Published on November 10, 2017
slide 1: International Journal of Engineering Research Science IJOER ISSN: 2395-6992 Vol-3 Issue-10 October- 2017 Page | 33 Investigation of Formation Laws of Clays Composition under High Pressures Valeriy V. Seredin 1 Alexander V. Rastegaev 2 Vladislav I. Galkin 3 Panova Е.G. 4 Tatyana Yu. Parshina 5 1 Professor and Head of engineering geology department of Perm state national research university 2 Professor of oil and gas geology department of Perm national research polytechnic university 3 Head of oil and gas geology department of Perm national research polytechnic university 4 Professor of geochemistry department institute of Earth science Saint- Petersburg state university 5 Graduate student of engineering geology department of Perm state national research university Abstract— It is found experimentally that while building-up of pressure applied to natural clay observed is general tendency of clay fraction content decrease and pulverescent fraction content increase. In montmorillonite natural clay granulometric changes progress more intensively than in kaolinite one. Within the pressure range of 0 – 125МPа processes of change of natural clay fractional compositions progress more intensively than at higher pressures. Under pressures within the ranges of 125-750МPа and 800-2200МPа revealed is different intensity of natural clay fractional compositions formation. Based on pressure index three classes are defined each is featuring different intensity of aggregation and dispersion processes progressing. While compression of natural clay defects are formed on crystallite surfaces increasing energy potential of crude ground. Additional energy enables formation of molecular attractive forces which cause particles aggregation. Keywords— Clay Pressure Granulometric Analysis Fraction Kaolin Montmorillonite. I. INTRODUCTION Natural clay properties are defined to a large extent by specific area of particle active surface which can be controlled by granulometric or micro-aggregative ground compositions. In the processes of sedimentation diagenesis hypergenesis and technogenesis «primary» particles of natural clays are transformed to «secondary» particles forming micro-aggregates. The issues of micro-aggregates formation in grounds are presented in the following studies Krivosheeva et al. 1977 Osovetsky 1993 Osipov Sokolov 2013 Savko 2015. Thus the consider of information on formation of granulometric and micro-aggregative composition of natural clays during the processes of their natural formation and transformation. In previously investigations the data on natural clays exposed to technogenic effect by the following solutions MgCl 2 CaCl 2 KCl and NaCl Seredin et al. 2013 Seredin 2014. Authors concluded that aggregation process is connected with concentration of salt solution and mineral composition of particles. «Primary» particles of natural clays exposed to oil contamination are connected between each other by electrostatic forces which are determined by contamination volume and type of hydrocarbons Boiko et al. 2009 Seredin Yadzinskaya 2014 Ilic et al. 2016. Effect of mechanical factor is of importance for example effect of pressure on formation of aggregates in dispersed crude grounds Krivosheeva et al 1977 Stefani et al. 2014 Friedlander et al. 2016. The studies carried out Sergeev 1946 exhibited that under pressures to 200 МPа observed is insignificant change of crude ground aggregative compositions. Under pressure of 300 МPа applied to pulverescent ground content of fine sand fraction increased from 13 to 51 pulverescent fraction from 5 to 23 and clay one from 215 to 542. Hence it appears that formation of clay aggregates at natural conditions as the result of mechanical exposure progresses in rather limited volumes. While testing of blanket loams under pressures of Р2000 МPа and Р3660 МPа analogous results were received Sergeev 1946 a. Procedures of prediction of ground granulometric compositions regarding not only earthy grounds Boiko et al 2009 but moon ones as well Korolyov 2016 are being developed based on experimental investigations. The above mentioned discloses that issues of pressure effect on formation of natural clay micro-aggregative compositions are studied not thoroughly enough. In this connection the aim of the study is investigation of formation of natural clay micro-aggregative compositions exposed to high pressure. slide 2: International Journal of Engineering Research Science IJOER ISSN: 2395-6992 Vol-3 Issue-10 October- 2017 Page | 34 II. SUBJECT TESTING METHODS AND