The concept of using biological process in soil improvement through bio-cementation of soil improvement technique has shown influences to change main geotechnical properties of soil in effective manner. This paper presents a review on the soil improvement by Microbially induced calcium carbonate precipitation (MICP) using calcium source obtain from waste having large extent of calcium chemical class present in its own matrix like egg shell, lime stone obtain from stone query. Improvements in the engineering properties of soil such as strength, stiffness and permeability as evaluated in various studies were discover. Potential applications of the process in geotechnical engineering and the challenges of eco-friendly mean of construction of soil stabilization method is identified.

1. “BIOCEMENTATION FOR SAND USING WASTE (CONTAIN
CALCIUM SOURCE)”
A Seminar Report Submitted
In Partial Fulfillment of the Requirements
for the Degree of
MASTER OF TECHNOLOGY
in
GEOTECHNICAL ENGINEERING
Submitted by:
ANIKET S. PATERIYA
(Scholar Number: 182111101)
Under the guidance of
Dr. KISHAN DHARAVAT
(Asstt. Professor)
DEPARTMENT OF CIVIL ENGINEERING
MAULANA AZAD NATIONAL INSTITUTE OF TECHNOLOGY
BHOPAL-462003
OCTOBER-2018
MAULANA AZAD NATIONAL INSTITUTE OF
TECHNOLOGY
BHOPAL
pg. 1

2. DEPARTMENT OF CIVIL ENGINEERING
DECLARATION
I Aniket Pateriya, student of M. tech, Geotechnical Engineering,
Department of Civil Engineering, Maulana Azad National Institute of
Technology, Bhopal, hereby declare that the work presented in this seminar
report is outcome of my own work, is Bonafide to the best of my knowledge
and this work has been carried out taking care of Engineering Ethics. The work
presented does not infringe any patented work and has not been submitted to
any University for the award of any degree or any professional diploma.
Aniket Pateriya
Scholar no. 182111101
MAULANA AZAD NATIONAL INSTITUTE OF TECHNOLOGY
BHOPAL
DEPARTMENT OF CIVIL ENGINEERING
CERTIFICATE
pg. 2

3. October 2018
This is to certify that the seminar entitled “BIOCEMENTATION FOR
SAND USING WASTE (CONTAIN CALCIUM SOURCE)” Submitted by
Aniket Pateriya (182111101) of M. tech 1st
year, Geotech (department of Civil
Engineering), Maulana Azad National Institute of Technology, Bhopal, is a
record of bonafide seminar carried out by him under my supervision and
guidance.
To the best of my knowledge, the presented seminar report has not been
submitted for the award of any other diploma or degree certificate.
Dr. Kishan Dharavat
(Asstt. Professor)
ACKNOWLEDGEMENT
I would like to express my gratitude to my mentor, Dr. Kishan Dharavat
for introducing me to the topic as well as for his useful comments, remarks and
engagement through the learning process of this project.
pg. 3

4. I am very thankful to Dr. S.K. Katiyar, Head of Department (Civil
Engineering) for his kind support and cooperation.
This seminar report would never have been completed without the
guidance and support of Dr. N. Dindorkar, Dr. P.K. Jain, Dr. Suneet Kaur
and Dr.Rakesh Kumar. I owe a hearty gratitude towards them.
My thanks and appreciation also goes to my colleagues and people who
have willingly helped me out with their abilities.
pg. 4

5. ABSTRACT
The concept of using biological process in soil improvement through bio-
cementation of soil improvement technique has shown influences to change main
geotechnical properties of soil in effective manner. This paper presents a review
on the soil improvement by Microbially induced calcium carbonate precipitation
(MICP) using calcium source obtain from waste having large extent of calcium
chemical class present in its own matrix like egg shell, lime stone obtain from
stone query. Improvements in the engineering properties of soil such as strength,
stiffness and permeability as evaluated in various studies were discover.
Potential applications of the process in geotechnical engineering and the
challenges of eco-friendly mean of construction of soil stabilization method is
identified.
CONTENTS
pg. 5

