Stabilizing clay soil with chemical solutions

A method of stabilizing clay soil comprising admixing the clay soil with an effective amount of a solution of chemicals comprising hydroxy-aluminum and a chemical selected from the group consisting of potassium chloride, potassium nitrate, potassium sulfate, ammonium chloride, ammonium nitrate, and ammonium sulfate.

BACKGROUND OF THE INVENTION 
Many clay deposits often need to be stabilized before they can carry any 
additional load such as is applied during filling and construction 
activities. This is specially true for the so-called quick clays which 
frequently are found, for example, in northern Soviet Union, Scandinavia, 
Canada, upper New York State, and New Zealand. Clays were originally 
deposited in marine and brackish water in a short period after the last 
glaciation, and later during the continental (isostatic) uplift were 
raised above sea level. However, only certain of these clay deposits were 
subsequently changed into sensitive quick clays. Two processes are mainly 
responsible for such a change. The original pore water salt content of the 
clay may have been leached by percolating ground water, or organic matter 
from logs or marshes which will act as dispersing agents may have been 
introduced into the clay. The first process has been most important in 
clays found in Norway, while quick clays containing high organic content 
formed by the second process are frequently found in Sweden and Canada. 
The quick clays will in the undisturbed state exhibit a certain limited 
strength, but will upon remoulding completely liquefy. This same phenomena 
has caused several quick clay slides in the lowlands of eastern and middle 
Norway, often with catastrophic consequences. Heretofore, several chemical 
stabilization schemes have been tried for such clays. Among them were 
aluminum chloride (AlCl.sub.3) and potassium chloride (KCl). The quick 
clays have been stabilized in two ways. The clay can be mixed and 
remoulded with the chemicals, or the chemicals can be allowed to diffuse 
into the undisturbed quick clay. The disadvantage of the salt diffusion 
method is the long time it takes to reach the required penetration. The 
diffusion method has been applied only once, so far as is known, in full 
scale in the field, when salt wells containing KCl were installed two 
years prior to a major highway construction. 
Heretofore, a method for deep stabilization with unslacked lime (CaO) was 
developed. Lime is an old stabilizing agent that has been used 
occasionally. In China it was used centuries ago as a construction 
material. In the U.S.A. in the 1940's and Europe in the 1950's lime was 
used as a surface stabilizing agent. The deep stabilization method 
involves mixing and molding the lime with the clay to form a series of 
piles which extend down into the clay. These piles provide lateral 
stabilization to the clay deposit. 
Both the lime and potassium chloride methods have some disadvantages. KCl 
will stabilize the undisturbed circumjacent clay, but not the disturbed 
clay. Furthermore, CaO makes an unhomogenous stabilization. Pockets of 
lime cause brittle cylinders with small sideways shear strength. In 
addition, CaO is not useful on clays with high water content. While 
hydroxy-aluminum as Al(OH).sub.2.5 Cl.sub.0.5 has not been used as a clay 
stabilizing agent in foundation engineering before it has been applied as 
a cementing agent in preparing desired clay microstructures for laboratory 
studies. Hydroxy-aluminum solution containing KCl has also been used in 
wells to treat water sensitive clay containing formations and to provide 
sand stabilization. Relatively dilute solutions and overflushes are 
commonly used in the field. These methods are disclosed in U.S. Pat. Nos. 
3,603,399 issued Sept. 7, 1971 and 3,827,495 issued Aug. 6, 1974 both to 
Marion G. Reed as assignor to Chevron Research Company. 
In summary, there is still need for a method of stabilizing clay soil with 
chemicals that provides lasting and effective stabilization for clay 
deposits. 
BRIEF DESCRIPTION OF THE INVENTION 
The present invention provides for stabilizing clay soil by admixing an 
effective amount of a solution, preferably of hydroxy-aluminum and 
potassium chloride with the clay. While potassium chloride is preferred, 
other chemicals useful in place of potassium chloride include potassium 
nitrate, potassium sulfate, ammonium chloride, ammonium nitrate and 
ammonium sulfate. The admixture is preferably done in a manner so that the 
stabilized clay forms a series of piles which extend into the clay deposit 
at spaced apart location to provide stability for the entire clay 
containing deposit. The desired size, location and number of the piles are 
determined. An effective amount of a solution of hydroxy-aluminum and 
potassium chloride is admixed with the clay in place in each location in 
the deposit to react with the clay and thereby form the desired piles. 
An effective amount means that enough hydroxy-aluminum is present to 
saturate the clay and to gel the water in or added to the clay by the 
solution. This usually requires that at least about 5 ml of 
hydroxy-aluminum solution of at least 4 molar concentration per 100 grams 
clay soil wet weight be used to get some benefits of the present 
invention. It is noted, however, that clays might be encountered where 
somewhat less hydroxy-aluminum solution will be effective. In preferred 
form the hydroxy-aluminum solution should be at least 6 molar 
concentration. It is highly preferred that the hydroxy-aluminum solution 
be as concentrated as possible without causing premature gelling. Thus, 
concentrations of 8 to 10 molar are often highly preferred. The potassium 
chloride is useful in diffusing into the undisturbed clay and should be 
present in sufficient amount to accomplish the desired diffusion. This is 
also generally at least 4 molar and often it is desirable to use higher 
concentrations of potassium chloride. 
Typically, the size, i.e. the volume of a desired pile to be formed in the 
clay containing deposit, is determined and the wet weight of the clay soil 
within such pile is determined. A solution having at least 4 molar 
concentration of hydroxy-aluminum and potassium chloride is admixed with 
the clay soil. 
OBJECTS OF THE INVENTION 
It is a particular object of the present invention to provide a method of 
stabilizing a clay containing soil deposit by admixing with selected 
portions of the clay soil in the deposit an effective amount of 
hydroxy-aluminum and potassium chloride solution having a concentration of 
at least 4 molar which reacts with the clay to form pile like intrusions 
in the clay deposit to anchor the deposit and thus provide stability to 
the deposit. Additional objects and advantages of the present invention 
will become apparent from reading the following detailed description in 
view of the accompanying drawings which are made a part of this 
specification.

DETAILED DESCRIPTION OF THE INVENTION 
The present invention is directed to stabilizing clay soil by admixing with 
at least portions of such soil an effective amount of a solution of 
chemicals including hydroxy-aluminum and a chemical selected from the 
group consisting of potassium chloride, potassium nitrate, potassium 
sulfate, ammonium chloride, ammonium nitrate and ammonium sulfate. 
