The effect of hybrid fibers and expansive agent on the shrinkage and permeability of high-performance concrete (original) (raw)
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Utilization of hybrid fibers in different types of concrete and their activity
Journal of the Mechanical Behavior of Materials, 2023
In this work, the influence of using hybrid fibers on the mechanical properties of two types of concrete: high-strength concrete (HSC) and lightweight concrete (LWC) was studied. Using hybrid fibers instead of using only one type reduced the negative effect on concrete mechanical performance. The glass fiber (GF) and polypropylene fiber (PPF) were used in different contents ranged from 0.2 to 1% as weight % of binder content. Moreover, combinations of both fibers "GF + PPF" were used in contents % of "0.3 + 0.5%," "0.5 + 0.5%," "0.3 + 1%," and "0.5 + 1%." LWC mixes were prepared by replacing 40% of the coarse aggregate of reference mix with volcanic material (pumice) as a volumetric replacing. To produce HSC, the water-to-cement ratio was reduced to 0.3, 10% silica fume was added, and 1% super plasticizer was used to obtain the consistency. Compressive strength, splitting strength, and flexural strength tests were carried out. The results showed that using 0.7% GF displayed the highest increases in compressive, splitting tensile, and flexural strength of HSC and LWC mixes. Furthermore, GF exhibited better performance and higher values in compressive, splitting tensile, and flexural strength tests in comparison with PPF. The optimum hybrid fiber content displaying the highest increment of all tested properties in both concrete types, HSC and LWC, was "0.5% GF + 0.5% PPF."
An Experimental Study on Concrete with Hybrid Fibers
Plain concrete has a very low tensile strength, limited ductility and little resistant to cracking. Internal micro cracks are present in the concrete and its poor tensile strength is due to the propagation of such micro cracks, leading to brittle fracture of the concrete. In the past attempts have been made to improve the tensile properties of concrete by way of using reinforced steel bars and also by applying restraining techniques. Although both the two methods provide tensile strength to the concrete members but do not increase the tensile strength of the concrete. Then Steel fibres are used to increase the tensile strength of concrete. The cracks present in the concrete will be controlled by adding coir fibres to the concrete.The study aims to evaluate the properties of concrete using steel and coir fibres. This project presents adding steel and coir fibres to the percentage of 0.5, 1.0, 1.5, and 2.0% to the weight of the concrete. Physical and chemical properties of steel and coir fibres have been studied. A concrete mix has been designed to achieve the grade of M30 as required by IS 10262-2009.The investigation contains two phases. The phase one contains to study and determine the properties of the material. In the phase two contains to determine the Compressive Strength, Split Tensile Strength and Flexural Strength of the concrete at 7, 14 and 28 days by adding steel and coir fibres to the percentage of 0.5, 1.0, 1.5 and 2.0% to the weight of the concrete.
Materials
A comprehensive program of experiments consisting of compression, uniaxial compression, direct shear, flexural as well as splitting tensile and air permeability tests were performed to analyse the effect of the level of fibre dosage and the water–cement ratio on the physical properties of hybrid fibre-reinforced concrete (HFRC). Two types of fibres were studied in terms of their effect on the properties of HFRC. The results indicated that the mechanical properties of concrete were significantly improved by increasing the fibre content. However, increasing the percentage fibre content past a certain peak performance limit (0.9% glass fibre (GF) and 0.45% polypropylene fibre (PPF)) led to a decrease in strength compared to reference mixes. Additionally, the incorporation of hybrid fibres yielded an increase in air permeability in the tested specimens. The results showed that the strength-related properties of HFRC were superior to the properties of single fibre-reinforced concrete.
An Experimental Study on Effect of Hybrid Fibres in Reinforced Concrete
This project focuses on the experimental investigation carried out on hybrid fibre reinforced concrete (combination of crimped steel fibre and a non-metallic polyester fibre) by varying the steel fibre content(0.1 to 0.25% of volume of concrete) and keeping a constant polyester fibre content(0.20% of weight of cement) which was prepared using normal mixing, compaction and curing conditions. The workability studies and the mechanical properties namely, compressive strength on cubes, splitting tensile strength and modulus of elasticity on cylinders, flexural strength on beams were studied for concrete prepared using 4 different proportions of steel fibre content. It is found that all HyFRC specimens shows better mechanical properties than conventional concrete mix. In our study the maximum strength parameters occurred for 0.15% of steel fibre content with constant polyester fibre content of 0.20%. The failure mode in HyFRC is different from that of conventional concrete mix. The fibres are able to hold the matrix together even after extensive cracking. Fibre addition results in decrease in workability and creates difficulty in compaction which may results in reduction in strength for increased fibre content. Steel fibre helps in bridging action and polyester fibre contributes in delaying the formation of micro cracks.
IRJET- Study on the Effect of Fibers on Concrete Shrinkage
IRJET, 2021
Plastic shrinkage cracking is possibly one of the earliest damages which arise in concrete, and it is capable of affecting the durability and life span of a structure, if not prevented. Severe early-age cracking may propagate further later and allow the entry of destructive agents such as water and chlorides leading to corrosion of the steel rebars and premature damage of concrete. The incorporation fibers in concrete for controlling plastic shrinkage cracking has shown good results. The influence of a wide variety of fibers on the plastic shrinkage cracking behavior of cement-based materials have been studied over the years. Most of the studies concluded that the investigated fiber type was successful in controlling the degree of plastic shrinkage cracking. However, there is no conclusive findings on which fiber properties are most influential. The aim of this study is to reveal how various fibers influence the plastic shrinkage cracking behavior of concrete.