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Cement - Science topic

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How can we know the flue gas composition from Coal-fired power plants, Refineries, Cement and Steel Industry?
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Buy a gas chromatograph for $250,000 and you'll know everything in no time
LOL....Mikhail
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Please share your knowledge and experience. How to write a review paper related to cement-based materials/concrete technology? What characteristics review paper should have? What should be the purpose of writing a review paper?
Thank you
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Often, a useful review paper can be produced efficiently if the following two conditions are met:
1) The paper does not already exist in the literature, and
2) you are starting a new research area and performing an extensive literature search so that you can get up to speed on the topic.
Defining of the scope of the review paper is still often a challenge, too broad and you won't be able to efficiently and effectively cover the topic(s) and too narrow and it will be of limited interest to the research community at large.
In addition to review papers, online bibliographies and annotated bibliographies for a research area can also be of interest and extreme value to others working in your field.
Happy review paper writing,
Dale
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Hybrid concrete consisting of fly ash (FA), ordinary portland cement (OPC), slag (GGBS) and sodium hydroxide (NaOH) shows deprived results for compressive strength. While alkali activated material cosisting of FA, GGBS and NaOH offers better compressive strength.
Why the partial (20-40%) replacement of aluminosilicate materials (FA and GGBS) with OPC reduces the strength concretes?
Previous researches based on FA, OPC and NaOH offers higher strength.
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Usually partial (20-40%) replacement of aluminosilicate materials (FA and GGBS) with OPC reduce the strength concretes.
But in most cases, there are two main reasons why concrete increases strength:
1) The content of aluminosilicate material and the content of Ca in it;
2) The size modulus of aluminosilicate materials (FA and GGBS).
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Hello
what is the relationship between the surface area and the hydration degree of cement? Does the increase in the surface area cause the hydration degree of calcium silicate hydrate C-S-H gel to rise?
Thanks,
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  • The fineness of cement affects hydration rate, and in turn, the strength. Increasing fineness causes an increased rate of hydration, high strength, and high heat generation.
  • Bleeding can be reduced by increasing fineness. However, increased fineness can also lead to the requirement of more water for workability, resulting in a higher possibility of dry shrinkage.
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Hello,
I have data for a BET analysis (surface area) in order to gain information about the surface area and the pore size of my samples (cement, cement with additive). and when I got the results, I get nothing about this size pores, just the surface area (m2/g) of the two samples and the volume of applied pressure, is there a method to extract the pore size of my sample from the information I have acquired (The test is to apply nitrogen pressure to the sample)?
Thanks,
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Brunauer–Emmett–Teller (BET) analysis is only specific surface area determination, that is why you got surface units (m2) over the specimen mass.
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Currently, the acceptance rate of MDPI Materials is about 65%. Normally, this rate is 20-30% for other journals. Is MDPI Materials publishing so many papers for money and compromising on the quality of work?
Thank you
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In my opinion, based on the quality of articles I have accessed in my area, I can say MDPI materials are of good quality.
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What kind of hydraulic binders do you know besides cement?
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There are many binders used in construction which include cement, fly-ash, ground, and/or granulated slag, lime, etc.
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Hello,
I'm looking for some help about the understanding of adsorption kinetics of composite cement paste (cement+quartz) towards starch.
My experiment like this: the starch dosage is calculated according to the powder mass cement+quartz), and the water-powder ratio is 0.4. For a given starch dosage, that is, the same starch concentration (g/L). In different systems (OPC_pure cement, Qz15_85% cement+15% quartz, Qz30_70% cement+30% quartz) calculated in the adsorption amount (normalization to cement mass) is different (mg/g cement). But the adsorption amount (normalized to powder mass) is consistent.
So I don't know how to interpret them. Or my analysis is wrong.
  • PS: The literature result shows that quartz basically does not adsorb starch.
Yichuan
Best regards
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Yuri Mirgorod I get it. Thank you. Prof. Yuri Mirgorod
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I have SEM images of cement paste samples, references and others doped with graphene oxide. After 28 days of hydration, the ettringite still appeared in all samples, since it is known that after 12 days of hydration, it turns and disappears.
what are the reasons for this appearance at a later age?
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Lounis, yes it all depends on the type of the cement, amount of sulfur and other factors. Primary ettringite can stay in the paste without any harm, worst case scenario is when delayed ettringite formation is happening, then it is a trouble for concrete performance.
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Regarding cement paste, why does the crystal size (CH) come out to be different (a significant difference) if it is calculated by XRD using Scherrer's equation or calculated using SEM images?
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XRD determines crystallite size. SEM measures particle size. Each particle can consist of several crystallites, so usually particle is bigger (or much bigger) than crystallite. Your results are not surprising.
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I am searching for methods measuring the pore saturation level of cement paste...
any suggestion or related papers?
truly appreciate it.
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Mercury intrusion porosimetry (MIP) is a widely used technique for characterizing the distribution of pore sizes in cement-based materials.
Many work and literature related to this methods is available easily.
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Hi all,
I have some x-ray tomography images of cements and I am interested in modelling their permeability using Lattice Boltzmann Modelling.
Does anyone know of any code to simulate flow throughout such a medium?
Cheers,
Jack
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Jack,
If you are simply interested in permeability, Nicos Martys and I have developed a 3-D Stokes solver that works on a 3-D digital image. See:
Unfortunately, the ftp server that used to supply the codes has been taken offline, but if you provide me with your e-mail address (dalebentz49@gmail.com), I can send you a zip file with the codes, documentation, etc., if you are interested.