Potassium chloride is the preferred chemical for mixture with the 
hydroxy-aluminum. In preferred form a plurality of pile-like deposits are 
formed in situ in the clay soil deposit by admixing with clay a 
hydroxy-aluminum and potassium chloride solution having a concentration of 
at least 4 molar and in an amount of at least 5 ml per 100 grams of clay 
soil wet weight. Best results appear to be obtained when the solution be 
at least 6 molar and preferably be as concentrated as possible without 
premature gelling. For different clays the optimum concentration of 
hydroxy-aluminum may, of course, vary. Optimum concentration for a given 
clay may be determined by simple laboratory tests as herein described. 
Hydroxy-aluminum, useful in accordance with the present invention, has a 
hydroxyl to aluminum ratio of at least 2.0. At low pressure, hydroxyl to 
aluminum ratios of less than 2.2 tend to be so acidic that carbonates 
contained in the clay soil turn to carbon dioxide which causes bubbles 
that are undesired in the present invention. Therefore, in carbonate 
containing soils it is preferred to use hydroxy-aluminum having a hydroxyl 
to aluminum ratio of 2.5 in the present invention. 
Thus, hydroxy-aluminum, useful in the present invention, has the general 
formula Al(OH).sub.n X.sub.3-n where n has a value of at least 2.0 and 
preferably 2.5 to 2.7 and x is an anion selected from the group consisting 
of chloride, bromide, iodide, nitrate, sulfate and acetate. The 
hydroxy-aluminum solutions used in accordance with the present invention 
are aqueous solutions. Hydroxy-aluminum is a commercially available 
chemical and can be obtained, for example, from Reheis Chemical Company of 
Berkeley Heights, N.J. or Hoechst Aktiengesellschaft, Frankfurt am Main, 
West Germany. 
In accordance with the invention the concentration of the hydroxy-aluminum 
solution should be at least 4 molar. Best results are obtained when the 
concentration of the hydroxy-aluminum is 6 molar or greater. Although at 
least one manufacturer indicates that a 6.2 molar solution of 
hydroxy-aluminum is saturated, it has been found that much higher 
concentrations can be used in accordance with the present invention. Thus, 
concentrations of hydroxy-aluminum solution of 9 to 10 molar are useful 
and desirable in accordance with the present invention. The highly 
concentrated solutions will gel more rapidly than the lower, i.e., 6.2 
molar solutions which are very stable and have a long shelf life. However, 
the more concentrated solutions, i.e. 7 to 10 molar, may be prepared in 
the field and have sufficient life before gelling to permit admixing with 
the clay to give beneficial results. The time at which a given 
hydroxy-aluminum solution will gel, depends both on concentration and 
temperature. 
Thus the higher the temperature and the higher the concentration, the 
shorter the gel time will be. A 9 molar solution of hydroxy-aluminum was 
prepared and remained in solution at 74.degree. F. for at least four 
hours. It was then left overnight and when observed sixteen hours later 
had gelled. Simple experiments knowing temperature expected and 
clay-hydroxy-aluminum solution-clay mixing times can be done to permit 
optimizing the molar concentration at the highest possible level. 
Concentration of the other chemical, for example potassium chloride, 
should preferably also be at least 4 molar to get the beneficial effects 
of the invention. 
In a broad form, the present invention contemplates utilizing a solution of 
hydroxy-aluminum and a chemical effective in diffusing into undisturbed 
quick clay. Potassium chloride is the preferred chemical. Other chemicals 
which give beneficial effects of the nature sought include potassium 
nitrate, potassium sulfate, ammonium chloride, ammonium nitrate and 
ammonium sulfate. Salts of nobidium and cesium also exhibit some 
beneficial effects but these are not economically feasible for commercial 
use. 
Broadly, in accordance with the present invention, a solution of at least 4 
molar concentration of hydroxy-aluminum and a chemical selected from the 
group consisting of potassium chloride, potassium nitrate, potassium 
sulfate, ammonium chloride, ammonium nitrate, and ammonium sulfate are 
thoroughly mixed with the clay soil to form pile-like extensions in the 
clay soil. Preferably, the solution is formed with hydroxy-aluminum and 
potassium chloride. Preferably, the mixing with clay is done in situ by a 
suitable mechanical means. In preferred form apparatus, such as 
schematically illustrated in FIGS. 1 and 2, is used to the solution of the 
present invention with the clay soil. 
Referring to FIGS. 1 and 2, a clay soil deposit 10 is shown. An auger-like 
device represented generally by the numeral 12, is shown penetrating the 
clay deposit in bore 14 which will form the pile. The auger 12 includes a 
bit 16 and a hollow drill stem 18. Means (not shown) are provided to 
rotate the auger 12 and to inject solution into and down drill stem 18 for 
mixing with the clay soil 10 in bore 14. 
FIG. 2 shows bit 16 in more detail. The bit is formed by a curved cutting 
element 20 which when rotated mixes the clay soil into which is advanced. 
A plurality of ports 22a, b, etc. are formed in the collar 24 at the lower 
end of drill stem 18. Solution is moved through the ports 22a, etc. and 
contacted with the clay as the auger is rotated and moved up or down into 
and out of the clay deposit. The solution mixes with the clay and reacts 
to stabilize the clay. The reaction is rapid but not immediate so that 
mixing can occur both as the auger is driven down into the earth and as it 
is moved back up the bore. Thus, the chemicals of the present invention 
can be more thoroughly mixed with the clay in situ insuring better 
results. 
FIGS. 3 and 4 show an example of a practical application of the present 
invention. FIG. 3 is a schematic plan view of an example layout of piles 
formed in accordance with the present invention useful in stabilizing a 
clay soil deposit under a roadbed. FIG. 4 is a sectional view taken at 
line 4--4 of FIG. 3. 
A roadbed 40 is illustrated in FIGS. 3 and 4. The roadbed passes over an 
unstable clay deposit indicated generally as 42. In order to stabilize the 
clay deposit 42 sufficiently to bear the stresses imposed by the roadbed 
40 a series of pile-like structures indicated generally as 44a, b, c, have 
been formed by mixing hydroxy-aluminum and potassium chloride with the 
clay soil. Preferably, piles 44a, b, c are formed along the sides of the 
roadbed as well as directly below the roadbed. Note that the piles not 
only serve to support the roadbed from below but also to assist in 
stabilizing the deposit on both sides of the roadbed including the sloping 
side which is supported by piles 44c. 