INVESTIGATION PROCEDURES Subjects of investigation are montmorillonite and kaolinite natural clays. Under the results of X-ray diffraction analysis montmorillonite natural clay consists mass. of: montmorillonite – 75 kaolin - 36 quartz - 114 albite - 67 calcite - 33. Kaolinite natural clay contains mass. : kaolin - 767 montmorillonite – 156 quartz - 77. High pressure device was developed and produced to apply pressure to clay samples Fig 1. Test spaces of the device pos. 3 Fig.1 were produced out of hard-alloy material their area constituted S075sm 2 . Press PLG-20 mark was used as loading device. Preparation of clay samples for granulometric analysis was provided as follows: initial clayey ground powder was grinded in mortar by pistil. It was followed by mounting of the ground sample of about 02 g mass in testing space pos. 3 Fig.1 of the device. Then press pos. 6 Fig .1 was used to apply vertical pressures to the ground under the following scheme: the first stage - initial material Р0 МPа the second and subsequent stages – vertical pressure was increased by Р10-50 МPа. Maximum pressure constituted Р2200 МPа. Then upper holder pos. 2 Fig.1 traveled relative to lower holder pos. 1 Fig.1 by 90° by turning handles pos. 4 Fig.1. FIG.1. SCHEME OF DEVICE TO STUDY GROUNDS AT HIGH PRESSURES 1-lower holder 2-upper holder 3-test space of 075 sm 2 area 4- handles to turn upper holder 5-centering ball 6-upper plate of loading device press 7- recorder to record load transferred to ground. Natural clay granulometric composition was defined using laser diffraction-type analyzer «Аnalizette-22 MicroTec plus» under the procedure described in Seredin et al 2017. The device capabilities allow to provide diagnostics of 008 µm to 20000 µm size particles. In the studies of Lepoytevin et al. 2014 Sun D et al. 2015 it was disclosed that fine clay fraction the sizes of which are lower than 1 µm defines to a large extent physicochemical properties of clays. That is why on the basis of the device capabilities and significant effect of fine-dispersed particles on ground properties we investigated the following fractions: F 01 F 01-02 F 02-05 F 05-1 F 1-2 F 2-5 F 5-50. There were carried out 319 identifications of granulometric composition of montmorillonite and 385 – of kaolinite natural clays. To evaluate changes of clay crystal lattice parameters there was provided X-ray diffraction analysis using the diffractometer «D2 Phase Bruker». The device characteristics: X-ray tube with copper anode radiation – Cu Kα λ154060 Å generator voltage – 30 кW current strength – 10 мА linear detector – LYNXEYE filter – Ni. Representative sample hanging was abraded with alcohol in agate mortar to the sizes of 20-40 мcм it was followed by its mounting in cuvette and then diffraction pattern survey was provided. The survey conditions: divergent slot 02 mm Soller’s slots – primary 25° secondary 25° angular range 5 to 70° 2θ impulse rate increase at each point 10 sec pitch – 002°. The survey of oriented preparations was carried out within the interval of 4 to 35º 2θ. The oriented preparations were produced out of clay fraction aqueous suspension by deposition on degreased slides followed by drying at room temperature. One sample air-dry was surveyed two next were additionally treated: saturation with glycerin during 24 hours ignition in muffle furnace during 1 hour at the temperature of 600˚С. slide 3: International Journal of Engineering Research Science IJOER ISSN: 2395-6992 Vol-3 Issue-10 October- 2017 Page | 35 The program «Diffrac Eva» was used for processing of curves measurement of basal reflection width at height midpoint as well as its area. III. RESULTS AND DISCUSSION The study was carried out in successive steps. At the first stage investigated was effect of natural clay mineral compositions on change of ground fractional compositions subjected to pressure. Granulometric studies revealed that in initial samples of montmorillonite and kaolinite natural clays fraction content accordingly is as follows mass : F 01 - 048 and 070 F 01-02 - 077 and 122 F 02-05 - 266 and 554 F 05-1 -830 and 148 F 1-2 -1773 and 3010 F 2-5 - 3295 and 4122 F 5-50 - 3711 and 642. Change of clay fractional compositions at pressure build-up is shown in Fig. 2. Р МPа F 01 : К : М -200 200 600 1000 1400 1800 2200 -01 01 03 05 07 09 Р МPа F 01-02 : К : М -200 200 600 1000 1400 1800 2200 02 06 10 14 а b Р МPа F 02-05 : К : М -200 200 600 1000 1400 1800 2200 0 2 4 6 Р МPа F 05-1 : К : М -200 200 600 1000 1400 1800 2200 2 6 10 14 c d Р МPа F 1-2 : К : М -200 200 600 1000 1400 1800 