Best regards,
Dale
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I need to complete a life cycle assessment of mixing graphene and cement to create a composite. I have found the OpenLCA software and tried to use the free databases available.
The elcd database has portland cement available, however no other free database has any values of graphene. Would anyone know a free database that contains graphene values and process, or anyway I could get these values to create my own data?
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A good LCA study will always have a clearly defined scope, phases and indicators and your study related with graphene composites are no exceptions. I would like to recommend you the following paper as a prototype:
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Recently, I have an idea: an innovation in the manufacture of traditional concrete. My idea is to use tailings instead of part of cement and add fly ash, steel slag and other materials as aggregate to reduce the proportion of cement to 0.3. And the use of foaming technology, plus some additives to increase the porosity of concrete. The concrete made in this way is cured in the environment of high temperature and high concentration of CO2, the mechanical strength is improved by CO2 and alkaline metal carbonation, and the CO2 is fixed.
To this end, I did a simple experiment. Here are some data: I made 4*4*4cm3 concrete according to the picture below,:
put them in 100% CO2 boxes, and did a comparative experiment on air curing, but nothing else. After a certain period of time, the removal results are as follows. I want to know in what ways I should improve my experiment. I have looked up a lot of articles, and the only clue at present is to carry out steam pre-curing before maintenance to ensure its water content.
You are welcome to post the discussion. If you need any other information, please let me know in the comments.
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paper‘s link
二氧化碳养护混凝土技术研究 (wanfangdata.com.cn)
二氧化碳养护混凝土技术研究 - 中国知网 (cnki.net)
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Cement has been in human use throughout history, and due to its binding nature, it is regarded as the backbone of the construction industry. A recent edition of the journal Nano Energy published the results from major breakthrough research conducted by engineers from Incheon National University, Kyung Hee University, and Korea University. The researchers have invented a cement-based composite (CBC) that can be used in concrete to develop electrical properties without affecting its structural performance. But what if cement could be used to generate electricity?
Any ideas from researchers?
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I need to know how to modify an agg process, based in an u-so process in GaBi. For example, I modified some flows of the cement BR (u-so) in ecoinvent 3.6 creating a copy, but I need to modify this date in agg process for I can calculate the environmental impacts, how can I vincule the modifications from u-so process with the agg process?
Best Regards,
Lucas
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Dear, Calculating the environmental impact or circularity or carbon footprint is based on 1001 assumptions. What is the accurancy of these numbers??? fe impact is related to the energy source (nuclear power, renewables, ...)
It is impossible to express the complexity in one number. Environmental impact is also always a compromise with other needs of the product. The way we prefer is the evalation with the lifecycle based ecodesign rules of thumb gathered in checklists.
Good luck
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Equipment needed for analyzing cementitious materials
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You can get XRD equipment in AUST, Abuja and FEDERAL UNIVERSITY Lafiya.
Meanwhile, I do XRD data analysis including Rietveld refinement for inorganic materials generally. Contact: umaruahmadu@futminna.edu.ng
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We have many standards and method for determination of water absorption of the cement paste, mortar and concrete. Is there the standard for determination of water absorption the powder such as fly ash?
What is the difference between the amount of moisture content (%) and water absorption (%) of powders such as fly ash or pozzolan materials?
In ASTM C618 &Table 1: Moisture content, max for fly ash class N, F and C is 3%.
Though, we can use ASTM C311-13, procedure No.11 and No.12 for calculation of Moisture content.
Is there any the standard for determination of water absorption of the powder such as fly ash or pozzolan materials?
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How can type 1 cement be anti sulfated using natural minerals? How much is it used ?
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Thanks a lot.
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The subject of my research is jet grout spoil and I want to do various tests on it.
Thank you for answering my questions.
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1- The water to cement ratio is calculated by dividing the water in one cubic yard of the mix (in pounds) by the cement in the mix (in pounds). So if one cubic yard of the mix has 235 pounds of water and 470 pounds of cement– the mix is a. 50 water to cement ratio.The lower the water to cement ratio, the less air pores and the more compact the concrete structure, which translates into higher strength. The high amount of water will reduces the compressive strength of concrete because it will increases the gap between cement and aggregates thus air voids will increases.
2- The water obsorption is affected by the following factors Porosity of concrete, Relative Humidity, Surface area of element, Exposure period of wetting and drying.
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Cement strength dropped at summer period, this problem repeated annually. Any one face this problem before and what is his recommendation?
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The strength of cement dropped in the summer for the concrete and this issue demande to be carefully, because during the hot weather the water evaporates and make porous concrete and this result the decrease of the strength.
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There are a number of scholars studied the blending of agro-waste ashes with cement and mentioned some of reasons to blend them
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Is it possible to convert the Heat power obtained from the calorimeter for a given cement paste into an adiabatic temperature rise curve?
Can anyone guide me in this regard?
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You would really need the isothermal calorimetry data at several temperatures to compute an activation energy. Then you can apply the basic principles of chemical engineering to numerically integrate over time the heat generation due to the reactions. You will need to specify the boundary conditions and geometry of your specimens. This can be done fairly straightforward in COMSOL or other 3-D computational packages. See the publications by Emilio Hernandez-Bautista that are available from his ResearchGate page and were part of his Ph.D. thesis
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Hello all,
We are researchers conducting a market research study on sustainable cement/concrete. This information will serve as input into research on the development of cement/concrete. Your responses are voluntary and will be held in strict confidence. All responses will be compiled and analyzed at an aggregate level. Neither you nor your responses will be identified. If you have any questions, please contact lassi@email.sc.edu. Thank you for your willingness to participate in this survey! Your candid responses are greatly appreciated. This survey should take less than 5 minutes to complete. https://lnkd.in/dUizjzc
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Thank you so much!
