scholarly journals The Mechanical and Microstructural Properties of Composite Structures Made of a Cement-Tailing Backfill and Rock Core

Minerals ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 159
Author(s):  
Yu-ye Tan ◽  
Kai Zhang ◽  
Xin Yu ◽  
Wei-dong Song ◽  
Jie Wang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Composite Structures ◽  
Failure Process ◽  
Strain Curve ◽  
Special Structure ◽  
Basic Knowledge ◽  
Rock Pillar ◽  
Triaxial Compressive Strength ◽  
The Difference

In underground metal mines that use sublevel or stage open-stope and backfilling mining methods (SSOBMMs), there is a special structure around which both sides of the rock pillar are wrapped by backfill. As a permanent part of an underground mine, how much can backfill improve the rock pillar’s compressive strength? What is the difference in the mechanical properties between the special structure and the signal rock? To explore these questions, a composite structure made of a cement-tailing backfill (CTB) and rock core (RC) was designed. Uniaxial and triaxial compressive strength tests and scanning electron microscope (SEM) were used to research the mechanical properties, failure process, failure characteristics, and microstructure characteristics of the cement-tailing backfill and rock core (CTB-RC) specimens. It was found that the full stress–strain curve of the CTB-RC specimen under triaxial compressive strength (TCS) test had two times the stress increases reaching a lower peak deviator stress two times after the RC was destroyed. The CTB can reduce the destruction and slow down the deformation speed of the inner rock cor (IRC). It can also prevent rigid slip of the IRC after it is damaged and maintain the stability and integrity of the overall structure. The findings of this study can provide some basic knowledge on the mechanical properties of the CTB-RB and provide theoretical guidance for the optimization direction of the width of the rock pillar and the room in mines using SSOBMMs.

scholarly journals Determination of Mechanical Properties of Altered Dacite by Laboratory Methods

Minerals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 813
Author(s):  
Veljko Rupar ◽  
Vladimir Čebašek ◽  
Vladimir Milisavljević ◽  
Dejan Stevanović ◽  
Nikola Živanović
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Rock Mass ◽  
Uniaxial Compressive Strength ◽  
Rock Material ◽  
Strength Parameter ◽  
Gradual Transition ◽  
Strength Parameters ◽  
Triaxial Compressive Strength ◽  
Heterogeneous Rock

This paper presents a methodology for determining the uniaxial and triaxial compressive strength of heterogeneous material composed of dacite (D) and altered dacite (AD). A zone of gradual transition from altered dacite to dacite was observed in the rock mass. The mechanical properties of the rock material in that zone were determined by laboratory tests of composite samples that consisted of rock material discs. However, the functional dependence on the strength parameter alteration of the rock material (UCS, intact UCS of the rock material, and mi) with an increase in the participation of “weaker” rock material was determined based on the test results of uniaxial and triaxial compressive strength. The participation of altered dacite directly affects the mode and mechanism of failure during testing. Uniaxial compressive strength (σciUCS) and intact uniaxial compressive strength (σciTX) decrease exponentially with increased AD volumetric participation. The critical ratio at which the uniaxial compressive strength of the composite sample equals the strength of the uniform AD sample was at a percentage of 30% AD. Comparison of the obtained exponential equation with practical suggestions shows a good correspondence. The suggested methodology for determining heterogeneous rock mass strength parameters allows us to determine the influence of rock material heterogeneity on the values σciUCS, σciTX, and constant mi. Obtained σciTX and constant mi dependences define more reliable rock material strength parameter values, which can be used, along with rock mass classification systems, as a basis for assessing rock mass parameters. Therefore, it is possible to predict the strength parameters of the heterogeneous rock mass at the transition of hard (D) and weak rock (AD) based on all calculated strength parameters for different participation of AD.

