Validity of uniaxial compression tests for indirect determination of long term strength of rocks

This paper is part of a study of earthen mixtures for 3D printing of buildings. To meet the ever-growing environmental needs, the focus of the paper is on a particular type of biocomposite for the stabilization of earthen mixtures—the rice husk-lime biocomposite—and on how to enhance its effect on the long-term mechanical properties of the hardened product. Having assumed that the shredding of the vegetable fiber is precisely one of the possible ways to improve the mechanical properties, we compared the results of uniaxial compression tests performed on cubic specimens made with both shredded and unaltered vegetable fiber, for three curing periods. The results showed that the hardened earthen mixture is not a brittle material in the strict sense, because it exhibits some peculiar behaviors, anomalous for a brittle material. However, being a “designable” material, its properties can be varied with a certain flexibility to get as close as possible to the desired ones. One of the peculiar properties of the hardened earthen mixture deserves further investigation, rather than corrections. This is the vulcanization that occurs (in a completely natural way) in the long term, thanks to the mineralization of the vegetable fiber by carbonation of the lime.

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Determination of anisotropy during a study of long-term strength under conditions of a plane stress state

Strength of Materials ◽

10.1007/bf01531841 ◽

1983 ◽

Vol 15 (9) ◽

pp. 1278-1281 ◽

Cited By ~ 3

Author(s):

A. M. Lokoshchenko

Keyword(s):

Stress State ◽

Plane Stress ◽

Plane Stress State ◽

Term Strength

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Identification of changes in mechanical properties of sandstone subjected to high temperature: meso-and micro-scale testing and analysis

Archives of Civil and Mechanical Engineering ◽

10.1007/s43452-021-00187-6 ◽

2021 ◽

Vol 21 (1) ◽

Author(s):

Adrian Różański ◽

Anna Różańska ◽

Maciej Sobótka ◽

Michał Pachnicz ◽

Mirosława Bukowska

Keyword(s):

Uniaxial Compression ◽

Temperature Treatment ◽

Uniaxial Compression Test ◽

Mechanical Parameters ◽

Compression Tests ◽

Micro Computed Tomography ◽

Micro Scale ◽

Investigative Techniques ◽

Comparison Of The Results

AbstractMaterial properties largely depend on their structure, and are strongly dependent on the scale of observation. Under the influence of various processes, the structure of a material can undergo evolution, which leads to major changes in the mechanical parameters and morphology of the medium. To understand the behaviour of a given material exposed to the influence of various factors, e.g. loading and temperature treatment, and to be able to modify it appropriately, it is crucial to recognize its structure both in the scale of engineering applications and at the micro-scale. The article proposes a procedure for assessing changes in the structure of sandstone exposed to the temperature treatment. The presented procedure allows the morphology of the material to be evaluated and the influence of temperature treatment on mechanical parameters of rocks to be analysed, by combining use of different laboratory techniques. The changes in rock material have been characterized using three investigative techniques, i.e. a uniaxial compression test, nanoindentation and micro-computed tomography. The uniaxial compression tests were carried out for 11 different temperature values in the range of 23–1000 °C, which enabled the determination of the change in uniaxial compressive strength and Young’s modulus of the sandstone as a function of temperature. Micro-scale laboratory tests were utilised to identify changes in the mechanical and morphological parameters of the sandstone exposed to the temperature of 1000 °C. The results were referred to those obtained for the reference samples, i.e. not subjected to heating (T = 23 °C). Comparison of the results showed an evident relation between the microstructure changes and the mesoscopic properties.

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Determination of Activation Energy and Prediction of Long-Term Strength of Creep Rupture for Alloy Inconel 740/740H: A Method Based on a New Tensile Creep Rupture Model

Metallurgical and Materials Transactions A ◽

10.1007/s11661-021-06484-2 ◽

2021 ◽

Author(s):

L. Chen ◽

Z. Dong ◽

X. L. Song ◽

J. Jia ◽

Z. D. Xiang

Keyword(s):

Activation Energy ◽

Creep Rupture ◽

Tensile Creep ◽

Term Strength ◽

Rupture Model

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Rice Husk Shredding as a Means of Increasing the Long-Term Mechanical Properties of Earthen Mixtures for 3D Printing

10.20944/preprints202112.0360.v1 ◽

2021 ◽

Author(s):

Elena Ferretti ◽

Massimo Moretti ◽

Alberto Chiusoli ◽

Lapo Naldoni ◽

Francesco De Fabritiis ◽

...

Keyword(s):

Mechanical Properties ◽

3D Printing ◽

Uniaxial Compression ◽

Rice Husk ◽

Brittle Material ◽

Strict Sense ◽

Compression Tests ◽

Vegetable Fiber ◽

Natural Way

This paper is part of a study of earthen mixtures for 3D printing of buildings. To meet the ever-growing environmental needs, the focus of the paper is on a particular type of bio-composite for the stabilization of earthen mixtures – the rice husk-lime bio-composite – and on how to enhance its effect on the long-term mechanical properties of the hardened product. Having assumed that the shredding of the vegetable fiber is precisely one of the possible ways to improve the mechanical properties, we compared the results of uniaxial compression tests performed on cubic specimens made with both shredded and raw vegetable fiber, for three curing periods. The results showed that the hardened earthen mixture is not a brittle material in the strict sense, because it exhibits some peculiar behaviors, anomalous for a brittle material. However, being a “designable” material, its properties can be varied with a certain flexibility to get as close as possible to the desired ones. One of the peculiar properties of the hardened earthen mixture deserves further investigation, rather than corrections. This is the vulcanization that occurs (in a completely natural way) in the long term, thanks to the mineralization of the vegetable fiber by carbonation of the lime.

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Experimental Research on Coupling of Swelling Rock between Swelling and Creep

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.353-356.293 ◽

2013 ◽

Vol 353-356 ◽

pp. 293-302

Author(s):

Qiu Yan Fan ◽

Mei Qian Wang ◽

Xian Li ◽

Bo Zhang

Keyword(s):

Creep Deformation ◽

Residual Deformation ◽

Swelling Pressure ◽

Initial Water Content ◽

Term Strength ◽

Compression Tests ◽

Initial Water ◽

Multi Stage ◽

Swelling Rock

Swelling rock has the properties of swelling and creep. Researches on coupling between swelling and creep have not yet been carried out. The expansive Paleogene mudstone is used to laboratory uniaxial compression tests, to find the coupling regularity between swelling and creep under different initial water contents, influent modes and loading methods. For coupling, the creep curves show similar characteristic of non-coupling. The creep deformation increases obviously and the long-term strength decreases comparing with non-coupling. With increasing initial water content, the creep deformation increases for coupling. The creep deformation increases with the enlargement of water-absorption area during the coupling creep. For single-stage and multi-stage loading, the creep regularity is similar to non-coupling. The sample will have a permanent residual deformation when unloaded at the second stable creep stage. The long-term strength of swelling rock is greater than the swelling pressure and the long-term strength is lower than that of non-coupling.

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