scholarly journals Study of marl stabilization with organic binders

Vestnik MGSU ◽  
2020 ◽  
pp. 58-71
Author(s):  
Egor I. Korolev ◽  
Evgeniya N. Sychkina ◽  
Andrey B. Ponomaryov
Keyword(s):  
Uniaxial Compression ◽  
Binder Content ◽  
Oil Fields ◽  
Strength Parameter ◽  
Plastic State ◽  
Uniaxial Compression Strength ◽  
Plastic Properties ◽  
Strength Tests ◽  
Dry Conditions ◽  
Water Saturated

Introduction. The paper considers marl used as the primary material for road embankments and multiple-well platforms at some oil fields of the Perm’ Territory. This ground has different strength parameters in dry and water-saturated conditions. Rather high values of the resistance to uniaxial compression in dry conditions abruptly fall when contacting atmospheric or ground water. Being damped and destroyed, marl is capable of transiting into the plastic state with abrupt reduction of strength and growth of deformability. Materials and methods. The optimal binder was selected. Strength tests were performed on samples made based on of various binder contents and hardening periods. The considered strength parameter is the ultimate uniaxial compression strength. A part of the laboratory tests was carried out with artificial marl, which was recreated by granulometric composition to expand the statistical data of the tests. Laboratory studies for non-stabilized marl were conducted to determine the optimal humidity, density of ground particles, yield limit, and plastic limit. The hardening of the samples occurred under different temperature conditions. Results. The study of both stabilized and non-stabilized ground samples is mainly focused on strength indicators, changes in plastic properties, compaction requirements, correlation of strength, and compressibility characteristics of the marl samples. There is a decrease in density and humidity, with an increase in the amount of binder in the sample. Significant improvement and stabilization of the studied samples were observed for 4-% binder content. Conclusions. The study proved many increases in the strength of marl during its stabilization. The optimal type of binder was proposed. Dependences of the strength of ground samples on the binder content were shown

scholarly journals Air Permeability of Air-Entrained Hybrid Concrete Containing CSA Cement

Buildings ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 119
Author(s):  
Wojciech Kubissa
Keyword(s):  
Air Permeability ◽  
Partial Replacement ◽  
Clear Correlation ◽  
Calcium Sulfoaluminate Cement ◽  
Calcium Sulfoaluminate ◽  
Multi Criteria Evaluation ◽  
Strength Tests ◽  
Dry Conditions ◽  
Sorptivity Test ◽  
Tensile Splitting Strength

This paper presents the results of research on series of concrete prepared with Portland cement CEM I 42.5R, with partial replacement of this cement with calcium sulfoaluminate cement. In part of the series, an air-entraining admixture was used. It was assumed that the mixture must remain workable for at least 45 min and to ensure that citric acid as the setting retarder was used. Compressive strength tests after 2, 7, 28, 56 and 90 days, tensile splitting strength test and sorptivity test after 28 days were performed. After 56 and 90 days, the moisture content of the specimens was determined, and Torrent air permeability was tested. Freeze-thaw scaling resistance was also investigated. It was found that the addition of 15% and 30% calcium sulfoaluminate cement results in a significant reduction in the relative humidity of the concrete, after storage under air-dry conditions and an increase in air permeability. The series with 30% calcium sulfoaluminate cement in the binder, regardless of aeration, showed significantly lower resistance to cyclic freezing in the presence of salt. A clear correlation between sorptivity, air permeability and surface scaling was not found. On the basis of a multi-criteria evaluation of the tested concrete and performed Performance Index calculations, the best parameters were achieved by concrete series C30-4.5.

scholarly journals The Effect of Bedding Structure on Mechanical Property of Coal

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
Zetian Zhang ◽  
Ru Zhang ◽  
Guo Li ◽  
Hegui Li ◽  
Jianfeng Liu
Keyword(s):  
Mechanical Property ◽  
Uniaxial Compression ◽  
Peak Stress ◽  
Natural Fracture ◽  
Test Results ◽  
Compression Tests ◽  
Average Amount ◽  
Uniaxial Compression Strength ◽  
Bedding Planes ◽  
Close Relationship

The mechanical property of coal, influencing mining activity considerably, is significantly determined by the natural fracture distributed within coal mass. In order to study the effecting mechanism of bedding structure on mechanical property of coal, a series of uniaxial compression tests and mesoscopic tests have been conducted. The experimental results show that the distribution characteristic of calcite particles, which significantly influences the growth of cracks and the macroscopic mechanical properties of coal, is obviously affected by the bedding structure. Specifically, the uniaxial compression strength of coal sample is mainly controlled by bedding structure, and the average peak stress of specimens with axes perpendicular to the bedding planes is 20.00 MPa, which is 2.88 times the average amount of parallel ones. The test results also show a close relationship between the bedding structure and the whole deformation process under uniaxial loading.

Surface‐to‐volume ratio, charge density, nuclear magnetic relaxation, and permeability in clay‐bearing sandstones

Geophysics ◽  
1990 ◽  
Vol 55 (1) ◽  
pp. 61-69 ◽  
Author(s):  
P. N. Sen ◽  
C. Straley ◽  
W. E. Kenyon ◽  
M. S. Whittingham
Keyword(s):  
Magnetic Relaxation ◽  
Decay Constant ◽  
Regression Coefficient ◽  
Volume Ratio ◽  
Oil Fields ◽  
Size Parameter ◽  
Exchange Cation ◽  
The World ◽  
Log Interpretation ◽  
Water Saturated

Based on measurements on some 100 sandstone core samples, mainly from oil fields from various parts of the world, we found the following regressions between volume‐to‐surface ratio [Formula: see text], permeability to fluid flow k, exchange cation molarity [Formula: see text], and proton NMR decay constant [Formula: see text] in water‐saturated rocks (see Figure 1): [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text]. Here R is the regression coefficient, ϕ is the porosity and m the conductivity exponent; [Formula: see text] in normality (meq/ml), k in millidarcies, and [Formula: see text] in milliseconds, [Formula: see text] in μm. Including the tortuosity factor [Formula: see text] in conjunction with a pore‐size parameter as represented by [Formula: see text], [Formula: see text], or [Formula: see text] improves the correlation with permeability and reduces the residual error. The best predictor for log k is log [Formula: see text]. The exponents in the above correlations agree reasonably with those expected from simple models. These correlations provide a numerical basis for assessing how well some of these quantities can be estimated from others in log interpretation. They also provide a basis for assessing the importance of the factors that interfere with and thereby weaken the correlations.

