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Kaolinite thermal evaluation in geotechnical engineering.

Introduction

There is very important to improvement of construction material from feasibility and economically techniques. In the geotechnical engineering could not find more modification of material from application of thermal technique based on crystallography investigation.

There is investigation on the effects of temperature and chemical admixtures on viscoelastic properties of cement paste using the oscillatory (Saak, 2000; Schultz, 1993; Chow, 1988; Saasen, 1991). Research interest in the thermo-mechanical behavior of soils is growing as a result of an increasing number of geomechanical problems involving thermal effects. These problems with non-isothermal situations are mainly encountered in the field of environmental geomechanics (Vulliet L, 2002). The thermal effect is dominant in some applications such as geothermal structures (Laloui L, 2003). In spite of the practical relevance of the thermo-mechanical applications, the effect of high temperatures on soil behavior is not yet completely understood. This is due to the complex influence of temperature on the behavior of soils, and the fact that thermo-mechanical testing of soils is much more complex (Cekerevac, 2003). There is an investigation on thermal effects on the mechanical behavior of saturated clay. The study was performed on CM clay (kaolinite) using a temperature-controlled triaxial apparatus. Applied temperatures were between 22 and 90 [degrees]C, The obtained results provide observations concerning a wide scope of the thermo-mechanical behavior of clays (Cane Cekerevac, 2004). Thermal effects are also relevant in other applications such as high level nuclear waste isolation, petroleum drilling, injection and production activities, improvement of soft clay characteristics by thermal stabilization and zones around buried high-voltage cables. Geomechanical applications to these problems require an understanding of the thermo-mechanical behavior of soils and their numerical modeling (Laloui L, 2001). It is very essential to investigation on construction material submitted to the thermal, the author's intention is performance an investigation for developing a new construction material based on evaluation of crystallography, stress-strain relationship and permeability of kaolinte when subjected to the thermal.

2. Methodology and Experiments:

The main objective of these experiments was to analysis of the construction materials based on its thermal reaction mechanism in the laboratory condition. The measurements of both for the macro and micro kaolinite characteristics have been taken systematically trough of laboratory experimental in the geotechnical laboratory of National Institute of Engineering, Mysore, India and physics laboratory of Physic Department, University of Mysore, and Mysore, India. In the soil testing laboratory compression, compaction and permeability tests conducted and in the physic laboratory X-ray diffraction have been performed. The stress-strain relationship, density and permeability of the kaolinite based on thermal affect and mineralogy has been evaluated.

Results and Discussion

A number of theoretical and computational studies have been performed by various researchers to evaluation of soil mineral for development a construction material with better quality. From these different existing studies it is understood that the soil characteristics are changing when it is under thermal. On the other hand, not many experimental studies have been made to assess the accurate understanding of kaolinite at different level of temperatures. It is also not known from the available literature, either from any experimental study or from the theory, about the effect of the thermal on the magnitudes changing kaolinite mechanical properties. This is the motive of the present research work. It is aimed to perform a series of the soil mechanic test on kaolinite under thermal from 100[degrees]C to 500[degrees]C in increment of 100[degrees]C on assessment the behavior of the kaolinite. It should be mentioned that the experiments on kaolinite provide quite an accurate way to assess better material in improvement of soil foundation, embankment and etc. The purpose of the entire research exercise would be to (i) predict the response of the kaolinite subjected to an elevation thermal, and (ii) formulate some useful guidelines to improvement of soil foundation and structure using modified kaolinite.

Research activity on the thermo-mechanical behavior of soil is leads to innovation of new material if in investigation micro and macro mechanical behavior of soil accurately evaluated. In the consideration of micro thermal behavior the XRD is one of the suitable method for studied of isotropic crystal and for un-isotropic based on mineral d-spacing and intensity could study changing atomic structural of kaolinite crystal. The intensity of three mineral peaks for studying atomic structural of kaolinite selected and affect of unknown mineral on soil mechanical properties investigated. The XRD result indicated that the kaolinite crystal is isotropic at the room temperature condition but when submitted to the thermal, its crystal structure converted to un-isotropic and entirely of its atomic structural was changed, this is resulted in changing kaolinite mechanical property from 100[degrees]C and strongly increasing kaolinite shear strength at 500[degrees]C [table 2a-b and table 3-7].