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I am aware that EN Standards have defined the following types of cement:
CEM I 42.5 N
CEM I 42.5 R
CEM I 52.5 N
CEM I 52.5 R
where N refers to Ordinary Early Strength and R refers to High Early Strength. In addition 42.5 and 52.5 refers to minimum 28-Day Strength.
But my question is how do we produce CEM I 42.5 R and CEM I 52.5 N?
Because in literature it is reported that increasing fineness increase early strength but how do we increase 28-Day strength then?
Kind Regards,
Muhammad Imran
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As you know, to produce cement, several chemical components are involved. Changing in amounts of each component can lead to a different cement grade.
For example, in the picture attached, you can see the chemical composition of cement CEM I 42.5 R
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Hello all, We are researchers conducting a market research study on sustainable cement/concrete. This information will serve as input into research on the development of cement/concrete. Your responses are voluntary and will be held in strict confidence. All responses will be compiled and analyzed at an aggregate level. Neither you nor your responses will be identified. If you have any questions, please contact lassi@email.sc.edu. Thank you for your willingness to participate in this survey! Your candid responses are greatly appreciated. This survey should take less than 5 minutes to complete. https://lnkd.in/dUizjzc
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yes
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I am looking to use the pozzolanic properties of slag, but it is impossible due to its crystalline structure. Therefore, the slag structure must be transformed to amorphous. What is your solution for converting slag crystal structure to amorphous?
Thanks for your contribution.
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Hello, I think you can use blast furnace slag because it has a significant amorphous silica content due to cooling and quenching by water, while the amorphous silica content in steel slag is low and often crystalline. Moreover, blast furnace slags are hydraulic materials and you can determine their hydraulic activity of them according to standards.
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Dear All, I would like to know the basic testing of cement plaster for cracking and adhesion . Thank you
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there are many steps to ensure the quality for the plaster morter
  1. make a sieve analysis for the sand used in the morter to ensure that the fine particles not more than needed.
  2. ensure that the cement was stored in right way , and not expired.
  3. make a compression test for the cement cube
  4. ensure that the mix design is designed well and adjusted in site well
  5. use the suitable mix design for the item
  6. add a bonding agent to increase the tension behavior for the morter
  7. don't forget the curing by water
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If possible, then what parameters could I investigate from the test?
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Dear Tadele Yigrem Yes you can conduct a flexural strength test for plain concrete having pozzolanic materials as a partial replacement of cement. I think in this case, you should concern about the percentage of replacement. For different types of pozzolanic materials, the percentage of cement replacement is different. You can get the proper idea if go through some review papers. Here I attach you some experimental paper for your better understanding.
6-with-cover-page-v2.pdf (d1wqtxts1xzle7.cloudfront.net)
Performance of High Volume Fly Ash Concrete (ijirst.org)
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what kind of tests should perform on self consolidated cement paste incorporating suplementary cementious materials such as fly ash, rice husk, etc. i am using differnt kind of materials for the measuring the durablity of the self consolidated cement paste after using other differnt materials. so what kind of test should i perform on such material
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Additionally, an important element is to check the compatibility of the chemical admixture with cement and the filler additive
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Apart from the US and China, many Indian companies (including Reliance, ADANI Power, Vedanta, TATA, NTPC, JSW Steel, Hindalco, Coal India, Shree Cement, Grasim Industries, JSW Energy, etc.), are among the top CO₂ producers in the world. Please find the file attached. #Soure: MSCI #GlobalWarming
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This is true because Indian comes second to China as being the industrial park of the world with so many industries.
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Hi, I was using the Malvern Zetasizer to measure the zeta potential of GNPs in simulated cement pore solution. when I measure the zeta potential of GNPs in simulate cement pore solution, the software shows the message "Problem with cell drive circuit". In the SOPs, the materials is "Polystyrene latex", the dispersant is added manually with a dielectric constant of 5.2 (I checked in the literature, the dielectric constant is around 5.2 of simulated pore solution). But the zeta potential cannot be measured with this SOPs, and shows the message "Problem with cell drive circuit". The GNPs is conductive and the concentration is 0.02 g/L. Do you know how to measure the zeta potential of GNPs in simulated cement pore solution?
The simulated cement pore solution is saturated Ca(OH)2 with 8g/L NaOH, 22.4g/L KOH and 27.6 g/L CaSO4. PH is around 13.3
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it sounds like this might be a challenging sample. You indicate a low dielectric constant and high salt and very high pH.
Can you check the log file and see which previous information may be mentioned in there, it might help to resolve. The log file is at This PC > Documents > Malvern Instruments > Zetasizer > Logs . Find the file from the date and open it (it is a text file, open with notepad) and scroll to the end to locate the event when it happened. Any relevant messages prior to the "Problem with cell drive circuit"?
Next I would check that the instrument performs OK with a normal sample, like polystyrene latex beads. I would then check if size measurements by DLS are possible. Does the sample look clear or opaque? What is the viscosity? Which cuvette type have you tried for this?
