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Effect of chloride salt concentration on unconfined compression strength of cement-treated Lianyungang soft marine clay

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Journal of Southeast University(English Edition) 2013年第1期29卷 79-83页

作者：章定文曹智国范礼彬邓永锋东南大学交通学院南京210096

This study aims to quantify the influence of the amount of cement and chloride salt on the unconfined compression strength （UCS） of Lianyungang marine clay. The clays with various sodium chloride salt concentrations were prepared artificially and stabilized by ordinary Portland cement with various contents. A series of UCS tests of cement stabilized clay specimen after 28 d curing were carried out. The results indicate that the increase of salt concentration results in the decrease in the UCS of cement-treated soil. The negative effect of salt concentration on the strength of cement stabilized clay directly relates to the cement content and salt concentration. The porosity-salt concentration/cement content ratio is a fundamental parameter for assessing the UCS of cement-treated salt-rich clay. An empirical prediction model of UCS is also proposed to take into account the effect of salt concentration. The findings of this study can be referenced for the stabilization improvement of chloride slat- rich soft clay.

关键词： soft marine clay salt concentration cementation unconfined compression strength

Comparison of Different Implant-Supported Fixed Restoration Types: A Literature Review

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Open Journal of Stomatology 2024年第11期14卷 421-432页

作者： Zeynep Sen Yilmaz Nuran Yanikoglu Merve Koseoglu Department of Prosthodontics University of Ataturk Erzurum Trkiye Department of Prosthodontics University of Sakarya Sakarya Trkiye

Background: The screw and cement-retained implant-supported fixed prosthesis has advantages and disadvantages. However, current research comparing the properties of these restorations is lacking. Objectives: The aim of the study was to review the current literature on the properties of screw and cement retained implant supported restorations. Material and Methods: A literature search was conducted from January 2010 to December 2023, using 4 databases to identify research. Sixty studies met the inclusion criteria. Results: Cement-retained restorations have some advantages. Passive fit is easier to achieve, and eliminating occlusal access holes can help with the occlusal adjustments in cemented restorations. However, in case residual cement is not completely removed after cementation, it becomes a predisposing factor for peri-implantitis and marginal bone loss. The main advantage of screw-retained restorations is the retrievability, which can be achieved without damaging the restoration or fixture. However, in case the implant is not ideally positioned, the location of the screw access channel can negatively affect the aesthetics of the screw-retained restorations. In addition, porcelain fracture and screw loosening occur more frequently in screw-retained restoration. Conclusions: Screw and cement-retained restorations display specific advantages and disadvantages;nevertheless, the selection of one retention method over another depends on the clinical scenario.

关键词： Implant-Supported Restorations Retention cementation Screw

Micromechanics-based model for cement-treated clays

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Theoretical & Applied Mechanics Letters 2013年第2期3卷 30-36页

作者： Zhenyu Yin Pierre Yves Hicher Department of Civil Engineering Shanghai Jiao Tong University Research Institute in Civil and Mechanical Engineering

cementation is produced by mixing a certain amount of cement with the saturated clay. The purpose of this paper is to model the cementation effect on the mechanical behavior of cement-treated clay. A micromechanical stress-strain model is developed considering explicitly the cementation at inter-cluster contacts. The inter-cluster bonding and debonding during mechanical loading are introduced in two ways： an additional cohesion in the shear sliding and a higher yield stress in normal compression. The model is used to simulate isotropic compression and undrained triaxial tests under various confining stresses on cement-treated Singapore clay with various cement contents. The applicability of the present model is evaluated through comparisons between numerical and experimental results. The evolution of local stresses and local strains in inter-cluster planes is dis- cussed in order to explain the induced anisotropy due to debonding at contact level under the applied loads.

关键词： microstructure cementation constitutive model clay anisotropy debonding

The Cementing Techniques Of Salt Formation

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西部探矿工程 1993年第5期5卷 6-12页

作者： Zeng yijin Ding shidong Xia Huade (Petroleum Drilling Reseach Institute,MGMR)

This paper analyzes mechnasim of casing failure and collapse by salt formation,discusses cementing techniques of salt zone about casing programme, casing design, preparation of well condition, mud and slurry properties required, cementing technology, and puts forward the measures for solving problems posed when cementing through salt sequences, and illustrates with examples.

关键词： salt formation cementation collapse strenghth plastic flow saturated slurry synthetic techniques

Reclamation of Mercury from Used Silver Oxide Watch Batteries

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Advances in Chemical Engineering and Science 2014年第1期4卷 1-6页

作者： Natarajan Sathaiyan Electro Hydro Metallurgy Division CSIR-Central Electro Chemical Research Institute Karaikudi India

This paper deals with the reclamation of mercury from the used silver oxide quartz wristwatch batteries employing leaching-cementation technique. The used batteries are first crushed to liberate the encapsulated active material from the case which is leached in nitric acid to bring all metal contents into solution. After the removal of silver in the solution as silver chloride by precipitation, the mercury which is present as Hg2+ in the solution has been reclaimed through cementation with zinc dust. Various effects like zinc sheet and dust, zinc quantity, pH of the solution, duration and temperature have been carried out to standardise the conditions for maximum mercury reclamation. At a temperature of 45℃ and at 3.9 pH, 92.3% of mercury was recovered using 74 μm size zinc dust with purity greater than 99.78% and the same is characterized by XRF and the results are discussed.

