Mechanical properties of a green hybrid fibre-reinforced cementitious composite

In this paper, a new green hybrid fibre-reinforced cementitious composite with high volume fly ash and steel and bagasse fibres is developed. High volume fly ash is used to partly replace cement and make the composite greener. Eco-friendly bagasse fibres from industrial waste and steel fibres are utilized to improve the mechanical behavior. In particularly, the influence of the parameters such as the sand/cement ratio and fly ash/cement ratio on the mechanical properties of the composite is investidated by evaluating the essential mechanical properties such as compressive strength and modulus of elasticity. The new green composite is found to be sustainable with high compressive. It is found that compressive strength of the composite decreases while the Young's modulus increases with the increase of the sand content, and that compressive strength and Young’s modulus of the composite decreases with the increase of the fly ash content

The influence of bagasse fibre and fly ash on the long-term properties of green cementitious composites

Both the long-term physical and mechanical properties of new green cementitious composites reinforced with bagasse fibre and steel fibre with ultra high volume of fly ash are investigated in this paper. Newly cast specimens were cured in the lab for the first 28 days, then these specimens were moved outside to be cured in weather conditions for up to 10 months. The physical properties (including bulk density, apparent porosity and water absorption), mechanical properties (such as compressive strength, Young’s modulus and modulus of rupture) are investigated experimentally at the age of 28 days, 3 months, 6 months and 10 months. SEM tests are also conducted to study the microstructure of the new composites. Through comparison with the mechanical behaviour of the composites at the age of 28 days, the long-term effect on the physical and mechanical properties of the composites are discussed, and the impact of fly ash content and bagasse fibre content on the composites under the weathering conditions are also analysed. The experimental results show that the compressive strength, Young’s modulus, modulus of rupture and tensile strength of the composites decrease with the reduction of the content of fly ash and bagasse fibre, but bending toughness of the material increases with fly ash content and peaks as fly ash to cement ratio achieves 2.0. The mechanical properties of the new composites are found to be comparable to those of conventional concrete and they are very promising green and sustainable construction and building materials for the next generation infrastructures

Ageing effect on tensile and shrinkage behaviour of new green hybrid fibre-reinforced cementitious composites

Ageing effects on both uniaxial tensile and shrinkage behaviour of new green cementitious composites reinforced with bagasse fibre and steel fibre with ultra-high volume of fly ash are investigated in this paper. The tensile behaviour of the composites is investigated at the age of 28 days, 3 months, 6 months and 10 months after curing in weather conditions. Restrained shrinkage behaviour of the composites after curing for 3 months is tested on ring specimens. SEM tests are also conducted to study the influence of the ageing on the microstructure of the new composites. The test results show that the tensile strength of the composites at all ages increases with the decrease of the content of the fly ash and the bagasse fibre, and that the increasing application of fly ash and bagasse fibre decreases the steel ring strain and restrains the development of crack. It is also found that the tensile strength and the shrinkage of the composites such as crack width ascend greatly with time

Numerical modelling of mechanical behaviour of fibre reinforced cementitious composites

In this paper, a new numerical model is developed to model the tensile behavior of the cementitious composites reinforced with hybrid bagasse fibres and steel fibres based on the extended finite element method. The numerical model considers random fibre distribution, which is generated automatically, and the cohesive behavior, which represents the bonding between fibres and the matrix. The cementitious matrix is modeled using extended finite element method. The developed numerical model is implemented in commercial software ABAQUS and the computed results are compared with the corresponding experimental results for numerical validation. It is found that the tensile behavior of the composites predicted from the new numerical model is consistent with that obtained from experimental study, and that the developed numerical model can accurately predict the uniaxial tensile behavior, including the post-cracking behavior of fibre reinforced cementitious composites

Recent advances in experimental studies of the mechanical behaviour of natural fibre-reinforced cementitious composites

This paper presents a review of recent research and development work involving natural fibre-reinforced concrete (NFRC). The recent developments in NFRC reinforced with different types of natural fibre, such as sisal fibre, bagasse fibre, coir fibre, banana fibre, eucalyptus fibre, flax fibre, jute fibre and pinus radiate fibre, are covered. Natural fibres and their modification methods are introduced first and the development history of natural fibre-reinforced concrete and the relevant research into the mechanical behaviour of NFRC in both the short- and long-term are reviewed. The applications of NFRC are also summarized

