Experimental investigation into the effects of composition and microstructure on the tensile properties and failure characteristics of different gypsum rocks

Hongfa Ma,Shaojie Chen,Dawei Yin,Xiaolong Li,Xiangshang Li,Yanqi Song

doi:10.1038/s41598-021-93947-6

Hongfa Ma, Shaojie Chen + Show 4 more

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https://doi.org/10.1038/s41598-021-93947-6

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Abstract

The present work investigated the differences in the composition and internal microstructure of four types gypsum rock—fiber gypsum, transparent gypsum, alabaster, and ordinary gypsum by X-ray fluorescence spectrometry, X-ray diffraction, scanning electron microscope and Brazilian split test, and analyzed its effects on the tensile strength and fracture characteristics of gypsum rock. For alabaster, fiber gypsum, transparent gypsum, and ordinary gypsum, CaSO4·2H2O is the main component with 72.78%, 72.72%, 72.57%, and 71.51% content, and tensile strength of 1.79, 2.22, 3.22, and 4.35 MPa, respectively. In addition, the fracture line is arc-shaped, vertical, and zigzag for fiber gypsum, ordinary and transparent gypsums, and alabaster, respectively. On the microscopic level, fiber gypsum has an evident striated structure while the gradual increased pore development for alabaster, transparent gypsum, and ordinary gypsum. Gypsum rock has an obvious layered crystal structure with the increase of CaSO4·2H2O, contributing to the phenomenon with a larger grain size and lower tensile strength. In addition, the number of particles for alabaster, transparent gypsum, and ordinary gypsum increased in turn, while their particle size decreased uniformly, indicating that the lower CaSO4·2H2O content, the more sufficient energy accumulation and release. This paper can provide a theoretical basis for the analysis of the mechanical properties of rocks with different mineral composition and contribute to the design for different ore grades mining.

Highlights

The present work investigated the differences in the composition and internal microstructure of four types gypsum rock—fiber gypsum, transparent gypsum, alabaster, and ordinary gypsum by X-ray fluorescence spectrometry, X-ray diffraction, scanning electron microscope and Brazilian split test, and analyzed its effects on the tensile strength and fracture characteristics of gypsum rock
X-ray fluorescence spectrometry (XRF) element analysis and X-ray diffraction (XRD) were carried out to investigate the differences in the composition of different gypsum rocks and the influence of composition on the tensile strength
XRF was performed on each group of samples to obtain the elemental composition and content of the gypsum rocks

Summary

Introduction

The present work investigated the differences in the composition and internal microstructure of four types gypsum rock—fiber gypsum, transparent gypsum, alabaster, and ordinary gypsum by X-ray fluorescence spectrometry, X-ray diffraction, scanning electron microscope and Brazilian split test, and analyzed its effects on the tensile strength and fracture characteristics of gypsum rock. To avoid the irregularity of tensile stress, indirect tensile method or Brazilian disc split test is often used locally and abroad for rock materials[13,14,15,16,17,18] This method investigates the influence of different loading rates on the tensile strength of a rock in a micro view and energy e volution[19,20,21]. Wanniarachchi et al.[26] studied the effect of mineral composition on the mechanical properties of shale gas reservoir, showing that tensile strength increased with kaolinite and calcite contents. Přikryl[37], Lindqvist et al.[38], and Johansson[39] examined the influence of the particle morphology, cementation degree, and microcrack distribution on the mechanical properties of rocks, respectively

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