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What are the methods for determining the adhesion of aggregate to the cement matrix?
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Dear
You can perform concrete petrography on ITZ area of the specimen. The line analysis can represent clear response to assess how interfacial transition zone perform. Also you can make some specimens with control aggregates and painted aggregate to evaluate how much is the cohesion between aggregate and hydrated cement.
Good luck
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I took a FESEM image of cement paste after 12 hours of hydration. There are numerous fibrillar structures, can anyone help what these structures are (CSH or ettringite)?
The hydration was ceased at 12 hours and samples were dried and coated before the analysis.
regards
saurabh
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In the same way, I suggest mapping in areas with a higher density of acicular crystals. Depending on the area of the detector, the optimization of the EDS system would be important, selecting between the normal variables, an intermediate processing time if the counts are low, and sufficient time during the acquisition. With proper Al and S mapping, phase confirmation could help.
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The alkali-silica reaction (ASR), known as "concrete cancer" is a deleterious swelling reaction that occurs over time in concrete between the highly alkaline cement paste and the reactive amorphous (i.e., non-crystalline) silica found in many common aggregates, given sufficient moisture. What are the emerging repair and prevention techniques for ASR?.
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Utilization of pozzolanic materials in concrete prevents alkali silica reaction by controlling and limiting lime (calcium hydroxide) content through pozzolanic reaction to produce more calcium silicate/aluminate hydrates (CSH or CAH).
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Hello. I am working on cement and concrete making materials. For microstructure study of materials, how should I select which technique is more feasible among the various techniques available today like SEM, XRD, TGA&DTA, FTIR, EDX etc. and is it required to select more than one technique to confirm the presence of material phases?
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To check the phase purity firstly XRD is needed. To check the surface topology SEM will be beneficial and also help to determine the average grain size. The FTIR analysis will help to detect the various functional groups present in a and EDX will give the elemental information. So you have to correlate these results to construct the overall idea about a material. From the XRD results, you can calculate the crystallite size and may tally with the avg. grain size, the FTIR, and the EDX results will be complementary to each other. The thermal stability will be confirmed by the TGA analysis. So, you have to focus on what are you trying to examine with your sample and what property would you like to elaborate on. I can suggest this from my point of view.
Regards
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Different results were obtained from both
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There is no simple answer to this question. So you are dealing with a situation where the results of the analysis of the elemental composition of a specific cement sample obtained by different methods differ significantly. Why do you think the differences are significant? Do these results have assigned uncertainty values? And would you like to know which method is generally more accurate? Theoretically, classical methods are more accurate, because XRF techniques are calibrated and checked with reference materials, the certified values of which were established mainly by classical methods. In a case like yours, this can only be checked with additional analyzes performed by another analyst in a specialized laboratory.
ZJ
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A low-calcium cement, which comprises, with the total mass of the oxides as 1, 50-60% of calcium oxide, 30-45% of silicon dioxide, 2-7% of aluminium oxide and 1-4% of iron oxide
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This later (2019) patent may also be useful.
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Hydration of cement paste starts as we add water to dry cement and different product will form with the passage of time due to the dissolution of alite, belite, aluminate, calcium sulfate, gypsum etc. Suppose I have to find out what are the phase contents of these aforementioned items and new products formed due to hydration of cement paste at 0.5hr, 1hr, 2hr, 3hr and so on and so forth. For the exact quantification of the same, hydration have to be stopped at that particular age. So, which is the best technique to stop hydration of cement paste?
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Hi Arup,
You would want to remove free water quickly and in early age pastes. Either short freeze drying or solvent exchange with isopropanol might work in your case. You might find the following links helpful for a comparative analysis of these methods:
1. Article: Comparison of methods for arresting hydration of cement, Zhang and Scherer, 2011
2. Book: A practical guide to microstructural analysis, Scrivener, Snellings and Lothenbach, 2018 [DOI: https://doi.org/10.1201/b19074].
In general all methods will alter the microstructure at least a little bit and cause decomposition of your hydrate phases. Especially the AFm and ettringite phases. So if that is something you would want to study and quantify precisely, it maybe an idea to check the time-resolved hydration and phase composition with XRD analysis. Check these:
and Quantitative in situ X-ray diffraction analysis of early hydration of Portland cement at defined temperatures, Hesse et al. [DOI: https://doi.org/10.1154/1.3120603]
Best.
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In order to prepare a small amount of mortar cement (less than 1 kg), what kind of equipment can be used to properly prepare the mixture?
Hand mixing is too heavy and inaccurate, we are planning to buy a dedicated instrument (but it depend on the previous outcome), in the meantime are there any set-up that can be used as temporary replacement?
Like old kitchen kneading machine etc?
Thank you!
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Shovel for mixing and head pan for carriage. but for automation, you can as well use a concrete mixer.
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Can anyone give an idea about the most suitable software (viz. GEMSFITS) used to do the thermodynamic calculation to predict phases after hydration of cement; along with the link for manual to do so. Thanks.
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You can use GEMS coupled with the CEMDATA Database:
A special version of GEMS dedicated to cements (CEMGEMS) runs also as web application:
see also here:
You can also use phreeqc:
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SCMs: Supplementary Cementitious Materials
CH: Portlandite (calcium hydroxide)
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In the hydration process of cement C2S and C3S react with water to form C-S-H gel and CH (Ca(OH)2). Due to presence of aforementioned CH in concrete makes it high alkaline in nature having pH 13. By adding SCMs in concrete, it react with CH (which is formed in hydration process) and water to produce additional C-S-H gel. This reaction is called pozzolanic reaction. Due to formation of additional C-S-H in SCMs concrete show higher strength than conventional concrete. But consumption of reserved level of CH in pozzolanic reaction reduce pH value of concrete (<13).
