Effects of Sample Preparation and Interpretation of Thermogravimetric Curves on Calcium Hydroxide in Hydrated Pastes and Mortars

2012 ◽  
Vol 2290 (1) ◽  
pp. 10-18 ◽  
Author(s):  
Taehwan Kim ◽  
Jan Olek
Keyword(s):  
Sample Preparation ◽  
Calcium Hydroxide ◽  
Cement Hydration ◽  
Pozzolanic Reaction ◽  
Hydration Products ◽  
Scanning Calorimetry ◽  
Mass Losses ◽  
Fast Procedure ◽  
Preparation Techniques ◽  
Portland Cement Paste

Calcium hydroxide [Ca(OH)2] is one of the major constituents of hydrated portland cement paste. Its content can be used to trace the progress of cement hydration or serve as an indicator of the extent of pozzolanic reaction. The thermogravimetric analysis (TGA) method is often used to determine the Ca(OH)2 content because it is a relatively easy and fast procedure. However, no universally accepted method exists for the preparation of TGA specimens and for the interpretation of the resulting TGA curves. This paper presents an investigation on the contents of Ca(OH)2 in samples subjected to different preparation techniques. The results showed that a certain amount of calcium carbonate (CaCO3) was produced as a result of carbonation during the sample preparation process. The degree of carbonation was dependent on the sample preparation, and carbonated Ca(OH)2 was considered to determine the accurate total Ca(OH)2 content. In addition, a modified interpretation of the TGA curve for Ca(OH)2 was suggested. In this interpretation, the mass losses caused by the other hydration products, except for the Ca(OH)2 and the carbonated Ca(OH)2, were considered so that the accurate content of Ca(OH)2 could be determined. The interpretation technique was verified by comparing the results with those obtained by differential scanning calorimetry. Ultimately, the actual contents of Ca(OH)2 in pastes undergoing different sample preparation techniques were determined by using the modified interpretation of the TGA curve for the Ca(OH)2. The results showed that this interpretation yielded comparable contents of Ca(OH)2 in most of the sample preparation techniques used in this study.

scholarly journals Effect of Nanosilica on Impermeability of Cement-Fly Ash System

2020 ◽  
Vol 2020 ◽  
pp. 1-13 ◽  
Author(s):  
Huaqing Liu ◽  
Yan Zhang ◽  
Ruiming Tong ◽  
Zhaoqing Zhu ◽  
Yang Lv
Keyword(s):  
Fractal Dimension ◽  
Fly Ash ◽  
Bond Strength ◽  
Pore Structure ◽  
Calcium Hydroxide ◽  
Cement Hydration ◽  
Pozzolanic Reaction ◽  
Surface Protection ◽  
Durability Of Concrete

Surface protection has been accepted as an effective way to improve the durability of concrete. In this study, nanosilica (NS) was used to improve the impermeability of cement-fly ash system and this kind of material was expected to be applied as surface protection material (SPM) for concrete. Binders composed of 70% cement and 30% fly ash (FA) were designed and nanosilica (NS, 0–4% of the binder) was added. Pore structure of the paste samples was evaluated by MIP and the fractal dimension of the pore structure was also discussed. Hydrates were investigated by XRD, SEM, and TG; the microstructure of hydrates was analyzed with SEM-EDS. The results showed that in the C-FA-NS system, NS accelerated the whole hydration of the cement-FA system. Cement hydration was accelerated by adding NS, and probably, the pozzolanic reaction of FA was slightly hastened because NS not only consumed calcium hydroxide by the pozzolanic reaction to induce the cement hydration but also acted as nucleation seed to induce the formation of C-S-H gel. NS obviously refined the pore structure, increased the complexity of the pore structure, and improved the microstructure, thereby significantly improving the impermeability of the cement-FA system. This kind of materials would be expected to be used as SPM; the interface performance between SPM and matrix, such as shrinkage and bond strength, and how to cast it onto the surface of matrix should be carefully considered.

Hydration Products, Microstructure and Durability of Concrete with Metakaolin Addition

2016 ◽  
Vol 680 ◽  
pp. 420-428
Author(s):  
Qiu Li ◽  
Hai Ning Geng ◽  
Yun Huang ◽  
Zhong He Shui
Keyword(s):  
Diffusion Coefficient ◽  
Calcium Hydroxide ◽  
Calcium Silicate ◽  
Calcium Silicate Hydrate ◽  
Analytical Techniques ◽  
Pozzolanic Reaction ◽  
Chloride Diffusion ◽  
Chloride Diffusion Coefficient ◽  
Hydration Products ◽  
Durability Of Concrete

The durability, microstructure and hydration products of concrete containing 0-6wt% metakaolin (MK) were studied by analytical techniques. The hydration products were calcium hydroxide (CH), ettringite and calcium silicate hydrate gels in the control concrete, and additional monocarboaluminate and hemicarboaluminate were identified in concrete containing MK. CH content decreased by 28 days hydration in concrete containing MK, due to the pozzolanic reaction between MK and CH. Chloride diffusion coefficient decreased with the increase of MK content. By addition of 6wt% MK, chloride diffusion coefficient decreased by 60%.