FIGS. 5 and 6 illustrate another example of a practical application of the 
present invention. FIG. 5 is a schematic plan view of an example layout of 
piles formed in accordance with the present invention useful in 
stabilizing a clay soil formation located under a foundation of a building 
or the like. FIG. 6 is a sectional view taken at line 6--6 of FIG. 5. 
A building foundation is schematically shown in FIGS. 5 and 6 and is 
indicated by the numeral 50. A clay soil deposit 52 is located below the 
foundation 50. A plurality of piles indicated by the numerals 56a, b, c, 
have been formed below, inside and outside of the foundation 50 to 
stabilize the clay deposit. 
A series of laboratory demonstrations involving stabilizing clay were 
conducted utilizing the chemicals of the present invention as well as 
other chemicals. These demonstrations will now be described in detail with 
reference to FIGS. 7-14. FIG. 7 is a schematic sectional view of test 
apparatus utilized in laboratory demonstrations of diffusion effects when 
utilizing the method of the present invention and FIGS. 8-14 are graphs 
showing plots of experimental data useful in understanding the present 
invention. 
Initially, two Norwegian clays were subjected to tests. These were a 
Norwegian quick clay and a marine salt clay. Almost all the present 
demonstration work was done on the Norwegian quick clay. Table 1 below 
sets out the properties of the two clays. 
TABLE I 
______________________________________ 
PROPERTIES OF THE NORWEGIAN QUICK 
CLAY AND MARINE SALT CLAY 
______________________________________ 
Clay Type 
quick salt 
______________________________________ 
Water Content (1% of dry weight - 
Measured on the original clay 
as an average value for each tube) 
35.0-38.3 52 
Shear Strength (kPa - Measured by 
the falling cone method) 
7-10 7.0 
Porewater Chemistry 
pH 7.9-8.2 8.0 
Na (ppm) 150-300 -- 
K (ppm) 10-20 -- 
Ca (ppm) 10-40 -- 
Mg (ppm) 3-20 -- 
Conductive power 6.4 Ohms -- 
CaCO.sub.3 1.4% -- 
Organic carbon 0.6% -- 
Salt content (expressed as N.sub.2 Cl) 
0.4 g NaCl/l 
20 g 
NaCl/l 
Grain size sand 1% 1% 
silt 57% 64% 
Clay 42% 35% 
Mineralogy (clay) (silt) 
Illite/Musc. 
65% 30% -- 
Chlorite 30% 10-15% -- 
Quartz 0-5% 20% 
K-feldspar 15-20% -- 
Plagioclase 
5% 15-20% -- 
______________________________________ 
Aluminum-hydroxy chloride Al(OH).sub.2.5 Cl.sub.0.5 (further noted as 
hydroxy-aluminum) has a stabilizing effect on Norwegian quick clay. The 
quick clay, which is very soft in natural state, is liquid when remoulded. 
After addition of hydroxy-aluminum the admixture will be solid at first, 
then soften somewhat with more silty properties. Within minutes the 
mixture will polymerize and after a few days it will be a hard clay. The 
addition of lime used heretofore in the prior art has a somewhat similar 
effect. However, the difference between hydroxy-aluminum of the present 
invention and lime as stabilizing agents lies in how they act upon the 
surrounding undisturbed quick clay. Hydroxy-aluminum has a stabilizing 
effect some centimeters into the undisturbed clay with a firmness of about 
one-tenth of the admixture. On the other hand, lime has very small effects 
on the undisturbed clay. Compared with KCl which was also used alone 
heretofore, hydroxy-aluminum has a much higher firmness in the mixture, 
but KCl diffuses much faster into the undisturbed quick clay and 
stabilizes the ground to some extent many centimeters from the mixture. It 
has been found that a combination of OH-Al and KCl takes care of the best 
properties of both stabilizing agents and give a hard core with a soft to 
medium undisturbed clay. As a result of attracting water the firmness of 
the hydroxy-aluminum mix will decrease somewhat to about one-third within 
a couple of months, but totally this effect has little influence on the 
beneficial effect of the present invention. 
In general, the laboratory demonstrations were divided into two parts. One 
part was concerned with determination of the optimum mixing ratio (Series 
A1) and the time dependency (Series A2) of dry hydroxy-aluminum and 
hydroxy-aluminum solution. The second part examined diffusion effects from 
a stabilized clay into an undisturbed clay. Liquid and solid 
hydroxy-aluminum as the only stabilizing agent are marked as Series B1and 
Series B2 respectively. Mixed with KCl they are marked Series C1 and C2 
and with methanol D1 and D2. 
The demonstrations of part one show the superiority of utilizing dry 
hydroxy-aluminum over hydroxy-aluminum solution. However, it is recognized 
that hydroxy-aluminum solution does provide substantial beneficial 
effects. Table II sets out the concentrations of hydroxy-aluminum used in 
the A1 series. In this regard note that the A1 refers to the particular 
series; the next number refers to the number of days passed before 
sampling and the latter indicates the segment number counting from the top 
where the test was made. 
TABLE II 
______________________________________ 
In Series Al, with concentration variations, the following 
mixing ratio was used: 
ml 6.2 M OH--Al or 
g OH--Al powder per 100 g 
g OH--Al/100 g 
Series No. 
clay wet weight clay dry weight 
______________________________________ 
Al-la 
5 ml 6.2 M 3.62 
Al-7a 
Al-1b 
5 ml 0.62 M 0.362 
Al-7b 
Al-1c 
5 ml 0.062 M 0.0362 
Al-7c 
Al-1d 
5 ml 0.0062 M 0.00362 
Al-7d 
Al-7e 0.8 1.09 
Al-7f 2.5 3.4 
Al-7g 5 6.8 
Al-7h 10 13.6 
Al-7i 15 20.4 
______________________________________ 
In Series A2, with time variations, only 5 ml 6.2 M OH-Al/100 g clay wet 
weight was used with an experimental duration of 1 h (hour), 1 d (day), 3 
d, 7 d, 30 d, and 100 d. The same procedure was used for the salt marine 
clay illustrated as Series A3 in Table III. 
The clay was mixed and put into a plastic beaker with cover. This was 
covered with plastic films and put aside in a container with N.sub.2 gas 
and stored at 7.degree. C. Shear strength was measured on each sample. 
Some were squeezed and the pore water measured with respect to pH and in a 
few cases Ca, Mg, K, and Na by atomic absorption. 
The results of a series of demonstrations conducted as described are set 
out in Table III below. 
