Video 1: Methods of Chemical Characterization
So, just to give you an idea about these are the XRF pallets, if you get a chance go tothe SAIF and you can see how these pallets are done.These are small aluminum pallets, all right half of them is filled with the adhesive theseall standard methods now a days they will help you.So, half of this is filled up in cellulose and rest of the half is filled up with thematerial for which you are trying to find out the chemical composition.So after this thing is done, you press the upper portion of the pallet, it becomes aconcealed pallet.The whole thing is kept under a UTM of about 5 to 10 tons so that it becomes a homogeneoussystem between the material which you want to analyze and the cellulose and cellulosedries up later on.So, this palette is inserted into the XRS machine, which I showed you and then you cando the analysis.Just to give you an idea about what type of calibrations are done before you can use theresults.There are 2 types of calibration certain physical and chemical calculus of the machine.Fortunately, chemical calibration are standards.So, these standards you have to buy from the market and you have to take along with youfor doing the analysis.As I said SRF analysis gives you elemental composition.This is the first time we are talking about the elemental composition.This elemental composition could be of soils this could be of admixture this could be ofany geomaterial.So, if you look at this, the way we read the value is percentage by weight of the material.So different type of geomaterials when they were analyzed, these are the results.Any lab will give you these results, the problem starts once the results are in your handsand are able to use that.That is where that entire catch is.And unfortunately, there is no guideline for that.Because I am sure that even if I write a book on how to read cardiograms.I am not going to become a cardiologist you agree a lot of information judgment is requiredand mental thinking is required to eliminate the doubts and come to the right point.But some quick analysis, which I wanted to show you, based on the XRF analysis wouldbe calcium is the most important thing and most of the materials are light.So, if you take Israeli chalk, which I was talking about earlier.They started the calcium presence is extremely high as compared to any other material.You know, in this series, this is naturally occurring source of calcium or if you lookat GGBFS, you will have very high value of calcium at 46.5 which is manmade.So, now, once you have understood the strength of the material you can utilize it.So, if I require this situation if I want a material for a situation where calcium isrequired, what I will be doing, I will be adding GGBFS to this alright.This is one of the strategies I will not be using this material as a fill material, wheremore silica is required.So, if you look at this material, you know sandstones you have very high amount of silicaalumina, iron and so on.So, depending upon which industry you are running and what is your professional activity,what are your interests?This information can be used some question you are asking few minutes back and I saidhold on.Why because I wanted to show you this.So if you are looking for a material which is inert, crystalline, if good fill materialfor the foundation is should be selecting something which is going to be having a lotof silica into it.This is a poor choice because here silica is not much this is an aquifer.So if I am in let us industry where I am trying to develop zeolites, yesterday, we were talkingabout zeolites conversion of silica in to zeolitic material.Normally, we talk about alumina silica ratio.So, if alumina silica ratio is of certain value, then only the material can be zeolitized.So, I have created another application of the material.Are you realizing?So, this is how the strategies have to be created.So coming back to the simple things, issue and if you had alumina silica and soon, andif this happens to be more than 70% there are some classifications of the fly asheswhere these fly ashes are supposed to be inert systems, good film material.However, it fly ashes are not having alumina, silica iron much around 20 30% but calciumis very high, it becomes a cementitious could be in.So, an industrial waste the moment you do XRF analysis, chances are that about 80 to90% of strategy of utilizing it can be created immediately and that is the crux of the discussion.So, just by doing the simple analysis, you can realize what I should be doing.Another question could be if you cannot do something with the material, how to do it,how to augment the properties.So, all these concepts which are loud is coming, you know in medical sciences, particularlysilica implantation of different types of artificial bones creation.So, from when you bring calcium, there must be a process where I can do segregation ofsilica from the inner systems.I can precipitate it in a solution, I can make it hyperactive is on.These are different industrial processes.I hope you are realizing this.Just to show you quickly how these ICP unit looks like earlier days, this used to be thesituation historic and nowadays everything is very compact.I will show you this is all the contemporary ICP looks like and very compact systems, youcan install them in the laboratory and a lot of literature available on ICP and ICPMS.So, when I was dealing with the projects from the atomic industry, and particularly fromBARC and atomic Energy Regulatory Board of India, then I used to use ICP and ICPMS quitea lot to detect how much portion of the radio activity has been solved by the science andhow much is released.And so on, these are very interesting gadgets.atomic absorption spectrophotometer you might have Using your environment engineering labto find out the concentration of contaminants up to PPM levels part per million, but whenyou are looking for parts per billion parts per trillion, then you have