Papers by Keyword: Fiber Reinforced Concrete

Abstract: A concrete mixture formulation consisting of industrial wastes such as fly ash and gypsum from ceramic mold waste as partial replacements for cement was developed in this two-part study to lessen the carbon footprint from processing the conventional materials used in the construction industry. The first part aims to determine the optimum composition of the ternary binder (cement, fly ash and recycled gypsum) and the curing period (7, 28 and 90) that will provide the highest compressive strength for the casted concrete cylinders. The second part focuses on establishing the effective polypropylene fiber (PPF) dosage, utilizing the pre-optimized binder composition. The structural integrity of the concrete cylinders was evaluated through compressive strength and split tensile tests following water curing periods of 7, 28, and 90 days. Results from the initial mechanical tests revealed that the optimum ternary binder composition was C60-F37.5-G2.5 cured for 90 days. While fiber reinforcement typically has limited impact on compressive strength, the addition of 1.5% PPF yielded better long-term compressive strength development compared with other PPF dosages. For tensile strength, 0.5%-1% PPF achieved the highest values at 28 days, whereas 1.5% PPF provided the peak performance under prolonged curing at 90 days. This shift in behavior is attributed to the progressive increase in fiber-bridging effectiveness over time. Findings from these mechanical tests were supported by the results from X-Ray Diffraction (XRD) analysis and optical microscopy.

Abstract: This research investigated the mechanical properties, impact resistance, and behavior under elevated temperatures of Fiber Rubberized High-Strength Concrete (FRHSC), which incorporates Waste Steel Fiber (WSF) and Crumbed Rubber (CR) obtained from waste tires. The study involved five different concrete mixtures to explore the impact of WSF and CR. WSF was consistently mixed in a ratio of 0.3% by volume of the concrete. CR was used to partially replace the fine aggregate in proportions of 10%, 20%, 30%, and 40% by volume. The study examined various characteristics of both the fresh and hardened FRHSC, including slump, unit weight, compressive, tensile, and flexural strengths, as well as its impact resistance. The effects of elevated temperatures at ambient, 200 °C, 400 °C, and 600 °C for a period of 2 hours were also analyzed, focusing on the failure shape, and residual compressive strength. Findings indicated that as the quantity of rubber in the concrete samples increased, there was a noted gradual decline in their mechanical properties. Concurrently, this increase in rubber content contributed to an enhancement in the ductility of the samples. The energy absorption by the rubberized specimens was found to be consistent, regardless of the variation in rubber content due to the presence of WSF. The residual compressive strengths of FRHSC subjected to elevated temperatures improved with the addition of CR. The presence of CR led to an increase in the concrete's porosity, and exposure to high temperatures resulted in more cracks due to CR evaporation and the replacement of air voids, causing a notable reduction in compressive strengths. Keywords Fiber reinforced Concrete; Crumb rubber; waste steel fiber; waste tires, Rubberized concrete; Impact energy; Mechanical properties; Elevated temperature.

Abstract: This research paper presents the findings of an experimental study conducted to investigate the influence of varying sizes and percentages of steel and nylon fibers on the mechanical and durability properties of concrete. The objective of this study was to explore the potential enhancements in concrete performance through fiber reinforcement, considering the two distinct fiber types - steel and nylon. A comprehensive testing program was devised, encompassing a wide range of fiber combinations to assess their individual and combined effects on concrete properties. The concrete specimens were prepared by incorporating different sizes (length and diameter) and proportions (percentage by volume) of steel and nylon fibers into the concrete mix. Mechanical properties, including compressive strength, tensile strength, and flexural strength, were evaluated to determine the impact of fiber reinforcement on the concrete's load-bearing capacity and resistance to cracking. Additionally, the durability properties, chloride ion penetration, and abrasion resistance, were assessed to understand the potential improvement in the concrete's long-term performance under adverse environmental conditions. The experimental results revealed significant variations in the mechanical and durability properties of the fiber-reinforced concrete compared to the conventional concrete mix. Steel fibers demonstrated superior performance in enhancing the concrete's load-carrying capacity and ductility, especially at higher percentages. On the other hand, nylon fibers exhibited exceptional resistance to and abrasion, contributing to improved durability. Notably, the steel and nylon fibers exhibited synergistic effects, leading to a balanced enhancement of mechanical and durability properties. In conclusion, this study provides valuable insights into the benefits of incorporating steel and nylon fibers in concrete, offering an effective means of optimizing the material's overall performance for diverse engineering applications. The results from this research can serve as a basis for developing more resilient and sustainable concrete structures, which can withstand harsh environmental conditions and contribute to the advancement of construction practices. Further exploration into the long-term behavior and cost-effectiveness of fiber-reinforced concrete is recommended for a comprehensive understanding of its feasibility in practical engineering applications.