TABLE III 
__________________________________________________________________________ 
Results of the concentration dependent 
experiments (Al), time dependent experiments (A2) 
and experiment with salt marine clay (A3) with dry 
hydroxy-aluminum and hydroxy-aluminum solution 
Shear Strength 
Water Pore Water 
Duration After the Experiment 
Content 
Composition (ppm) 
Code (days) 
Undisturbed (kPa) 
(%) pH 
Ca Mg K Na 
__________________________________________________________________________ 
Al-00 
0 9.8 36.0 7.9 
10.4 
4.0 
13 
170 
Al-1a 
1 18.5 6.1 
Al-1b 
1 5.0 7.2 
Al-1c 
1 0.5 7.7 
Al-1d 
1 &lt;0.1 7.7 
Al-7a 
7 50 
Al-7b 
7 6.5 
Al-7c 
7 1.2 
Al-7d 
7 &lt;0.1 
Al-7e 
7 39 
Al-7f 
7 70 
Al-7g 
7 145 6.9 
6900 
900 
370 
920 
Al-7h 
7 240 
Al-7i 
7 &gt;375 
A2-01 
1h 25 
A2-1 1 18.5 6.1 
A2-3 3 61 4880 
610 
140 
660 
A2-7 7 50 
A2-30 
30 6.7 
6950 
740 
230 
890 
A2-100 
104 60 6.7 
A2-7* 
7 63 6.0 
6670 
720 
170 
790 
A2-30* 
28 75 
A2-100* 
102 78 7.5 
A3-00 
0 7.0 52.2 
A3-01 
1h 0.6 
A3-1 1 0.6 
A3-3 3 0.6 
A3-7 7 0.8 
A3-30 
30 2.4 
A3-100 
100 3.8 
A3-7f 
7 1.9 8.0 
260 
680 
240 
6300 
__________________________________________________________________________ 
The results shown in Table III show that results obtained with dry 
hydroxy-aluminum is superior to the results obtained with hydroxy-aluminum 
solution. The concentration of hydroxy-aluminum admixture varied from 
0-15% of clay wet weight (or 0-20% dry weight) (Series A1). The results 
presented in drawing in Table III show that the shear strength varies from 
that of liquid (&lt;0.1 kPa) to a hard compacted clay (&gt;375 kPa) when the 
admixture of hydroxy-aluminum rises. A comparison of the liquid admixture 
with the dry admixture shows that the addition of water together with 
hydroxy-aluminum decreases the stabilizing effect. 
Small additions of dry hydroxy-aluminum (up to about 5%, i.e. 8% dry 
weight) turns the clay plastic immediately. While small addition of 
hydroxy-aluminum gave plastic clay immediately, increased addition gave at 
first a stiffer clay that within a minute of mixing turns looser. Then it 
got a silty character and changes slowly into a harder clay. If the solid 
hydroxy-aluminum is not sufficiently mixed, it will attract water and make 
a brittle gel. 
Clay and hydroxy-aluminum solution were mixed at the standard ratio of 5 ml 
of 6.2 M OH-Al to 100 g of clay wet weight and put aside for 1 h (hour), 1 
d (day), 3 d, 7 d, 30 d, and 100 d. Shear strength tests were carried out 
and the results are given in drawing in Table III. Tests marked with * are 
carried out later than the others on perhaps less oxidized clay. It is 
noteworthy that the shear strength is raised above that of the undisturbed 
clay after only a few minutes. 
Salt marine clay and OH-Al were mixed at standard ratio of 5 ml of 6.2 M 
OH-Al to 100 g of clay (wet weight) and put aside for 1 h (hour), 1 d 
(day), 3 d, 7 d, 30 d, and 100 days. Shear strength was measured and the 
results are presented in drawing in Table III. Because of the very high 
water content in the clay, additional water from liquid OH-Al made the 
clay liquid. Within 100 days the remoulded salt marine clay never reached 
the original shear strength. The results will obviously be better with dry 
hydroxy-aluminum in this case. 
The part two demonstrations to illustrate diffusion effects from the 
stabilized clay will now be discussed in detail. The diffusion experiments 
there utilized small brass cylinders 35 mm in diameter with varying height 
as schematically illustrated in FIG. 7. The cylinders were sealed in the 
bottom and the uppermost 5 cm above the top of the undisturbed quick clay 
were filled with the mixture. As indicated in Table IV below, in the 
indicated series the remoulded clay mixture comprised: 
TABLE IV 
______________________________________ 
B1 5 ml 6.2 M OH--Al/100 g clay wet weight 
B2 15 g OH--Al powder/100 g clay wet weight 
C1 5 ml 6.2 M OH--Al + 9.5 g solid KCl/100 g clay wet 
weight 
C2 15 g OH--Al powder + 9.5 g solid KCl/100 g clay wet 
weight 
D1 5 ml 6.2 M OH--Al + 5 ml methanol/100 g clay wet 
weight 
D2 15 g OH--Al powder + 5 ml methanol/100 g clay wet 
weight 
______________________________________ 
The samples were sealed with plastic and put aside for 7 d (days), 30 d, 
and 100 d in an N.sub.2 filled container at 7.degree. C. The consistency 
of the mixtures caused only small problems. The remoulded clay in the B 
series was liquid, in the C series dry and plastic, and in the D series 
wet and plastic. 
After storage the clay columns were pushed out and shear strength measured. 
Afterwards the clay was cut into slices 2.5 cm each. Out of each slice, 
one part was measured with regard to water content, and another part 
squeezed and measured with regard to pH and analyzed for Ca, Mg, K, and Na 
in pore water by atomic absorption. 
Tables V through IX below and FIGS. 8-14 illustrate the results of these 
demonstrations. 
In these tables the series number is followed by a specimen number 
indicating the experimental duration in days. A third number indicates the 
segment number, counted from the top of the cylinder downwards. For 
instance, C2-30-8, where C-2 denotes solid OH-Al mixed with KCl, 30 
denotes 30 days' duration and 3 denotes the third segment from the top. 
Each segment is measured with regard to shear strength. The method applied 
is the falling cone method, where a sharp cone penetrates by its own 
gravity into the clay. Millimeters of penetration are transformed into kPa 
(kN/m.sup.2) by a standard curve. Other measured parameters were water 
content (in % of dry weight), pH, and Ca-, Mg-, K-, and Na-content of the 
squeezed pore water. The elements were measured by atomic absorption with 
a precision that may reach an uncertainty of .+-.60% in some of the 
results. As a reference for the experiments, the natural quick clay was 
analyzed with regard to mineralogy, grain size distribution, cation 
exchange capacity, inorganic and organic carbon and salt content. 
