Properties Of Hybrid Fiber Reinforced Concrete Research Articles

An optimisation approach for mechanical and durability properties of hybrid fibre-reinforced concrete using steel and sisal fibres

This article proposes an optimisation approach for improving the performance of hybrid fibre-reinforced concrete (HFRC) in compression with varying fibre content. The proposed approach uses the Atomic Orbital Search (AOS) control scheme. The major objective of the proposed method is to raise the compressive strength, tensile strength and flexural strength of sisal fibre. The AOS approach is used to predict the stress–strain issues and provides an optimal solution. The Hybrid fibres combine multiple fibre types, which significantly improves ductility and energy absorption while the capability is compared to single-type fibre additions. By then, the proposed model is implemented in MATLAB/Simulink working stage and the execution is calculated with the proposed method. The compressive strength in HFRC is 47.6, split tensile strength in HFRC is 6.12, flexural strength in HFRC is 8.81, water absorption in HFRC is 0.67 and the mass loss in HFRC is 97.3. From the result, it concludes that the performance of hybrid fibre-reinforced concrete is improved.

Mechanical and Thermal Properties of Hybrid Fibre-Reinforced Concrete Exposed to Recurrent High Temperature and Aviation Oil.

Over the years, leaked fluids from aircraft have caused severe deterioration of airfield pavement. The combined effect of hot exhaust from the auxiliary power unit of military aircraft and spilt aviation oils have caused rapid pavement spalling. If the disintegrated concreted pieces caused by spalling are sucked into the jet engine, they may cause catastrophic damage to the aircraft engine or physical injury to maintenance crews. This study investigates the effectiveness of incorporating hybrid fibres into ordinary concrete to improve the residual mechanical and thermal properties to prevent spalling damage of pavement. Three fibre-reinforced concrete samples were made with micro steel fibre and polyvinyl alcohol fibre with a fibre content of zero, 0.3%, 0.5% and 0.7% by volume fraction. These samples were exposed to recurring high temperatures and aviation oils. Tests were conducted to measure the effects of repeated exposure on the concrete’s mechanical, thermal and chemical characteristics. The results showed that polyvinyl alcohol fibre-, steel fibre- and hybrid fibre-reinforced concrete suffered a 52%, 40% and 26.23% of loss of initial the compressive strength after 60 cycles of exposure to the conditions. Moreover, due to the hybridisation of concrete, flexural strength and thermal conductivity was increased by 47% and 22%. Thus, hybrid fibre-reinforced concrete performed better in retaining higher residual properties and exhibited no spalling of concrete.

Effect of Using Hybrid Polypropylene and Glass Fibre on the Mechanical Properties and Permeability of Concrete.

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.

Experimental and numerical study on damage evaluation of hybrid fiber-reinforced concrete

In this present study, static and dynamic properties of hybrid fiber-reinforced concrete (HFRC) were experimentally investigated. The mechanical properties accompanied by compressive strength, splitting tensile strength and flexural strength were evaluated for several combinations of mixtures containing hybrid fibers. In addition, dynamic properties such as damping ratio, mode shape and fundamental natural frequency have also been experimentally determined for the prismatic beams in free–free condition in order to evaluate the damage characteristics of HFRCs. Total fiber volume fractions of 0.25, 0.5 and 0.75% with different combinations of steel and polypropylene (PP) fibers have been considered in this investigation. Among various percentage additions of hybrid fibers, a mixture that contains 0.25% of total fiber volume fraction with the combination of 75% of steel and 25% of PP fibers has acquired the best performance. Furthermore, the natural frequencies of HFRC specimens decrease with the increase in fiber content as well as decrease with the increase in structural damage, whereas the damping ratio increases with the increase in fiber content and structural damage. Numerical modeling was also developed for control and HFRC specimens using ANSYS software to compare the experimental results with the analytical model prediction. It was also found that the HFRC with the combination of 75% of steel and 25% of PP fibers with total fiber volume fraction of 0.75% has the highest damping properties.

Mechanics and failure characteristics of hybrid fiber-reinforced concrete (HyFRC) composites with longitudinal steel reinforcement

While the properties of hybrid fiber-reinforced concrete (HyFRC) have been well-reported in the literature, the behavior of reinforced HyFRC (i.e., HyFRC with embedded steel rebar) is less understood. This paper investigates the mechanics and failure characteristics of reinforced HyFRC under direct tension. Samples with a low longitudinal steel reinforcement ratio were studied to evaluate the feasibility of reducing rebar congestion in structural applications through the use of fiber-reinforced concrete. Although reinforced HyFRC forms multiple cracking sites when loaded, rebar strain and HyFRC crack opening are generally concentrated at a single location under post-yield displacements. The onset of rebar plastic deformation and the exhaustion of fibers’ bridging load capacity are coincident events at a dominant crack. For a cracked reinforced HyFRC section to strengthen, the magnitude of load resistance increase from strain hardening rebar must exceed the magnitude of load resistance decrease from fiber pull-out processes. Comparisons are made with studies reported in the literature to demonstrate how longitudinal reinforcement ratio and fiber type influence cracking behavior and ultimate strain capacity. The research presented herein has far-reaching impacts on the structural design of all types of reinforced fiber-reinforced concrete materials detailed for a ductile response under large displacements.

Mechanical properties of hybrid fibre-reinforced concrete – analytical modelling and experimental behaviour

Mechanical properties of hybrid fibre-reinforced concrete (HFRC) are studied and the role of constituent fibres on overall response of HFRC is investigated. HFRC was produced using different proportions of hooked-ended steel, crimped polypropylene and plain Kevlar fibres with a total fibre volume fraction of 1·2% and 1·4%. The test results indicate that the incorporation of hybrid fibres in concrete improve the compressive and tensile strengths moderately and toughness considerably. Analytical models are developed to quantify the effect of individual fibres on compressive and tensile strengths, stress–strain curves and flexural toughness ratio of HFRC in terms of a comprehensive fibre reinforcing index. The proposed models show a marked improvement over existing models. The existing models are for single (steel) fibres only, whereas the proposed models are general and applicable to HFRC containing any number of fibres.

Study on Flexural Fatigue Performance and Damage Laws of Hybrid Fiber Reinforced Concrete

The flexural fatigue experiment of plain concrete (C) and Steel - Polypropylene Hybrid Fiber Reinforced Concrete (HFRC) is carried out to study the flexural fatigue performance and damage laws under cyclic loading. With the strain gauges pasted on the bottom of the specimens, the strain is collected by dynamic acquisition instrument.We obtain the fatigue life and the maximum strain - cyclic ratio ( ) curves by counting and analyzing the results of fatigue experiment ,which move forward a single step for analysis of fatigue damage laws of HFRC. The study would provide reference for flexural fatigue properties of HFRC.

Mechanical properties of hybrid fiber-reinforced concrete at low fiber volume fraction

Concretes containing different types of hybrid fibers at the same volume fraction (0.5%) were compared in terms of compressive, splitting tensile, and flexural properties. Three types of hybrid composites were constructed using fiber combinations of polypropylene (PP) and carbon, carbon and steel, and steel and PP fibers. Test results showed that the fibers, when used in a hybrid form, could result in superior composite performance compared to their individual fiber-reinforced concretes. Among the three types of hybrids, the carbon–steel combination gave concrete of the highest strength and flexural toughness because of the similar modulus and the synergistic interaction between the two reinforcing fibers.