Ehime University Institutional Repository

Ehime University (愛媛大学)博士(医学)doctoral thesi

竹本, 幸司

TAKEMOTO, Koji

English

Adiponectin/resistin levels and insulin resistance in children: a four country comparison study

山口, 正隆

野中, 浩一

宇都宮, 好博

畑田, 佳男

Japanese

第3世代波浪推算モデルSWANの基本挙動の調査

海面抵抗係数とToba定数の変動に関する考察

三浦, 和尚

大学教員による提案的授業実践の意義 : 地域貢献と授業改善と

田邉, 隆

福富, 彩子

音楽表現の可視化に関する研究

苅田, 知則

樫木, 暢子

中野, 広輔

石丸, 利恵

薬師神, 裕子

吉松, 靖文

重症心身障害児に適切に対応できる特別支援教育教員養成プログラムの開発 : 医療的ケアを中心とした学際的知識・技能の養成

Ehime University (愛媛大学)博士(工学)thesi

MATEBIE, METEN ENDALEW

GIS-based Landslide Susceptibility Modeling in the Blue Nile Gorge, Jema River Gorge and Debre Sina areas of the Central Ethiopian Highlands

DEBENDRA, NEUPANE

1 
 
Dissertation Summary 
氏   名 (Name): Neupane Debendra 
論 文 名：   Evaluation of insitu mineralized carbonate grout to improve the 
(Dissertation Title)  engineering properties of soils and other porous materials 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
The mechanical properties of soils may not be adequate for the civil engineering structures 
to be founded on it. Soil improvement is necessary in places where the soils do not meet 
the engineering requirements.  
A mineralized carbonate grouting has been evaluated as a potential soil improvement 
technique. This technique employs enzyme of urease to hydrolyze urea. Dissolved urea 
dissociates into ammonium ion and carbonate ion in the presence of urease Eq. (1). 
Calcium ion, supplied with the solution of soluble calcium salt (i.e., CaCl2) combines with 
the carbonate ion insitu. The reaction in turn brings about the insoluble calcium carbonate 
Eq. (2) . The calcium carbonate, precipitates as white mass, is supposed to cement the soil. 
The cementation is expected to improve the physical and mechanical properties of loose 
sandy soil. A schematic representation of the whole process of this technique is shown in 
Figure 1. 
2
2 2 2 4 3CO(NH ) 2H O 2NH +CO
   , 
2 2
3 3Ca +CO CaCO
     ,   
A series of experiments are conducted. First series of experiments are conducted to 
evaluate the rate and quantity of the precipitation. Direct and indirect analyses are 
(1) 
(2) 
2 
 
conducted in test tube scales. Various combinations of urea solutions and urease solution 
are mixed in PP, polypropylene, tubes for indirect analysis. When urea is dissociated into 
ammonium and carbonate ions, the pH of solutions should increase by corresponding to the 
production of ammonium ions. Therefore, the measurements of evolution in pH with time 
may define indirectly the rates and magnitude of the urea dissociation. Again, the 
equimolar urea-CaCl2 solution and urease solution are mixed in PP tubes for the direct 
evaluation of the amount of the precipitated material. An appreciable precipitation ratio 
(i.e., up to 85%) is obtained. The X-ray Diffraction analysis of the precipitated material is 
shown in Figure 2. A clear XRD pattern of calcite is observed in the figure. It proves that 
the precipitated materials are the crystals of calcite as expected. 
Second series of experiements are conducted for evaluating the efficacy of the grout to 
improve the mechanical properties of sandy soils. Small scale sand specimens, prepared in 
PVC molds, are treated with grout. The grout is allowed to react within the specimens for 
one day at room temperature. The improved mechanical properties of the cured samples 
are evaluated. Table 1 summarizes the experiemtnal conditions for the samples preparation. 
Figure 3 summarizes the unconfined compressive strengths of a few improved samples. 
As is apparent in the figure, an appreciable increase in compressive strength is obtained 
with the treated samples. A maximum compressive strength of 1.6 MPa and an E50 of up to 
160 MPa is obtained.  
Third series of experiemtns are conducted to explore the prospects of this technique for the 
real site application. Larger scale experiments are conducted in drum-cans utilizing the 
suitable grout. Grout is injected into the center of the sand specimens prepared in a drum-
can with a diameter of 56 cm and a height of about 80 cm. Three sampling tubes are 
inserted into the drum-can vertically to collect the sand samples from various locations, 
and to quantify the calcite precipitated at these locations. 
Various calite quantification methods, that are based on the basic principles of chemistry, 
are evaluated. Among these methods, CO2 Volume Evaluation method (CVE) is found to 
be the most simple and reliable one. In this method, known mass of the treated sand is 
allowed to react with acid, and the CO2 gas, produced by the reaction of the acid with 
calcite is collected and measured. Calcite is quantified by comparing the produced gas with 
a comparison graph prepared beforehand. The schematic of the CVE method and the 
comparison graph are shown in Figures 4 and 5 respectively.   
 