TABLE V 
__________________________________________________________________________ 
Results of the Diffusion Experiments with Hydroxy-aluminum 
OH--Al Solution (B1) and Dry Hydroxy-aluminum (B2) 
Shear Strength 
Water 
Duration After the Experiment 
Content 
Pore Water Composition (ppm) 
Code (days) 
Undisturbed (kPa) 
(%) pH 
Ca Mg K Na 
__________________________________________________________________________ 
B1-7-1 
7 63 44.3 7.6 
B1-7-2 63 43.1 6.7 
5000 
1410 
150 750 
B1-7-3 14 31.6 7.3 
610 
270 64 610 
B1-7-4 11.7 34.8 200 
89 44 440 
B1-7-5 36.6 
B1-7-6 9.2 36.8 
B1-30-1 
28 73 44.5 
B1-30-2 63 47.9 7.1 
5010 
500 5700 
510 
B1-30-3 22 33.2 3520 
530 2570 
610 
B1-30-4 23 36.0 7.9 
660 
270 330 500 
B1-30-5 21 37.0 
B1-30-6 15 37.8 
B1-100-1 
100 52 44.3 
B1-100-2 73 44.5 7.8 
4020 
450 110 720 
B1-100-3 14 33.2 7.4 
3600 
480 88 960 
B1-100-4 11 36.3 8.3 
2260 
460 99 610 
B1-100-5 10 37.2 8.3 
1480 
390 75 670 
B1-100-6 15 38.2 8.3 
780 
400 86 710 
B2-7-1 
7 310 33.9 
B2-7-2 310 40.7 
B2-7-3 27 34.2 3720 
610 110 680 
B2-7-4 25 35.8 7.3 
370 
98 27 440 
B2-7-5 15 36.3 7.6 
31 
5.2 13 200 
B2-7-6 24 34.3 7.8 
65 
6.2 18 200 
B2-30-1 
30 140 40.4 
B2-30-2 98 43.5 
B2-30-3 25 36.9 6.5 
3550 
660 270 810 
B2-30-4 31 38.0 7.9 
760 
350 110 750 
B2-30-5 27 35.7 8.1 
160 
140 60 620 
B2-30-6 23 35.0 8.5 
28 
21 77 450 
B2-100-1 
100 90 44.6 
B2-100-2 125 42.7 
B2-100-3 40 35.6 7.2 
6120 
870 200 1210 
B2-100-4 52 34.3 7.2 
2200 
420 100 850 
B2-100-5 32 33.1 1850 
580 200 950 
B2-100-6 20 33.5 1150 
530 220 1040 
__________________________________________________________________________ 
TABLE VI 
__________________________________________________________________________ 
Results of the Diffusion Experiments With 
Hydroxy-aluminum Solution and Potassium Chloride 
Shear Strength 
Water 
Duration After the Experiment 
Content 
Pore Water Composition (ppm) 
Code (days) 
Undisturbed (kPa) 
(%) pH 
Ca Mg K Na 
__________________________________________________________________________ 
C1-7-1 
7 26 55.4 
C1-7-2 31 52.0 6.0 
4260 
540 
64700 
600 
C1-7-3 26 34.4 7.0 
2390 
560 
39500 
620 
C1-7-4 15 33.3 8.2 
770 500 
12000 
780 
C1-7-5 10 36.0 8.6 
250 170 
960 
520 
C1-7-6 9.5 36.8 63 121 
580 
210 
C1-30-1 
30 72 42.9 6.5 
5080 
580 
58500 
740 
C1-30-2 55 43.4 
C1-30-3 53 32.7 
C1-30-4 33 35.5 6.8 
1470 
560 
21800 
820 
C1-30-5 31 36.5 710 470 
7740 
570 
C1-30-6 32 36.7 6.7 
520 370 
1610 
590 
C1-30-7 27 36.5 6.8 
270 180 
450 
520 
C1-30-8 16 37.1 7.1 
74 34 
48 
370 
C1-30-9 15 35.2 
C1-30-10 3.0 38.1 7.8 
45 8.0 
40 
240 
__________________________________________________________________________ 
TABLE VII 
__________________________________________________________________________ 
Results of the Diffusion Experiments With 
Dry Hydroxy-aluminum and Potassium Chloride 
Shear Strength 
Water 
Duration After the Experiment 
Content 
Pore Water Composition (ppm) 
Code (days) 
Undisturbed (kPa) 
(%) pH 
Ca Mg K Na 
__________________________________________________________________________ 
C2-7-1 
7 280 32.0 
C2-7-2 &gt;375 36.1 
C2-7-3 33 33.7 7.3 
2880 
670 32700 
820 
C2-7-4 31 35.6 8.0 
570 
420 6800 
630 
C2-7-5 18 37.3 7.6 
105 
64 180 
380 
C2-7-6 11 34.9 7.8 
37 
5.3 21 
180 
C2-30-1 
30 310 37.9 
C2-30-2 375 38.6 
C2-30-3 30 34.8 7.6 
4160 
800 52000 
960 
C2-30-4 36 34.4 7.7 
1540 
630 26400 
880 
C2-30-5 30 36.9 
C2-30-6 27 40.5 8.4 
450 
380 3840 
710 
C2-30-7 31 34.4 
C2-30-8 12 38.1 8.3 
38 
15 39 
340 
C2-30-9 11 35.8 
C2-30-10 15 7.5 
19 
5.1 20 
270 
C2-100-1 
100 95 44.4 
C2-100-2 240 45.0 
C2-100-3 29 33.6 7.6 
3620 
890 35500 
1210 
C2-100-4 39 37.3 
C2-100-5 39 38.4 8.0 
1700 
660 20200 
1000 
C2-100-6 42 34.8 
C2-100-7 42 39.9 8.2 
660 
470 5780 
750 
C2-100-8 24 34.9 
C2-100-9 23 37.3 8.3 
360 
300 1240 
620 
C2-100-10 23 36.0 
C2-100-11 19 36.9 8.3 
54 
36 79 
440 
C2-100-12 14 37.2 
C2-100-13 11 38.2 8.3 
25 
6.8 53 
280 
C2-100-14 8.3 33.8 8.3 
150 
9.0 69 
350 
__________________________________________________________________________ 
TABLE VIII 
__________________________________________________________________________ 
Results of the Diffusion Experiments with 
Hydroxy-aluminum Solution and Methanol 
Shear Strength 
Water Pore Water 
Duration After the Experiment 
Content 
Composition (ppm) 
Code (days) 
Undisturbed (kPa) 
(%) pH 
Ca Mg K Na 
__________________________________________________________________________ 
D1-7-1 
7 26 55.4 
D1-7-2 31 52.0 6.0 
4400 
500 
93 440 
D1-7-3 26 34.3 7.0 
1480 
300 
64 460 
D1-7-4 15 33.3 8.2 
150 
56 
28 360 
D1-7-5 10 36.0 8.6 
58 
13 
16 190 
D1-7-6 9.5 36.8 
D1-30-1 
29 31 56.7 
D1-30-2 31 49.6 6.9 
3530 