The chemical composite of kaolinte submitted to the thermal play important factor in changing mechanical properties, and it could be observed when kaolite is under 400[degrees]C and 500[degrees]C temperature.

The table 1 indicated that the density and natural moisture content of kaolinte submitted to thermal almost is constant and the optimum moisture content from applying 100[degrees]C strongly increased and could observe of increasing imperviously when this submitted to the thermal. It is negative correlation between optimum moisture content and permeability of kaolinte submitted to the thermal. The thermal behavior of soil at any level of temperature for any kind of soils is based on atomic structural and chemical composite, For any of natural soil which is intention to modify its mechanical behavior by thermal method this is required to conducting experimental based on identification of micro and macro behavior of the soils.

The table 8 presented of kaolinite mineral intensity and maximum peak of three main mineral of kaolinite at any temperature level [table 2-7 and fig 2-7], the investigation shown that due to increasing of thermal from the 200[degrees]C number of unknown minerals is increased but when kaolinite is submitted to the 400[degrees]C and 500[degrees]C three main peaks which have been find from the XRD are very close and only difference is in the one peak it is indicated that small changing of atomic structural and chemical composite of minerals of a crystal shown huge change of soil mechanical properties, this could be observed that [table 9 and fig 9] due to this reason the kaolinte when is under 500[degrees]C thermal based on very less changing in its atomic structural and chemical composite appear of very high level of shear strength compare to when it is under 400[degrees]C, to optimum modification of stress-strain relationship of a soil it is necessary of geotechnical engineer to understand and accurate analysis of mineralogy of crystal of a soil.

This investigation revealed the strength, density and permeability of construction material when it is under thermal modified. This is not complicate method but accuracy is very important when case study is a natural soil with huge number of unknown minerals it is strongly suggested in application of this method, the same soil is under investigation should be use as construction material, the small changing in atomic structural or chemical composite of a soil resulted big variation of soil mechanical properties.

[FIGURE 1 OMITTED]

Conclusion:

* This is important for geotechnical engineer to understanding the characteristics of materials when subjected to the thermal based on changing chemical composite and atomic structural.

* The XRD result indicated that the kaolinte crystal converted from isotropic to un-isotropic when it is submitted to the thermal.

* The XRD result shown that the thermal changed kaolinite atomic structural from 100[degrees]C, it is resulted of changing kaolinite mechanical properties from this temperature.

* The chemical composite of kaolinte submitted to the thermal play important factor in changing mechanical properties, it could be observed when kaolite is under 400[degrees]C and 500[degrees]C temperature.

* The kaolinite when submitted to thermal at different temperature shown that the application of 400[degrees]C thermal is not acceptable method for increasing its mechanical properties.

* It is negative correlation between optimum moisture content and permeability of kaolinte submitted to the thermal.

[FIGURE 2 OMITTED]

[FIGURE 3 OMITTED]

[FIGURE 4 OMITTED]

[FIGURE 5 OMITTED]

[FIGURE 6 OMITTED]

[FIGURE 7 OMITTED]

[FIGURE 8 OMITTED]
NOMENCLATURE

OMC % =                   Optimum Moisture Content %
[gamma][kN/[m.sup.3]] =   Unit Weight
RT =                      Room Temperature
NMC% =                    Natural Moisture Content %


References

Cekerevac, C., L. Laloui, L. Vulliet, 2003. Thermo-mechanical testing of soils: equipment, procedures and experimental results, Geotechnical Testing Journal.

Cekerevac, Cane and Lyesse Laloui, 2004. Experimental study of thermal effects on the echanical-behaviour of a clay, Int. J. Numer. Anal. Meth. Geomech., 28: 209-228 (DOI: 10.1002/nag.332).