to do ICP analysis.This is all the gas promotor graph looks like.High resolution mass spectrophotometer.As I said, environmental geomechanics relies heavily on in fact, the practice of environmentalgeomechanics relies heavily on these gadgets.These are tools which will help you in identifying the problem.This is how the FTIR looks like this is a Fourier transform infrared spectra for a meteris spectroscopy.And then NMR.He wanted to do some experiments by using NMR at in one of the universities in France,this is a place where most of these facilities are housed in IIT Bombay.It is known as SAIF, sophisticated analytical instrument facility.And this is worth visiting.But these are the latest development since last 5, 6, 10 years what is going on.pH determination emission simple thing, I am sure you must have used it in environmentalengineering lab.We have a water quality analyzer different type of electrodes which can be utilized asglass calomel electrodes you must have used for finding out the pH because then the reactiontakes place between the material and the environment, water or any contaminant, we would like tosee how pH alters the way the pH of the body changes, you know, similarly, the pH of thesystem changes soil contaminants system and that becomes very problematic many times.So most of the industrial byproducts are at different pH values.Either they are highly acidic, or they are highly basic.So the question is how would you neutralize them how would you create a synergy betweenthe soil and something which is quite aggressive and pH value.So, these type of thoughts people are having and lot of research is being done Jasmineis working on a project we are trying to utilize you know highly basic industrial byproductsthe pH is 12 13 by injecting gases into it and this trial we are doing the laboratoryso that the whole thing can be injected at one of the heaps in the real life.So, we will have to design a complete piping system in a system you have to force gasesto go inside and complete mathematical modeling.So, you must be aware that for determining pH, we dissolve the soils in water at differentL by S ratios, liquid solid ratio and then the mixture are it and these are the parametersthat you can obtain.You can obtain the pH, the temperature, the TDS, total dissolved solids, electrical conductivityand now a days in our profession.This oxygen demands BOD and CODs are becoming very very important.You see when I was a student, I never thought that these things are going to be a part ofgeotechnical engineering.But sometime back I give you an example of my students thesis Dr. Sushmitha Sharma overdown the sediments from the different water bodies and sedimentation tanks, which hadapart from chemical activity, the pathogenic activity also.So there we realized that COD, BOD are going to be very important for the sediments also.Because they add up to the kinetics of the system.Whatever you do not think today becomes a part of the mandate which you have to takefor surviving tomorrow.Like this is a simple thing.And maybe that is what R and D is you have to keep on moving with the concepts and theproblems that society is facing it is.
Video 2: Cation-Exchange Capacity
This is a cation-exchange capacity, which you are talking about.So, and one of the ways to characterize wise would be the best way would be its CEC.So, if you see our papers which we have written we have created a soil classification systembased on SSA and CEC, and this is a published work by Shusha Lakshmi I think Dr. ShrinivasKadali.So for us, if cation-exchange capacity is known, nothing else is required.Why?Because calculations capacity includes in it the physical properties attributes, thechemical attributes.And mineralogical attributes and all sorts of other attributes which otherwise we willnot be able to detect.So I can say that cation-exchange capacity happens to be a parameter which is the holisticrepresentation of the material.Now, the question is how would you obtain this.So, there is a code IS code 2720 which describes this method.As I said this is a base exchange process to take the soil allows interaction with acalcium solution mostly calcium chloride of certain concentration.So, when you are allowing interaction between soil and calcium chloride, all the calciumions will get added onto the soil particle they will replace sodium ions you agree becausethe valence of the calcium is 2 and sodium is only 1, so higher relevancy replaces alesser valence.So, this is the first cycle, then what you have to do is, after this interaction is overyou wash the soil sample with sodium acetate what you are trying to do now you are tryingto see whether sodium iron can displace calcium irons which have got adhered on the soil particlesor not.So this process has to be done several times it is a intricate process.So, when you do this process, at the end of it, if you can measure the concentration ofcalcium ions equivalent weight of the cations weight of the sample and what is the volumeof the solution which you have taken it is a simple titration this gives you the cation-exchangecapacity is the answer to your question clear.you please read the published papers by anybody from my lab because, for us, this is the startingpoint.So we do not talk in terms of size of the particle and its minerology separately, whatwe do is, we define the potential of the material to interact with the environment based onits cation-exchange capacity.And just as a quick match of numbers, what you will observe here is I have given youknow, sort of an application of how corrections capacity can be utilized to decipher the characteristicof the material.First of all, you should realize that the units of CEC are milli equivalents per hundredgram as per standard.What you will observe here is that cenospheres are exhibiting extremely less value of cation-exchangecapacity yesterday we discussed their cenospheres quartz balls.So quartz is the least reactivity alright