430 
82 390 
D1-30-3 22 51.7 7.7 
2130 
380 
61 430 
D1-30-4 21 38.6 8.0 
840 
280 
47 440 
D1-30-5 19 36.9 
D1-30-6 9.1 37.4 8.3 
62 
12 
15 280 
D1-30-7 10 36.7 
D1-30-8 7.6 37.6 8.1 
17 
4.5 
14 170 
D1-30-9 7.8 35.9 
D1-30-10 9.2 38.8 8.2 
12 
4.0 
13 170 
D1-100-1 
105 &lt;0.1 89.9 
D1-100-2 39 52.0 6.1 
2850 
420 
150 
660 
D1-100-3 15 38.4 6.5 
2360 
420 
130 
710 
D1-100-4 18 39.1 7.0 
1370 
370 
94 760 
D1-100-5 15 39.4 7.3 
970 
330 
106 
810 
D1-100-6 11 35.9 7.5 
310 
220 
83 770 
__________________________________________________________________________ 
TABLE IX 
__________________________________________________________________________ 
Results of the Diffusion Experiments with 
Solid Dry Hydroxy-aluminum and Methanol 
Shear Strength 
Water Pore Water 
Duration After the Experiment 
Content 
Composition (ppm) 
Code (days) 
Undisturbed (kPa) 
(%) pH 
Ca Mg K Na 
__________________________________________________________________________ 
D2-7-1 
7 125 42.7 
D2-7-2 90 49.8 
D2-7-3 41 35.4 7.9 
1630 
380 
52 600 
D2-7-4 24 36.0 8.3 
230 
110 
38 470 
D2-7-5 13 37.0 8.4 
25 
5.9 
14 170 
D2-7-6 7 34.9 8.5 
22 
5.6 
45 150 
D2-30-1 
30 48 49.7 
D2-30-2 27 55.9 
D2-30-3 33 34.7 7.4 
4200 
540 
102 
720 
D2-30-4 35 35.1 8.2 
930 
290 
63 690 
D2-30-5 27 36.3 
D2-30-6 18 39.4 8.3 
32 
14 
29 340 
D2-30-7 14 34.0 
D2-30-8 34.8 8.3 
43 
5.8 
25 190 
D2-30-9 7.1 49.0 
D2-30-10 10 35.3 8.5 
40 
3 15 180 
D2-100-1 
102 &lt;0.1 51.5 
D2-100-2 &lt;0.1 33.5 
D2-100-3 49.0 4190 
710 
200 
630 
D2-100-4 34.2 2250 
550 
160 
740 
D2-100-5 34.0 1350 
500 
170 
860 
D2-100-6 33.0 1530 
530 
180 
960 
__________________________________________________________________________ 
In the demonstrations of part 2 and as shown in Tables V-IX above and FIGS. 
8-14, cylinders of undisturbed quick clay were used. The length of the 
cylinders varied from 10 to 30 cm. Some of them contained silty layers, 
which caused varying shear strength and water content, and most probably 
also somewhat affected the diffusion. 
The inhomogeneity of the cylinders may cause disturbances both when the 
clay is pushed into the cylinders and out of them. Sometimes the 
disturbances caused drainage of water, that was gathered at the bottom. 
Oxidation of the clay was depressed because the cylinders were stored in 
N.sub.2 atmosphere at 7.degree. C. 
As shown in FIG. 7 the remoulded clay stabilized with either 
hydroxy-aluminum and KCl or hydroxy-aluminum and methanol or 
hydroxy-aluminum alone was placed at the top of the cylinders. Then the 
cylinders were sealed with several plastic layers and put aside for 7, 30 
or 100 days. At the end of each run the clay was pushed out and the 
various parameters measured down the cylinder. 
When remoulded and mixed with (6.2 M) hydroxy-aluminum solution, the clay 
turns stiff (60 kPa) and remains stiff (50-80 kPa) throughout the testing 
period. Table V and Table VI, show rather low shear strength values in the 
undisturbed clays caused by diffusion. The efficiency and the penetration 
of the stabilizing effect in the undisturbed clay are not clear. 
The water content shows that the hydroxy-aluminum admixture draws the water 
out of the undisturbed clay. This effect is also observed in all the other 
experiments. Another parameter with much the same development in all 
experiments is the pH value. Hydroxy-aluminum has an acidic reaction, 
which penetrates to some extent down the column, but will be neutralized 
by time. 
The pore water chemistry is much the same in the three experiments. There 
are two exceptions: Extremely high potassium release in B1-30 series and 
high magnesium content in B1-7 series. 
Remoulding of the quick clay with hydroxy-aluminum apparently releases a 
substantial amount of cations to the pore fluid. For instance the 
potassium concentration increases by a factor of nearly 10, magnesium by 
about 100 and calcium by more than 200. The resulting concentration 
difference between the remoulded and the undisturbed clay, subsequently 
drives the diffusion of these cations into the undisturbed clay. 
Dry hydroxy-aluminum admixture gives much better geotechnical results 
compared to hydroxy-aluminum solution admixture. The remoulded clay 
immediately gets a higher shear strength which with time reduces to about 
1/3 of the original shear strength value as shown in Tables V, VI, VII and 
VIII. The stabilizing effect with time on the undisturbed clay are less 
ambiguous with dry hydroxy-aluminum than with hydroxy-aluminum solution. 
The penetration series into the original clay develops a medium strength 
(25-50 kPa) 4-9 cm down the column during the test period. 