2200 4 8 12 16 20 24 28 32 Р МPа F 2-5 : К : М -200 200 600 1000 1400 1800 2200 5 15 25 35 45 e f slide 4: International Journal of Engineering Research Science IJOER ISSN: 2395-6992 Vol-3 Issue-10 October- 2017 Page | 36 Р МPа F 5-50 : К : М -200 200 600 1000 1400 1800 2200 0 20 40 60 80 К – kaolin М – montmorillonite g FIG. 2. CHANGE OF FRACTIONAL COMPOSITION OF MONTMORILLONITE М AND KAOLINITE К OF NATURAL CLAYS UNDER PRESSURE. FRACTIONS: а - F 01 b - F 01-02 c - F 02-05 d – F 05-1 e - F 1-2 f - F 2-5 f - F 5-50 It is evident in figure that correlation fields have approximate behavior for different fractions. However fraction correlation fields F 01 –F 2-5 of kaolinite natural clay are positioned above applicable fields of montmorillonite natural clay and on the contrary for F 5-50 fraction. The above fact reveals that pressure effects differently formation of fractional composition of kaolinite and montmorillonite natural clays that is: mineral composition of natural clays effects significantly change of clay fraction contents in ground when compressed. Statistical methods Galkin 2013 were used to confirm the conclusion on effect of natural clay mineral compositions on formation of their granulometric composition. The matter of them is that if mineral composition effects change of crude ground fraction contents under pressures statistical discrepancies will be observed between samples of kaolinite and montmorillonite natural clays. Measure of discrepancy is to be evaluated as per Student’s criterion t. In case when the calculated value t р is higher than the tabulated one t т it is considered that mineral composition effects change of ground fraction contents under pressures. Student’s criterion constitutes t т 003 at the degrees of freedom кn 1 +n 2 2704 and the significance level α005. Calculated statistical parameters are exhibited in table 1. TABLE 1 CLAY STATISTICS Fractions Kaolinite natural clay Montmorillonite natural clay Calculated value of Student’s coefficient t р Identification of samples Mean Stat. deviation Mean Stat. deviation Kaolinite natural clay Montmorillonite natural clay Total F 01 045 014 018 012 259 800 859 830 F 01-02 079 015 047 012 292 934 850 891 F 02-05 218 094 151 040 118 423 834 633 F 05-1 696 229 426 142 178 836 834 835 F 1-2 1464 454 967 2 80 165 675 821 750 F 2-5 2320 664 1881 533 91 446 746 599 F 5-50 4996 1396 6269 920 -135 584 818 704 Z -176 102 168 098 -429 970 934 952 The table demonstrates that calculated values of Student’s coefficient for each studied fraction are higher than t т 003 so it can be concluded that mineral composition effects significantly formation of crude ground fractional compositions subjected to pressure. Student’s criterion reveals that samples are statistically different. Linear discriminant analysis was used for quantitative estimation of differentiation. Calculation results of samples identification are shown in table1. The table exhibits that maximum difference between kaolin and montmorillonite is observed for fractions F 01-02 and F 01 and minimum – for fraction F 2-5 . The rest of the fractions have intermediate position. slide 5: International Journal of Engineering Research Science IJOER ISSN: 2395-6992 Vol-3 Issue-10 October- 2017 Page | 37 For them t-criterion changes from 91 to 178 and total identification correctness – from 595 to 835. It should be mentioned that for prevailing majority fractions of montmorillonite natural clay are identified better than fractions of kaolinite natural clay. Maximum difference of kaolinite natural clay from montmorillonite natural clay is observed as the result of complex analysis of all the fractions using step-by- step LDA. LDF expression is as follows: Z 3.32537 – 7.50608F 01-02 + 3.15488F 02-05 - 0.93596F 1-2 +0.32878F 2-5 at R 086 χ 8543 multidimensional centers of groups Z К -176 Z М 168. The calculations indicate that degree of sample difference of kaolinite natural clay from montmorillonite natural clay is maximum as per t-criterion Table 1 and identification correctness regarding both – total and each class value. Thereby it was found experimentally and proved statistically that formation of micro-aggregative composition of kaolinite and montmorillonite natural clays has different scenarios when compressed with shear. It can be explained from the position of mineral crystal lattice structures. One tetrahedral sheet and one octahedral sheet forming structural layer provide kaolin structure. They are connected between each other by hydrogen bonds strength of which constitutes 5-40 кJ/mole Osipov Sokolov 