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If I have a concrete mix with a density of 1800kg/m3 (cement, sand, aggregate, water)
How much in kg/m3 should I add if I want to add 1% of steel fibre?
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Greetings! Regarding your question, 1% by volume of steel fiber can be calculated through the density of steel fiber per se. If steel fiber with 7850 kg per cubic meter, then you need 78.5 kg steel fiber for every cubic meter of concrete.
I hope the following is helpful.
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Hello friends,
I intend to simulate the cementation process in porous media (i.e. granular soil). I'm not sure if I can model the cement slurry as a mere fluid with high viscosity and density. If it is possible, does it act as a Newtonian fluid or as a non-Newtonian one? If the slurry cannot be accurately modeled as a fluid, how can one simulate the flow of cement slurry/paste in a porous medium?
Any suggestion is appreciated. Thanks a lot in advance.
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For a cement slurry for oil and gas wells its rheological characterisation has been carried out by many authors (i.e. Bourgoyne A. et al 1991, Technip 1982 and many of the service company manuals/books & publications). This characterisation has been based on a number of assumptions such as that temperature has no influence on the rheology until the slurry is in place. In other words that its rheological behaviour is either assumed at surface or downhole temperature and prior to the onset of dehydration and setting of the slurry. Passage of the slurry through the porous media (invasion) has been modelled by Chin W. (Formation Invasion 1995) which is worth reading. Invasion (Also know as filtrate invasion) can also be modelled using the algorithms used to calculate fluid loss in fracturing treatments, they are based on viscosity, pressure and rock properties. These can be found in most manuals of hydraulic fracturing. I hope it helps
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I'm planning the calcium leaching experiment. Thereby, the cement paste specimens were immersed in the 6M ammonium nitrate(NH4NO3) solution. If the specimens were removed at a specific immersion age, what method should be used to maintain the condition at that time? (For example, can it be maintained when the specimens were immersed in acetone and then dried?)
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Hello,I am pleased to answer your question.I think you can put the cement paste specimen into the constant temperature and humidity curing box to ensure its condition. If you follow your method, making the specimens were immersed in acetone and then dried, the moisture content of the specimen will change with the drying time. I hope my answer will help you.
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Geotechnical applications
Soil improvement
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The following article might help you:
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Is it possible to use Portlandite (Ca(OH)2) percentage (determined by TGA) as an internal standard phase to determine absolute phases in Rietveld refinement of cement paste?
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In the same subject:
Regarding Reitveld's improvements or (Reitveld refinements ), it is difficult to apply them to the samples in form of thin films for several considerations, which we include below:
1- Hugo Rietveld described a technique for the characterization of crystalline materials called Rietveld refinement. Powder sample diffraction with neutrons and X-rays produces a pattern with reflections (intensity peaks) at certain locations. Many features of the crystalline material's structure can be determined by measuring the height, width, and position of these reflections. The Rietveld technique refines a theoretical line curve using a least-squares approach until it fits the measured curve. As a result, this process is utilized to analyze powder samples for the crystalline materials in order to cope with significantly overlapping reflections.
2- In summary, Rietveld evaluation is a method that uses the d-value to filter and determine the lattice parameters, allowing the real intensity of a phase or plane to be theoretically computed. This method yields very precise values for d, lattice parameters (a, b, and c), and another parameter. Thus, according to this method, the analyzed powder sample's strain, crystallinity, estimated Intensity, statistical analysis ( W% of elements, phases), and so on may all be computed. It's challenging with thin-film samples.
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If the ash has greasy nature, can be used as an alternative to cement in cement mortar or concrete? and what is the procedure and materials to be used when using this greasy ash?
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Taghreed Kh Mohammed Ali Alrekabi , i couldn't find the place i saw it. I saw something different now. The greese as you choose to call it has a positive effect on the compressive and flexural strength. Please check this
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Please, could you help me with this question?
I have been doing rheological assays with mortar mixtures. They contain different types of admixtures. In my experiments, the speed decreases step by step from 100 to 5 rpm. I am using a rheometer specialized in cement mortars with a double helical ribbon agitator. If I analyze mixtures with polycarboxylate ether, I reach the lineal behavior between shear rate and shear stress. However, if I do not include it, the shear stress quickly decreases, and the behavior differs significantly from linearity. In the mortar with superplasticizer, the water to cement ratio is 0.4, and I obtain good results. In other mixtures, when I increase the W/C even until 0.6, I do not have a Bingham behavior. Why could this be happening?
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Looking at your results, it is clear that some of your mixes do not show Bingham behavior (i.e., the viscosity changes with the shear rate).
Some of them seem to present shear thickening behavior (i.e., viscosity increases with shear rate), while others seem to present shear thinning behavior (i.e., viscosity decreases with shear rate). This is very common for cementitious mixtures, especially with plasticizers.
I suggest you use other models which can describe properly these behaviors, such as Herschel-Bulkley, modified Bingham model, or Casson model. I think the use of these other models is a better solution than trying to adapt your samples or test to fix the Bingham model. But, in general, the cementitious materials normally tend to the Bingham behavior at higher shear rates.