Water content measurements confirm the already predicted osmotic effect of 
hydroxy-aluminum. The remoulded clay contains 30% more water than the 
undisturbed clay after 100 days. pH-measurements also confirm the acid 
reaction of hydroxy-aluminum. The difference may be at least 2 pH-units 
from the disturbed to the undisturbed clay. The pore water chemistry 
exhibits much the same trend as described before. The B2-100 series, 
however, shows for unknown reason higher release of Ca, Mg, and Na. 
Compared with hydroxy-aluminum solution dry hydroxy-aluminum releases K 
and Mg to the same extent (factor of 10 and 100), but Ca to a somewhat 
lesser extent; a factor of 100-200. 
As shown in Table VI, admixing (6.2 M) hydroxy-aluminum solution and solid 
KCl gives a stiff remoulded clay with a shear strength of 50-80 kPa which 
is independent of experimental duration. The diffusion of species 
downwards in the undisturbed clay causes a medium stiff clay (25-50 kPa) 
to a depth of 6 cm (B1-7) and 11 cm (B1-30). Compared with 
hydroxy-aluminum solution alone the increased shear strength in the 
undisturbed clay is most probably caused by the diffusion of potassium 
ions. 
Water content measurements indicate that some water drainage has taken 
place in the C1-7 series. Still it is possible to notice the osmotic 
effect of hydroxy-aluminum as indicated above. pH-measurements show a 
great difference between stabilized and undisturbed clay (at least 2.5 
pH-units) at the beginning of the experiments. With time, the acid (H+) 
penetrates down the column and is slowly neutralized. The pore water 
chemistry has no different trends compared with already described 
experiments, except for the great addition of potassium. One dimensional 
diffusion constants have been estimated for K in both experiments in the 
C1 series. Approximate values are 6.times.10.sup.-6 cm.sup.2 sec.sup.-1 
for 7 days experiment and 3.times.10.sup.-6 cm.sup.2 sec.sup.-1 for 30 
days' experiment. The values are approximate because of no exact 
information of the reservoir concentration, or of the constancy of the 
reservoir concentration, the inhomogeneity of the clay and no chemical 
reactions or physical changes of the clay have been taken into account. 
The contents of Mg and Ca in the pore water are much the same as in series 
B1. 
Table VII shows the results of dry hydroxy-aluminum and potassium chloride 
as stabilizing chemicals. This admixture gives a hard remoulded clay with 
an initial shear strength of 300-400 kPa which decreases during the test 
period to 100-200 kPa. The diffusion of species downward in the 
undisturbed clay causes a medium stiff clay (25-50 kPa) to a depth of 5 cm 
(C2-7), 10 cm (C2-10), and 20 cm (C2-100). It is noteworthy that the 
maximum shear strength in the undisturbed clay increases a little during 
the experimental period. As in series C1, potassium diffusion is the main 
reason for this increased shear strength. 
Water content measurements show the same development as described earlier. 
The water content of the stabilized mixture increases with about 30% from 
7 to 100 days. However, the decreased water content of the undisturbed 
clay is not explicitly expressed in the measurements of the undisturbed 
clay. 
pH-measurements are available from only the undisturbed clay and show only 
a slight increase down the column. This trend is like those described 
before. 
There are no considerable differences between these and the previous 
described pore water chemistry results. The one dimensional diffusion 
coefficients estimated for K in the three experiments were: 
4.times.10.sup.-6 cm.sup.2 sec.sup.-1 (C2-7), 4.times.10.sup.-6 cm.sup.2 
sec.sup.-1 (C2-30), and 3.times.10.sup.-6 cm.sup.2 sec.sup.-1 (C2-100). 
The content of Ca and Mg in pore water are much the same as B2 series. 
Demonstrations were conducted with hydroxy-aluminum solution containing 
methanol. The results are given in Table VIII. This admixture gives a 
rather soft remoulded clay which partly turns liquid during the test 
period (D1-100). The stabilizing effect of diffusing substances seems 
rather small. Only the uppermost 1 cm of the undisturbed clay has shear 
strength above 25 kPa in the beginning of the period, while some 
additional centimeters give values between 15 and 25 kPa. These results 
are not far from the B1 series which indicates that any positive effect of 
added methanol must be insignificant. 
Water content measurements are ambiguous in showing the water attracting 
tendencies, probably because of additional liquid content in methanol. The 
pH-measurements show clearly a pH-gradient with H+ diffusion from the 
source down the column. The pore water chemistry values are very similar 
to those previously described. 
Demonstrations were also conducted with dry hydroxy-aluminum with methanol 
as a stabilizing agent. The results are shown in Table IX. This admixture 
gives a stiff to very stiff (approximately 100 kPa) remoulded clay mixture 
within 7 days. After 30 days however, the shear strength has dropped to 
that of a medium clay (about 40 kPa). Unfortunately the D2-100 series was 
destroyed and no shear strength results were obtained from it. It is 
noteworthy that the upper 3 centimeters of the remoulded clay was turned 
liquid, the next centimeters very soft and the last centimeters stiff or 
very stiff. In the undisturbed clay shear strength increased to that of a 
medium clay (25-50 kPa) 4 cm down the column in 7 days and 7 cm in 30 
days. It was impossible to estimate the penetration in the D2-100 series. 
Water content measurements show great irregularities, but it is obvious 
that the admixture attracts water and even makes the remoulded clay 
liquid. The pH-gradients have the same trends as described before. The 
pore water chemistry also shows the same concentrations and trends as in 
the other series with dry hydroxy-aluminum. Specially for D2 series, 
however, is the penetration of species into the undisturbed clay somewhat 
slower. 
FIG. 8 shows a comparison of hydroxy-aluminum solution alone and with 
various additives after 7 days. The hydroxy-aluminum solution admixture 
gives a stiff clay mixture (65 kPa) after 7 days. The addition of KCl 
causes no changes, but the addition of methanol reduces the shear strength 
to about 30 kPa probably due to increased liquid addition. In the 
undisturbed clay the hydroxy-aluminum solution causes a very small 
increase in shear strength and only to a depth of a few centimeters. The 
addition of methanol gives a little more efficient increase of the shear 
strength in the same few upper centimeters. The addition of KCl increases 
shear strength to a greater depth than the two others. The reason is most 
probably the addition of potassium, but some of the shear strength 
increase could have been caused by the released diffusing species like Ca 
and Mg. 
FIG. 9 shows a comparison of dry hydroxy-aluminum alone and with various 
additives after 7 days. Dry hydroxy-aluminum admixture increases the shear 
strength of the remoulded clay to about 300 kPa (hard clay). Admixture of 
dry hydroxy-aluminum and KCl gives about the same shear strength, while 
addition of hydroxy-aluminum together with methanol only results in a 
shear strength of 100 kPa. The lower strength obtained with methanol, is 
obviously caused by the liquid addition. 
