Mix Design and Proportioning

Materials

Preparation of Cylindrical Mortar Specimens

Preparation of Microbial Culture Media

MAB Culture Media

SRB Culture Media

Post Exposure Analysis

X-Ray Diffraction Studies

Visualization of the Surfaces

Degradation Parameters in Microbial Cultures

Biofilm Characterization Studies in Bacterial Cultures

Epifluorescence Microscopic Analysis

Confocal Laser Scanning Microscopy Analysis

XRD Analysis

DISCUSSION

CONCLUSIONS

LITERATURE CITED

INTRODUCTION

Nuclear structures are generally designed with a service life of about 40 years. The present interest is to extend their life span over 60–100 years, using the new technologies, in order to reduce the cost per unit power production. There are many concrete structures associated with a power plant, for example, cooling water system, intake pipes, etc., which are exposed to harsh and aggressive marine environments, either directly or indirectly. The structural stability of concrete structures in contact with seawater is of extreme importance for the long term service of a nuclear industry [1–3]. Concrete structures are severely affected by factors like carbonation, ingression of chloride and sulfate ions, microbial corrosion, etc. The corrosion due to acid producing microbes takes place through the formation of active biofilms on the concrete surface [4]. Among various factors affecting the deterioration of concrete structures, the one due to biological origin is very significant in aggressive environments due to the production of biogenic corrosive substances by the microorganisms [5,6]. Microorganisms form colonies over the surface of concrete and results in the structural, functional, and aesthetic damage of concrete structures [7]. Microbial growth over concrete surfaces can take place under a wide range of environments like elevated humidity, prolonged freezing and thawing, high levels of carbon dioxide or chloride ingress, high concentrations of sulfates, and very small amount of acids [8]. The scope of improving the durability and performance of concrete through incorporation of mineral and chemical admixtures paved the way to development of a class of concrete called high performance concrete (HPC) with a reduced water to cement (w/c) ratio and enhanced properties. There are many pozzolanic materials like burning rice husk, blast furnace slag, fly ash, etc. that can replace cement in the production of concrete. But CO2 emissions from burning rice husk also form a part of the global carbon cycle [9]. Thus, the need of the hour is to reduce the emission of CO2 in the construction industry through the application of sustainable techniques and technologies [10]. Among the most commonly used mineral admixtures, fly ash, a waste product from coal based power plants, is incorporated in concrete in order to reduce the utilization of cement and to improve its durability, thereby making it an environment friendly green concrete. Despite these advantages, there are some early-age performance issues reported for fly ash concrete like low early-age strength, high calcium leaching, etc. [11,12].

Abundant high quality coal resources exist in the Ordos and Yulin coal fields, China, which have developed into an important modern coal production bases. However, the bedrock is relatively thin with low shear bond strength. This specific roof strata structure, as well as the high mining dynamic stress caused by the high strength mining. Severe dynamic disasters, such as large area roof falls and shield damaged were occurred by the high ground pressure. The specific physical and mechanical properties of the overlying strata are the internal factors causing the dynamic disasters. Therefore, the study of the physical properties of the overburden strata under this mining conditions is the fundamental research for the prevention of the dynamic disasters. In recent years, many scholars have researched in this area with great success. Many valuable achievements on strata movement and control, and the microstructures of the shallow buried have been produced [1–12]. For micro-structure research, the relationship between micro-structure and rock mechanics properties has been analyzed [13–15]. Lindqvist et al. studied the effects of mineral composition, grain size, porosity and micro-fissures on rock mechanics properties [16]. Johansson confirmed that mineral composition, micropore porosity, grain size and shape as well as lamination are the most important factors influencing rock mechanics properties, He also summarized the different characteristics of various mineral composition and structure porosity as well as their effects on rock mechanics properties [17]. Tug˘rul et al. recognized that the physical and mechanics properties of rock are functions of mineral composition and structure [18]. Prˇikryl concluded that the uniaxial compressive strength (UCS) of granite is closely related to its grain size [19]. Although many significant results have been obtained by numerous researchers in the past, there exist many problems in theoretical research and production process. Therefore the research on rock’s mineral composition, structure and rock mechanics, especially the relationships among them are needed. In order to study the effect of rock composition, micro structure and porosity on rock mechanics properties, five kinds of sandstones located at different depths were selected for this research. Their compositions were analyzed by X-ray diffraction instrument. The semi quantitative analysis of the components was carried out by using the Jade 6.0 analysis software. The microstructure characteristics were observed by using the scanning electron microscope of SM-6390LV.