Water Absorption and Hydration Products of Metakaolin Modified Mortar

2017 ◽  
Vol 726 ◽  
pp. 505-509 ◽  
Author(s):  
Hai Ning Geng ◽  
Qiu Li
Keyword(s):  
Compressive Strength ◽  
Pore Structure ◽  
Water Absorption ◽  
Calcium Hydroxide ◽  
Packing Density ◽  
Pozzolanic Reaction ◽  
Early Age ◽  
Hydration Products ◽  
Hydroxide Water

The compressive strength, water absorption and hydration products of mortar with metakaolin addition were characterized by a range of techniques to evaluate the effect of metakaolin on the properties and hydration of mortar. Metakaolin is more effective on the improvement of compressive strength of mortar after curing for 7 days, due to the refinement of pore structure and pozzolanic reaction between metakaolin and calcium hydroxide. Water absorption of mortar was reduced by introducing metakaolin, especially in the very early age, due to the optimization of packing density of mortar by superfine metakaolin particles. There is no correlation between compressive strength and water absorption of mortar due to the differences between mechanisms affecting the compressive strength and water absorption of mortar by metakaolin. The hydration products of mortar without metakaolin were Portlandite and ettringite. Additional hemicarboaluminate and monocarboaluminate were identified in mortar with metakaolin addition. Metakaolin addition reduced the calcium hydroxide content due to the pozzolanic reaction.

A Freeze Shadow Technique for the Preparation of Soft Paint Latexes for Electron Microscopy

1977 ◽  
Vol 35 ◽  
pp. 314-315
Author(s):  
Earl R. Walter ◽  
Glen H. Bryant
Keyword(s):  
Sample Preparation ◽  
High Vacuum ◽  
Vacuum System ◽  
Latex Particles ◽  
New Methods ◽  
Diffusion Pump ◽  
Film Forming ◽  
Routine Basis ◽  
Distribution Studies ◽  
Preparation Techniques

With the development of soft, film forming latexes for use in paints and other coatings applications, it became desirable to develop new methods of sample preparation for latex particle size distribution studies with the electron microscope. Conventional latex sample preparation techniques were inadequate due to the pronounced tendency of these new soft latex particles to distort, flatten and fuse on the substrate when they dried. In order to avoid these complications and obtain electron micrographs of undistorted latex particles of soft resins, a freeze-dry, cold shadowing technique was developed. The method has now been used in our laboratory on a routine basis for several years.The cold shadowing is done in a specially constructed vacuum system, having a conventional mechanical fore pump and oil diffusion pump supplying vacuum. The system incorporates bellows type high vacuum valves to permit a prepump cycle and opening of the shadowing chamber without shutting down the oil diffusion pump. A baffeled sorption trap isolates the shadowing chamber from the pumps.

Advanced TEM sample preparation techniques for submicron Si devices

1995 ◽  
Vol 53 ◽  
pp. 516-517 ◽  
Author(s):  
P. B. Basham ◽  
H. L. Tsai
Keyword(s):  
Sample Preparation ◽  
Process Development ◽  
Light Transmission ◽  
Specific Area ◽  
Turnaround Time ◽  
Small Hole ◽  
Area Of Interest ◽  
Transmission Electron ◽  
Polished Side ◽  
Preparation Techniques

The use of transmission electron microscopy (TEM) to support process development of advanced microelectronic devices is often challenged by a large amount of samples submitted from wafer fabrication areas and specific-spot analysis. Improving the TEM sample preparation techniques for a fast turnaround time is critical in order to provide a timely support for customers and improve the utilization of TEM. For the specific-area sample preparation, a technique which can be easily prepared with the least amount of effort is preferred. For these reasons, we have developed several techniques which have greatly facilitated the TEM sample preparation.For specific-area analysis, the use of a copper grid with a small hole is found to be very useful. With this small-hole grid technique, TEM sample preparation can be proceeded by well-established conventional methods. The sample is first polished to the area of interest, which is then carefully positioned inside the hole. This polished side is placed against the grid by epoxy Fig. 1 is an optical image of a TEM cross-section after dimpling to light transmission.

Novel Failure Analysis Sample Preparation Techniques for PoP Packaging

2012 ◽  
Author(s):  
Ng Sea Chooi ◽  
Chor Theam Hock ◽  
Ma Choo Thye ◽  
Khoo Poh Tshin ◽  
Dan Bockelman
Keyword(s):  
Sample Preparation ◽  
Failure Analysis ◽  
Failure Mechanisms ◽  
Preparation Process ◽  
Space Saving ◽  
Optical Probing ◽  
Preparation Techniques

Abstract Trends in the packaging of semiconductors are towards miniaturization and high functionality. The package-on-package(PoP) with increasing demands is beneficial in cost and space saving. The main failure mechanisms associated with PoP technology, including open joints and warpage, have created a lot of challenges for Assembly and Failure Analysis (FA). This paper outlines the sample preparation process steps to overcome the challenges to enable successful failure analysis and optical probing.