6. DISCRIPTION PAGE
NUMBER
Introduction 7
Method to produce soluble calcium from eggshells 10
Method to produce soluble calcium from limestone 11
Sample preparation and testing methods using egg shell as calcium source 14
Sample preparation and testing methods using limestone as calcium source 17
Testing results using egg shell as calcium source 20
Testing results using limestone as calcium source 23
Discussion 28
Conclusion 29
References 30
pg. 6

7. CHAPTER 1
1.1 Introduction
In geotechnical engineering, Conventional ground improvement techniques are highly
un-economical (jet grouting, permeation grouting, the formation of soil-cement/lime piles
etc.) and often require the introduction of environmentally damaging chemicals or carbon-
intensive materials into the subsurface (e.g. chemical grouts, cement). Cement production
alone is estimated to contribute 5%–7% of total global CO2 emissions. This above condition
also encounter for soil stabilization method done by various parameter which result in
improvement of soil properties but at same time affect the environment in large extent. In the
recent years, an environmentally friendly bio-based cement material has been developed for
geotechnical applications. Bio-cement is a construction material that can be made from
calcium salt (Ca2+
), a small amount of urea (CO(NH2)2), and in environment of bacteria (In
general use class of urease-producing bacteria). Where carbonate (CO3
2 −
) is produced from
urea decomposition that is catalyzed by UPB. Carbonate then reacts with calcium ions to
form calcium carbonate (CaCO3) in situ, which can fill small pores, bridge cracks, and bind
loose particles. Biocement can be used for both construction and repair. it can be used in a
manner similar to that for cement to reduce the hydraulic conductivity and increase the shear
strength of soil as well as repair cracks in internal matrix of soil.
This review seeks to present the developments for soil stabilization by biological
cementation outlining in particular the processes which have been shown to be most
promising for altering the hydraulic and mechanical responses of soils and rocks also by
focused on eco-friendly mean of improvement in required soil. Much of the research effort in
this new field of biogeotechnics has been focused on microbially induced
carbonate(calcite) precipitation (MICP) done by various bacterial matrix helps for
improving required properties in soil along with consider it effect on environment.
MICP reaction :
CO(NH2)2 + H2O → 2NH4 +
+ CO3
2–
(UPB catalyst)
pg. 7

8. Ca2 +
+ CO3
2–
→ CaCO3 ↓(In situ)
Recently, there are many reports on the use of the microbial induced calcite
precipitation (MICP) process for soil improvement. In almost all the studies previously
mentioned, calcium salt such as CaCl2 was used. However, excessive presence of CaCl2 in
soil can be harmful. It is also expensive to use CaCl2 in large amounts. On the other hand,
calcium may be also extracted from various waste materials such as eggshell, seashell,
limestone powder derived from aggregate quarries etc. as a replacement for the reagent grade
CaCl2 in the MICP process while acetic acid derived from fast pyrolysis of lignocellulosic
biomass also use as dilute acid required for the formation of soluble calcium.
Jason T. DeJong et al (2006) studied the production of MICP using the
microorganism Bacillus pasteurii introduced to the sand specimens in a liquid growth
medium amended with urea and a dissolved calcium source and compare whole assembly
with and with-out presence of gypsum into given sand matrix.
Qian Zhao et al (2014) studied factors included bacteria concentration, urease
concentration, cementation media concentration, reaction time, sand type, and curing
conditions effects on the MICP process and give optimum dose value.
Sun-Gyu Choi et al (2016) studied the production of water-soluble calcium using
eggshell and vinegar (dilute acid) and introduced it into the sand using urease-producing
bacteria (UPB) as bacteria source.
Hai Lin et al (2016) studied mechanical behavior of sands treated using microbially
induced carbonate precipitation (MICP) has been investigated at the macro scale and the
micro scale by tri-axial and unconfined compression strength test by altering parameter such
as confining pressures and calcium chloride (CaCl2) concentrations.
Sun Gyu Choi et al (2017) studied the limestone powder derived from aggregate
quarries and acetic acid derived from fast pyrolysis of lignocellulosic biomass, as a
replacement for the CaCl2 in the MICP process for sand matrix stabilization using UPB as
bacteria source.
pg. 8