 
 
3 
 
 
 
 
Table 1. Experimental conditions for unconfined compression experiments 
Sample case Sample name 
Concentration 
[mol/L]
*
 
Injection 
number 
Urease [g]
**
 
C1 bio-1, 4, 6 0.5 8 1.0 
C2 bio-2, 5 1.0 4 1.0 
C3 bio-3, 7 0.5 8 0.5 
*Concentrations of CaCl2-urea solutions 
**Urease is mixed with 300 g of sand. 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Figure 1. Schematic of calcium carbonate precipitation process 
and grouting mechanism [Yasuhara et al. 2012] 
Calcite
Bare sand
Urea
CO(NH2)2CaCl2
Ca2+Cl－ NH4
+CO3
2－
Urease
Calcite-precipitated sand
Input solution
4 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Figure 2. XRD pattern of the precipitated material 
[Neupane et al. 2013] 
Figure 3. Stress-strain curves of improved sand samples 
 [Yasuhara et al. 2012]  
0
50
100
150
200
0 10 20 30 40
In
te
n
s
it
y
 [
c
p
s
]
Deviation angle, 2 [o]
5 
 
 
 
  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Figure 4. Schematic representation of CVE method [Neupane et al. 2015] 
0
40
80
120
160
0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7
Experiment
Theoretical
V
o
lu
m
e
 o
f 
C
O
2
 g
a
s
 [
c
m
3
]
Mass of calcite [g]
Figure 5. Comparison curve for CVE method [Neupane et al. 2015] 
% Error = 5% 
6 
 
 
 
 
 
 
 
 
 
The unimproved or partially improved sand is removed by a gentle spray of water. 
Samples are collected form the improved block for strength evaluations. The blocks are 
thoroughly washed and cut into 8 cm long cylindrical samples with a diameter of 3 cm as 
shown in Figure 6. The maximum compressive strength of about 400 kPa is obtained.  
A multiphysics simulator that considers the calcite precipitation reaction during the 
transport of solution is adopted to predict the amount of the precipitated calcite on sand. 
TOUGHREACT, developed by the Lawrence Berkeley National Laboratory, which 
considers the transport of species by the advection-diffusion process, is followed. This 
simulator is capable of dealing with the mineral precipitation under either local equilibrium 
or kinetic controls, along with coupling the changes in porosity. All the mathematical 
formulations are described in detail by Xu et al. [2004].  The important processes and 
calculations are summarized in this section. 
This simulator considers the transport of aqueous species by advection and molecular 
diffusion, which can be mathematically expressed as shown in Eq. 3. 
  2( )j j j n
C
uC D C R
t



    

  , 
where ф [-] is the porosity, Cj [mol/m
3
] is the concentration of aqueous chemical 
component j, u [m/s] is the Darcy velocity, τ [-] is the medium tortuosity, and D [m
2
/s] is 
the diffusion coefficient. Rn [mol/m
3
/s] is the reaction term (i.e., calcium carbonate 
precipitation reaction), which is expressed as shown in Eq. (4). 
Figure 6. Improved sample in drum-can experiment [Neupane et al. 2015] 
 
(3) 
7 
 
1n n n w nR k A

   , 
Where kn [mol/m
2
/s] is the precipitation rate constant, An [m
2
/kg] is the specific reactive 
surface area per kg H2O, ρw [kg/m
3
] is the water density, and  
n [-] is the kinetic mineral 
saturation ratio. Parameters θ and n are the constants; they are considered unity for calcite 
precipitation.  
Comparison between experimental result and prediction 
Domains with the dimension equal to the dimension of the experimental specimen are 
created for predicting the amount of precipitated CaCO3. The equal volume of injection 
and the specimen concentrations used in the experimental work. The distribution of calcite 
at various vertical and horizontal locations are predicted and plotted along with the 
experimental result. The comparison between the experimental and predicted calcite 
distribution is shown in Figures 7, 8 and 9. As is apparent in these figures the prediction is 
in fairly close agreement with the experimental results. The prediction and experimental 
result follows the same trends. 
 