fly ashes by virtue of having some chemicaladulteration in them might show you a bit high cation-exchange capacity but the maximumcation exchange capacity comes in the soils the CS is a normal silty soil where you getvery high value of cation exchange capacity and chalk where also you have high cation-exchangecapacity.So, these are tentative numbers.But these numbers tell you how reactive the system could be some time back, I was talkingto you about spillage of activity, nuclear activity of the cause of the disaster.And that spillage took place on in the water body.And from water body, it came on the beaches and the sands and the soil got completelycontaminated.So, at that time, some people contacted me that can I create a material of a certainCEC value.So, imagine the similarity between the cements which are being sold in the market, you havea great of the cements, is it not?Now people are asking that can you create the soil of a certain grade are you realizingwhat is happening in the international market.So you might be very lucky to have a certain mineral in your country, but that mineralmight not be available everywhere.So, can you convert or can you alter the existing minerals to a level which becomes a medicineor it becomes a commodity for the industry.So, this is where a lot of processes are being done and a SEMs which I showed you in theprevious lecture, we are on the quartz balls you are having some deposition either becauseof the zeolitization or because of you know, agglomeration of the particles which I showedyou when you do dual gas conditioning, flue gas conditioning.Ultimately what happens is the CEC gets enhanced.So, this becomes a precious catalyst for me.And these all catalysts are created by human beings.Hope you have understood the whole thing."Professor - student conversation starts" Yes.Sir, Silica fumes.Their specific surface area was very high.So, it was used to be it should be highly reactive.So that cation exchange capacity of silica fumes should be high.So, you must realize that I have been repeatedly saying that you know, what happens is becausethese are all gravimetric processes."Professor - student conversation ends" So, if you are adding a material to liquid, whereit floats in it you are defined the concept of titration or concept of dry gravimetricanalysis.So, unfortunately silica fumes cation-exchange capacity cannot be obtained by this method,because the moment you make a solution out of it, they will only thought like numberone.So, if you have to find out cation-exchange capacity of silica fumes, then you have touse some other method and that would be SSA based.So, if you see the papers which are written by Susha Lakshmi and Srinivas Kadali where,we have come out with generalized relationship between different parameters which are usedin conventional geomechanics.And we have related all these parameters with SSA and CEC input in liquid plastic limitshrink a limit and specific gravity also.So, my idea was to get rid of the conventional scheme of classification, which is partial,which is not holistic, it takes into account only physical attributes and replace the entirething with something which is more holistic.So, this is what the state of the affairs is right.One more question which might be linked with this discussion is suppose, there is a microbialactivity which is harping in the soil mass or the geomaterials what will happen to thecation-exchange capacity?So, in our opinion, any process which occurs in the geomaterials can be monitored by regularsampling of the material and checking cation-exchange capacity.So, if CEC changes that changes because of some mechanism and then I can trace back thatis because of what.So, this is a present and future of the subject I hope you got enough ideasJust to touch upon the microbial characterization.read the papers by Shashank and Dr. Sowmiya, Meenu, Asha these are my students who areworking in this area and we are probably very good papers on microbial characterizationof geomaterials from where the subject on bio-geo interface started this is a paperwhich referring to the state of the art on geotechnical engineering perspective on biomediated processes.If you read the introduction of this paper, you will realize that we are absolutely antiterzhaghi geomechanics and why we are saying that all the concepts should be dry-clean.So, you have to read the paper to understand that twice as type of tones, we have acquiredin the process of doing R and D.And this is the slide which I have taken from Shashank’s thesis if you remember, thisis the microbial activity which is harping in the Soils and which cannot be ignored differenttype of bacterial growth, microbiological growth and this is the harping of the biologicalactivity on sands.So, we were talking about bio sorption, biosuction, bios CEC and so on this work is still ongoing.But very interestingly this concept started with one of my consulting projects where nobodywas able to define the cause of failure of a huge raft, piled raft system.And this piled raft system had been under severe distresses and the company was unableto start up their process.So, mechanistically everything was absolutely all light, but even then, the settlementsare occurring.So that is a time when these thoughts came to our mind that let us take samples fromas deep as 40,50 meter, the pipes are resting and do some microbial analysis examinationand then we realized that there was a big microbial effect on the stability of the soil.This is all this subject started.But did you find any evidence regarding that raft settlement before yes, so, we ultimatelylinked everything to the microbial activities.So, the whole dimension of the project got changed, then adequate precautions were takento not let microbial activity survive at that particular depth.From this point onward the decay of the material also became a major thought in our researchprocess.
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