Chow, T.W., L.V. Mclntire, K.R. Kunze and C.E. Cooke, 1988. "The rheological properties of cement slurries: Effect of vibration, hydration conditions, and additives." SPE Prod. Eng., 3(4): 543-550.

Laloui, L., M. Moreni, L. Vulliet, 2003. Comportemnent d'un pieu bi-fonction, fondation et echangeur de chaleur. Canadian Geotechnical Journal., 40(2): 388-402.

Laloui, L., 2001. Thermo-mechanical behaviour of soils. Revue Franc, aise de g! enie civil., 5(6): 809-843.

Saak, W.A., 2000. "Characterization and modeling of the rheology of cement paste with application toward self-flowing materials." Ph.D. thesis, Northwestern Univ., Evanston, Ill., 97-116.

Schultz, M.A. and L.J. Struble, 1993. "Use of oscillatory shear to study flow behaviour of fresh cement paste." Cem. Concr. Res., 23(2): 273-282.

Saasen, A. and C. Marken, 1991. "Oscillatory rheometer measurements on oilfield cement slurries." Cem. Concr. Res., 21(4): 109-119.

Vulliet, L., L. Laloui, R. Harding, 2002. Environmental geomechanics: an introduction. In Environmental Geomechanics, Vulliet L, Laloui L, Schrefler B (eds). EPFL-Press: Lausanne., 3-12.

Corresponding Author: Abdoullah Namdar, Islamic Azad University of Jolfa International Branch, Iran. E-mail: ab_namdar@yahoo.com

Abdoullah Namdar

Islamic Azad University of Jolfa International Branch, Iran.
Table 1: kaolinite mechanical properties in elevation temperature.

Sl No   Temperature   Density(gr/cc)   OMC     NM     Permeability
        [degrees]C                                    Coefficient

1       RT            1.34             31.43   0      1.14 * 10-6
2       100           1.31             38.24   0      7.28 * 10-7
3       200           1.35             36.58   0      8.10 * 10-7
4       300           1.33             35.34   0.12   8.10 * 10-7
5       400           1.33             37.36   0      8.02 * 10-7
6       500           1.31             38.00   0      7.18 * 10-7

Table 2A: cell analysis of kaolinite in room temperature.

H    K   L   SST-OBS    SST-CALC   DELTA       2TH-OBS   2TH-CALC

0    0   1   0.005950   0.005940    0.00001     8.848     8.841
0    1   1   0.007119   0.007128   -0.000009    9.680     9.686
0    0   2   0.023935   0.023761    0.000175   17.800    17.734
0   -1   1   0.028160   0.028244   -0.000084   19.321    19.350
1    1   0   0.030213   0.030188    0.000026   20.020    20.011
1    2   0   0.034919   0.035094   -0.000175   21.540    21.595
     1   1   0.042732   0.042553    0.000179   23.860    23.809
1    0   0   0.048858   0.048773    0.000085   25.540    25.517
0    0   3   0.053550   0.053462    0.000088   26.760    26.738
1    3   2   0.058199   0.57871     0.000328   27.920    27.840
1    3   0   0.063454   0.063492   -0.000039   29.180    29.189
1    1   2   0.066639   0.066799   -0.000160   29.920    29.957
1    3   3   0.072680   0.072881   -0.000201   31.280    31.324

H   D-OBS

0   9.9862
0   9.1296
0   4.9790
0   4.5904
1   4.4316
1   4.1222   1
    3.7264
1   3.4849
0   3.3287
1   3.1930
1   3.0580
1   2.9840
1   2.8573

A =4.570467 A   ALFA =61.892030 DEG
B =10.415380 A  BETA =99.450570 DEG
C =13.073990 A  GAMMA =61.709690 DEG

Unit Cell Volume = 418.94 A ** 3

Table 2B: XRD data of kaolinite for peak search under room
temperature, [[degrees]C].