9. In this report, an attempt was made to produce soluble calcium from waste having
large extent of chemical contain calcium source such as eggshell, limestone powder derived
from aggregate quarries and use it for the MICP process to treat sand. To assess the
effectiveness of this method, a comparative study of the shear strength and permeability of
sand treated using the MICP process with calcium from eggshell and those of sand with
calcium from CaCl2 was carried out as well as study sand treated with limestone powder
waste for soil stabilization study given by Choi.
In almost all the studies previously mentioned, calcium salt such as CaCl2 was used.
However, excessive presence of CaCl2 in concrete or soil can be harmful. It is also expensive
to use CaCl2 in large amounts. On the other hand, calcium may be extracted from waste
materials such as eggshell, limestone powder derived from aggregate quarries. Hence based
on previous researches how different waste source can dispose in effective manner in soil
along with stabilization of soil discus in given report:
CHAPTER 2
2.1 Method to produce soluble calcium from eggshells
Eggshell contains more than 94% of calcium carbonate, and it can be dissolved using
an acid liquid. In this study, distilled white vinegar diluted with water to 5% acidity was used.
The steps for making soluble calcium using eggshell and vinegar are as follows. Eggshells
pg. 9

10. were washed with distilled water, put in the oven at a temperature of 105°C for one day, and
then crushed into powder. The crushed eggshell was mixed with vinegar in a bottle and
placed in a shaker for several days. Eggshells have an inner membrane. The ratio of eggshell
and inner membrane in eggshell was 96.8/3.2 by weight (w/w). Choi. (2016) suggested
removing the membrane when using eggshells to produce a calcium source. In this study, a
comparison between the use of eggshell with and without inner membrane was made to study
the influence of inner membrane. The calcium concentrations of the soluble calcium solution
made from eggshell with and without membrane were measured using the ASTM D4373-14
method and the results are shown in Fig. 1. The calcium production versus time curves are
shown in Fig. 1(a) in which 10 g eggshell without membrane and 10.32 g eggshell with
membrane were used. It can be seen that there is little difference in terms of production of
soluble calcium between the use of whole eggshell (eggshell and membrane) and eggshell
without membrane.
It also implies that the inclusion of inner membrane in the eggshell has little effect on
the production of soluble calcium. Intuitively, one would think the size of the powder made
from eggshell will affect the production of soluble calcium. Two sizes of eggshell powder
were tested. One was above 0.85 mm and another was between 0.85 and 0.075 mm. As
shown in Fig. 1(b), the test using finer powder gives about 10% higher calcium
concentration. This difference is only marginal. The results shown in Figs. 1 (a and b) were
carried out using an eggshell to vinegar ratio of 1∶4 by weight. To check the effect of the
eggshell-to-vinegar ratio, tests with other eggshell to vinegar ratios of 1∶8 and 1∶12 were also
conducted and results are shown in Fig. 1(c). In general, a sufficient amount of vinegar
pg. 10

11. should be used, but too much may not help in producing more soluble calcium. The data
shown in Fig. 1(c) indicate that an eggshell-to vinegar ratio of 1∶8 appears to produce the
highest calcium concentration. The data in all the tests in Fig. 1 also show that the production
of calcium reaches a peak in three days. Thus, three days were taken as the duration for the
production of calcium using eggshell.
Fig. 1. Optimum ratio of eggshell and vinegar: (a) influence of membrane in eggshell; (b)
influence of size of eggshell; (c) influence of ratio of eggshell to vinegar
[Source: Sun-Gyu Choi et al (2016)]
2.2 Method to produce soluble calcium from limestone
Calcium ion solution was produced by dissolving a limestone powder in an acetic
acid-rich solution. The limestone powder was obtained in this study from the martin Marietta
limestone quarry in Ames, Iowa, USA. It had a particle size passing through 200 screen (less
than 0.075 mm) and a specific gravity of 2.70. The limestone contained 50.7% (by weight)
CaO as a major composition, with a small amount of SiO2 (2.39%), Al2O3 (0.85%), and Fe2O3
(0.35%).
pg. 11

12. The acetic acid rich stream was received from the bioeconomy institute at Iowa State
USA. The stream was a byproduct from the fast pyrolysis of lignocellulosic biomass for
producing drop-in fuels. It contained more than 7% (w/v) acetic acid with a relatively small
amount of acetol (5.06%), total phenolic (2.09%), and formic acid (1.22%). The calcium ion
is produced as follows:
CaCO3 + 2CH3COOH→ Ca2 +
+ 2(CH3COO) −
+ CO2 + H2O
To optimize the ratio of limestone to acetic acid, limestone powder (100 g) was mixed
with acetic acid solution (200, 400, 800, and 1200 ml) at different ratios (w/v), i.e. 1:2, 1:4,
1:8, and 1:12, respectively. After a 5-day reaction at room temperature (∼25 °C), calcium
concentration and pH value of the limestone/acetic acid mixture solution were determined.
As shown in table 1, the resulting solution contained calcium ion ranging from 0.83 to 0.64
M and pH from 5.2 to 4.8.
Limestone powder
(g)
Acetic Acid
Solution(mL)
Calcium ion conc.
(M)
pH
100 200 0.83 5.2
100 400 0.80 5.1
100 800 0.76 5.0
100 1200 0.64 4.8
Table 1. Different ratios of limestone powder to acetic acid solution used for
preparing calcium ion solution
pg. 12

13. [Source : Sun-Gyu Choi et al (2017)]
The raw acetic acid stream derived from biomass pyrolysis contains various
compounds, such as Acetol, 5-hydroxymethylfurfural, Phenolic, and furfural, which are
strong inhibitors for bacterial growth. Considering the case that 800 ml of acetic acid solution
resulted in a relatively high calcium concentration with a large volume, and the fact that
1,200 ml of acetic acid contains substantial inhibitory compounds, the 800 ml of acetic acid
solution was selected for producing calcium ions in the following MICP process
development.
The calcium solution prepared from 800 ml of acetic acid solution was further added
with distilled water to adjust the final calcium ion concentration to 0.3 M. The pH of this
solution was further adjusted to 7.0−7.5 using ∼4.5 g of sodium hydroxide pellets. The
solution was then centrifuged at 4,000 rpm for 20 min to obtain supernatant, which serves as
the final calcium ion solution in the following MICP processes in both free solution and sand
column tests.
pg. 13

14. CHAPTER 3
3.1 Sample preparation and testing methods using egg shell as calcium source
The soluble calcium was used for Biocementation for soil samples prepared in PVC
pipes with an inner diameter of 50 mm. The sand used was Ottawa sand with a mean grain
size of 0.42 mm. Sporosarcina pasteurii (ATCC 11859) was used as the urease-producing
bacteria (UPB).
All samples were prepared using the following procedure: A drainage layer of 10-
mm-thick gravel and synthetic filter was put at the bottom of the tube. Above the drainage
layer, a 100-mm-high dry sand column was formed through a funnel, and then a filter was
placed on top of the sample as shown in Fig. 2. The sand was compacted by taping to achieve
a relative density of 40%. The UPB solution was poured into the sample with a rate of 2.5
m/M/min and kept there for 2 h before it was drained out. For tests treated using CaCl2, the
CaCl2 solution with a concentration of 0.45 M was added to the top of the sample. For
samples treated using the soluble calcium, the calcium solution with a concentration of
0.45M was used. This process was repeated 15 times. The UPB in a freeze-drying state was
added to distilled water to make a 50-mL solution using a ratio of 1∶100 by weight (solution
A).
pg. 14

15. Fig.2 Arrangement for bio treatment of sand sample
[Source : Sun-Gyu Choi et al (2016)]
The 50-mL solution A was applied by adding it to the top of the samples and letting it
drain out from the bottom using a setup as shown in Fig. 2. The solution that drained out was
collected, and added to the samples for the second time. This time, the solution was allowed
to remain in the samples for 3 h before being drained out. After the samples were treated with
UPB, 300 ml of solution A with a mixture of calcium and urea solution was applied. For the
control tests, the solution used contained 0.45 M of calcium chloride and 1 M of urea in a 2∶1
proportion (referred to as solution B). For the rest of the tests, a solution with 0.45 M eggshell
aqueous solution and 1 M urea in the proportion of 2:1 (referred to as solution C) was used.
Either solution B or C was applied in the same way by pouring the solution on top of a
sample and draining it out from the bottom. The drainage rate was controlled in a way that a
complete drainage would take about two days. The solution that drained out was collected
and reapplied to the samples. This process was repeated 15 times. A summary of the three
solutions used is given in Table 2. The pH of the solution was measured every time after it
was drained out. The pH increased to 8.2–8.5 after solution B was applied and to 8.3–8.7
pg. 15

16. after solution C was used. To promote uniformity of the treatment, the sample column was
turned upside down after eight times of treatment. After 15 times of treatment, the sample
was taken out of the mold and dried in an oven under 50°C for 24 hr.
METHOD Solution A
(UPB)
Solution B Solution C
CaCl2
(Mole)
Urea
(Mole)
Calcium-
Egg Shell
(Mole)
Urea
(Mole)
UPB+ CC (CaCl2) 1/100 0.45 1 - -
UPB+ ES (Egg
Shell)
1/100 - - 0.45 1
Table.2 Mixing Ratio of various Calcium source
[Source: Sun-Gyu Choi et al (2016)]
The calcium carbonate content produced in the samples was measured using the rapid
calcite content determination method suggested by the ASTM D4373-14 (ASTM 2014a).
3.2 Sample preparation and testing methods using limestone as calcium source
Development of MICP-based Biocementation process in free solution tests. The
MICP process for Biocementation was illustrated in Fig 1. The UPB culture broth (30 ml)
grown for 2 days with a density of OD600 = 0.8−1.2 was mixed with 0.3 M urea solution (30
ml) at a ratio of 1:1 (v/v). The mixture had a pH 7.0−7.5 and was stored in a beaker for 1 day,
and then added with calcium solution (30 ml) which was prepared based on the procedures
fig.3. Schematic illustration of the MICP process in free-solution tests
pg. 16

17. Fig.3. Schematic Illustration of the MICP Process in
Free-Solution Tests
[Source : Sun-Gyu Choi et al (2017)]
Precipitation was observed immediately after addition of the calcium solution. This
precipitated material was filtered out by filter paper and dried at 115 °C for 1 day. The dried
material was then analyzed using X-ray diffraction (XRD). Development of MICP-based
Biocementation in sand column tests. A total of six sand columns were tested for MICP-
based Biocementation. The schematic setup of the MICP-based sand column Biocementation
test is shown in Fig. 4. As shown in the Fig.4 experimental setup for MICP-based
Biocementation in sand column tests scheme, sands were placed in a PVC cylinder (5 cm
diameter and 10 cm length) in 10 layers with a density of approximately 1.70 g/cm3
. Two
scotch-brite scouring pads were placed at each end of the sand column as filters. The PVC
cylinder was placed on a funnel filled with gravel. A beaker was used to collect the solution
penetrating through the sand column, which was then circulated to the top of the column.
pg. 17

18. Fig. 4. Experimental Setup for MICP-Based
[Source : Sun-Gyu Choi et al (2017)]
Biocementation in Sand Column Tests to implement the MICP process, 80 ml of UPB
seed solution was placed in the beaker and recirculated through a peristaltic pump to the top
of the sand column (Fig. 2). The pumping rate was controlled at 1.5−2.0 ml/min. The liquid
circulation was run for 3 h to ensure the UPB cells were evenly distributed within the
column. Then, the solution in the beaker was replaced with a mixture of fresh UPB seed
solution (30 ml), urea solution (150 ml at 0.3M), and calcium solution (150 ml at 0.3 M).
This mixed solution was recirculated through the column for 9 h. The above recirculation
procedure (3 h of UPB seed and 9 h of UPB/urea/calcium solution) was repeated twice a day
for 7 days, at which point calcium carbonate began to precipitate in the column. The
recirculation procedure was continued for another 3 days. After being treated for a total of 10
days, the outlet from the column was blocked completely. The cemented sand column was
then washed with distilled water, and the outer cylinder layer was removed. Evaluation of the
properties of the bio cemented sand columns. The cemented sand columns were tested to
evaluate their engineering properties, including water permeability, unconfined compressive
stress (UCS), tensile stress (TS), microstructure image, and CaCO3 content. To carry out the
permeability tests, the sand column (both before and after MICP treatment) was soaked in
distilled water for 24 h and then subjected to a constant head based on the ASTMD 2434
method. The sand columns were then placed at 23 °C and 50% RH conditions for two-days
pg. 18