Mechanical behaviours of green hybrid fibre-reinforced cementitious composites

New green cementitious composites reinforced with bagasse fibre and steel fibre with ultra-high volume of fly ash are developed in this paper. The mechanical properties of bagasse fibre such as the tensile strength, Young's modulus and stress-strain relationship are determined via conducting single fibre tensile test. Mechanical behaviours of the new composites, including compressive strength, Young's modulus, bending behaviour and uniaxial tensile behaviour, are investigated experimentally. The influence of the content of bagasse fibres and fly ash on the mechanical behaviour of the composites is also evaluated. The obtained results show that the compressive strength, Young's modulus, modulus of rupture and tensile strength of the composites decrease with the deduction of the content of the fly ash and bagasse fibre, but the bending toughness and tensile ductility of the material increase with fly ash content and peak as fly ash to cement ratio achieves 2.0. It is found that the mechanical properties of the composites are comparable to those of conventional concrete and are very promising green and sustainable construction and building materials and have strong potential to be used in engineering practice

Analytical study on material properties of fibre reinforced cementitious composites

In this paper, a new micromechanical analytical model is developed to model the material properties of the Fibre Reinforced Cementitious Composites (FRCCs) based on the general self-consistent method. In the developed model, a hexagonal-shaped representative volume element model with multiple micro-cracks is established based on the microstructure of the FRCC to represent the transversely isotropic material characteristics. The developed analytical model is employed to evaluate the equivalent Young’s modulus of a typical type of FRCC before and after cracking. The evaluated results are compared to those obtained from other analytical models for validation. The predicted results for the Young’s modulus from the new analytical model is consistent with that obtained from other analytical models, while the developed analytical model shows advantages in predicting the influence of fibre orientation on the Young’s modulus of the composite

The application of general self-consistent model on mechanical behaviour of fibre-reinforced cementitious composites

Fibre-reinforced cementitious composite (FRCC), by adding short discrete fibres randomly in cementitious composites, exhibits substantially improved mechanical properties than conventional cementitious composites due to the fibre bridging action and the existence of multiple micro-cracks. In this paper, based on the general self-consistent method a new micromechanical analytical model is developed to model the material properties of the FRCCs. A hexagonal-shaped representative volume element model with multiple micro-cracks is established based on the microstructure of the FRCC to represent the transverselyisotropicmaterial characteristics. Thedeveloped modelisusedtoevaluatetheequivalent Young’s modulus of a typical FRCC before and after cracking, and the results obtained are compared to those obtained from other analytical models and experimental data for validation. The influence of the aligned orientation of fibre and the crack density of the matrix on Young’s modulus of the composite is also studie

Cardiac telerehabilitation under 5G internet of things monitoring: a randomized pilot study

Abstract Owing to issues such as time and cost, patients often show poor acceptance of and adherence to center-based cardiac rehabilitation (CBCR), which impacts the effectiveness of rehabilitation. Therefore, there is growing interest in home-based cardiac rehabilitation and cardiac telerehabilitation (CTR), which entail less time and cost than CBCR. This study aimed to compare the changes in physiological and psychological indicators, compliance, and satisfaction after CTR and CBCR. In this single-blind, randomized, controlled trial, the intervention group received CTR via the 5G Internet of Things platform, while the control group received CBCR. Data from 50 patients (age 66.28 ± 4.01 years) with acute myocardial infarction who underwent percutaneous coronary intervention were analyzed. After an intervention period of three months, the maximal oxygen uptake and metabolic equivalent of task were 5.53 ± 0.12 and 19.32 ± 0.17, respectively, in the intervention group, and 4.15 ± 0.13 and 16.52 ± 0.18, respectively, in the control group. After three months of intervention, there were significant differences between the two groups in all observed indicators (p  0.05). The use of a 5G Internet of Things platform cardiac rehabilitation model effectively improved outcomes in patients with acute myocardial infarction who underwent percutaneous coronary intervention. Trials registry: The study protocol was registered at Chinese Clinical Trials Registry (ChiCTR), first trial registration 07/08/2023, identification number ChiCTR2300074435