Size-Independent Flexure Test Technique for the Mechanical Properties of Geocomposites Reinforced by Unidirectional Fibers

• Published in: Ceramics Vol. 6; no. 4; pp. 2053 - 2069
• Main Authors: Tran Doan, Hung, Kroisova, Dora, Bortnovsky, Oleg
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 01.12.2023
• Subjects: Composite materials; Composition; Dynamic testing; Failure; flexural properties; Flexural strength; geocomposite; Geocomposites; Geopolymers; Geosynthetics; Materials; Mechanical properties; Modulus of elasticity; Modulus of rupture in bending; Parameters; Shear modulus; Shear strength; size-independent; Testing; unidirectional fibers; Viscosity; Vietnam
• ISSN: 2571-6131; 2571-6131
• DOI: 10.3390/ceramics6040126

In assessing the bending attributes for geopolymer composites augmented with uni-directional fibers, methodologies aligned with the established American and European standards yield quantifiable values for flexural strength, denoted as σm*, and its corresponding elasticity modulus, E*. Notably, these values exhibit a pronounced dependency on the size of the testing parameters. Specifically, within a judicious range of support span L relative to specimen height H, spanning a ratio of 10 to 40, these metrics can vary by a factor between 2 and 4. By conducting evaluations across an extensive array of H/L ratios and adhering to the protocols set for comparable composites with a plastic matrix, it becomes feasible to determine the definitive flexural elastic modulus E and shear modulus G, both of which can be viewed as size-neutral material traits. A parallel methodology can be employed to deduce size-agnostic values for flexural strength, σm. The established linear relationship between the inverse practical value E* (1/E*) and the squared ratio (H/L)2 is acknowledged. However, a congruent 1/σm* relationship has been recently corroborated experimentally, aligning primarily with Tarnopolsky’s theoretical propositions. The parameter T, defined as the inverse gradient of 1/σm* about (H/L)2, is integral to these findings. Furthermore, the significance of the loading displacement rate is underscored, necessitating a tailored consideration for different scenarios.