Peak No   2theta   Flex Width   d-value   Intensity   I/Io

1          8.900     0.447      9.9277      6030       50
2          9.680     0.471      9.1294     11357       94
3         17.800     0.471      4.9789      2060       17
4         19.340     0.447      4.5857      4866       40
5         20.020     0.424      4.4315      2160       18
6         21.540     0.659      4.1221      1354       12
7         23.860     0.494      3.7263      1089        9
8         22.540     0.447      3.4848      1146       10
9         26.760     0.471      3.3287      5080       42
10        27.920     0.471      3.1929      1526       13
11        29.180     0.471      3.0579     12194      100
12        29.920     0.424      2.9839      1838       16
13        31.280     0.471      2.8572      1270       11

Table 3: XRD data of kaolinite for peak search under 100[degrees]C.

Peak No   2theta   Flex    d-value   Intensity   I/[I.sub.o]
                   Width

1          8.760   0.447   10.0860    6506           52
2          9.540   0.471    9.2631   12626          100
3         17.660   0.471    5.0180    2173           18
4         19.220   0.447    4.6141    5307           43
5         19.920   0.471    4.4535    2159           18
6         21.380   0.847    4.1526    1250           10
7         22.860   0.447    3.8870     994            8
8         23.780   0.447    3.7386    1134            9
9         25.420   0.471    3.5010    1324           11
10        26.640   0.471    3.3434    5226           42
11        27.800   0.447    3.2065    1602           13
12        29.040   0.471    3.0723   12103           96
13        29.820   0.424    2.9937    1961           16
14        31.160   0.447    2.8679    1335           11

Table 4: XRD data of kaolinite for peak search under 200[degrees]C.

Peak No   2theta   Flex Width   d-value   Intensity   I/[I.sub.o]

1          8.780   0.447        10.0631    7110          54
2          9.560   0.471         9.2437   13373         100
3         17.680   0.471         5.0124    2274          17
4         19.220   0.447         4.6141    5205          39
5         19.940   0.447         4.4491    2186          17
6         20.900   0.447         4.2468    1240          10
7         21.460   0.682         4.1373    1175           9
8         22.860   0.447         3.8870     987           8
9         23.780   0.471         3.7386    1114           9
10        25.460   0.471         3.4956    1424          11
11        26.660   0.471         3.3409    5610          42
12        27.820   0.447         3.2042    1552          12
13        29.060   0.471         3.0702   13101          98
14        29.840   0.424         2.9917    2002          15

Table 5: XRD data of kaolinite for peak search under 300[degrees]C.

Peak No   2theta   Flex Width   d-value   Intensity   I/[I.sub.o]

1          8.840     0.424      9.9949      2779         27
2          9.620     0.471      9.1862      8944         86
3         17.760     0.471      4.9900      1143         11
4         19.300     0.424      4.5952      4042         39
5         20.040     0.494      4.4271      2345         23
6         21.360     1.012      4.1564      1686         17
7         23.880     0.494      3.7232       875          9
8         25.520     0.471      3.4875      1106         11
9         26.720     0.471      3.3336      3073         30
10        27.920     0.447      3.1929      1182         12
11        29.140     0.447      3.0620     10407        100
12        31.240     0.471      2.8608       967         10
13        35.080     0.941      2.5559      1830         18
14        37.180     0.494      2.4162      2015         20

Table 6: XRD data of kaolinite for peak search under 400[degrees]C.

Peak No   2theta   Flex Width   d-value   Intensity   I/[I.sub.o]

1         8.740      0.424      10.1091     3874         28
2         9.520      0.471      9.2825     14340        100
3         17.660     0.471      5.0180      1545         11
4         19.200     0.447      4.6189      6222         44
5         19.940     0.494      4.4491      2267         16
6         21.280     1.176      4.1719      1609         12
7         22.840     0.447      3.8903       907          7
8         23.780     0.494      3.7386       940          7
9         25.420     0.471      3.5010      1218          9
10        26.620     0.471      3.3459      3202         23
11        27.840     0.447      3.2019      1287          9
12        29.020     0.471      3.0744     13311         93
13        35.000     0.800      2.5616      1829         13
14        37.080     0.494      2.4225      1947         14

Table 7: XRD data of kaolinite for peak search under 500[degrees]C.

