Uses and Applications for Steel Fiber Concrete Full-time Job2022-06-09 07:41 Engineering Darzāb 21 views
Uses and Applications for Steel Fiber Concrete
Steel fiber concrete flooring can provide superior resistance to minimize cracks in hardened concrete, as well as maximum resistance to withstand heavy loads, either dynamic or static. If you decide to use steel fiber concrete flooring, you can select to use a ‘joint-less floor’. Joint-less floors are floors that have minimal joints, providing spaces without joints as large as 40 or 50-meter span wide.
Steel fiber dosage will vary greatly upon the project intended use, and the types of mesh being replaced. Common dosages are in the range between 20-30kg/m3 to 40-50kg/m3 for joint-less floors. Trowelling concrete will help to embed steel fibers into the concrete surface producing a better-finished product. Steel fibers will enhance the crack resistance of the concrete, and they can also be used to replace or supplement structural reinforcement. It only can be done through a structural engineer and with proper guidance.
How and When the Fiber is AddedSteel fiber reinforced concrete is a composite material having fibers as the additional ingredients, dispersed uniformly at random in small percentages, i.e. between 0.3% and 2.5% by volume in plain concrete. SFRC products are manufactured by adding steel fibers to the ingredients of concrete in the mixer and by transferring the green concrete into moulds. The product is then compacted and cured by the conventional methods. Segregation or balling is one of the problems encountered during mixing and compacting SFRC. This should be avoided for uniform distribution of fibers. The energy required for mixing, conveying, placing and finishing of SFRC is slightly higher. Use of pan mixer and fiber dispenser to assist in better mixing and to reduce the formation of fiber balls is essential. Additional fines and limiting maximum size of aggregates to 20mm occasionally, cement contents of 350 kg to 550 kg per cubic meter are normally needed.Steel fibers are added to concrete to improve the structural properties, particularly tensile and flexural strength. The extent of improvement in the mechanical properties achieved with SFRC over those of plain concrete depends on several factors, such as shape, size, volume, percentage and distribution of fibers. Plain, straight and round fibers were found to develop very weak bond and hence low flexural strength. For a given shape of fibers, flexural strength of SFRC was found to increase with aspect ratio (ratio of length to equivalent diameter). Even though higher ratios of fibers gave increased flexural strength, workability of green SFRC was found to be adversely affected with increasing aspect ratios. Hence aspect ratio is generally limited to an optimum value to achieve good workability and strength. Grey suggested that aspect ratio of less than 60 are best from the point of handling and mixing of fibers, but an aspect ratio of about 100 is desirable from strength point of view. Schwarz however suggested aspect ratio between 50 and 70 is more practicable value for ready mix concrete. In most of the field applications tried out to date, the size of the fibers varies between 0.25 mm and 1.00mm in diameter and from 12mm to 60mm in length, and the fiber content ranged from 0.3 to 2.5 percent by volume. Higher contests of fiber up to 10% have also been experimented. Addition of steel fibers up to 5% by volume increased the flexural strength to about 2.5 times that of plain concrete. As explained above, mixing steel fibers considerably improves the structural properties of concrete, particularly tensile and flexural strength. Ductility and post cracking strength, resistance to fatigue, spalling and wear and tear of SFRC are higher than in the case of conventional reinforced concrete. SFRC is therefore found to be a versatile material for the manufacture of wide varieties of precast products such as manhole covers, slab elements for bridge decks, highways, runways, and tunnel linings, machine foundation blocks, door and window frames, piles, coal storage bunkers, grain storage bins, stair cases and break waters. Technology for this manufacture of SFRC light, medium and heavy duty manholes covers has been developed in India by Structural Engineering Research Centre, Chennai. Field experiments with two percent of fiber content indicated that SFRC runway slabs could be about one half the thickness of plain concrete slabs for the same wheel load coverage. Cement Research Institute of India (CRI) also demonstrated the use of SFRC in one of the jet bays at Delhi airport.
Ultra-High Performance Concrete
Advances in the science of concrete materials have led to the development of a new class of cementitious composites called ultra-high performance concrete (UHPC). The links above will direct you to pages detailing UHPC projects, bridges with UHPC components, articles that focus on UHPC research, and the main contact at Turner-Fairbank Highway Research Center (TFHRC) for UHPC.
Advantages of Fibre-Reinforced Concrete
Concrete is an integral part of any construction project, whether you are building roads, a a ground floor in your private home, or a power plant. This is because concrete is very durable, but it can be susceptible to fractures as subsoil frosts and thaws, if it shifts, or if tree roots press upward on the concrete. This can be a major problem for construction projects, as fractures lead to costly repairs and could spell disaster. The solution to this problem is the introduction of reinforced concrete.
What Does It Mean for Concrete to Be Reinforced?
Concrete is reinforced when it has suitable fibres in the mix to increase its toughness and ductility. Unlike non-reinforced concrete that is likely to break down when it fractures and cracks, reinforced fibre concrete will maintain its structural integrity, as it is held together by these fibres when a crack develops.
Suppose you are looking to embark on a construction project. In that case, you must analyse the advantages and disadvantages of using fibre-reinforced concrete, and the different types of fibres used. Trusted professionals like SB Civil Engineering would take this burden off you and ensure your project is completed hitch-free.
The advantages of fibre-reinforced concrete include the following: