 talking about various things related to the genesis scope you know then of the environmental geomechanics and in the last lecture I talked about the particle energy field theory and I gave you some hints that maybe this is one of the ways to address the issues which modern day society is facing and this is where I also gave you an idea about that this subject requires interdisciplinary approach, you should have a open mind and a very different way of looking at the things you know unconventional observation of the things which I was talking about and we discussed for subsequently the long term phenomena, short term phenomena. We also talked about the basics you know which are involved in or the assumption which have been made for analysis of geotechnical engineering systems. And then we were discussing about the shortcomings which are prevailing in conventional geomechanics and I suggested a sort of a neo classification system which should be implemented for understanding the soils better and their response under various environmental you know fluxes or stresses you may call it and in today's lecture I will be talking about the details of the particle energy field theory. The subtopics would be the components of PEF theory, what are the assumptions involved in this? We will be talking about different types of energy fields until now I have been talking about apart from mechanical stresses, what are the stresses which influence the geomaterials. So today we will try to explain these things in greater details and then comes the applications of all these situations or the energy fields which we are going to talk about alright. And then studies which are conducted by IIT Bombay researchers, my students and how we have tackled different types of energy fields and their response on the geomaterials and vice versa that is the response of the geomaterial when it comes in contact with different types of energy fields. So this is what I will be discussing under realm of particle energy field theory. So this theory as I discussed in the previous lecture also was pronounced or proposed by Professor H. Y. Fang the personality who has done lot of work in environmental geotechnology and the credit goes to him for finding this idea. So the major components of these theory are elementary particles, particle system and energy fields and in addition to this we talk about the different phenomena which occur in the environment and which are posing great difficulty in understanding you know how to model them, how to incorporate them in our models. So now what happens is if you have these type of questions in mind as we discussed in the previous lecture, ion exchange reaction, adsorption, redox reaction, soil bacterial interaction, mineralogical alteration all these issues have to be talked about. So what we are trying to see is these are the good examples of how a geomaterial would interact with a given energy field and ultimately what happens to this. So good example is if I am trying to see the reaction between a geomaterial and the chemical flux, the first thing which I should be doing is I will be talking about the ion exchange reactions, sometimes you also call this as a cation exchange capacity of the material. So this is the quantification of the interaction between the geomaterials and the energy fields. Similarly adsorption alright we will be talking about this redox reaction, these are all the chemical reaction where the reduction of and oxidation of the material might be happening because of different environmental condition. Second bacterial interaction we have discussed a lot mineralogical alteration. As we have been discussing when geomaterials come in contact with you know extreme environmental conditions like very high temperatures and very high concentrations of chemicals, their mineralogy gets altered and one good example of mineralogical alteration is zeolite formation, zeolite Z E O L I T E zeolite. So a good example of mineralogical alteration would be zeolite formation which I will be discussing in details. So these are the practical applications you know where the particle energy field theory can be employed directly. So now let me introduce one by one the major components of PEF theory and we will begin with elementary particles. So what are the assumptions associated with this theory? The first assumption is that the matter constitutes of atoms, ions and molecules, I am taking back you to your chemistry classes and the particles may attract or repel each other depending upon their charges alright and hence the following particle systems can be formed. I hope you are aware of this so solids is the attraction between the particles and gases are neutral one of our forces and the liquids where the interaction or the particle attraction is you know sorry not neutral gases is where the repulsion is much more and the liquids are slightly neutral or somewhere in between. So this is where we talk about the bonding energy, most of the geo environmental engineering issues in contemporary world are pivoting around the application of bonding energy. A good example would be suppose soil is contaminated with some contaminant. Now this contaminant could be in the gaseous phase, it could be in the liquid phase and it could be even the solid phase clear crystallization what microbes do inside the soil system. So under all the circumstances there is a bond which gets created between the soil and the contaminant this is part clear. Now if I want to do the remediation of the soil if I want to clean it up you remember the 4 5 scopes of the environmental geo technology which I talked about there was