 This is a view to show you how the most of the geomaterials which are manmade looks like. We have been talking about blast furnace slag, we have been talking about the silica fumes and so on in the previous lecture. And one obvious question is if you want to understand how to use a material for a specific project, you have to look into its microscopic structure. So we were quite excited to see that silica fumes look like this. Remember sometime back I said that these are very light material, this specific gravity would be 0.5, 0.6, 0.7, so transportation is a big issue I think we discussed in the class. Why this happens? Because if you look at the surface of these particles, these are very furry structures, they have protrusions on the surface. And these protrusions are the first they create these materials very light and airborne. So one of the major issues associated with silica fumes is that this material becomes airborne and people inhale it and because of high activity of silica, if it goes in your lungs what it will do, it will suck all the water from the lungs, it will produce dead cells in the lungs, it could be lung cirrhosis. So these are very, very hazardous materials, so industrialization versus health of the people and the environmental chaos, if you are trying to understand these type of things become useful. We were dealing with the blast furnace slag also in a big way because in some of my student thesis, we have been talking about blast furnace slag as a manmade resource and rather than mining for calcium from the mines, I wanted to use the calcium which is present in the blast furnace slag. So we were thinking of a process by which the calcium oxide can be extracted from the slags, clear? Now this is a very philosophical word, I mean I might not be able to take out calcium oxide but what I can do is I can break calcium in an ionic form and I can remove cations that is calcium ions from this system and induce them into the marine clays. On this concept, Ganraj has a patent where we have used a new material for stabilizing the marine clays and if you follow his thesis, you will realize he has published a paper also on this. These are the materials which are non-chemical stabilizers because nowadays you cannot insert a chemical inside the ground, that self is hazardous because in the long run these chemicals would react with the groundwater and they will get transported from one place to another place. So these type of themes are coming in ground modification, soil augmentation, soil rejuvenation and remember my dream project, this manmade soils, so I wanted to create manmade soils, I do not want to use natural soils because these resources are quite limited now. So how to convert all these industrial byproducts and the waste material into a resource is a challenge which we are trying to address and work on. So the blast furnace slag normally looks very angular, remember this comes out of the steel making process and then once you grind it, pulverize it, it becomes GGBFS that is the ground granulated blast furnace slag which is cement and very active cement and you can create PPC out of it by substituting 30-40% of the material in OPC. Now I will discuss about the morphological characterization of geomaterials, morphological characterization is basically shape, size, dimensions, regularity is regularity. So normally morphological characterization is done by using two techniques, one is two-dimensional technique and one is three-dimensional technique and you will be surprised to know that we have shown that shear wave velocities and the liquefaction potential of the sands are the shear strength depends upon the morphological features. So these are the thoughts which take the subject ahead of what exists. So the standard sands which you are using and which you are teaching to under-graduates by saying that these are standard spherical materials, you never question that how spherical they are. We question this and to our surprise we realize that these standard sands which you use that is spherical materials are truly like this, one of them is a perfect sphere. These are as flaky as possible. So these are the two-dimensional sections, you take the particle and cut it and then you take the images micrographically, the material looks like this. So SS1 is the coarse sand, SS3 is the fine sand and these are the senospheres which have peculiar characteristics. And 3D, if you do the imaging, these are known as optical micrographs, this is how the sands and the glass build looks like. What we have done from this information is we went too much into the morphological characterization of the materials, each grain has to be photographed. So what you are seeing over here is this is one of the grains of the sand on which you are working. And then we inscribe as many circles as possible, this is a game of patience, you have to sit down and analyze each of the image which you take and then one circle you have to subs, which subscribes the particle. And once these dimensions are known, you can define this veracity, roundness and regularity of the particle. So this is the best way to characterize the morphology of the materials at microscopic level, alright. So I mean I will not go into the details of all these things, if you are interested, please read the papers which are written by Anjan Patel and Prasad Bhadrakate. We have used this concept also to define the crushability of the sands, crushability of the particle or the crushing strength of the particles, what they call it as. Crushing strength has a lot of application in different industries right now. I mean you should appreciate one fact that industry understands that we are the experts in the minerals and soils, so they approach you having full faith that you are the only one who can solve their problems. So where these type of issues become useful in the halology, yes. If during site investigation the data is very erratic, so can we use like for a certain type of area, the morphology of the sands we can say it more or less will be same. So can we use this morphology characterization to predict the behavior of my given area, engineering behavior. It depends upon whether you are having an outlook of microscopic models or microscopic models. So this is an interesting question that how particles of random sizes and shapes would create a matrix through which let us say which can be compacted through which the population of water may take place or through which the shear wave velocity will travel, heat will travel, contaminants will travel and so on, bacteria will travel. So these are the questions which you have to really sit down and plan the crushability. I just have to focus on engineering behavior, a macroscopic mechanical like for a given area from morphology point of view can be predict like if ground investigation. If the sphericity is very close to unity one, you know that these soils are going to liquefy very easily because you cannot compact them. So everything gets related to the Rd value, relative density, e maximum alright and not only to that even your friction angles, internal friction angles are also a function of the true friction angle plus dilation angle plus minus depends upon how you are defining this what you call it as interest, you know how you are defining that true friction angle would depend upon the dilation angle and the real friction angle, aspirates sorry, angle of aspirates. So angle of aspirates have to get added up to the friction angle or it has to be subtracted depending upon how the shearing process is taking place. These are the micro detailing of the materials which conventional geomechanics also talks about. This is what R and D is where you go too much into the details of the material and try to see this. Yeah but these are very simple ideas but later on we realize that they have a lot of application industry. I might have done several projects from you know the companies which make glues, adhesives, toothpaste, different types of bumps which are packed in the tubes because ultimately it is all the allergy is it not, different types of what is putties which you use for sealing the cracks of the in the concrete and so on. It becomes very interesting. Whether this morphology data can be used for already existing structures. Structures of. I mean for if they are prone to liquefaction or something. Yeah, there are several papers if you check it on net where now people are realizing how shear wave velocities would depend upon the three parameters, sphericity, roundness and regularity. So truly speaking these three parameters are defining the morphology of the material quantified form. So VS is a function of S, R and epsilon. So RD is a function of all these. See there is a shift in the concepts which you have been studying in the basic soil mechanics. Now I am sure that somebody must be working or must have worked on RD as a function of all these parameters not only Emacs-Emin because Emacs-Emin would have been a gross injustice with the material. I hope you can realize. So when you redefine the systems and the interesting thing is those who are designing chips or you know IC circuits. So where you are packing the silica particles. So what civil engineers do it at macro level compaction. Here the compaction is going out at nano level and they are also a spherules in spherical particles. So how would you compact the spherical particles at that level and what type of distortions and defects can come in the system is a very big subject where electronics guys have to sit with us to learn the theory of compaction, theory of packing, theory of packing of the nanoparticles. Because if we are experts we have learnt maximum you know how the particles can be packed, how they can be compacted yes. If they are round like the void ratio cannot be less than 0.3435. So is there some way alteration like if it is not perfectly round that you can take below it. Yeah I mean once you understood the concepts how are you going to give a solution is your prerogative. I do not know whether you guys have realized this or not there is a new concept in the market liquefaction is being tackled by purging gas bubbles. They create a specific size of bubbles in the soils which are liquefiable. So what these bubbles are going to do they act as a springs between the grains of the sides. So when earthquake comes you know as if you have introduced some sort of a shock absorbers and hence the particles are not liquefying. There is a lot of papers which are being published in these concepts.