You can see more details in these articles:
Regards,
José Andrade
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We know that superplasticizers' properties vary in terms of PH, Density, Mass average molecular weight, Sidechain density of carboxylic acid groups, Impeller rotational velocity, Viscosity cP, and so on.
I wonder which type of superplasticizer can disperse Nano-SiO2 in water in the best way possible to make concrete?
Furthermore, is there any test that shows how well the nanoparticles dispersed in water?
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Dear Mheran there are many chemical admixtures (superplasticizers) use to modify the properties of fresh concrete. The best approach is to perform a test using various types of superplasticizer and select the best one. An empirical selection is not always efficient.
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Hello everyone,
I tried to look for these standards many times and unfortunately didn't succeed.
It will be really helpful if somebody can tell me where to find it.
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I got both Chinese standards, but they are written in Chinese. I hope it will be useful for you.
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We are trying to develop sustainable cement sand mortar incorporating fine waste materials. To know the actual comparison of prepared and reference samples. What is the standard criterion??
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Dear Farabi Bin Ahmed nice explanation. can you tell me the reference of strength variation 15 to 28 MPa... I think it is very high for mortar......
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I am Mayank Rawal Managing Director ASIAN LABORATORIES New Delhi India.
I would like to know whether any country has published code of practice or method of tests on different cements with Pce based superplasticizer to check the competibility issues in the field.
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You can benefit from each superplasticizer data sheet individually. No code discussed this phenomenon as I remember (may be there is) but you can benefit from the great book,
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Clay calcination is required for the makingof LC3 (low carbon content cement) so we have clay in raw form so what's the size of clay particle to put in the oven and from which protocol kindly explain
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The fineness :
Amount retained when wet-sieved on 45 μm (No. 325) sieve = 34% max
The protocol of the oven :
Temperature = 750: 850 C, retention time = 2 hr, stirring 3 times minimum, and fast cooling at the end of the process
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Heat capacity constants would be excellent, but heat capacity values for a temperature range would also work.
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for more details about heat capacity values for C3A & C4AF and a summary about the heat of hydration reaction you can check below link
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Hi, I would ask about the magnitude signal in AFM, especially in force modulation mode. Is the signal a real way to map the elasticity properties of a material? If this is correct, then, thinking about a cement matrix, values around 0 could mean a pore or we couldn't do this relation so easily?
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Hi Monique, from the info you sent it seems that the amplitude of the oscillation is what they called Mag. What I still don't get it is why the units are in nA, instead of volts which is what you normally get from a good lock-in amplifier.
In principle in Force Modulation smaller amplitude (dark areas in your image) would imply smaller modulus than brown areas.
You can compare that image with the topography image to check if dark areas in Mag image matches with pores in topography.
Problem of Force Modulation is that it is a little bit obsolete as you cannot obtain quantitative data of the modulus (only cualitative). Also, when working with polymers, it can be difficult even to get reliable cualitative results.
Ashkan Nikiyan is mismatching the amplitude /phase description with the dinamic mode (or tapping). There the amplitude is used by the feedback to track the surface and get the topography, while in Force Modulation the static deflection is used for topography.
My suggestion is that you try also to perform static force vs distance curves on the dark and brown areas. There you could estimate the YOung modulus and double check that what you get in the Mag image is correct (higher slope indicates higher stiffness). You can check more here:
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There is a bunker which is almost 10 ft underground and its wall was built with stone masonry and plastered with grey cement. Now the plaster is not getting dry. Is there any solution or what will be the effect of applying white cement on the wall?
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Forest Olaf Peterson Thank you for your time and the remedies you have suggested. Will try to apply these solutions and check which one is more effective.
White Cement is actually a variant of ordinary grey Portland Cement. They are both used as a bonding agent and are quite similar in all aspects except for the color and the quantity of iron and magnesium, while white cement possesses high water-resistant properties.
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I have make mix of mortar with ordinary Portland cement and standard sand, according ASTM C109 the mix ratio of cement:sand:water was (1:2.75:0.485) but the flow value was very low (about 24%) where it should be 110+-5, so I have increase the water cement ratio to 0.7 to get flow of 108, is it ok?
what if I use W/C of 0.485 and using superplasticizer to increase the flow value?
is it better?
thank you
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You can test different w/b and perform the flow test. After that you will get different values of w/b and flow, which will make it possible to build a graph (flow x w/b). From this graph, with the equation of the straight line, you can determine the ideal amount of water for the mortar to reach the XXX mm flow, for example.
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I have performed TGA_DSC of cement paste with different clays. Samples 1-4 showed similar total weight loss and DSC curves, but samples 5 and 6 showed less weight loss.
As all the samples have similar compositions (determined from XRD), what could be the reason for different weight loss for samples 5 and 6?
For samples 1 to 4, 50 mg weight is used whereas for samples 5 & 6, 35 mg weight is used for doing TGA. Can this be a reason for the above change?
thanks
saurabh
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It is important to have a representative sample size when conducting TGA analysis of cementitious or other multi-phase materials. At NIST, we generally tried to use our large volume TGA pans and get a sample size close to or exceeding 100 mg.
Also, results often depend on from which temperature you are measuring your final weight loss. In your figure 7, one can observe that already by 100 C, when the sample should be losing mostly free water, samples 5 and 6 have much less mass loss than those of 1-4. Perhaps these samples were allowed to "dry out" more prior to being loaded into the DSC. You can try renormalizing your mass loss results using the 100 C masses of each specimen as the new basis. This should definitely get rid of some of the variability between specimens.
