A simple model to predict the effect of volume fraction, diameter, and length of fibres on strength of fibre reinforced brittle matrix composites

Kundu, T.; Jang, Heui Suk; Ma, Y. H.; Desai, C. S.

doi:10.1002/(sici)1096-9853(200006)24:7<655::aid-nag93>3.0.co;2-m

Cited by 2 publications

(2 citation statements)

References 12 publications

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“…Although there is no important difference between flexural strength and static modulus of aged and unaged samples, the most interesting observations are the toughness decreasing with ageing and the decrease of strain at maximum load (ε MOR ). The fracture behavior of fiber reinforced cement-based materials can be described by the bridged crack model [36,37] and the toughening mechanisms of fiber reinforced cement-based materials are based on fiber/matrix interactions. These mechanisms include interfacial debonding, frictional sliding and inclined angle effects.…”

Section: Mechanical Propertiesmentioning

confidence: 99%

Nondestructive Monitoring of Ageing of Alkali Resistant Glass Fiber Reinforced Cement (GRC)

et al. 2013

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Glass fiber reinforced cement (GRC) is a composite material made of portland cement mortar and alkali resistant (AR) fibers. AR fibers are added to portland cement to give the material additional flexural strength and toughness.However ageing deteriorates the fibers and as a result the improvement in the mechanical properties resulted from the fiber addition disappears as the structure becomes old. The aim of this paper is monitoring GRC ageing by nondestructive evaluation (NDE) techniques. Two different NDE techniques -1) nonlinear impact resonant acoustic spectroscopy analysis and 2) propagating ultrasonic guided waves -are used for this purpose. Both techniques revealed a reduction of the nonlinear behavior in the GRC material with ageing. Specimens are then loaded to failure to obtain their strength and stiffness. Compared to the un-aged specimens the aged specimens are found to exhibit more linear behavior, have more stiffness but less toughness. Finally, undisturbed fragments on the fracture surface form mechanical tests are inspected under the electron microscope, to understand the fundamental mechanisms that cause the change in the GRC behavior with ageing.Keywords: Glass Fiber Reinforced Cement, Material Ageing, Ultrasonic Guided Waves, Nonlinear Impact Resonant Acoustic Spectroscopy, Nondestructive Evaluation. IntroductionAlkali resistant glass fiber reinforced portland cement is a cement-based composite material that has higher flexural strength and toughness than plain cement [1]. However, GRC undergoes a rapid ageing process especially in humid and alkaline environment (pH>12). This ageing can nullify the positive effects of glass fibers undergoing from a ductile to a brittle material. Different strategies for improving the durability of GRC have been attempted by modifying the fibers and/or by altering the alkalinity of the matrix [7][8][9]. All these improvements have been evaluated by mechanical tests after accelerated ageing. Accelerated ageing tests have been broadly accepted for testing the durability of GRC. They can be classified as i) Deemed to satisfy tests, (EN 1170-8 [10]) where the GRC specimens are exposed to severe conditions, and ii) predictive accelerated ageing tests [11] that are commonly used to predict the service life of the material, in real weather conditions. For example, Purnell et al. [2] established that GRC soaked for 1 day in water at 55ºC, corresponds to 100 days of exposure to the real weather conditions in the United Kingdom. However, it should be noted that the correspondence between the accelerated ageing tests and the real aging conditions is still being investigated, especially when different matrix compositions are to be compared [11][12]. Typically the ageing process has been assessed by mechanical testing or by strand in cement (SIC) tests [13][14]. The aim of this work is to assess the ageing process in GRC by two nondestructive testing techniques -1) resonance frequency tests at different impact energy levels called Nonlinear Impact Resonance Acousti...

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Section: Mechanical Propertiesmentioning

confidence: 99%

Nondestructive Monitoring of Ageing of Alkali Resistant Glass Fiber Reinforced Cement (GRC)

et al. 2013

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“…The readers who are interested in such quantitative modeling work are referred to other publications. 36…”

Section: Calculation Of Damage Zone Areasmentioning

confidence: 99%

Statistics of acoustic emission waveforms in characterizing the fracture process zone in fibre-reinforced cementitious materials under mode I fracture

Sagar,

Saha,

Basu

et al. 2023

Structural Health Monitoring

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This article reports on the characteristics of fracture process zone in steel fibre-reinforced concrete (SFRC) under the mode I fracture process using acoustic emission (AE) testing. The generated AE waveforms during mode I fracture process in SFRC were recorded in the laboratory. Using a statistical analysis of AE waveforms, it was observed that as the loading increases, a damage zone consisting of numerous microcracks develops ahead of the predefined notch tip. The location of the generated AE events related to the numerous microcracks were classified into three zones namely (i) major damage, (ii) moderate damage and (iii) low damage. The areas of these regions were evaluated from the distribution of the AE events around the pre-notch. The number of AE events reduced with the increase in the steel fibre content under the same experimental conditions. The major damage zone was located ahead of the notch tip very closely and it comprised of AE events with (i) high peak amplitude, (ii) low information entropy and (iii) longer AE waveform duration.

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A simple model to predict the effect of volume fraction, diameter, and length of fibres on strength of fibre reinforced brittle matrix composites

Cited by 2 publications

References 12 publications

Nondestructive Monitoring of Ageing of Alkali Resistant Glass Fiber Reinforced Cement (GRC)

Nondestructive Monitoring of Ageing of Alkali Resistant Glass Fiber Reinforced Cement (GRC)

Statistics of acoustic emission waveforms in characterizing the fracture process zone in fibre-reinforced cementitious materials under mode I fracture

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