Abstract: Fiber reinforcement is widely used in construction engineering to improve the mechanical properties of concrete such as compressive and tensile strengths. Concrete is strong in compression but weak in tension and is a brittle material. In the construction industry, strength, durability and cost are among the major factors for selecting the suitable construction materials. During this investigation, the mechanical properties of sisal fibers reinforced concrete (SFRC) were assessed namely, flexural strength, tensile strength ad interfacial bond strength. The said properties were assessed in two types of reinforcement namely, randomly oriented sisal fibers and parallel oriented sisal fibers reinforcement. In both cases the sisal fibers were varied in volume fractions so as to establish the optimum value. The mechanical properties of flexural and tensile strengths were found to increase considerably with increasing fiber volume fractions until an optimum volume fraction is reached, thereafter, the strengths were found to decrease continuously. The prominent increment of 32.4% in flexural strength at fiber volume fraction of 2.0% parallel reinforced fiber concrete composite was observed. There was very small increment on both flexural and tensile strength for randomly oriented chopped sisal fibers reinforced concrete (SFRC). The Interfacial bond strength was found to be 0.12 N/mm² and was observed to be prominent for chopped sisal fibers reinforced concrete specimens tested for flexural strength. During failure, fiber pull-out was observed and the composite was observed to behave in a ductile manner whereby the fibers were able to carry more load while full fracture had occurred on the specimen. The water absorption capacity of the SFRC was found to increase with increasing sisal fiber volume fraction.

Abstract: This paper presents the feasibility study of adding recycled Polyethylene Terephthalate (PET) fiber obtained from drinking water bottle as admixture material in the concrete. A few numbers of tests were conducted to determine the physical and mechanical properties of recycled PET fiber reinforced concrete such as slump test, compressive strength test and flexural strength test. The effect of incorporating the recycled PET fiber on various volume fractions of concrete by 0.5%, 1%, and 1.5% of weight of cement were experimentally investigated. The test specimens comprising of cubes and beams were prepared and tested at 3, 7, 14 and 28 days after curing process completed. Generally, it was found that the workability of concrete reinforced recycled PET has reduced as the volume fraction of PET fiber increased. The compressive strength of concrete reinforced recycled PET has reached the highest value at volume fraction of 0.5%. However, the flexural strength of concrete was significantly increased by incorporating 1.0% of recycled PET fiber. It can be concluded that the concrete which contains 0.5% of recycled PET fiber has the highest of average percentage of relative. Hence, it can be categorized as the optimum percentage of recycled PET fiber to be utilized in concrete. It is recommended to use recycled PET fiber in concrete for the construction of structures and infrastructures as a green construction material in order to achieve clean and sustainable environment in the year future.

Abstract: Ordinary concrete - a stone like structure which is formed by the chemical reaction of the cement, aggregate and water and is a brittle material which is strong in compression but very weak in tension, which causes cracks under small loads. These cracks gradually propagate to the compression end of the member and finally, the member breaks. These increase in size and magnitude with time and finally fails. One of the successful reinforcing methods is providing steel reinforcement but even then, cracks in reinforced concrete members extend freely. Thus, need for multidirectional and closely spaced steel reinforcement arises. Fiber reinforcement gives the solution for this problem. So, to increase the tensile strength of ordinary concrete a technique of introduction of fibers in concrete is being used. These fibers act as crack arrestors and prevent the propagation of the cracks, improves the post cracking response of the concrete, i.e., to improve its energy absorption capacity and apparent ductility, and crack control. The Present study focuses upon, Synthetic (Polypropylene) Fiber Reinforcement (SFRC) of 1% and 3% and Natural (Jute) Fiber Reinforcement (NFRC) of 1% and 3% by weight and are compared with respect to their compressive strength and flexural strength. The present study concludes considering the practical issue of workability of fibers, that in between synthetic and natural fibers selected, 1% Polypropylene fibers can be added as a reinforcement to ordinary concrete to enhance both compressive strength by nearly 2 times at 28 days curing duration and flexural strength by 35%% at 28 days curing duration. History and Development