 
 
 
 
 
 
 
 
 
 
 
(4) 
Figure 7. Vertical distribution of calcite near centre [Neupane et al. 2015] 
0
2
4
6
8
0 10 20 30 40 50 60
Experiment
Prediction
C
a
lc
it
e
 c
o
n
te
n
t 
[%
]
Distance from the bottom [cm]
 
 
 
 
 
 
 
 
 
 
8 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
In the fourth series of the experiemtns  attempts are made to further increase the treatment 
area of the grout. The rate of calcite precipitation is the main factor that controls the 
treatment area of this technique. The rate of calcite precipitation is reduced to delay the 
precipitation time and hence to increase the treatment area. 1-m long sand column 
experiments are conducted to evaluate the potential of this technique to achieve a radial 
treatment length of 1 m. The schematic representation of the 1-m long column is shown in 
Figure 10. At first, the distributions of the each grouting material are evaluated separately.  
Figure 9. Calcite distribution on the central vertical plane of drum-can 
(a) experimental result, (b) prediction [Neupane et al. 2015] 
(a) (b) 
Figure 8. Horizontal distribution of calcite at centre [Neupane et al. 2015] 
0
2
4
6
8
0 5 10 15 20 25 30
Experiment
Prediction
C
a
lc
it
e
 c
o
n
te
n
t 
[%
]
Distance from the center [cm]
 
 
 
  
 
 
 
9 
 
The uniform distributions of the urea and CaCl2 are achieved at the first attempt, but the 
uniform distribution of urease is achieved after several attempts. Different experimental 
conditions are summarized in Table 2. The distribution of urea and calcium chloride are 
shown in Figures 11 and 12.  The distribution of urease for different conditions are shown 
in Figure 13. Afterwards, the grout (i.e., all grouting materials mixed together) is injected 
and the distribution of the precipitated calcite is evaluated after 24 hours. The experimental 
conditions for the case of grout injection is shown in Table 3. The calcite distribution 
throughout the sand column is shown in Figure 14. The lower temperature employed is 
likely to delay the rate of precipitation, and consequently to distribute the grout uniformly 
up to a longer distance.  As expected, the calcite is found to be distributed relatively 
uniformly in the case of lower temperature prescribed. The precipitation rate is found to be 
a main factor to control the treatment distance. A uniform distribution of the precipitated 
calcite is achieved over a radial distance of 1 m, expanding the potential of this technique 
for real field applications.  
 
 
 
 
 
 
 
 
 
 
 
 
 
Figure 10. Schematic of the 1-m sand column experiments  
(a) keisa #6, (b) keisa #8 
 
 
 
 
 
 
 
 
 
 
 
    
Tubing 
pump 
 
 
 
 
   
 
 
6
0
 c
m
 
9
8
 c
m
 
9
.8
 
c
m
 
 
 
 
 
(b) (a) 
10 
 
Table 2. Conditions for 1-m sand column experiments for the evaluation of distribution of 
individual grout material 
Exp. 
name 
Injecting 
solution 
Injection 
volume [PV] 
Head 
[cm] 
Sand 
type 
Dilution Mixing 
solution 
Evaluation  
method 
Ca1 1 mol/L CaCl2 1.0 60 Keisa #6 NA NA ICPAES 
Ca2 1 mol/L CaCl2 1.0 Pu Keisa #8 NA NA ICPAES 
Ua1 1 mol/L urea 1.0 60 Keisa #6 10 times 30 g/L urease Ion meter 
Ua2 1 mol/L urea 1.0 Pu Keisa #8 10 times 30 g/L urease Ion meter 
En1 15 g/L urease 1.0 60 Keisa #6 10 times 1 mol/L urea Ion meter 
En2 15 g/L urease 1.0 80 Keisa #6 10 times 1 mol/L urea Ion meter 
En3 15 g/L urease 1.5 80 Keisa #6 10 times 1 mol/L urea Ion meter 
En4 15 g/L urease 1.5 Pu Keisa #8 10 times 1 mol/L urea Ion meter 
*NA ––Not applicable ** Pu–– solution is injected using a pump . 
 
Table 3. Conditions for 1-m sand column experiments for the evaluation of the calcite 
distribution 
 
 
 
 
 
 
 
 
 