Roller compacted concrete (RCC) is defined as a type of concrete that, in its unhardened state, is able to support a roller while being compacted. The amount of cement paste required in this concrete is just as much as filling the voids between the aggregates and the water content is designed for having enough workability [1]. The first implementation of roller-compacted concrete pavement (RCCP) dates back to 1930 in Sweden [2]. In North America, the first experience with the construction of RCCP occurred in 1942 during the construction of an airport runway in Washington. However, in Canada, the RCC was first used as a surface layer in 1976 in the construction of a log sorting yard. The initial design was a layer of stabilized aggregates with a thickness of 14 in. as the base layer and 2 in. of asphalt concrete surface. However, a pavement with a thickness of 14 in. consisting of an 8 in. stabilized base with 8% cement and 6 in. aggregates with 13% cement was built upon the request of the owners. This positive experience in the construction of RCCP increased the application of this type of pavement in Canada in the following years. The main difference between the RCC and conventional concrete is the amount and gradation of the aggregates, amount of cement, and water; so that the aggregates used in the construction of the RCC are dense- or well-graded and make up 75% to 85% of the total volume of the materials. Also, the amount of fine aggregates is higher than those of conventional concrete. These factors cause high stiffness of the fresh RCC and zero (or less) value of the slump, so that it cannot be compacted using traditional concrete paving machines [3]. Due to the large surface of RCCP and its potential exposure to a variety of harsh conditions (e.g. freeze–thaw cycles), durability of this type of concrete and its proper performance under these conditions is very important. Although concrete is damaged due to various factors, water transport properties have a direct influence on concrete durability against non-mechanical damages [4,5]. Water transport in concrete is carried out by various mechanisms, including diffusion (displacement of mass or ion due to concentration difference), sorption (water displacement due to capillary action), permeability (movement of water under pressure), migration (displacement of ions due to force of electrical field) and adsorption (fixation of water molecules on the surface of materials) as the main cases among others [6–10]. The surface contact of unsaturated concrete with water leads to the absorption of moisture due to the porosity of concrete and its capillary action. This is the most important measurable property in porous solids and can be used as a suitable indicator for the evaluation of various building materials, considering the ease of testing and the reproducibility of its results [11].

مقاله سال 2016

استراتژی سنتز مقایسه‌ای چارچوب‌های فلز-آلی، مانند دانشگاه فناوری هنگ‌کنگ-1{HKUST-1[Cu3(BTC)]2} (تری‌کربوکسیلات-بنزن-1،3،5 = BTC) توسط روش سولووترمال و الکتروشیمیایی در اتانول:آب (1:1) هدایت شده است. مواد به‌دست آمده با استفاده از پراش پرتو ایکس پودری، میکروسکوپ الکترونی روبشی (SEM)، طیف‌سنجی مادون قرمز-تبدیل فوریه (FT-IR)، آنالیز وزن‌سنجی حرارتی (TGA) و آنالیز مساحت سطح (SAA) مورد آنالیز قرار گرفتند. درحالی‌که ولتاژ در روش الکتروشیمیایی در محدوده از 12 تا 15 تغییر داده شده است. نتایج نشان داد که در 15 ولت، بافت مواد در مقایسه با محصول سولووترمال بهترین درجه تبلور را دارد. این نتیجه از طریق داده‌های XRD نشان داده شده و توسط تصویر SEM به‌منظور نمایش مورفولوژی تأیید شده است. پایداری حرارتی ترکیبات سنتز شده بالای °C 320 است. شکل ایزوترم جذب نیتروژن ترکیب، مربوط به نوع I از طبقه‌بندی ایزوترم جذب آیوپاک برای مواد میکرومتخلخل با مساحت سطح BET m2/g 2/629 و 3/324 (به‌ترتیب برای محصول سولووترمال و الکتروشیمیایی) است و نوید‌ دهنده برای کاربرد ذخیره‌سازی گاز است. در اینجا، ظرفیت‌های ذخیره‌سازی متان این ترکیبات نیز تست شده‌اند.