Peak No   2theta   Flex Width   d-value   Intensity   I/[I.sub.o]

1          9.520     0.471      9.2825     11810        100
2         17.660     0.471      5.0180      1333         12
3         19.180     0.447      4.6236      4714         40
4         19.940     0.518      4.4491      2614         23
5         21.140     0.682      4.1992      1776         16
6         23.760     0.471      3.7471       884          8
7         25.420     0.494      3.5010      1060          9
8         26.620     0.471      3.3459      2698         23
9         29.020     0.471      3.0744     11361         97
10        31.140     0.471      2.8697       909          8
11        34.880     0.565      2.5701      1470         13
12        37.060     0.518      2.4238      1789         16
13        39.100     0.471      2.3019       823          7
14        43.860     0.447      2.0625       913          8

Table 8: Mineral of kaolinite.

25[degrees]C     3.058   Norbergite, Samuelsonite,
                         Fersmanite, Fergusonite-
                         beta-(Ce)

                 9.129   Pseudojohannite
                 9.928   Pseudolaueite
100[degrees]C    9.263   Ferricopiapite, Mordenite
                 3.072   Laitakarite
                10.086   Fluorannite, Shirozulite
200[degrees]C    9.244   --
                 3.070   Cuprotungstite, Hauerite,
                         Haycockite, Mooihoekite,
                         Chambersite, Stistaite,
                         Chalcothallite,
                         Cuprobismutite,
                         Cheralite-(Ce),
                         Thoreaulite, Lithosite,
                         Polylithionite,
                         Kintoreite,
                         Kalipyrochlore,
                         Maikainite, Sobolevskite,
                         Talmessite, Anthoinite,
                         Chambersite, Stistaite,
                         Cheralite-(Ce),
                         Lithosite,
                         Polylithionite, Jeppeite
                10.063   --
300[degrees]C    3.062   Trabzonite, Cuspidine,
                         Dickinsonite-(KMnNa),
                         Dickinsonite-(KMnNa)

                 9.186   --
                 4.595   --
400[degrees]C    9.282   --
                 3.074   Skippenite, Gabrielsonite
                 4.619   --
500[degrees]C    9.282   --
                 3.074   Skippenite, Gabrielsonite
                 4.624   --

Table 9: Shear stress--strain of kaolinite from compression tests.

Strain    Shear Stress
          At 25[degrees]C   At 100[degrees]C   At 200[degrees]C

0         0                 0                  0
0.58824   0.03921           0.17646            0.15686
1.17647   0.09804           0.58822            0.39214
1.76471   0.19607           0.88232            1.05879
2.35294   0.33332           1.05879            1.33329
2.94118   0.50979           1.19604            1.47054
3.52941   0.64704           1.26466            1.60779
4.11765   0.74507           1.31368            1.64701
4.70588   0.78429           1.21565            1.64701
5.29412   0.78429                              1.6274
5.88235   0.84311
6.47059   0.86272
7.05882   0.88232
7.64706   0.88625
8.23529   0.86272
8.82353   0.84311

Strain
          At 300[degrees]   At 400[degrees]C   At 500[degrees]C

0         0                 0                  0
0.58824   0.45097           0.2745             0.39214
1.17647   0.45097           0.549              1.47054
1.76471   1.49015           1.49015            3.23519
2.35294   2.15679           2.09797            4.21555
2.94118   2.62737           2.35287            4.78416
3.52941   2.82344           2.52933            5.01945
4.11765   3.05872           2.78422            5.07827
4.70588   3.15676           2.56854            4.86259
5.29412   3.17637
5.88235
6.47059
7.05882
7.64706
8.23529
8.82353
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Title Annotation:Original Article
Author:Namdar, Abdoullah
Publication:Advances in Natural and Applied Sciences
Article Type:Technical report
Geographic Code:7IRAN
Date:Apr 1, 2011
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