19. prior to the UCS and TS tests based on the ASTMD 4219 and ASTMC 496 methods,
respectively. Among six sand columns tested, three were used for UCS tests (designated as
UCS1, UCS2, and UCS3) and the other three for tensile strength tests (designated as TS1,
TS2, and TS3). About 5 g of biocemented sand samples were collected from the centers of
the failed sand columns for the microstructure image observation through a scanning electron
microscope (SEM) and for the determination of the CaCO3 content using the ASTMD 4373-
14 method.
CHAPTER 4
4.1 Testing results using egg shell as calcium source
pg. 19

20. Unconfined compression (UCC) and permeability tests were carried out to assess the
strength and permeability of the samples treated by both methods. The permeability was
measured using a falling head method. The calcite content in each sample was measured at
the top, center, and bottom positions. Table 3 summarizes the testing results obtained from
these tests. The UCC results are shown in Fig. 5 for both CC and ES series. It can be seen
that the results for both are comparable and the UCC strength for samples treated with
calcium source produced from eggshell is slightly higher. The main reason for having a
higher UCC strength from the samples treated with calcium source produced from eggshell
was because the calcium contents in the ES samples are higher (Table 3). The difference was
caused mainly by the difference in the bacteria and the MICP procedure used in these three
studies. The correlations between permeability and unconfined compressive strength (UCS),
permeability and calcium carbonate content, and UCS and calcium carbonate content are
shown in Fig. 6. It can be seen that UCS increases and permeability decreases with increasing
calcite content. This is consistent with the mechanisms of Biocementation and bio clogging it
is the calcium carbonate precipitated in soil that binds the sand grains together to increase its
shear strength and fills in the pores to reduce its permeability.
pg. 20

21. Table 3: Summary of testing results
[Source : Sun-Gyu Choi et al (2016)]
Fig. 5. UCS results using different calcium source: (a) UCS results using calcium chloride;
(b) UCS results using eggshell [Source : Sun-Gyu Choi et al (2016)
pg. 21
Test
Identifier
Calcium
Source
UCS Permeability
(10^-6m/s)
Quantity of calcite (%)
Top Center Bottom Average
CC-1 Calcium
chloride
316 3.82 5.3 4.1 6.4 5.3
CC-2 Calcium
chloride
291 5.56 5.1 4.3 6.3 5.2
CC-3 Calcium
Chloride
360 1.27 6.4 5.1 7.2 6.2
CC-4 Calcium
chloride
370 1.06 6.9 5.4 7.5 6.6
ES-1 Eggshell 392 6.54 7.1 5.6 7.7 6.8
ES-2 Eggshell 418 1.63 8.2 7.0 8.0 7.7
ES-3 Eggshell 404 2.68 8.0 6.8 8.1 7.6
ES-4 Eggshell 335 4.41 7.4 4.4 7.7 6.5

22. Fig. 6. Test results: (a) permeability versus UCS; (b) UCS versus calcite carbonate content;
(c) permeability versus calcite carbonate content
[Source : Sun-Gyu Choi et al (2016)]
Fig. 7. Calcium carbonate precipitated between sand grains
[Source : Sun-Gyu Choi et al (2016)]
Based on the data presented in Fig. 6, it requires 7% or more calcite to reduce the
permeability to an order of 10−6
to 10−7
m/s. At this calcium carbonate content, the UCS is at
a level of 400 kPa.
Scanning electron microscope (SEM) photos were taken for tested samples using
calcium produced from eggshells. Fig. 7 shows that calcium carbonate is formed between
sand grains as is commonly observed by other researchers
4.2 Testing results using limestone as calcium source
pg. 22

23. Confirmation of the MICP process from limestone and acidic acid in free solution
tests. The precipitated material was produced from the MICP process using acetic acid and
limestone. These precipitated materials were analyzed by XRD (figure 8). The XRD pattern
of the precipitated materials (figure 8A) perfectly matched that of the pure reagent grade of
calcium carbonate (CaCO3) (figure 8B). The result confirms that the precipitate was indeed
CaCO3, and validated the use of acetic acid derived from biomass fast pyrolysis and the
limestone to produce calcium carbonate in the MICP process. In the following work, sand
column tests were conducted to evaluate the effectives of the unique MICP process.
Figure 8. XRD results of the materials precipitated from the MICP process (A), and pure
reagent grade calcium carbonate (B)
[Source : Sun-Gyu Choi et al (2017)]
The MICP process, CaCO3 content and permeability of the sand columns. The CaCO3
content of the cemented sand ranged from 5.67% to 8.19%. This was within the CaCO3
content range used in previous studies where reagent grade CaCl2 was used in the MICP
process. The variation in the CaCO3 contents in the six sand columns was due to the
experimental variations such as the liquid flow patterns inside the sand columns, the surface
areas of the sands in each column, etc.
pg. 23

24. Figure 9. Permeability of MICP-treated sand as a function of CaCO3 content in the sand
column. Permeability of untreated sands is also presented as a baseline.
[Source : Sun-Gyu Choi et al (2017)]
The water permeability of the cemented sand is plotted as a function of the CaCO3
content in figure 9, along with the permeability of the untreated sand as a comparison. It can
be seen that the permeability has reduced from 1 × 10−4
m/s for untreated sand to 8.17−1.52 ×
10−6
m/s for MICP treated sand. This is similar to the observation made in previous studies
that the permeability of the MICP treated sand decreases with the CaCO3 content nonlinearly.
Strength of the sand columns, Figure 10 shows unconfined compressive stress (UCS)
and tensile stress (TS) as functions of the axial strain of the cemented sand columns. As
shown in the figure, the stress−strain behaviors were similar for each set of UCS or TS tests.
Based on the data in figure 10, the strength values obtained from the UCS and TS
tests are plotted as a function of CaCO3 contents, respectively. As shown in figure 10A, both
the UCS and TS strengths of the cemented sand increased with calcium carbonate content,
which is similar to the previous studies. The trend lines of the UCS and TS vs. CaCO3
contents were also determined with high correlation coefficients (r2
) obtained within the
pg. 24

25. calcium carbonate content range 5.5−8.5% (figure 11A). The UCS/TS strength ratio of the
treated sand is also presented to monitor its brittleness (figure 11B). In general, the higher the
UCS/TS strength ratio, the more brittle the material. The strength ratio can change with rock
types from 2.7 to 39 with an average of 14.7. Here the strength ratio was determined based on
the two regression curves in figure 11A.
Fig. 10. Strain−stress relationship of the sand columns cemented with the MICP process
using limestone powder and acetic acid solution derived from lignocellulosic biomass: (A)
unconfined compression (UC); (B) splitting tensile (TS)
[Source : Sun-Gyu Choi et al (2017)]
Series of hypothetical CaCO3 contents (5%−9%) were selected to cover the true
CaCO3 contents in this work. Under each hypothetical CaCO3 content, the UCS and TS
strength values were determined based on their corresponding regression equations in figure
6A. The UCS/TS strength
pg. 25

26. Fig. 11. Strength (maximum unconfined compressive stress (UCS) and tensile stress
(TS)) of the sand columns as functions of theCaCO3 content in the columns (A) and strength
ratio of UCS/TS (B).
[Source : Sun-Gyu Choi et al (2017)]
Ratio was then calculated and plotted as a function of the corresponding CaCO3
contents (figure 11B). As shown in figure 11B, the strength ratio increased with calcium
carbonate content. At 9% of CaCO3, the column has a strength ratio of 6.87. It should be
noted that the UCS/TS strength ratio can be extrapolated as 7.3−7.6 at a calcium carbonate
content of 11− 13%, which is almost the same strength ratio as reported at the same calcium
carbonate content but using calcium chloride for the MICP process. The results in figure 6B
also suggest that when the calcium carbonate content of the MICP-treated sand is within
5−9%, the brittleness of the MICP-treated sand is less than that of the rock materials.
Microstructure of MICP treated sand columns. The microstructures of the
biocemented sand columns are shown in figure 12. Figure 12A shows that, after the MICP
treatment, sand particle surfaces were covered with CaCO3. Clumps of CaCO3 also filled the
spaces between the sand particles (area “A”). Figure 12B illustrates the particles bridged by
CaCO3. Figure 12C indicates that CaCO3 covered the sand surface with a size approximately
ranging from 5 to 20 μm, which is compared to those observed from the previous MICP
study where reagent grade CaCl2 was used as the calcium source.
In some other areas of the sand column, precipitated CaCO3 with different
morphologies was observed. For example, loosely packed, smaller size sphere-shaped CaCO3
crystals with radial striations were observed (figures 7D−F). The different morphologies of
the CaCO3 crystals might be related to bacteria types, calcium sources, and medium types.
pg. 26