2013 that is why kaolin crystal is featuring sufficient rigidity in common case. As to montmorillonite natural clay structural layers consisting of two tetrahedral and one octahedral sheets are connected between each other by molecular bonds strength of which twice and more as lower than of hydrogen ones. Due to the abovementioned montmorillonite crystal rigidity is lower than that of kaolin. Therefore processes of aggregation and dispersion progress more intensive in montmorillonite natural clays at application of vertical load and shear compared to kaolinite natural clays. The result of this is that clay fraction content in kaolinite natural clay varies not so significantly as in montmorillonite natural clays. The second stage included investigation of pressure effect on general laws of natural clay micro-aggregative compositions change revealing of classes. Changes of natural clay fractional compositions at pressure build-up are shown in Fig 2. It is evident that building-up of pressure to Р125 МPа leads to significant reduction of clay fraction F 5 contents and increase of pulverescent F 5-50 fraction content. Content of clay fractions changes differently directed and pulverescent one – increases under pressure build-up to Р750 МPа. Further building-up of pressure to Р2200 МPа results in increase of clay fraction contents and chaotic change of pulverescent fraction content. Thus with regard to qualitative feature it can be assumed that pressure effects formation of granulometric composition of natural clays. Two terminal pressures Р125 МPа and Р750 МPа are revealed at which aggregation and dispersion processes have different intensity of progressing. Linear discriminant analysis LDA was used to confirm the assumption on availability of terminal pressures of Р125 МPа and Р750 МPа the main point of which is that if boundaries between classes are acceptable then there should be maximum identification between them classes Galkin Silaycheva 2013. For this purpose all samples were divided to three classes under the “pressure” criterion. Class 1 includes the experimental data n61 obtained at Р0÷125 МPа inclusive class 2 – the data n91 at Р150÷750 МPа inclusive and class 3 – the data n167 at Р800÷2200 МPа. Two discriminant functions for each were provided for kaolinite and montmorillonite natural clays: the first one – to validate the boundary between Cl.1 and Cl. 2 Z 1-2 the second – between Cl. 2 and Cl. 3 Z 2-3 . The natural clay fractional compositions data were used for calculations. For kaolinite natural clay the following functions were obtained: Z K 1-2 –430310 – 30265F 01 – 10016F 01-02 + 19803F 02-05 +15040 F 05-1 –03170 F 1-2 + 02595F 2-5 +06258 F 5-50 Multidimensional centers of classes: Z Cl.1 -454344 and Z Cl. 2 279596 R 096 χ 2 5201. Z K 2-3 -324909 + 213266F 01 + 115974F 01-02 + 98014F 02-05 +10194 F 05-1 – 17571 F 1-2 + 06667F 2-5 – 00143F 5-50 Multidimensional centers of classes : Z Cl 2 -326488 and Z Cl.3 18437 R 093 χ 2 6096. slide 6: International Journal of Engineering Research Science IJOER ISSN: 2395-6992 Vol-3 Issue-10 October- 2017 Page | 38 For montmorillonite natural clay LDF are as follows: Z М 1-2 -388093 – 07017F 01 – 30345F 01-02 - 16975F 02-05 +17205F 05-1 + 24931F 1-2 - 04997F 2-5 + 03155 F 5-50 Multidimensional centers of classes: Z Cl.1 517712 and Z Cl.2 -358416 R 098 χ 2 5055. Z М 2-3 617964 + 413331F 01 – 68428F 01-02 – 125794F 02-05 +22471F 05-1 – 02790 F 1-2 – 05695F 2-5 – 06605F 5-50 Multidimensional centers of classes: Z Cl.2 -296914 and Z Cl.3 160828 R 091 χ 2 5669. Discriminant function calculations exhibited that correct identification of all the samples constitutes 100. Thereby it is proved that pressure terminal values Р125 МPа and Р750 МPа are well-grounded choice. That means that each class has different intensity of aggregation and dispersion processes progressing that is why conditions of natural clay fractional compositions formation are featuring their individual specific character as well. The third stage concerned study of pressure effect on change of natural clay micro aggregative compositions with regard to classes revealed inside classes. Correlation analysis was provided the essence of which is that if observed are statistical relations rr т where r – pair correlation coefficient between natural clay fractional compositions F and pressure Р it is considered that pressure effects formation of clay micro-aggregative compositions. It should be mentioned that the tabulated value of correlation coefficient constitutes r т 025 at α005 and n61 for class 1 r т 020 at α005 and n91 for class 2 and r т 017 at α005 and n167 for class 3. Let’s consider correlation analysis results for each class. Class 1 Р0-125 МPа: mean content of clay fractions is lower than that of initial sample table 2. This change probably concerns clay particle aggregation processes resulting in increase of pulverescent fraction Ф 5-50 content. TABLE 2 MAIN STATISTICAL CHARACTERISTICS OF CLAYS Fraction Class Kaolinite clay Montmorillonite clay σ r a k σ r a k F 01 Cl.1 044 018 -098 07163 -00043 037 009 -093 05047 -00023 Cl.2 032 011 083 01013 00005 007 004 036 00395 0000069 Cl.3 052 008 034 04190 0000074 017 006 077 -00047 00001 F 01-02 Cl.1 101 017 -095 12735 -00042 069 008 -087 08030 -00019 Cl.2 070 006 -046 07638 -00001 042 005 -070 04976 -00002 Cl. 3 076 008 018 07033 0000041 042 005 081 02618 00001 F 02-05 Cl.1 390 111 -097 55854 -0027 223 029 -080 25963 -00064 Cl.2 174 014 -029 18336 -00002 136 015 -062 15705 -00005 Cl.3 185 013 038 16461 00001 133 015 069 09355 00003 F 05-1 Cl.1 1120 244 -096 148988 -00591 696 099 -088 83198 -00236 Cl.2 627 067 -078 75343 -00028 353 036 -055 40035 -0001 Cl.3 590 038 035 53675 00004 367 034 075 27079 00007 F 1-2 Cl.1 2343 360 -094 287528 -0085 1497 167 -071 168207 -00322 Cl.2 1366 144 -068 160368 -00052 887 111 -059 104361 -00035 Cl.3 1218 065 008 119696 00002 818 064 032 74068 00006 F 2-5 Cl.1 3572 285 -086 395856 -00617 2767 351 -073 316779 -00697 Cl.2 2338 318 -081 296140 -00137 1914 323 -055 233908 -00094 Cl.3 1886 157 -079 236591 -00035 1540 192 -034 178553 -00018 F 5-50 Cl.1 2302 870 093 102629 02036 4631 632 080 383612 01381 Cl.2 5257 369 081 453052 00159 6407 465 057 576770 00142 Cl.3 5769 483 047 487852 00065 6793 293 042 633412 00033 Notes: – mean value σ – standard deviation r – correlation coefficient а –free term of the equation k – angular coefficient tangent of line inclination in equation of Р and F relation. slide 7: International Journal of Engineering Research Science IJOER ISSN: 2395-6992 Vol-3 Issue-10 October- 2017 Page | 39 Calculations revealed that statistical relations are provided between Р and F the evidence of which is significant coefficients of pair correlation Table 2. Availability of negative values r between Р and F 5 confirms our conclusion that content of clay fractions is reduced if pressure increases. Positive values r between pressure and content of pulverescent fraction on the contrary prove that build-up of pressure causes increase of F 5-50 content. To evaluate degree of pressure effect on change of investigated fraction contents there is used index k – angular coefficient which is the tangent of line inclination in equation of pressure P and F relation. It can be interpreted as follows: the higher are k values more is effect of pressure on change of investigated fraction content. Calculation results are presented in Table 2 and Fig. 3. k : К : М F 01 F 01-02 F 02-05 F 05-1 F 1-2 F 2-5 F 5-50 -01 00 01 02 k : К : М F 01 F 01-02 F 02-05 F 05-1 F 1-2 F 2-5 F 5-50 -0015 -0005 0005 0015 k : К : М F 01 F 01-02 F 02-05 F 05-1 F 1-2 F 2-5 F 5-50 -0004 0000 0004 0008 Cl.1 Cl.2 Cl.3 FIG. 3. DEPENDENCE OF PRESSURE EFFECT DEGREE ON CHANGING OF INVESTIGATED FRACTION CONTENTS FOR KAOLINITE AND MONTMORILLONITE NATURAL CLAYS REFERRING TO CLASSES 1 2 AND 3 The figure illustrates that less is particle size less is effect of pressure on these fraction contents change meanwhile the most sensitive to pressure is pulverescent fraction F 5-50 and less sensitive – clay fraction F 01 . It should be mentioned that fractions F 1-2 and F 2-5 of montmorillonite and kaolinite natural clays accordingly are subjected to pressure more among all the clay fractions. Rate of clay fraction contents change at pressure increase in kaolinite natural clay is higher compared to montmorillonite one higher values of k index are evidence of the abovementioned Fig. 3. Class 2 Р150÷750 МPа: similar to class 1 reduction of content of clay fraction F 5 and increase of pulverescent fraction F 5-50 are observed Table 2. For fraction F 01 different law is exhibited: build-up of pressure results in increase of F 01 content conditioned by dispersion processes of another fractions. Increase of F 5-50 content is connected with aggregation processes of clay particles to the sizes of pulverescent fraction. There are statistical relations between Р and F significant coefficients of pair correlation prove it Table 2. Hence it appears that pressure effects significantly formation of clay fractional compositions. The largest effect pressure has on formation of fraction F 5-50 the least – on formation of fraction F 01-02 Fig.3. Among all clay fractions the most sensitive to pressure is fraction F 2-5 . Meanwhile pressure effects more kaolinite natural clay compared to montmorillonite one higher values of k index are evidence of the above mentioned. Class 3 Р800÷2200 МPа: effect of pressure on change of clay fractional compositions is basically different from classes 1 and 2. While pressure building up content of all the fractions except F 2-5 increases confirmation of this are positive values r. There are statistical relations between Р and F significant coefficients of pair correlation are evidence of the above Table 2. The largest effect pressure has on formation of fraction F 5-50 and the least – on formation of F 01 fraction . Among all clay fractions similar to foregoing classes the most sensitive to pressure is fraction F 2-5 . Meanwhile pressure effects kaolinite natural clay more significant compared to montmorillonite one higher values of k index are evidence of the above mentioned. Thus reduction of clay fraction content and increase of pulverescent one – is the general tendency while pressure build-up. Alongside with this law each class shows local changes of clay fractional compositions content subject to pressure. So class 1 exhibits that build–up of pressure P leads to decrease of clay fraction F 5 content and increase of pulverescent one. Class 2 taking into the account the abovementioned law of class 1 demonstrates inversion only for the fraction of less than 01 мcм build-up of pressure causes increase of F 01 content. Concerning class 3 formation of fractional composition is slide 8: International Journal of Engineering Research Science IJOER ISSN: 2395-6992 Vol-3 Issue-10 October- 2017 Page | 40 provided based on opposite to classes 1 and 2 scenario that is build-up of pressure results in increase of all fractions content and F 2-5 fraction on the contrary is decreased. The fourth stage included study of conditions of natural clay microaggregative compositions formation when compressed. Change of content of natural clay ground fractional compositions are connected with particles aggregation and dispersion processes. Aggregation of particles is effected by pressure compression being exhibited as physicochemical processes causing formation of new structural relations under the attractive forces Osipov Sokolov 2013 Zhu et al. 2016. Forces of compression and shear also effect dispersion grinding of particles resulting in destruction of structural relations and grinding of particles. The following assumption is the basis of clay particles aggregation process caused by pressure applied to ground: when clay is compressed with shear by displacement of device upper holder relative to lower one additional energy centers should be provided on surface of ground particles. Due to free energy structural relations are formed between particles causing their aggregation. To prove the abovementioned assumption it was required to choose evaluation criterion of clay particle surface energy state. The investigation results analysis Shlykov 2006 Cora et al. 2014 Zhu et al. 2016 revealed that it is available to use as the above criterion – the size of coherent –scattering region CSR of X-rays in the direction of с axis crystallographic direction. This index correlates with particles structure micro-assemblies and their energy activity. Small values of CSR demonstrate that micro-assemblies have small sizes and are featuring high values of cation-exchange capacity typical for kaolin Shlykov 2006. Besides the study Radiography.. 1983 Trofimof et al 2005 exhibited that in case of CSR small value there are as usual water molecules between micro-assemblies which facilitate unrestricted displacement of sub- packings relative to each other and this in turn leads to increase of particles energy activity. So coherent–scattering region expressed as Мк index quantity of elementary layers in defect-free blocks can be compared with cation-exchange capacity CEC as index of particle energy activity. In case of Мк 40 CEC constitutes 2-5 mg-equiv/100 g at Mк40-25 capacity is increased to 6-12 mg-equiv/100 g and at Мк25 capacity takes the value of CEC12 mg-equiv/100 g Shlykov 2006. The results of diffractometer analysis carried out by us presented in table 3 do not conflict with the investigation Shlykov`s results. TABLE 3 RESULTS OF CLAY DIFFRACTOMETER ANALYSIS Clay Pressure Р МPа Class Diffractio n angle 2Ө Interplanar spacing d Å Half-width of basal reflection В/2 Peak area intensity of basal reflection Quantity of