关键词： Used Silver Oxide-Zinc Watch Batteries Leaching Zinc Dust cementation Mercury

Removal of Aqueous Lead and Copper Ions by Using Natural Hydroxyapatite Powder and Sulphide Precipitation in Cyanidation Process

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Materials Sciences and Applications 2013年第4期4卷 231-237页

作者： José Refugio Parga Jesús Leobardo Valenzuela Víctor Vazquez Mario Rodriguez Héctor Moreno Departament of Chemical Engineering and Metallurgy University of Sonora Hermosillo Mexico Department of Chemistry Institute Technology of Laguna Torreon Mexico Department of Metallurgy and Materials Science Institute Technology of Saltillo Saltillo Mexico

Mining, ore processing, and smelting activities have contaminated soil and water resources with cyanide and heavy metals throughout the world. In-situ chemical immobilization is a remediation technology that decreases the concentrations of dissolved ions of copper cyanide and lead hydroxides by adsorption or precipitation. This study deals, with a process to recover lead hydroxides with natural hydroxyapatite powder and copper cyanide ions with sulphide precipitation from solutions of the cyanidation process. This technology is based on inducing nucleated precipitation of copper and silver in a serpentine reactor, using sodium sulfide as the precipitator, and sulfuric acid for pH control. Results show that pH value has a significant effect on copper cyanide removal efficiency, and it was determined the optimal pH range to be 2.5 - 3. At this pH value, the copper cyanide removal efficiency achieved was up to 99% with 60 percent of copper purity and the cyanide ions associated with this complex the recovery was 90%. For the elimination of lead hydroxides ions from the aqueous cyanidation process with natural hydroxiapatite powder the recovery was 99%. The abundance of cow bones, its low price and non-aggressive nature towards the environment are advantages for its utilization in point of view of wastewater cleanup and Dore with higher quality.

关键词： Natural Hydroxyapatite Sulphide Precipitation Zinc cementation

The Effects of Different Ratios of Feldspathic Sandstone and Sand Compound Soil on Water-stable Aggregates in 4 Years Crop Planting

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Asian Agricultural Research 2017年第3期9卷 96-101,109页

作者： Tong ZHAO Jichang HAN Yang ZHANG Huanyuan WANG Xian JI Shaanxi Land Engineering Construction Group/Key Laboratory of Degraded and Unused Land Consolidation Engineering Ministry of Land and Resources

To study the formation process of feldspathic sandstone and sand compound soil in the Mu Us Desert,1∶ 1,1∶ 2 and 1∶ 5 ratios of feldspathic sandstone and sand were mixed to obtain compound soil to plant crops,and analyze the rules of changes in water-stable aggregates of the compound soil among the 4 years crops growing process. The results showed,before crop planting,the order of mass percent of> 0. 25 mm and 0. 25-2. 00 mm water-stable aggregates in three kinds of compound soil was 1∶ 1 > 1∶ 2 > 1∶ 5,showing that the overall content was low; the mass percent of > 0. 25 mm water-stable aggregates remained at 18. 38%-28. 22%; the mass percent of 0. 25-0. 50 mm,0. 50-2. 00 mm,2. 00-5. 00 mm,and > 5. 00 mm water-stable aggregates was close with each other in each kind of compound soil. After4 years of planting,the mass percent of > 0. 25 mm water-stable aggregates in 1∶ 2 compound soil increased significantly and exceeded other2 kinds of compound soil,reached 32. 34%; the main components of > 0. 25 mm water stable aggregates in 1∶ 1,1∶ 2,and 1∶ 5 compound soil were 0. 25-0. 50 mm( 53. 54%),0. 25-0. 50 mm( 59. 43%),0. 05-2. 00 mm( 52. 16%),aggregates; 0. 25-2. 00 mm aggregates increased significantly in all three kinds of compound soil,with the highest increase in 1∶ 2 compound soil; the organic matters of 1∶ 2 compound soil were significantly correlated with 0. 25-0. 50 mm and 0. 25-2. 00 mm water-stable aggregates. The results showed that the ratio of 0. 25-2. 00 mm aggregates in the three kinds of compound soil was increased after 4 years of crop planting and 1∶ 2 compound soil was most favorable for the formation of aggregates.

关键词： Feldspathic sandstone and sand compound soil Water-stable aggregates cementation

Logging interpretation method for reservoirs with complex pore structure in Mesozoic-Cenozoic faulted basin around Daqing exploration area

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Global Geology 2019年第3期22卷 209-216页

作者： YUE Shanshan FAN Xiaomin HUANG Buzhou College of Geo-Exploration Science and Technology Jilin University

In Mesozoic-Cenozoic faulted basin in the periphery of Daqing exploration area, the clastic reservoirs mainly consist of siltstone and gravel-bearing sandstone. The electrical conductivity of the reservoirs is complicated due to the complex pore structures, which cannot be accurately interpreted with commonly used model. In order to solve the problem, a three-water model has been applied in this study based on in-depth analysis of the conductive mechanism of rocks in the explored area, and favorable application results are achieved.

关键词： Daqing exploration area Mesozoic-Cenozoic faulted basin complex pore structures cementation index saturation index

Solidification of Spent Ion Exchange Resin Using ASC Cement

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Tsinghua Science and Technology 2002年第6期7卷 636-640页

作者：周耀中云桂春叶裕才 Institute of Nuclear Energy Technology Tsinghua University Beijing 100084 China

Ion exchange resins (IERs) have been widely used in nuclear facilities. However, the spent radioactive IERs result in major quantities of low and intermediate level radioactive wastes. This article describes a laboratory experimental study on solidification processing of IERs using a new type of cement named ASC cement. The strength of the cementation matrix is in the range of 1820 MPa (28 d); the loading of the spent IER in the cement-resin matrix is over 45% and leaching rates of 137Cs, 90Sr and 60Co are 7.92×10 -5, 5.7×10 -6, and 1.19×10 -8 cm/d. The results show that ASC cement can be a preferable cementation material for immobilization of radioactive spent IER.

关键词： radioactivity spent ion exchange resins cementation solidification