Two-Parameter Parabolic Mohr Strength Criterion and Its Damage Regularity

2006 ◽  
Vol 306-308 ◽  
pp. 327-332 ◽  
Author(s):  
Chun Guang Li ◽  
Xiu Run Ge ◽  
Hong Zheng ◽  
Shui Lin Wang
Keyword(s):  
Uniaxial Tension ◽  
Principal Stress ◽  
Uniaxial Compression ◽  
Strength Criterion ◽  
Friction Angle ◽  
Tensile Failure ◽  
Compression Tests ◽  
Uniaxial Compression Strength ◽  
Griffith Criterion ◽  
Two Parameter

A series of formulas about two-parameter parabolic Mohr strength criterion(2-PP Mohr criterion) are derived. Based on the results of uniaxial tension and uniaxial compression tests, the parameters involved in the criterion can be easily determined, then the criterion in terms of the major principal stress and the minor principal stress is derived, and the damage pattern is also discussed. At last, the formulas about the rupture angle and the friction angle are presented, and their relationship is also given. 2-PP Mohr criterion can describe not only shear but also tensile failure. In this criterion the ratio of the uniaxial compression strength and the uniaxial tension strength is not confined as in Griffith criterion. The formula about the rupture angle provides steady theoretical foundation for determining the direction of crack faces and damage patterns in the computation of macro crack propagation. In fact, Griffith criterion is only a special case of the two-parameter parabolic Mohr strength criterion proposed in this present paper.

scholarly journals Specific Energy of Hard Coal Under Load

2015 ◽  
Vol 37 (1) ◽  
pp. 9-16 ◽  
Author(s):  
Anna Bogusz ◽  
Mirosława Bukowska
Keyword(s):  
Kinetic Energy ◽  
Total Energy ◽  
Uniaxial Compression ◽  
Specific Energy ◽  
Compression Strength ◽  
Longitudinal Strain ◽  
Full Range ◽  
Dissipated Energy ◽  
Uniaxial Compression Strength ◽  
Recoverable Energy

Abstract The article presents results of experimental tests of energy parameters of hard coals under loading, collected from research sites located within five main geologic structures of Upper Silesian Coal Basin (GZW) - Main Trough, Main Anticline, Bytom Trough, Rybnik Trough and Chwałowice Trough. Coals from12 mines were analysed, starting with seams of group 200, through groups 400, 500, 600 and, finally, seams of group 700. Coal of each of the groups of seams underwent uniaxial compression stress of the energy parameters, in a servo-controlled testing machine MTS-810NEW, for the full range of strain of the tested coal samples. Based on the tests the dependence of different types of specific energy of longitudinal strain of coals on the value of uniaxial compression strength was determined. The dependence of the value of dissipated energy and kinetic energy of coals on the uniaxial compression strength was described with a linear function, both for coals which due to their age belong to various bed sand for various lithotypes of coal. An increase in the value of dissipated energy and in kinetic energy was observed, which was correlated with an increase in uniaxial compression strength of coal. The share of dissipated energy is dominant in the total energy of strain. Share of recoverable energy in the total energy of strain is small, independent of the compression strength of coals and is at most a few per cent high. In coals of low strength and dominant share of dissipated energy, share of recoverable energy is the biggest among the tested coals. It was shown that following an increase in compression strength the share of recoverable energy decreases, while the share of dissipated energy in the total energy increases. Further studies of specific energy of longitudinal strain of rocks in the full-range strain will be the next step inperfecting methodology of research into natural rock burst susceptibility of Carboniferous rock mass and changes in the susceptibility resulting from mining activity.

scholarly journals Effect of lignin and hemicelluloses on the tensile strength of micro-veneers determined at finite span and zero span

Holzforschung ◽  
2012 ◽  
Vol 66 (4) ◽  
Author(s):  
André Klüppel ◽  
Carsten Mai
Keyword(s):  
Tensile Strength ◽  
Combined Treatment ◽  
Sodium Chlorite ◽  
Wet Strength ◽  
Finite Span ◽  
Significant Strength ◽  
Strength Determination ◽  
Dry Conditions ◽  
Water Saturated ◽  
Moisture Conditions

Abstract Scots pine micro-veneers were subjected to hydrolysis with sulphuric acid or delignification with acidic sodium chlorite and a combination of both treatments. The tensile strength of untreated and treated veneers was determined at finite span (f-strength) and zero span (z-strength) under both dry (20°C, 65% relative humidity) and water-saturated conditions. Acidic hydrolysis resulted in significant strength losses in both testing modes and both moisture conditions, with the greatest strength reduction found for f-strength tested dry. After delignification, only f-strength under wet conditions was substantially reduced; dry f-strength and both dry and wet z-strength hardly changed. A combined treatment of prehydrolysis and delignification resulted in disintegration of the veneers, which made strength determination impossible. It was concluded that, in addition to cellulose, the hemicelluloses determine the f-strength under dry conditions, while lignin confers wet strength but appears not to contribute to interfibre adhesion and f-strength under dry conditions.

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