Mechanical Properties of Carbon Cathodes during Aluminium Electrolysis

2011 ◽  
Vol 399-401 ◽  
pp. 2155-2159
Author(s):  
Qing Sheng Liu ◽  
Hui Fang
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Elastic Modulus ◽  
Great Influence ◽  
Strain Curve ◽  
Experimental Simulation ◽  
Ambient Conditions ◽  
Aluminium Electrolysis ◽  
Electrolysis Condition ◽  
Carbon Cathode

Based on the service ambient with aluminium electrolysis condition, the evolution of compressive strength, elastic modulus and stress-strain curve of carbon cathode samples under various conditions are investigated by experimental simulation method; the deterioration mechanism of the mechanical of carbon cathode is also studied. Results show that different carbon cathode materials and ambient conditions have great influence on strength and elastic modulus of carbon cthode. The mechanical properties such as compressive strength and elastic modulus of carbon catodes can be degraded by the erosion of sodium and molten salt during aluminium electrolysis, that has been confirmation by the SEM and XRD analysis.

scholarly journals COMPARATIVE EVALUATION OF EFFECT OF TWO LIGHT CURING UNITS ON MECHANICAL PROPERTIES OF FILTEK BULK FILL COMPOSITE

2021 ◽  
Vol 9 (02) ◽  
pp. 104-110
Author(s):  
Akshay Punjabi ◽  
◽  
Rahul Rao ◽  
Ashish K. Jain ◽  
Meenakshi Verma ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Compressive Strength ◽  
Testing Machine ◽  
Dental Composite ◽  
Light Curing ◽  
Circular Rings ◽  
The Difference ◽  
Diametral Tensile Strength

Context:The quality of light curing units can profoundly influence mechanical properties of dental composite materials. Aim: To compare effect of Woodpecker RTA Mini-S and Elipar Deep Cure-L curing units onmechanical properties (compressive strength, diametral tensile strength and microhardness) of Filtek Bulk-Fill. Methods and Materials: A total of 32 samples of Filtek Bulk Fill composite were divided into 2 equal groups (n=16). 12 samples in each group were fabricated using a tooth shaped mold and 4 in circular rings to test compressive strength, microhardness and diametral tensile strength, respectively. Theblocks were evaluated for the above parameters using Universal Testing Machine and Vickers Microhardness Tester.Independent sample-t test was used in this study (p< 0.05). Results: The results of this study showed that the group of composites cured using Elipar Deep Cure-L curing unit showed better mechanical properties and the difference between the groups was statistically significant for compressive strength and diametral tensile strength (p < 0.05) Conclusion: It was concluded that a curing unit of higher intensity and quality of output used in conjugation with bulk fill composites are likely to give better results.

scholarly journals Mechanical Tests and Numerical Simulations for Mining Seafloor Massive Sulfides

2019 ◽  
Vol 7 (8) ◽  
pp. 252 ◽  
Author(s):  
Yu Dai ◽  
Feiyue Ma ◽  
Xiang Zhu ◽  
He Liu ◽  
Zhonghua Huang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Numerical Simulations ◽  
Laboratory Tests ◽  
Mineral Resources ◽  
Friction Angle ◽  
Mechanical Tests ◽  
Massive Sulfides ◽  
Triaxial Compressive Strength ◽  
Ucs Test

With the decrease of primary resources in recent years, deep seabed mineral resources, especially the massive sulfides, are of extensive research significance. In this paper, firstly, the uniaxial compressive strength (UCS) test and triaxial compressive strength (TCS) test on the seafloor massive sulfides (SMS) samples from three different segments are conducted to obtain the key mechanical properties, including the cohesive force, internal friction angle, compressive strength, elastic modulus and Poisson’s ratio. Then, by leveraging the PFC3D code, the uniaxial and triaxial numerical simulations of SMS are performed. During this process, the micro properties in the simulation are altered through a calibration process until they match the macro properties of the SMS samples measured in the laboratory tests. Finally, the micro properties are applied to simulate the cutting process of single cutting pick and two adjacent cutting picks; meanwhile, the cutting force in the fragmentation process of SMS is monitored and collected. This research can provide some guidance for the mining simulation of SMS and effectively predicting the maximum force on the cutting pick.

scholarly journals Mechanical Properties of Concrete Containing Liquefied Red Mud Subjected to Uniaxial Compression Loads