The increase of shear strength in the undisturbed clay are much the same in 
all three experiments with a medium stiff clay (25-50 kPa) down to 4-5 cm. 
The differences between the series with and without KCl are also shown by 
the pore water chemistry where Ca, Mg, and K almost everywhere are higher 
in the KCl addition experiment. Why the shear strength in the D2 series 
lies above all the other, may be caused either by the Ca-concentration in 
the pore water or by the methanol content. 
FIG. 10 shows a comparison of hydroxy-aluminum solution alone and with 
various additives after 30 days. Hydroxy-aluminum solution addition gave 
shear strength of about 70 kPa in the remoulded clay (drawing 036), nearly 
the same as hydroxy-aluminum solution and KCl admixture (about 60 kPa), 
while hydroxy-aluminum solution with methanol addition only reached 30 
kPa. 
In the undisturbed clay hydroxy-aluminum solution with or without methanol 
addition follow each other to a great extent. They have a strength of 
about 20 kPa 7-8 cm down the column even if the pore water chemistry of 
the series are not the same. Hydroxy-aluminum solution and KCl admixture 
is much more efficient than the other since it gives a medium stiff clay 
11 cm down the column. Except for the first two centimeters the pore water 
content of Ca, Mg, and of course K are much greater in the C1-30 series 
than in the others, and this may be the reason why the shear strength 
values are much higher. 
FIG. 11 shows dry hydroxy-aluminum data after 30 days. Dry hydroxy-aluminum 
admixtures give greater spreading in the shear strength values for 
different additions. Dry hydroxy-aluminum admixture gives about 100 kPa in 
the remoulded clay (drawing 037) while hydroxy-aluminum and KCl additions 
are much more efficient with 300-400 kPa. On the other hand 
hydroxy-aluminum and methanol admixture causes lower shear strength: 30-60 
kPa. 
In the undisturbed clay the hydroxy-aluminum and methanol admixture are 
most efficient the first 2 cm (about 35 kPa) just like the 7 days series. 
For the next 7 cm gives the hydroxy-aluminum and KCl admixture the 
greatest shear strength (25-35 kPa). There is a greater difference between 
the shear strength of the different admixtures after 30 days than after 7 
days. In this series (B2-30, C2-30, and D2-30) there is no obvious 
connection between shear strength in undisturbed clay and pore water 
chemistry like that described before. 
FIGS. 12 and 13 show comparison of the different stabilizing agents after 
100 days. Hydroxy-aluminum solution admixture gives a stiff clay (50-80 
kPa) even after 100 days, while the hydroxy-aluminum solution and methanol 
admixture gives varied values from that of a liquid (&lt;0.1 kPa) in the 
uppermost 3 cm to 40 kPa in the lower 2 cm. The experiment with 
hydroxy-aluminum solution and KCl was not carried through. 
The undisturbed clay are affected only to a small extent by the mixtures. 
The shear strength scarcely exceed 15 kPa to a depth of about 7 cm in 
hydroxy-aluminum solution and methanol admixture and only about 1 cm with 
the hydroxy-aluminum solution alone. There is a decrease of the shear 
strength in the undisturbed clay from 7 and 30 days experiments with 
hydroxy-aluminum solution. 
As shown in FIG. 13, dry hydroxy-aluminum addition to quick clay gives a 
shear strength that increases from 90 to about 400 kPa from the top to 
bottom of the remoulded clay. This result is not far from the addition of 
dry hydroxy-aluminum and KCl which varies within the same values. The 
experiment with dry hydroxy-aluminum with methanol was destroyed and shear 
strengths were not obtained. In this case the uppermost 3 cm were in a 
liquid state. 
In the undisturbed clay the shear strength exceed that of 30 days series to 
some extent. With dry hydroxy-aluminum alone the shear strength varied 
from 20-50 kPa to a depth of 9 cm, 4 cm of this exceed 40 kPa. On the 
other hand, admixture of dry hydroxy-aluminum and KCl shows shear strength 
between 25 and 50 kPa to a depth of 14 cm and higher than 20 kPa for 
additional 7 cm. There is a relatively good correlation between shear 
strength and pore water content of Ca, Mg, and K. 
FIG. 14 shows a comparison of solid dry hydroxy-aluminum alone; KCl; and 
CaO stabilization after 100 days. Comparison of shear strength in the 
remoulded clay shows that dry hydroxy-aluminum admixture reaches a 
stiffness that exceeds that of CaO. This may be a coincidence because 
other mixing ratio and better tamping may increase the shear strength. KCl 
alone gives no stabilization effects. 
In the undisturbed clay the stabilization effect is limited. Within 3 cm 
the shear strength below the CaO-stabilized clay drops from 100 to 20 kPa. 
With dry hydroxy-aluminum it drops from 50 to 20 kPa, 9 cm down the column 
while KCl have 20-25 kPa to a depth of 19 cm. The increased shear strength 
in the undisturbed clay is in CaO stabilization caused by the great water 
absorbing effect of lime. Hydroxy-aluminum has also as earlier described, 
a water attracting effect, but in this case the effect goes deeper into 
the column, probably because of higher cation content. In the lime 
stabilization experiment, the water transport upwards is camouflaged by 
the chemical reaction CaO+H.sub.2 O.fwdarw.Ca(OH).sub.2, which binds a 
large amount of water. KCl has probably no effect on the water content. 
Hydroxy-aluminum and potassium chloride solution having at least 4 molar 
concentration is a very promising stabilizing agent. As a practical matter 
at least a 6 molar solution should be used. Optimum results may be 
obtained at even high concentrations. An increased hydroxy-aluminum 
concentration is expected to give a further increase of the shear strength 
in the remoulded clay. Surprisingly, in the remoulded clay KCl does not 
reduce the effect of the strength attained by hydroxy-aluminum alone. In 
the undisturbed clay where hydroxy-aluminum has less effect, KCl diffuses 
relatively fast and causes stabilized zone deeper into the clay. This 
property of KCl is not interfered with by hydroxy-aluminum. 
From the above description it is evident that the present invention 
provides a method of stabilizing clay of said deposits by hydroxy-aluminum 
and potassium solution with the clay soil. Although only specific 
embodiments of the present invention have been described in detail, the 
invention is not limited thereto but is meant to include all embodiments 
coming within the scope of the appended claims.