scholarly journals Application of electro-hydraulic shock in concrete technology

2021 ◽  
Vol 2131 (5) ◽  
pp. 052002
Author(s):  
M Titov ◽  
G Nepomnyashchev ◽  
D Dorofeeva
Keyword(s):  
Compressive Strength ◽  
High Voltage ◽  
Electric Pulse ◽  
Applied Pressure ◽  
Voltage Source ◽  
Cement Stone ◽  
Cement Slurry ◽  
Concrete Technology ◽  
Closed Chamber ◽  
Processing Modes

Abstract The aspects, related to the influence of the electrohydraulic shock method use in a water-cement slurry passing in a closed chamber (activation reactor) with a pre-applied pressure to the system under various processing modes are highlighted in the article. In order to test the effect of this method on water-cement slurry, an installation was developed, consisting of: a high-voltage source, a high-voltage diode, capacitor banks, a closing element and an activation reactor. The necessary experiments were carried out on the completed installation. The procedure for conducting experiments is described in the work, shows a schematic diagram of the installation for performing activation, a diagram of the reactor, and the processing modes. Several activation modes were considered, depending on: the number of pulses (1-4), pulse energy (0.5-8 kJ), water-cement ratio (0.2-0.35), time intervals for starting treatment from the moment the cement was mixed with water (0 -120 minutes), volume and shape of the container (activation reactor), holding temperature (20-60°C), etc. According to the results of the data obtained, it was experimentally established that the use of electric pulse treatment of water-cement suspension has a positive effect on strength (cup compressive strength) indicators, obtained as a result of processing cement stone samples at different times of hardening (1-3 days). The compressive strength of the treated specimens’ increases in comparison with the untreated specimens, increase in strength reaches up to 45%, depending on the activation mode. The resulting effect was achieved due to many factors (high pressure, magnetic, temperature, energy, ultrasonic and other influences), which were applied in the most optimal period of time (stage) of the cement grain hydration process.

Preparation and Research of the High-Strength Lightweight Concrete Based on Hollow Microspheres

2013 ◽  
Vol 746 ◽  
pp. 285-288 ◽  
Author(s):  
Evgeniy Valerjevich Korolev ◽  
Alexandr Sergeevich Inozemtcev
Keyword(s):  
Compressive Strength ◽  
Lightweight Concrete ◽  
Precast Concrete ◽  
Iron Hydroxide ◽  
High Strength ◽  
Average Density ◽  
Hollow Microspheres ◽  
Cement Stone ◽  
Concrete Technology ◽  
High Rise

The paper presents the results of research aimed at development of nanomodified high-strength lightweight concrete for construction. The developed concretes are of low average density and high ultimate compressive strength. It is shown that to produce this type of concrete one need to use hollow glass and aluminosilicate microspheres. To increase the durability of adhesion between cement stone and fine filler the authors offer to use complex nanodimensional modifier based on iron hydroxide sol and silica sol as a surface nanomodifier for hollow microspheres. It is hypothesized that the proposed modifier has complex effect on the activity of the cement hydration and, at the same time increases bond strength between filler and cement-mineral matrix. The compositions for energy-efficient nanomodified high-strength lightweight concrete which density is 1300...1500 kg/m3 and compressive strength is 40...70 MPa have been developed. The approaches to the design of high-strength lightweight concrete with density of less than 2000 kg/m3are formulated. It is noted that the proposed concretes possess dense homogeneous structure and moderate mobility. Thus, they allow processing by vibration during production. The economic and practical implications for realization of high-strength lightweight concrete in industrial production (in particular, for construction of high-rise buildings) have been justified. The results of industrial testing of new compositions in precast concrete technology are shown.

Research on New Materials to Improve the Bonding Strength and Relieve Contamination of the Cement Slurry with Oil Based Muds

2016 ◽  
Vol 847 ◽  
pp. 510-518
Author(s):  
Zao Yuan Li ◽  
Hong Hua Liu ◽  
Xiao Yang Guo ◽  
Xiao Wei Cheng ◽  
Hong Juan Ou ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Shale Gas ◽  
Bonding Strength ◽  
Filter Cake ◽  
Honeycomb Structure ◽  
Cement Stone ◽  
New Materials ◽  
Cement Slurry ◽  
Current Application ◽  
Gas Well

During shale gas well drilling and completion, the oil based muds (OBMs) would reduce the bonding strength of cement slurry by filter-cake and oil-wettability. At the same time, mixing cement slurry with the OBMs can lead to contamination, and subsequently creates significant problems, such as, reducing the normal thickening time and the compressive strength, and hence affecting the quality of the cementing of the shale gas well. Therefore in the present investigation, the mechanism of the interface displacement, wetting conversion and the contamination was explored by Atomic Force Microscopy (AFM), X-Ray Diffraction (XRD), scanning electron microscope (SEM) and other methods. And then the new materials with the enhanced bonding strength and the contamination relieving by OBMs were obtained. The results showed that the chemical composition of filter-cake determined the properties of chemical preflush, the combined systems (LSS) efficiently flushed filter-cake and increased the bonding strength. It has been found that the reverse wetting agent (APG) has better reverse wetting properties than Tarim Oilfield current application system, which effectively changes the wettability of cementing surface from lipophilicity to hydrophilic. The OBMs and cement slurry mixing generated the emulsion structure and honeycomb structure, and the structures can affect the rheology and the strength of cement slurry; the contaminative relieve agent (SCW) can form a thin film on the surface of the cement stone, the film covers the hole and improves cement compressive strength, thus the SCW can relieve the contamination by OBMs.