Materials ◽  
2020 ◽  
Vol 13 (4) ◽  
pp. 854 ◽  
Author(s):  
Gyeongcheol Choe ◽  
Sukpyo Kang ◽  
Hyeju Kang
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Red Mud ◽  
Construction Material ◽  
Strain Curve ◽  
Peak Strain ◽  
Cement Type ◽  
Mixing Method ◽  
Relationship Of ◽  
The Relationship

This study used liquefied red mud (RM) sludge, an aluminum industry by-product, as a construction material. Accordingly, various methods were examined that used the fabricated liquefied red mud (LRM) as an admixture for concrete, and the mechanical properties of concrete were then evaluated according to the cement type and the amount of LRM. The LRM mixing methods (replacement and addition) were compared, and the slump and compressive strengths of concrete were evaluated for each method. To examine the mechanical properties according to the cement type and the amount of LRM, two types of cement (ordinary Portland cement and slag cement (SC)) were used, and 20 and 40 wt% LRM (with respect to the cement weight) were added. The mechanical properties of the stress–strain curve (SSC), compressive strength, peak strain, and elastic modulus were quantified. When the slump and compressive strength of concrete were considered based on the experimental results, the addition LRM mixing method was recommended as the appropriate method for LRM. As the addition of LRM increased, the mechanical properties of concrete degraded. However, when SC was used, the mechanical properties did not significantly change when different amounts of LRM were added (up to 20%). In addition, the SSC of LRM concrete could be approximated based on the use of the relationship of the compressive strength and peak strain according to the cement type and the amount of LRM.

The Research of Test on Stress-Strain Constitutive Relations of Straw Concrete

2014 ◽  
Vol 584-586 ◽  
pp. 987-992
Author(s):  
Wei Liu ◽  
Wei Xi ◽  
Yi Lu Zhang
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Elastic Modulus ◽  
Fly Ash ◽  
Constitutive Relations ◽  
Strain Curve ◽  
Green Building ◽  
Corn Straw ◽  
Stress Strain Curve ◽  
Stress Strain

As a new green building material, straw concrete are introduced about its mechanical properties and characteristics. Mechanical properties test such as prism compressive strength, elastic modulus and Poisson's ratios use standard prismatic blocks. Under different rate of corn straw, cement, sand and fly ash, test gets the full stress-strain curve. Results show that with increase of volume of corn straw, the prism compressive strength reduces significantly. Comparing with natural concrete, elastic modulus of straw concrete can reduces greatly. Poisson’s ratio reduces with increase of volume of corn straw. Fly ash could improve property of the material and replace cement, but excessive replacement will reduce the strength of material.

Properties of Aerial Lime-Based Mortars with Chitosan Ethers

2018 ◽  
Vol 276 ◽  
pp. 75-82 ◽  
Author(s):  
Tomáš Žižlavský ◽  
Martin Vyšvařil ◽  
Patrik Bayer ◽  
Pavla Rovnaníková
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Compressive Strength ◽  
Carboxymethyl Chitosan ◽  
Curing Time ◽  
Chitosan Derivatives ◽  
Early Stages ◽  
Binder Ratio ◽  
The Difference ◽  
Water Binder Ratio

This paper studies the possibility of usage of chitosan derivatives (hydroxypropyl chitosan (HPCH) and carboxymethyl chitosan (CMCH)) as admixtures for aerial lime-based mortars. The physical-mechanical properties were studied on the specimens prepared with constant water/binder ratio and binder/aggregate ratio 1:3 by weight using siliceous sand with the grain size up to 4 mm and doses of admixture ranging between 0.5 and 10‰. The properties were studied on the specimens up to 365 days. The addition of admixtures improves workability of mortar, but in the early stages also decreases strengths of mortars, especially the compressive strength. The addition of HPCH significantly reduces the bulk densities of specimens, while CMCH decreases them just slightly. With the increasing amount of time, the difference in strengths between reference and tested mortars decreases, reaching the similar values after 90 days of curing time. The further ageing causes additional growth of strengths with a significantly higher increase in the case of CMCH.