Sample Preparation Challenges In WLCSP Epoxy Underfill Coating Removal

2012 ◽  
Author(s):  
Jason H. Lagar ◽  
Rudolf A. Sia
Keyword(s):  
Sample Preparation ◽  
Failure Analysis ◽  
Vital Role ◽  
Fault Isolation ◽  
Wafer Level ◽  
Chip Scale Package ◽  
Coating Removal ◽  
Customer Returns ◽  
Preparation Techniques ◽  
Mechanical Defect

Abstract Most Wafer Level Chip Scale Package (WLCSP) units returned by customers for failure analysis are mounted on PCB modules with an epoxy underfill coating. The biggest challenge in failure analysis is the sample preparation to remove the WLCSP device from the PCB without inducing any mechanical defect. This includes the removal of the underfill material to enable further electrical verification and fault isolation analysis. This paper discusses the evaluations conducted in establishing the WLCSP demounting process and removal of the epoxy underfill coating. Combinations of different sample preparation techniques and physical failure analysis steps were evaluated. The established process enabled the electrical verification, fault isolation and further destructive analysis of WLCSP customer returns mounted on PCB and with an epoxy underfill coating material. This paper will also showcase some actual full failure analysis of WLCSP customer returns where the established process played a vital role in finding the failure mechanism.

A New Method of Wafer Level Plan View TEM Sample Preparation by DualBeam

2008 ◽  
Author(s):  
Hyoung H. Kang ◽  
Michael A. Gribelyuk ◽  
Oliver D. Patterson ◽  
Steven B. Herschbein ◽  
Corey Senowitz
Keyword(s):  
Sample Preparation ◽  
Ex Situ ◽  
Wafer Level ◽  
Cross Sectional ◽  
Plan View ◽  
Manufacturing Line ◽  
Transmission Electron ◽  
Thin Lamella ◽  
Preparation Techniques

Abstract Cross-sectional style transmission electron microscopy (TEM) sample preparation techniques by DualBeam (SEM/FIB) systems are widely used in both laboratory and manufacturing lines with either in-situ or ex-situ lift out methods. By contrast, however, the plan view TEM sample has only been prepared in the laboratory environment, and only after breaking the wafer. This paper introduces a novel methodology for in-line, plan view TEM sample preparation at the 300mm wafer level that does not require breaking the wafer. It also presents the benefit of the technique on electrically short defects. The methodology of thin lamella TEM sample preparation for plan view work in two different tool configurations is also presented. The detailed procedure of thin lamella sample preparation is also described. In-line, full wafer plan view (S)TEM provides a quick turn around solution for defect analysis in the manufacturing line.

Recent Developments in CE-MS Based Metabolomics

2020 ◽  
Vol 16 ◽  
Author(s):  
Mustafa Çelebier ◽  
Merve Nenni
Keyword(s):  
Sample Preparation ◽  
Scientific Information ◽  
Analytical Techniques ◽  
Living Organism ◽  
Analytical Technique ◽  
Ionic Compounds ◽  
Recent Sample ◽  
Recent Developments ◽  
Endogenous Metabolites ◽  
Preparation Techniques

Background: Metabolomics has gained importance in clinical applications over the last decade. Metabolomics studies are significant because the systemic metabolome is directly affected by disease conditions. Metabolome-based biomarkers are actively being developed for early diagnosis and to indicate the stage of specific diseases. Additionally, understanding the effect of an intervention on a living organism at the molecular level is a crucial strategy for understanding novel or unexpected biological processes. Results: The simultaneous improvements in advanced analytical techniques, sample preparation techniques, computer technology, and databank contents has enabled more valuable scientific information to be gained from metabolomics than ever before. With over 15,000 known endogenous metabolites, there is no single analytical technique capable of analyzing the whole metabolome. However, capillary electrophoresis-mass spectrometry (CE-MS) is a unique technique used to analyze an important portion of metabolites not accessible by liquid chromatography or gas chromatography techniques. The analytical capability of CE, combined with recent sample preparation techniques focused on extracting polar-ionic compounds, make CE-MS a perfect technique for metabolomic studies. Conclusion: Here, previous reviews of CE-MS based metabolomics are evaluated to highlight recent improvements in this technique. Specifically, we review papers from the last two years (2018 and 2019) on CE-MS based metabolomics. The current situation and the challenges facing metabolomic studies are discussed to reveal the high potential of CE-MS for further studies, especially in biomarker development studies.

Sign in / Sign up

Export Citation Format

Share Document