elementary layers in defect- free blocks Мк Montmorillo nite initial 6061 14570 0574 4988 166 0-125 1 6230 14173 0631 3054 147 150-750 2 6243 14148 0600 1836 156 800-2200 3 6202 14242 0523 0961 177 Kaolinite initial 12348 12162 0386 4271 263 0-125 1 12324 7176 0435 3153 207 150-750 2 12321 7178 0441 2953 203 800-2200 3 12323 7177 0476 2577 188 The table exhibits that when crude grounds are compressed crystallite surfaces defectiveness energy capacity of montmorillonite natural clay is higher М147-177 than that of kaolinite natural clay М188-263. Hence it follows that particle aggregation processes are more intensive in montmorillonite natural clay than in kaolinite one. This conclusion conforms to the experimental data of the first stage of the studies. Let’s consider conditions of clay fractional compositions formation as per classes revealed. Class 1. Extra energy centers are formed on crystallite surfaces at pressures from 0 to 125 МPа due to defectiveness increase displacement of crystal lattice vacancies or relative displacements of layers. Free energy of centers enables formation of molecular attractive forces which cause aggregation of 01 мcм to 5 мcм particle sizes. Due to the abovementioned there is observed decrease of clay fraction content and increase of pulverescent one in the experiment carried out. It should be slide 9: International Journal of Engineering Research Science IJOER ISSN: 2395-6992 Vol-3 Issue-10 October- 2017 Page | 41 mentioned that if pressure range constitutes from 0 to 125 МPа formation of extra energy centers on particle surfaces is more intense than formation of 2 and 3 classes numerical values of Мк index are confirmation of this. Class 2. Defects on crystallite surfaces probably are «healed» at pressure build-up 125 МPа to 750 МPа in montmorillonite natural clay that is why there is observed some increase of coherent–scattering region from Мк147 – class 1 to Мк156 – class 2. In kaolinite natural clays mean values of Мк practically do not change. Insignificant variation of Мк index confirms that energy potential on crystallite surfaces changes insignificantly as well. Thereby clay particle aggregation processes are less intensive within the range of these pressures and in the first place effect change of fraction F 01-02 and F 1-2 contents. Reduction of clay particles except F 01 fraction reveals that molecular attractive forces are formed between them causing their aggregation. It is important that based on abovementioned law for particle sizes of less than 01 мcм build-up of pressure results in increase of their content. The indication of this is that energy on crystallite surfaces composing F 01 fraction is realized in the form of electrostatic repulsion forces that can lead to process of fraction particles dispersion. Meanwhile the second scenario version is available: dispersion of larger fractions is provided due to which content of F 01 is increased. Class 3. Pressures of 800 МPа to 2200 МPа cause further «healing» of defects on crystallite surfaces of montmorillonite natural clay which is conditioned by some increase of coherent-scattering region from Мк156 – class 2 to Мк177 – class 3. This process reduces energy on crystallite surfaces. Kaolinite natural clays are featuring opposite law: CSR index is decreased from Мк203 – class 2 to Мк188 – class 3. Therefore in kaolinite clay pressures of 800 МPа to 2200 МPа cause further deteriorations of crystallite surfaces which are realized in the form of crude ground energy potential increase. Based on the results obtained it can be concluded that this class of montmorillonite natural clay is characterized mainly by dispersion processes and kaolinite one on the contrary by aggregation processes. Thereby compression of natural clay on crystallite surfaces causes mainly formation of the defects which increase crude ground energy potential. Free energy enables formation of molecular attractive forces which result in particles aggregation. Dispersion processes being the result of particles grinding are provided in small volumes which is not in conflict with the data Sergeev1946. IV. CONCLUSION 1. It is found experimentally that while building-up of pressure applied to natural clay there is general tendency of clay fraction content decrease and pulverescent fraction content increase. Montmorillonite natural clay changes are more intensive compared to kaolinite ones. 2. It is revealed that processes of natural clay fractional compositions change are featuring higher intensity of progressing under pressures within the range of 0–125 МPа