The Effect of Mineral Admixtures on Mechanical Properties of High Performance Concrete at very Low Temperature

2014 ◽  
Vol 584-586 ◽  
pp. 1509-1513
Author(s):  
Nan Zhang ◽  
Juan Liao ◽  
Tao Zhang ◽  
Wen Zhan Ji ◽  
Bao Hua Wang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Compressive Strength ◽  
Low Temperature ◽  
High Performance ◽  
High Performance Concrete ◽  
Splitting Tensile Strength ◽  
Mineral Admixtures ◽  
The Difference ◽  
Very Low Temperature

The effect of very low temperature on high performance concrete (HPC) mechanical properties is studied by using a reasonable testing method. The results show that the compressive strengths of concrete are increasing with lower temperatures. Fly ash (FA), compared to ground granulated blast-furnace slag (GGBFS), is positive to the compressive strength increasing at low temperature. The splitting tensile strengths of concrete appear a maximum at-40°C~-80°C. The compound replacement by GGBFS and FA makes the splitting tensile strength present the extreme value at higher temperature. At very low temperature, the single or compound replacement by mineral admixtures can result in the difference of the relationship between compressive strength and splitting tensile strength, and the degradation of concrete subjected to cold-thermal shocks.

scholarly journals Experimental Study on Mechanical Properties of Steel-Polyvinyl Alcohol Fibre-Reinforced Recycled Concrete

2021 ◽  
Vol 11 (22) ◽  
pp. 10550
Author(s):  
Haicheng Niu ◽  
Lei Wang ◽  
Jianhua Li ◽  
Jiakun Ji
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Polyvinyl Alcohol ◽  
Strain Curve ◽  
Recycled Concrete ◽  
Test Results ◽  
Stress Strain Curve ◽  
Polyvinyl Alcohol Fibre ◽  
Alcohol Fibre ◽  
Uniaxial Compressive Stress

Research on the utilization of recycled concrete in civil engineering applications is gaining popularity world-wide due to the increased efforts to promote preservation of the environment and sustainable development. Recycled concrete is, however, presently still limited to nonstructural applications. This is due to the poor mechanical properties of recycled concrete, which make it difficult to cope with complex mechanical environments. Therefore, an experimental work is presented to investigate the mechanical behaviour of recycled concrete, focusing on the cube, flexural, and uniaxial compressive mechanical properties of steel-polyvinyl alcohol fibre-doped specimens. The test results showed that the compressive strength and the flexural strength of the recycled concrete increased by 6.0% and 55.2%, respectively, when steel fibre was single-incorporated. The cubic compressive strength of the recycled concrete decreased by 14.1% when polyvinyl alcohol fibre was single-incorporated, but there was a 47.9% increase in the flexural strength of recycled concrete. Based on these tests, the elastic modulus, the Poisson’s ratio, and the uniaxial compression toughness were digitised to derive mathematical expressions that provided a theoretical understanding of the mechanical properties of steel-polyvinyl alcohol fibre-reinforced recycled concrete. Moreover, combining the characteristics of the uniaxial compressive stress–strain curve of fibre-reinforced recycled concrete, an equation for the uniaxial compressive stress–strain curve of recycled concrete associated with the fibre characteristic value was established, which agreed well with the test results.

Study of the Effect of Joint Trace Lengths on Failure Strength of Rock

2014 ◽  
Vol 501-504 ◽  
pp. 603-606
Author(s):  
Yun Jie Zhang ◽  
Tao Xu
Keyword(s):  
Compressive Strength ◽  
Process Analysis ◽  
Failure Process ◽  
Strain Curve ◽  
Peak Stress ◽  
Experimental Results ◽  
Peak Strain ◽  
Joint Orientation ◽  
Trace Length ◽  
Failure Patterns

Numerical simulations the different rock sample in the uniaxial compression have been conducted using Rock Failure Process Analysis program (RFPA2D) to evaluate the effects of joint trace lengths on the overall mechanical behaviour of jointed rock masses in this paper. Numerically simulated stress-strain curve, peak stress, peak strain and failure patterns were compared with the corresponding experimental results. We found that for a series of partially-spanning joint geometries with the same joint orientation, the projected area will be proportional to the square of the trace length. Thus, the relationship between compressive strength and partially-spanning joint geometry for the tests carried out to explore the influence of joint trace length may be expressed as a linear correlation between compressive strength and projected area.Numerical simulations agree well with experimental results.

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