1. مقدمه:
متان یک سوخت تجدیدپذیر و فراوان است. به‌علاوه، این گاز به دلیل سوختن پاک آن نسبت به بنزین، دوست‌دار محیط زیست است. همچنین این گاز می‌تواند به‌طور محلی (موضعی) از زیست‌گاز و زیست توده تولید شود. توسعه و کاربرد متان برپایه‌ی اقتصاد مقاومتی و اجتماعی به منظور حمایت از برنامه‌های دولتی به سوی جامعه‌ای خودکفا در انرژی است. درضمن، موفقیت در کشف انرژی تجدیدپذیر باید توسط سیستم‌های موثر ذخیره‌سازی انرژی حمایت شود.
به تازگی دپارتمان انرژی ایالات متحده یک برنامه جدید ذخیره‌سازی متان را با اهداف تعیین شده زیر شروع کرده است: g 5/0 (متان) در هر گرم (جاذب) برای ظرفیت وزنی و (mmol/cc 741/11) g/cc 188/0 =r برای ظرفیت حجمی، که مربوط به دانسیته گاز طبیعی فشرده شده (CNG) در bar 250 و K 298 است. هدف حجمی جدید برابر با cc 263 (در شرایط STP : K 15/273 و atm 1) در هر cc است که به‌طور قابل توجهی بالاتر از هدف قبلی cc 180 (STP) در هر cc در bar 35 است.

مقاله سال 2017

ما در این تحقیق احتمال کاهش فشار فروپاشی سنگ و افزایش آسیب پیرامون ترک هیدرولیکی را با استفاده از تزریق تناوبی پیش از ‌شکست طی شکست هیدرولیکی تحت شرایط تنش سه محوره ارزیابی می‌کنیم. برخلاف افزایش یکنواخت فشاری که در شکست هیدرولیکی عادی استفاده می‌شود، سیال در چند سیکل تا زمان ‌شکست تزریق می‌شود. طی تزریق تناوبی، فشار بیشینه هر سیکل با فواصل 10% فشار فروپاشی مرجع افزایش پیدا می‌کند. فشار فروپاشی مرجع سنگ فشاری است که سنگ طی شکست هیدرولیکی در اثر تزریق عادی به نقطه تسلیم می‌رسد. برای به دست آوردن فشارهای ‌شکست مرجع، نمونه‌هایی از ماسه‌سنگ خشک و اشباع تنسی به‌صورت هیدرولیکی با تزریق عادی شکسته شد. کاهش فشار فروپاشی و افزایش آسیب حین تزریق تناوبی به‌طور کمّی باحالت شکست هیدرولیکی عادی مقایسه شد. انتشار صوت (AE)، نفوذپذیری شکست و تصاویر میکروسکوپ الکترونی روبشی (SEM) برای سطح شکست جهت مقایسه آسیب حین شکست‌های هیدرولیکی ناشی از شکست هیدرولیکی عادی و شکست هیدرولیکی ناشی از تزریق تناوبی بکار گرفته شدند. نتایج آزمایشگاهی نشان داد آسیبی که حول ترک هیدرولیکی ناشی از شکست در اثر تزریق تناوبی در ماسه‌سنگ تنسی ایجاد می‌شود تقریباً دو برابر آسیب ناشی از تزریق عادی است. هم‌چنین، فشار فروپاشی‌ای که حین شکست ناشی از تزریق تناوبی در ماسه‌سنگ خشک تنسی ثبت شد کمتر بود و بیش از دو برابر انحراف معیار تزریق عادی تغییر یافت.