27. Further study is needed to study the factors affecting the formation of CaCO3 morphologies in
different MICP processes.
Fig. 12. SEM images of MICP-based cemented sand columns. The MICP process was
prepared in free solution with limestone powder and acetic acid solution derived from
lignocellulosic biomass.
[Source : Sun-Gyu Choi et al (2017)]
pg. 27

28. CHAPTER 5
5.1 Discussion
 The results indicate that soluble calcium effectively improve the strength and reduce
the permeability of the sand.
 Presently the use of chemical grouting is becoming increasingly popular but it is very
costly on the other hand, the use soluble calcium is cheaper as compared to CaCl2.
 Eggshells are easily available so we can use it on large scale at the same time
limestone powder derived from aggregate quarries and acetic acid derived from fast
pyrolysis of lignocellulosic biomass obtain in their respective place in large scale and
there disposal solution take advantages in given research work.
 As it is suitable for nature it will not cause any harm to nature.
 UC strength for sand treated using calcium from such waste source also given
higher value.
CHAPTER 6
pg. 28

29. 6.1 Conclusion
 Using the egg shell, the permeability of the sand can be reduced to an order of 10-6
to 10-7
m/s from the original value of 10-4
m/s at a calcium carbonate content.
 The use of soluble calcium from eggshell in the MICP process for soil
improvement is feasible. The optimum mixing ratio between eggshell and vinegar
is 1:8 (by weight). The finer eggshell, the higher amount of soluble calcium
provided. A size of 0.85 mm or less for eggshell fragment will be adequate.
 A new soluble calcium source has been obtained from a mixture of limestone
powder and acetic acid with pH adjustment. Such a calcium solution can replace
CaCl2 for production of precipitated CaCO3 via MICP.
 The sand columns treated using the new calcium sources using limestone
demonstrated similar engineering properties as those treated using CaCl2.
REFERENCES
pg. 29

30.  Jason T. DeJong ; Michael B. Fritzges; and Klaus Nüsslein – “Microbially Induced
Cementation to Control Sand Response to Undrained Shear” - J. Geotech.
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 Qian Zhao; Lin Li; Chi Li; Mingdong Li; Farshad Amini ; and Huanzhen Zhang. -
“Mechanical Behavior of Sands Treated by Microbially Induced Carbonate
Precipitation”. - J. J. Mater. Civ. Eng., 2014, 26(12): 04014094
 Sun-Gyu Choi; Shifan Wu; and Jian Chu – “Biocementation for Sand Using an
Eggshell as Calcium Source.” - J. Geotech. Geoenviron. Eng., 2016, 142(10):
06016010
 Hai Lin; Muhannad T. Suleiman; Derick G. Brown; and Edward
Kavazanjian Jr. –“ Mechanical Behavior of Sands Treated by Microbially Induced
Carbonate Precipitation.” - J. Geotech. Geoenviron. Eng., 2016, 142(2): 04015066
 Sun Gyu Choi, Jian Chu, Robert C. Brown, Kejin Wang, and Zhiyou Wen –
“Sustainable Biocement Production via Microbially Induced Calcium Carbonate
Precipitation: Use of Limestone and Acetic Acid Derived from Pyrolysis of
Lignocellulosic Biomass” - ACS Sustainable Chem. Eng. 2017, 5, 5183−5190
 ASTM D4373-14, “Standard Test Methods for rapid calcite content determination”
 B.K.G. Theng - “Sand–Chemical interactions. Summary and perspectives, - 310
(2012) 1–10”.
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