Abstract: The study aims to explore the effects of crimped polypropylene fiber (PP) inclusions in slag (GGBS) based concrete, which was used as cement replacement. The mode of accelerated curing on mechanical properties of the GGBS based concrete for various mixes of concrete was investigated systematically. The addition of PP fiber in the concrete increases the strain hardening properties of the concrete due to matrix reinforcing efficiency offered by discrete fibers present in the matrix. The experimental test results showed an increase in bending stress in concrete with an increase in percentage of PP fibers from 0.1% to 0.3% V_f of concrete. In the case of slag concrete, the optimum addition of slag up to 25% proved to be effective in improving the concrete strength properties. Further replacement of OPC in GGBS up to 50% concrete mixes showed a reduction in the compressive strength in normal curing. Indeed, an apparent increase in the compressive and flexural strength of slag based concrete was noticed in accelerated curing for various mixes of structural concrete.

Abstract: This study focuses on the study of the mechanical behavior of non-metallic hybrid Basalt-PVA fiber reinforced concrete. Total five mixes were investigated with one control plain concrete and four with fiber volume fraction of 0.3%, 0.6%, 0.9% and 1.2%. Basalt and PVA were used in same quantity. Fiber decreased workability, therefore superplasticizer was used to maintain workability constant. The increase in superplasticizer and fiber content decreased compression, split tensile and flexure strengths because of formation of big size pores. Whereas fiber enhanced the post peak load zone in the load-deflection curve. Fiber improved the bridging action by increasing energy absorption. Fiber vanished the brittle behavior of high strength concrete and increased first crack toughness, flexure toughness and also maximum deflection. 0.3% volume fraction of fiber was found to be optimum with the negligible decrease in compression, split tensile and flexure strength while caused the considerable increase in first crack toughness, flexure toughness, and maximum deflection.

Abstract: The building industry offers a wide range of materials which can be used for the production of various structural elements. Fibre reinforced concrete (FRC) is a material which is more frequently utilized for concrete structures. The reason is its physical and mechanical properties which contribute to traditional concrete elements and structures various economical benefits such as structure subtlety, part or full elimination of conventional reinforcement, resistance to mechanical loading and surrounding environment. Therefore, it is necessary to search for appropriate structures where the benefits of FRC could be used. First of all it is necessary to seek for structures which owing to their geometry and intended use seem to be appropriate for FRC application. It can be either new structural elements or existing structural elements made of a different material. During a material optimization there are many parameters to take into account which include production costs, manufacturing technology, structural behaviour, ultimate bearing capacity and durability of proposed member. The efficiency of material optimization is determined by comparing these parameters. While it is relatively easy and cost efficient to determine and evaluate the production costs, structure durability and manufacturing technology, to describe the structural behaviour of innovative elements is a complex task. However there are many sophisticated software which are capable to accurately simulate the behaviour of structural elements by using modern computational methods. At the end of feasibility study, experimental testing is conducted on full-scale pilot elements with the aim to verify their real behaviour as well as to optimize the computational model. As a result, many innovative FRC based structural elements have been developed at Czech Technical University in Prague in cooperation with construction companies.

Abstract: The paper deals with the determination of the modulus of elasticity in tension for cementitious composites and comparing these values with the values of modulus in compression. It describes several methods, which are usually used for determination of modulus of elasticity of concrete and fibre reinforced concrete. In the experimental program modulus of elasticity in compression and tension of various types of concrete and fibre reinforced concrete were compared. The classic test with prismatic specimens was used for determination of the modulus in compression; a new arrangement of uniaxial tension test of cementitious composites was used for determination of the modulus of elasticity in tension.