scholarly journals Hybrid Effect of Wollastonite Fiber and Carbon Fiber on the Mechanical Properties of Oil Well Cement Pastes

2020 ◽  
Vol 2020 ◽  
pp. 1-9
Author(s):  
Jianglin Zhu ◽  
Jiangxiong Wei ◽  
Qijun Yu ◽  
Mingbiao Xu ◽  
Yuwei Luo
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Carbon Fiber ◽  
Impact Strength ◽  
Flexural Strength ◽  
Cement Stone ◽  
Oil Well ◽  
Cement Slurry ◽  
Oil Well Cement ◽  
Well Cement

Oil well cement is a type of natural brittle material that cannot be used directly in cementing operations. Fiber is a type of material that can effectively improve the strength and toughness of cement stone, and hybrid fiber materials can more effectively improve the performance of a cement sample. To overcome the natural defects of oil well cement, the new mineral fiber, i.e., wollastonite fiber, and common carbon fiber were used in oil well cement, and the micromorphology, mechanical properties, and stress-strain behavior of the cement were evaluated. The experimental results show that carbon fiber and wollastonite fiber are randomly distributed in the cement paste. The mechanical properties of the cement paste are improved by bridging and pulling out. The compressive strength, flexural strength, and impact strength of cement stone containing only carbon fiber or wollastonite fiber are higher than those of the pure cement, but too many fibers are not conducive to the development of mechanical properties. A mixture of 0.3% carbon fiber with 6% wollastonite fiber in oil well cement slurry results in a greater increase in compressive strength, flexural strength, and impact strength. In addition, compared with blank cement stone, the strain of the mixed cement stone increases substantially, and the elastic modulus decreases by 37.8%. The experimental results supply technical support for the design of a high-performance cement slurry system.

scholarly journals Effects of Water-to-Cement Ratio on Pore Structure Evolution and Strength Development of Cement Slurry Based on HYMOSTRUC3D and Micro-CT

2021 ◽  
Vol 11 (7) ◽  
pp. 3063
Author(s):  
Shaojun Zheng ◽  
Tianle Liu ◽  
Guosheng Jiang ◽  
Changliang Fang ◽  
Bo Qu ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Pore Structure ◽  
Regression Function ◽  
Structure Evolution ◽  
Strength Development ◽  
Cement Stone ◽  
Micro Ct ◽  
Capillary Porosity ◽  
Cement Slurry ◽  
Water To Cement Ratio

Changing the water-to-cement ratio is one of the major ways to develop cement slurry with different densities, which in turn will greatly affect the pore structure and mechanical properties of cement slurry. In the current study, the cement hydration model HYMOSTRUC3D was used to investigate the effects of water-to-cement (w/c) ratio (0.40, 0.44, 0.50) on the pore structure evolution and strength development of cement slurry. The microstructure of the cement stone was characterized via scanning electron microscope (SEM) and micro-computed tomography (micro-CT), and the mechanical strength of the cement stone was tested and analyzed via a mechanical tester. The simulated compressive strength and capillary porosity are in good agreement with the measured data, where the relative error between the simulated results and measured results are within 0.6~10.7% and 13.04~25.31%, respectively. The capillary porosity is proved as the main factor affecting the compressive strength of cement stone with different w/c ratios. Herein, the mathematical relationship between the measured capillary porosity and compressive strength could be well fitted via the mathematical prediction models of the Balshin function (R2 = 0.95), Ryshkewitch function (R2 = 0.94), Schiller function (R2 = 0.96), and the linear regression function (R2 = 0.95). Moreover, the linear regression function (y = −2.38x + 82.76) can be used to characterize and predict the quantitative relationship between the compressive strength and capillary porosity of cement stone. The findings in this study will provide a reference value in the fields of oil and gas cementing and building concrete.

scholarly journals Influence of the Addition of Silica Nanoparticles on the Compressive Strength of Cement Slurries under Elevated Temperature Condition

Energies ◽  
2021 ◽  
Vol 14 (17) ◽  
pp. 5493
Author(s):  
Anna Pikłowska ◽  
Jan Ziaja ◽  
Marcin Kremieniewski
Keyword(s):  
Compressive Strength ◽  
Silica Nanoparticles ◽  
Rheological Parameters ◽  
Cement Stone ◽  
Cement Slurry ◽  
Average Strength ◽  
Significant Deterioration ◽  
Strength Tests ◽  
Type 3

Drilling ever deeper, and thus in increasingly difficult conditions, is associated with restrictive requirements that must be met by cement slurries. This implies the need to use advanced, innovative measures that will significantly improve the performance parameters of the cement slurry and cement stone. Due to its unique properties, an admixture of nanosilica improves the properties of the cement stone and allows for appropriate zone insulation. The article presents the results of strength tests of cement stone samples with the addition of silica nanoparticles deposited in an environment of increased temperature of 90 °C. In all three cases of modification with an admixture of nanosilica (type 1, 2 and 3, concentration 0.5%, 1% and 5%), the cement stone shows an improvement in mechanical properties, which is manifested by an increase in compressive strength. The most homogeneous results of strength measurements are for cement slurries with an admixture of type 3 nanosilica (the highest average strength: 132–149% in relation to the base sample). They show the smallest stretch marks and deviations from the average. The highest average increase in strength is for the sample with the addition of 1% nanosilica (on average 124% in relation to the base sample). This amount causes the greatest increase in strength with no significant deterioration of rheological parameters.