 
Exp. 
name 
Urea-CaCl2 
[mol/L] 
Urease 
[g/L] 
Head 
[cm] 
Inj. Vol. 
[PV] 
Mixing  
temperature [°C] 
Sand 
Cal1 1.0 15 80 1.5 5.0 Keisa #6 
Cal2 1.0 15 80 1.5 23.5 Keisa #6 
0.0
0.5
1.0
1.5
0 20 40 60 80 100
Ua1
Ua2
N
H
4
+
 [
m
o
l/
L
]
Distance from inlet [cm]
Figure 11. Vertical distribution of the ammonium ion obtained 
from the injection of urea 
11 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Figure 12. Vertical distribution of the calcium ion obtained from 
the injection of CaCl2 
0.0
0.5
1.0
1.5
0 20 40 60 80 100
Ca1
Ca2
C
a
2
+
 [
m
o
l/
L
]
Distance from inlet [cm]
0.0
0.5
1.0
1.5
0 20 40 60 80 100
En1
En2
En3
En4
N
H
4
+
 [
m
o
l/
L
]
Distance from inlet [cm]
Figure 13. Vertical distribution of the ammonium ion 
obtained from the injection of urease 
12 
 
 
 
 
 
 
 
 
 
 
 
Additionally, various chemicals which do not require enzymes to precipitate, are also 
studied as a candidate grout materials. The chemical combinations producing carbonate 
and phosphate minerals of calcium and magnesium are analyzed in PP tubes. The 
combinations yielding an appreciable amount of hard crystalline materials are selected. 
The selected chemicals are analyzed further. The potential of these chemicals combinations 
to enhance the soil properties are examined. The potential of these combinations to reduce 
the permeability through the concrete cracks are also appraised. Concrete specimens (M30) 
with a diameter of 10 cm and a height of 20 cm are utilized. The specimens are craked 
using Brazalian Test machine. The initial permeability of the specimen is evaluated. 
Phosphate based grout is injected three times at an interval of every two days. The final 
permeablity of the treated specimen is also evaluated. Figure 15 schematically represents 
the permeability test arrangement. The summary of the permeability test specimen are 
given in Table 4. Permeabilities of the concrete samples before and after treatmtent are 
shown in Figure 16. As shown in the figure, permeability reduction of up to three orders of 
magnitude is obteined.  
 
 
 
0
2
4
6
0 20 40 60 80 100
Cal1
Cal2
C
a
lc
it
e
 p
re
c
ip
it
a
ti
o
n
 r
a
ti
o
 [
%
]
Distance from inlet [cm]
Figure 14. Vertical distribution of the precipitated calcite 
obtained from the injection of grout solution 
13 
 
 
 
 
 
Table 4. Detail of the specimen and grouting 
Concrete specimen composition (1:2:2) 
Specimen size  ф = 100 mm, h = 195 mm  
Immersed in water for 7 days 
Solution injection 
100 mL each, 3 times at an interval of every 2 
days 
Grout content 
NaH2PO4 [1.0 mol/L] + 
Mg(NO3)2.6H2O [0.5 mol/L] + 
NaOH [0.2 mol/L] 
 
 
 
 
 
Figure 15. Schematic representation of permeability experiment set-up 
14 
 
 
 
 
 
 
 
 
 
 
 
 
These results exhibit that a remarkable reduction of the permeability through the concrete 
cracks is achieveable through this method. The explained results show the efficacy of this 
method as a concrete permeability reduction method.   
 
Lists of references 
Neupane, D., Yasuhara, H., Kinoshita, N. and Ando, Y. (2015). “Distribution of 
mineralized carbonate and its quantification method in enzyme mediated calcite 
precipitation technique.” Soils and Foundations, 55(2), 447–457. 
Neupane, D., Yasuhara, H., Kinoshita, N., and Unno, T. (2013). “Applicability of 
enzymatic calcium carbonate precipitation as a soil-strengthening technique.” J. 
Geotech. Geoenviron. Eng., 139(12), 2201–2211. 
Xu, T., Sonnenthal, E., Spycher, N., and Pruess, K. (2004). “TOUGHREACT user’s guide: 
A simulation program for non-isothermal multiphase reactive geochemical transport 
in variably saturated geologic media.” Lawrence Berkeley Lab. Report LBNL-55460, 
Berkely, California, pp. 192. 
Yasuhara, H., Neupane, D., Hayashi, K., and Okamura, M. (2012). “Experiments and 
predictions of physical properties of sand cemented by enzymetically-induced 
carbonate precipitation.” Soils & Found., 52(3), 539–549. 
Figure 16. Initial and final permeabilites of the treated samples 
10
-6
10
-5
10
-4
10
-3
10
-2
10
-1
P1 P2 P3 P4 P5 P6
Initial
Final
H
y
d
ra
u
lic
 c
o
n
d
u
c
ti
v
it
y
 [
c
m
/s
]
Specimen name


Evaluation of insitu mineralized carbonate grout to improve the engineering properties of soils and other porous materials

瀬戸内海沿岸地点における1980年以前の風観測資料の特性およびその再現性の検討

REINELT, Rudolf

German

Aufgaben in weiterfuhrenden Deutschkursen am Beispiel von S1 II

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