Regarding the heat flow plot, it would be better to plot the y-axis as heat flow per unit mass as otherwise it is difficult to compare the various curves.
From the mass loss curves, the mass loss between 400 C and 500 C is usually attributed to water lost from calcium hydroxide and while it is difficult to tell exactly from viewing the curves, the six specimens appear to have fairly similar absolute mass losses between 400 and 500 C. This would suggest that the free water loss (prior to 100 C) may indeed be biasing the subsequent cumulative mass loss curves and normalizing based on the mass measured at 100 C may be a good way to go.
Good luck,
Dale
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I'm doing a life cycle analysis type of calculation and would need to compare several products that use concrete; however, the literature sources list either concrete or cement consumption but not both. What would be appropriate values for converting from cement consumption to weight of finished concrete product, or from finished concrete product to cement consumption? I'm interested in average concrete as used globally.
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I think the following open access articles will provide you with useful information:
1-
2-
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Sorry
I want to ask a question?
We are measuring the contact angle of cement mastic
Asphalt is PG 64-22
The larger the contact angle, the more hydrophilic, the smaller the more hydrophobic
However, the measured value of the contact angle of cement mastic is small. Isn't the cement resistant to water damage? Isn't more hydrophobic.
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Hi, everything is right, you just confuse a little bit. The contact angle is the angle between the cement matrix surface and water/air border (see https://en.wikipedia.org/wiki/Contact_angle#/media/File:Contact_angle.svg). That is why, the larger the contact angle is - the more hydrophobic material is and vice versa. In your case, if the angle is small it means that the material is hydrophilic. The contact angle depends on different parameters like the composition of the cement mastic or roughness (it can be because of the surface irregularities). In general, cement-based materials are porous (7% in the case of ordinary concretes) so, even if they are not hygroscopic, they absorb some quantity of water.
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Looking for the quantity of cement, sand, and gravel of footings and columns. Thank you!
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For the fence foundation, plot the length versus width of each segment on a graph then calculate the area under the graph( using specific graphical software) later multiple it to the thickness. Remember to subtract the total volume of the steel rebars from the final calculated volume. For the certainty of the results, multiple the final volume of the concrete (I.e. after subtracting the volume of the steel rebars) by 98% ( Considering the porosity content of the concrete mixture is 2%) otherwise you may have left over concrete volume.
Similar calculations can be used for the column.
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I am wondering if EN197 1 2000 specifies any non-portland hydraulic cement and nonhydraulic cement?Or in other words EN197 1 2000 only specifies Hydraulic cement that includes Portland cement and Portland-based blended cement?Thanks
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Non-hydraulic cement is like lime, gypsum and they do not harden initially when water is added. While hydraulic cement harden with water. So the code talks about the two types.
Section 5.2.1, 5.2.2 of the code talks about hydraulic cement and Section 5.2.3 talks about non-hydraulic cement
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The manufacturing of bricks and kiln with coal contributes a huge amount of CO2 emission, especially in the cement industry and in the brick burning process.
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You have two main approaches. (i) You can use Life Cycle Assessment and use an evaluation method like IPCC2013, which would provided results on kgCO2eq. (ii) Alternatively, you can estimate the amount of "fuel" used in the process of a functional unit (eg. 1kg of brick). you can then calculate the emission associated with the burning of the fuel. You should also account for inefficiencies on the process. E
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In Roller Compacted Concrete (RCC), cement is mixed with aggregates and compacted to its final form at the optimum moisture content (OMC) in order to achieve maximum dry density (MDD). However, at the time when compaction starts, cement has already begun to hydrate and we cannot control or predict the hydration.
How to account this moisture loss?
Can we model hydration of cement using a software?
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Perhaps, it will depend on the sensitivity of your equipment, etc. Is this the 0.5 hours just after first mixing the materials together? Quite often, the calorimeter requires some time to equilibrate after the materials are added to it and thus the data during the first 30 minutes or so are unreliable.
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While the magnetite particles are much above single-domain limit, they indeed form spike-like structure under strong magnetic field. Would not that be predominantly caused by aligning of particles physically rather than realignment of their magnetic domain, due to the not very high temperature and magnetite being ferrimagnetic? If that magnetic orientation is locked by congealing the "spikes" by cement or wax, would that arrangement have a net arranged magnetic field upon withdrawal of external magnetic field, provided that the particles can move no longer? If this is not possible, then why? If possible, then what would be the strength of that magnetic field compared to a bar magnet? (for a comparable distance and geometry)
Will the slurry be fluid enough to allow the magenit spikes to form like in gas or vacuum?(relation between % solid ,% magnetic particles allowed and time to set as well as maximum residual magnetic field of the arrangement are asked; or at least hint to the model). Another point to mention, melting point of wax would be below 100 degrees C to not affect magnetite magnetism, but what would be role of Typical cement chemicals (e.g. portland, plaster of paris) that may chemically degrade the magnetite?
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You might have problems getting the cement slurry liquid enough for the particles to move and align within the magnetic field. If you actually try it, I would recommend using a superplasticizer otherwise you will need a huge amount of water and your product will be very porous. If you use a white cement you could test if spikes did form within by slicing the hardened product. You could be able to see from the magnetite particle distribution if it worked.
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How to remove the sintered material which has been fully stuck at the base of alumina crucible? It is synthesized as stone like material after sintering at 1400 deg C. Should any other kind of non sticky crucible is required or any other method exists to extract out the melted sticky sintered synthesized material?
