Mechanical and Fracture Behavior of Sedimentary Rocks under Uniaxial Compression

Abstract

Energy-related characterizations can provide important information regarding mechanical behavior of rocks. A series of uniaxial compression tests were carried out on intact rock samples obtained from Wyoming, USA. The physical properties of the samples (i.e., porosity and grain size) were first examined. To investigate the fracture behavior of sedimentary rocks, a compilation of published dataset and our experimental data were employed to develop a new approach for estimating uniaxial compressive strength (UCS) based on the amount of energy released during rock deformation, which is known as the rock toughness. The energy release is calculated as the area under the stress-strain curve until the peak stress is reached. This energy shows a strong correlation with the density of the rock. Moreover, a predictive empirical model was proposed to estimate the rock UCS based on the rock toughness. The proposed empirical model was validated by comparing the predicted and measured UCS values of experimentally tested rocks, and the comparison showed a good agreement with a mean bias (the ratio of measured to the predicted compressive strength) of 1.002.

Production and Incorporation of Calcium-Hydrolyzed Nanoparticles in Alkali-Activated Mine Tailings

“…The quantitative X-ray diffraction data of these gold MTs were also reported in a previous research work [ 57 ]; the results indicate that the main crystalline mineral phase was quartz (SiO 2 ) [ 50 , 58 ], followed by muscovite (KAl 2 (FOH) 2 or (KF) 2 (Al 2 O 3 ) 3 (-SiO 2 ) 6 ) [ 50 ], magnetite (Fe 3 O 4 ) [ 41 , 59 ], albite (Na(AlSi 3 O 8 )) [ 50 , 58 , 60 ], C-A-S-H (Ca 3 Al(Al 3 SiO 10 )(OH) 2 ) [ 57 ], and N-A-S-H (Na 17.6 (Al 16 Si 56 O 144 )(H 2 O) 38.4 ) [ 57 ]. Additionally, a low percentage of amorphous phase was also identified [ 57 ].…”

“…The QXRD data obtained using the Rietveld refinement method ( Table 2 ) show that all AAM samples mainly contained the same crystalline phases as previously identified in the original MTs ( Section 3.1 ) except the N-A-S-H phase. The primary crystalline phases are quartz (SiO 2 ) [ 41 , 50 , 69 ], albite (Na(AlSi 3 O 8 )) [ 50 , 58 , 60 ], and muscovite (KAl 2 (FOH) 2 or (KF) 2 (Al 2 O 3 ) 3 (-SiO 2 ) 6 ) [ 50 ]. However, some additional crystalline phases were detected in low quantities; these phases are magnetite (Fe 3 O 4 ) [ 41 , 59 ], portlandite [Ca(OH) 2 ] [ 41 , 70 , 71 ], calcite (CaCO 3 ) [ 70 , 72 ], zeolite [ 41 , 72 , 73 , 74 ], C-S-H [ 70 , 73 , 75 ], and C-A-S-H [ 76 ].…”

“…However, the group of signals at 798 cm −1 , 777 cm −1 , and 694 cm −1 indicates the existence of Si–O–X bonds in the resulting AAM systems (X stands for tetrahedral silicates or aluminates). The magnitude of the absorption bands is related to the amounts of silicates or aluminates and the degree of inorganic polymerization [ 50 ]. As the concentration of calcium species increased, there was an increase in the overlapping signal at 740 cm −1 ; apparently, this band is generated by either one or more calcium ions interacting with nitrate ions [ 86 ].…”

“…Prior to mixing, raw MTs were manually crushed and sieved to control the particle size with 30-mesh filtering (particle size below 600 µm). Then, primary NaOH solutions at 10 M were prepared by mixing water with NaOH pellets at 97% purity (Sigma-Aldrich, Burlington, MA, USA) according to a previous study by Zhang et al [ 50 ]; the solutions were then placed at room temperature (21 ± 1 °C) for 30 min to dissipate the heat generated during dissolution. AAM pastes were then made by hand by combining the MTs with 10 M NaOH solution until a uniform paste was obtained.…”