Power Quality Improvement of High Voltage DC Link using Modified Shunt Active Power Filter

2018 ◽  
Vol 1 (1) ◽  
pp. 54-66
Author(s):  
Rakan Khalil Antar ◽  
Basil Mohammed Saied ◽  
Rafid Ahmed Khalil
Keyword(s):  
Power Quality ◽  
High Voltage ◽  
Pulse Width Modulation ◽  
Active Power Filter ◽  
Active Power ◽  
Voltage Source ◽  
Active Power Filters ◽  
Power Filter ◽  
Power Filters ◽  
Power Quality Improvement

A new control strategy for active power filters is proposed, modeled and implemented in order to improve the power quality of a line commutated converter High voltage DC link. The ability of reactive power and harmonics reductions are generally met by using passive and active power filters. In this paper, modified active power filter with a modified harmonics pulse width modulation algorithm is used to minimize the source harmonics and force the AC supply current to be in the same phase with AC voltage source at both sending and receiving sides of a line commutated converter high voltage DC link. Therefore, it is considered as power factor corrector and harmonics eliminator with random variations in the load current. The modified harmonics pulse width modulation algorithm is applicable for active power filter based on a three-phase five-level and seven-level cascaded H-bridge voltage source inverter. Simulation results show that the suggested modified multilevel active power filters improve total harmonics distortion of both voltage and current with almost unity effective power factor at both AC sides of high voltage DC link. Therefore, modified active power filter is an effective tool for power quality improvement and preferable for line commutated converter high voltage DC link at different load conditions.

Applications of Nanomaterials in Wellbore Fluids in Oil and Gas Fields

2021 ◽  
Vol 881 ◽  
pp. 33-37
Author(s):  
Wei Na Di
Keyword(s):  
Oil And Gas ◽  
Drill String ◽  
Wellbore Stability ◽  
Petroleum Engineering ◽  
Cement Stone ◽  
Drilling Fluids ◽  
Cement Slurry ◽  
Oil And Gas Fields ◽  
Gas Channeling ◽  
Gas Fields

The application of nanomaterials in oil and gas fields development has solved many problems and pushed forward the development of petroleum engineering technology. Nanomaterials have also been used in wellbore fluids. Nanomaterials with special properties can play an important role in improving the strength and flexibility of mud cake, reducing friction between the drill string and wellbore and maintaining wellbore stability. Adding nanomaterials into the cement slurry can eliminate gas channeling through excellent zonal isolation and improve the cementing strength of cement stone, thereby facilitating the protection and discovery of reservoirs and enhancing the oil and gas recovery. This paper tracks the application progress of nanomaterials in wellbore fluids in oil and gas fields in recent years, including drilling fluids, cement slurries. Through the tracking and analysis of this paper, it is concluded that the applications of nanomaterials in wellbore fluids in oil and gas fields show a huge potential and can improve the performance of wellbore fluids.

The Effect of Opal-Containing Rocks on the Properties of Lightweight Oil-Well Cement

2021 ◽  
Vol 325 ◽  
pp. 47-52
Author(s):  
Fedor L. Kapustin ◽  
N.N. Bashkatov ◽  
Rudolf Hela
Keyword(s):  
Flexural Strength ◽  
Oil And Gas ◽  
Gas Production ◽  
Cement Stone ◽  
Oil Well ◽  
Cement Slurry ◽  
Water Separation ◽  
Oil And Gas Production ◽  
Geological Conditions ◽  
Cement Grinding

When constructing deep wells for oil and gas production in difficult geological conditions, special lightweight oil-well cements are used. To reduce the density and water separation of the cement slurry as well as to increase the strength, corrosion resistance of cement stone and the quality of well cementing, opal-containing rocks, fly ash, microsphere and other lightening additives are introduced into the cement composition. The influence of sedimentary rocks, such as opoka, tripoli, and diatomite containing from 43 to 81% amorphous silica on the grindability, rheological and physical-mechanical properties of lightweight oil-well Portland cement has been studied. The twelve cement compositions with different content of additives (from 30 to 45%) that meet the requirements of the standard for density, spreadability, water separation, thickening time and flexural strength were selected. The introduction of 45% diatomite or tripoli significantly reduces the duration of cement grinding, provides the cement slurry with water-cement ratio of 0.9 with better density and flexural strength, respectively, 1480 kg/m3 and 1.1–1.5 MPa.

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