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Have you tried scrubbing with wire brush slowly?
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if i want to classify opc, ppc using there hyperspectral data and deeplearning how should i do it.
please tell name of any pretrained network that can help via transfer learining.
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Dear Aman Jaiswal.
Hyperspectral sensors look at specimen utilizing a tremendous segment of the electromagnetic range. Certain items leave interesting 'fingerprints' in the electromagnetic spectrum. Thus, the 'fingerprints' can be used to identify materials such as concrete, cement. Nevertheless, research- work must be carried out, protocols established concerning the application in concrete. Besides, i found the link below given by Matthias very useful.
Thank you
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I am a beginner in rietveld refinement, my samples contain numerous overlapped peaks and amorphous phases. I have few doubts related to rietveld refinement of cement paste:
1. My quantifications shows 93-95% chemical composition. Should refinement shows 100% chemical composition?
2. If it shows 95% chemical composition after refinement then will it means the rest 5% is related to amorphous phases?
3. Can we quantify/estimate amorphous phases through rietveld?
I have prepared samples to minimize preferential orientation (polished cement disk) and I am using Profex for all the analysis.
regards
saurabh
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I send my rather skeptical look. One peak is unevaluated, it is probably some hydrocalumite phase. (Rexp: 5.64, Rwp: 7.09, Rp: 5.50, GOF: 1.26, all in %)
The calculated crystallinity from the peak areas is 72%.
Another note, in Rietveld analysis it is possible to enter only one structurally and chemically close phase. I would recommend a longer measurement time.
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Concrete block bricks companies are marketing that their products are eco-friendly, as they are not emitting carbon dioxide and not using soil. At that viewpoint, they are right.
But,in their manufacturing process, they are largely using cement and sand. Cement manufacturers also badly polluting environment by particulate matters and others emissions activities. Overconsumption of natural resources as well as sand extraction can cause environmental damage.
My question is, how much eco-friendly concrete block bricks is?
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Ecofriendly concrete bricks could be produced globally by using less of cement but more of pozzollanic ashes from industrial and agro activities. But most brick makers will first consider acceptance from consumers alongside the financial implications. Standards and other logistical challenges are other factors affecting it's global acceptance and adoption.
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I have studied your graphs related to 'Relative flexural strength of cement-based materials with recycled plastic aggregate'. I want to know how does this impact the cement strength overall being it a solid structure. And also, is there nanotechnology used in this process? For the smaller or larger grain size?
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Strength Impact of the structure is clearly explained in this link
Please visit and let me know whether its the right one....interesting views too
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Cement mill with spray nozzles are being used since many years. Experience suggests that it sometime helps in preventing unnecessary increase of mill temperature which in turn gives no harm to cement quality. On the other side, sometime spray nozzle does not work properly due to coating formation on it and also causes unnecessary stoppages of cement mill due to high temperature. What should be the soluton to avoid coating fornmation on spray nozzle.
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Bhautesh Mistry I am very much interested in the question you have raised. I also have a cement mill nozzle which keeps blocking especially when there is a power failure. Have you found a solution to your problem? if yes, please do share. Also is there a special type of nozzle that helps prevent this blockage? How efficient is the use of grinding aid in the nozzle in preventing this blockage and improving overall grinding efficiency? Thank you.
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There are many articles in the literature on ordinary portland cement concretes produced using recycled aggregates coated with pozzolanic slurries (cement + [fly ash, silica fume, micro/nano silica etc.]).
As you know, the quality of recycled aggregates is lower than natural aggregates. In some studies in the literature, the quality of the aggregates is improved by coating the surfaces of recycled aggregates by using slurries prepared with pozzolanic materials and cement.
My question is this: Suppose we have recycled aggregate soaked in slurry, dried and coated on the surface. Will the sodium hydroxide and sodium silicate, which we use in producing geopolymer concrete, damage or remove the coating on the surfaces of aggregates whose surface has been improved? Do you think this practice makes sense? If you were the supervisor of a thesis, a jury member or a reviewer of an article, what would you comment on this application?
I would be very happy if you share your valuable ideas with me.
Best Regards,
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This is the realy good question and need need further elaboration and study of conditions! In general words the answer will be: the result will depend from the content of aggregate coating: the CAS phases will be destoing by alkaline, but at the same time, pozzolanic one - strengthening...
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Dear Sir,
Please inform me if there is any specification of pull off adhesion test of cement based plaster. Is there any impact of substrate on pull off adhesion test?
Thank You
Best Regards
Darshan
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Dear Darshan,
maybe in the following standards you can find something useful:
  • ASTM D4541:17 Standard Test Method for Pull-Off Strength of Coatings Using Portable Adhesion Testers,
  • ASTM D7234:12 Standard Test Method for Pull-Off Adhesion Strength of Coatings on Concrete Using Portable Pull-Off Adhesion Testers,
  • UNI EN ISO 16276-1:2007
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In my sample, I got 4 DTG peaks for the (OPC) cement paste hydrated for 28 days. The peaks for portlandite and calcite are very clear but the peaks for ettringite and C-S-H are bit confusing. What other peaks can be identify in these region (50-200 C) since the DTG peaks overlapped a lot here?
Is there any specific meaning if the ettringite peak shows shoulder?
(samples were prepared by solvent exchange and vacuum drying).
Correction: the peak marked as C-S-H is AFm.
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