one scope which deals with remediation of contaminated lands ok. If you could not control the spread of contaminants and if the geo materials get contaminated too much then you would like to clean them alright remedial actions. So when you talk about the remediation you have to break the bond between the geo material and the contaminant clear. And this bonding could be inic it could be covalent it could be a dipole interaction or so on. So the crux of the situation is that when you talk about remediation of soils you have to study what is the bond strength and how these bonds can be broken. And your 10 plus 2 understanding of the chemistry would tell you I can heat up the material to break the bond I can wash the material to break the bond I can use some chemicals to break the bond is this correct or you may devise another method to break the bond ultimately it boils down to the bonding energy. So nowadays we have different tools in the market and good example would be FTIR analysis which I will talk about subsequently Fourier transform infrared spectroscopy FTIR analysis FTIR analysis tells you what type of contamination the system has because if you look at the patterns of the FTIR analysis you can make out what type of bonding exists in the system and then I can create a strategy to get rid of this this is part ok. A good example of breaking of the bonds could be suppose if you take heavy water which has lot of minerals in it and if I boil it what happens all your carbonates they settle down they get dissociated from the liquid phase. So what you have done you have broken the bond between the ions which are present in the system and the water molecules alright. So these type of strategies are utilized to decontaminate the geomaterials. Now coming to the elementary particles all of you know the elementary particles are electron proton and neutron and depending upon the charge we have sometimes neutral systems or sometimes we have charge systems and charge systems are known as ions. Now ions could be of two types we have cations and we have anions you are refreshing your chemistry 10 plus 2 chemistry clear. So cations are the ones which are positively charged magnesium sodium potassium calcium iron all those things fine anions are the chlorides oxygen hydroxyl OH and so on ammonium iron but before we come to that we will differentiate between the ions also. Now whatever we have listed here these are the simple ions individual ions sometimes they could be in a group also like I said ammonium iron so NH4 alright. Then we have atoms sodium magnesium carbon nitrogen oxygen hydrogen. So when you are trying to analyze the soils you have to do the atomic analysis to understand what are its constituents and what are the charges which the soil system is carrying and what are the species of cations or anions which are present in the system. Now these are the poly atom ions which we were talking about alright hydroxyl is OH minus NO3 nitrate and carbonate CO3 minus 2 and so on. Now if there is a sharing of electrons what will happen the sharing of electron will bind the atoms together to create a particle which is known as a molecule. So water is a molecule HCl is a molecule ammonia is a molecule methane is a molecule little bit of chemistry is required will not use much of this alright but yes because you are doing environmental geotechnology geomechanics so you have to understand a bit of the chemical processes which occur inside the system is this fine. The second component is the particle systems what are the particle systems which we can think of so we have 3 phases of the matter solid liquid and gas and similarly we have best example would be of solids single phase system would be dry soils we are ignoring air over here alright though it will be constituted it will be classified as a single phase system because we are ignoring the air but gases could be contaminants they are fumes water vapours and so on. We have let us say saturated soil all the pores are filled up with water so this becomes a 2 phase system is this okay and then we have let us say partially saturated soils or unsaturated soils this is what is termed as a 3 phase system it is very interesting to see how would you model the particle systems which would govern the mechanisms associated with different state of the material. So first of the mechanism which would like to study is stress strain relationships so for that matter stress strain relationship for the dry soils partially saturated soils and completely saturated soils are going to be different alright and from the response of the load deformation characteristics we can make out you know whether the system is dry whether it is partially saturated or is fully saturated. So this again depends upon how the particles are you know bound with each other a good example would be water bound mechanism WBM so what do you do there you take different sizes of the particles you arrange them in a matrix sprinkle a little bit of water and compact it and ultimately what happens this forms a excellent bound system on which you design the pavements alright. Another example would be flow of water through these type of systems which might result dry soils getting transformed to partially saturated soils and partially saturated soils getting transformed to saturated soils. So again this is a interplay of the energies between you know particles reverse process could be I will start with the saturated soils I will heat it up and then I will create a dry soil. So I am expelling out one phase from the system of the particles and then I am interested in seeing how the response looks like.