than under higher pressures. It is revealed that there is different intensity of natural clay fractional compositions formation under pressures within the range of 125-750 МPа and 800-2200 МPа. Thereby three classes are identified regarding «pressure» index each has different intensity of aggregation and dispersion processes progressing. Due to the abovementioned conditions of natural clay fractional compositions formation have their individual specific character as well. 3. It is disclosed that when clay is compressed defects are formed on crystallite surfaces which increase energy potential of crude ground. Extra energy enables to form molecular attractive forces which cause particles aggregation. Dispersion processes referring to particles grinding progress in small volumes. REFERENCES 1 Boiko V.F. Verkhoturov А.D. Ershova Т.B. Vlasova N.М. 2009. Dependence of granulometric characteristics of dispersed nemalite on storage time. Refractories and technical ceramics 6 47-49. 2 Cora I. Dódony I. Pekker P. 2014. Electron crystallographic study of a kaolinite single crystal. Applied Clay Science 90 6-10. 3 Friedlander L.R. Glotch T.D. Phillips B.L. Vaughn J.S. Michalski J.R. 2016. Examining structural and related spectral change in marsrelevant phyllosilicates after experimental impacts between 10-40 GPA. Clays and Clay Minerals 64 №3 89-209. 4 Galkin V.I. Silaycheva V.А. 2013. Development of statistical model of permeability coefficient prediction on the basis of geological and technological indices. Petroleum engineering 9 10-12. 5 Ilic B. Mitrović A. Radonjanin V. Malešev M. Zdujić M. 2016. Effect of mechanical and thermal activation on pozzolanic activity of kaolin containing mica. Applied clay science 123 173-181. 6 Korolyov V. А. 2016. Modeling of granulometric composition of moon rocks. Engineering geology 5 40–50. slide 10: International Journal of Engineering Research Science IJOER ISSN: 2395-6992 Vol-3 Issue-10 October- 2017 Page | 42 7 Krivosheeva Z.А. Zlochevskaya R.I. Korolyov V.А. Sergeev Е.М. 1977. On nature of change of clay rocks composition and properties during lithogenesis. Bulletin of Moscow University 4. 60-73. 8 Lepoitevin M. Janot J.-M. Dejardin P. Balme S. Jaber M. Guégan R. Henn F. 2014. BSA and lysozyme adsorption on homo- ionic montmorillonite: influence of the interlayer cations. Applied Clay Science 95 396-402. 9 Osipov V.I. Sokolov V.N. 2013. Clays and their properties. Composition structure and properties formation. М.: GEOS 576 p. 10 Osovetsky B.М. 1993. Fractional granulometry of alluvium. Perm: Perm university. 343 p. 11 Radiography of main types of rock-destroying minerals layered silicates and tectosilicates. Edited by V.А. Frank-Kamenestky. L.:Nedra 1983. 359 p. 12 Savko A.D. Sviridov V.A. 2015. Evolution of clay mineral compositions depending on conditions of their sedimentation and diagenesis. Evolution of sedimentary processes in Earth history. Materials of VIII Russian lithologic conference. pp. 293-296. 13 Seredin V.V. 2014. To the issue on solidity of saline clayey grounds. Engineering geology 1 66-69. 14 Seredin V.V. Kachenov V.I. Siteva О.S. Paglazova D.N. 2013. Study of laws of clay particles coagulation. Fundamental researches 10 3189-3193. 15 Seredin V.V. Rastegayev A. V. Panova E. G. Medvedeva N. A. 2017. Changes in physical-chemical properties of clay under compression. International Journal of Engineering and Applied Sciences V.4 3 18-26. 16 Seredin V.V. Yadzinskaya М.R. 2014. Investigation of mechanism of particles aggregation in clay grounds when contaminated by hydrocarbons. Fundamental researches 6 1408-1412. 17 Sergeev Е.М. 1946 a. Compressibility of large fragmental and sand grounds. Pedology 3 13-19. 18 Sergeev Е.М. 1946. To the issue of pulverescent ground compression by high loads. Bulletin of Moscow University 1 91-93. 19 Shlykov V.G. 2006. X-ray analysis of mineral composition of dispersed grounds. М.:GEOS 176 p. 20 Stefani V.F. Conceição R.V. Balzaretti N.M. Carniel L.C. 2014. Stability of lanthanum-saturated montmorillonite under high pressure and high temperature conditions. Applied Clay Science 102 51-59. 21 Sun D. Zhang L. Zhang B. Li J. 2015. Evaluation and prediction of the swelling pressures of GMZ bentonites saturated with saline solution. Applied Clay Science 105-106 207-216. 22 Trofimov V.Т. Korolyov V.А. Voznesensky V.А. Golodkovskaya G.А. Vasilchuk Yu.К. Ziangirov R.S. 2005. Pedology M.: МSU 1024 p. 23 Zhu X. Zhu Z. Lei X. Yan C. 2016. Defects in structure as the sources of the surface changes of kaolinite. Applied Clay Science 124-125 127-136.