concrete elements. When the tensile flexural stress exceeds the effective tensile strength fcteff, then a check for pre-stressed concrete is required. This should normally occur when sections do not have tendons near the tension face or there is no exposure to chlorides, so decompression doesn’t have to be checked. The analysis using uncracked section will be done in sections controlled for decompression and have tendons near the surface tension. As the cracked section analysis is done by computer, it solves the complexity of the calculations. However, this does not mean that pre-stressed cannot be calculated directly from a set of equations as with crack width checks for RC.
According to major supplies, “Use of synthetic fibers for reinforcing concrete is continuously, increasing. The increase has been considerable since 1980, but slowed somewhat in 1990, a year of substantial construction cutbacks. Apparently the construction community believes there are advantages in the use of synthetic fibers in concrete.” (Schupack) Synthetic fibers are used to improve crack control in concrete. Some reports say that synthetic fiber reinforced concrete (SFRC) would replace welded wire fabric in many slab-on-grade applications. But in reality if the welded wire fabric is placed properly it controls crack width better than the synthetic fiber reinforced concrete. In a case study of the use of synthetic fibers in reinforced concrete, the following conclusions were obtained. No matter what concrete placing job is being done, there is no substitute for good concrete practices. The use of a low fiber volume mix will help control plastic shrinkage cracks and bleeding, but not give good cracking control once the crack forms. The synthetic fibers running through a crack have a poor bond providing no shear friction. Impact and toughness tests on synthetic fiber reinforced concrete imply less edge spalling will occur. The American Concrete Institute (ACI) conducted two studies on polypropylene fiber reinforced concrete, one dealing with plastic shrinkage cracking and the other on permeability characteristics. Plastic shrinkage cracking occurs when the surface water on the concrete evaporates faster than the bleed water reaches the surface of the concrete. It was determined by the plastic shrinking cracking study that polypropylene fibers helped reduce the total plastic shrinkage crack area on test panels. Also determined is that the screeding rate affects the total crack area in polypropylene reinforced concrete, while finishing operations showed no significant effects. This study also suggests the use of longer fibers (about 0.75in.) will produce less crack area. “Permeability plays an important role in long-term durability of concrete materials. Permeability of concrete generally refers to the rate at which particular aggressive substances (water, sulfates, chloride ions, etc.) can flow through the concrete.” (Soroushian) As discussed in the plastic shrinkage study that polypropylene fibers reduce cracking. Less cracking in the concrete surface that surface would be less permeable. In the permeability study, they concentrated on the effects of chloride and the permeability of the concrete. The results of this study concluded polypropylene fibers had little effects on chloride permeability of concrete. The polypropylene fibers only help reduce plastic shrinkage cracks.
ABSTRACT: This article is a portion of a comprehensive study on carbon fibre reinforced plastics. The thermal behaviour and dynamic and tensile mechanical properties of polypropylene carbon fibres composites are discussed. Carbon Fibre Reinforced Plastic is similar to fibre glass which is woven into a textile material and resin such as epoxy resin is applied and allowed to cure. The resulting material is very strong and has the best strength to weight ratio of all construction materials. It is an improvement on glass fibre-reinforced plastic, although much more expensive. Carbon Fibre Reinforced Polymers tend to be used in the manufacture of expensive sports cars, where strong and light materials are required. Expensive, competition bicycles
In this paper we have studied compressive strength of concrete by replacing natural aggregate with recycled aggregate by 25%, 50% and 75%.This mixture formed in the sample of cubes of dimension 150x150x150mm3.
3) Super workable concretes have the ability to fill the heavily reinforced sections without internal or external vibration, without segregation and without developing large sized voids
Carbon fiber has applications in professional roles such as aerospace, military, and engineering materials . On their everyday uses carbon fiber is used in high-performance vehicles, sporting equipment, and musical instruments just to name a few. One field many people may not think of that affect a wide range of people is energy with carbon fiber applications for windmill blades, natural gas storage, and transportation, fuel cells.Carbon fiber is also used in Construction for lightweight pre-cast concrete and earthquake protection. Carbon fiber is utilized in oil exploration in deep water drilling platforms and drill pipes
An attempt was made to report the comparative analysis of the modulus of rupture and the splitting tensile strength of normal concrete by (Akinkurolere, 2010). The two properties were usually used to estimate the tensile strength of concrete; however, they didn’t usually yield the same results. Taguchi's optimization technique was employed to reduce the number of trials needed to get the results. The results showed that the splitting tensile strength ranged between 60-80% of the modulus of rupture which was also known as the flexural
It is used in aerospace engineering, automotive engineering, civil engineering, and sporting goods. Aerospace engineering utilizes CFPR for the strength and lightweight properties. The Airbus A350 XWB has the highest weight ratio for CFRP at 52%. This includes wing spars and fuselage components. This is one of the first commercial aircrafts to have a structural composite components, the utilization of CFRP has helped optimize aerodynamic efficiency. Using CFRP is a fairly new transition from metallic
In this report, we will introduce and illustrate on precast concrete, pre-stressed concrete, ready-mix concrete, reinforced concrete, terrazzo and Urbanite in details.
With its relative lower weight, the stiffness and strength of the composite material are relatively higher than the original materials.
One of the pioneers who used reinforced concrete as a building material is Auguste Perret. Auguste Perret was heavily influenced by reading the works of Eugène Emmanuel Viollet-le-Duc who backed the unification of architectural form and techniques of construction which had lost its technique in the 19th century. Perret spent 1891-1895 in the Académie des Beaux-Arts under the guidance of Julien Guader. He taught his students the classical principles of composition and proportion with the analysis of building types. Perret left ...
There are considerable differences in published property data for Metal matrix composite. This is partly due to the fact that there are no industry standards for metal matrix composites, as there are for metals. Reinforcements and composites are typically made by proprietary processes, and, as a consequence, the properties of materials having the same nominal composition can be radically different. The issue is further clouded by the fact that many reinforcements and they are still in the developmental stage, and are continually being refined. Numerous test methods are used throughout the industry, and it is widely recognized that this is a major source of differences in reported properties. Some properties cannot be measured as they would be for monolithic metals. For instance, toughness is an important but hard to define material property. Standard fracture mechanics tests and analytical methods for metals are based on the assumption of self-similar crack extension; i.e., a crack will simply lengthen without changing shape. Composites, however, are non-homogeneous materials with complex internal damage patterns. As a result, the applicability of conventional fracture mechanics to metal matrix composite is controversial, especially for fibre-reinforced ma...
Sustainable concrete materials and sustainable steel reinforcement have been introduced to civil engineers to get closer to the sustainable development. Sustainable buildings constructed with use of these materials have shown an increased service life and the final cost has been reduced due to them.