1. Research Proposal
1. Introduction
Research background
Construction on soft soil poses many problems due to low shear strength, differential
settlement etc. It has been challenging task to improve the soft ground. To improve the soft
ground, there are many methods such as vertical drain, replacement, stabilization by
chemical binder. Cement-treated soil is a method that uses cement to stabilize soft ground,
is widely used for a purpose of enhancing the properties of soil foundation structures,
especially for deep mixing treatment. It is known that the compressive strength of
cement-treated soils still increases considerably for several years. The short-term strength is
produced by cement hydration and the long-term strength development is mostly attributed
to pozzolanic reaction. The previous study on temperature history of field deep mixing
column revealed that temperature in the core of column produced from cement hydration
reached approximately 50C and maintained at that temperature for several months. Other
previous studies on cement-stabilized clay found that the strength development in both short
and long-term increased under high curing temperature. However, the discussions on the
changes of mechanical and microstructural properties of cement-treated soil under high
temperature curing through physic-chemical investigations are not adequate.
Objective:
This research aims to evaluate the strength development of cement-treated soils cured under
sealed condition at (20, 40, and 60
C) through physic-chemical investigations such as
thermal analysis, X-ray diffraction (XRD), mercury intrusion porosimetry (MIP).
Research plan:
Carry out conducting experiments: Casting cement-treated sand (10%, 15%, 20% cement
contents; W/C 100%) and the specimens are sealed and cured under 20, 40, and 60
C. The
compression test is conducted for the specimen at the ages of 3, 7, 14, 28, 56, and 91 days.
In parallel, physic-chemical tests (thermal analysis, X-ray diffraction (XRD), mercury
intrusion porosimetry (MIP)) are also conducted at the ages of 3, 7, 14, 28, 56, and 91 days.
2. Materials proposal
The total mass needed for 1 specimen (10%;15%;20% cement contents):
m=ms + mc+ mw
ms: mass of sand ; mc: mass of cement; mw: mass of water
γ =
m
𝑉
(
g
cm3) ;V =
𝜋𝑑2
4
ℎ (cm3)
Detailed calculations refer to Table 5.
2. Table 1.Specimen quantity corresponding with curing day
Curing day 3 7 14 21 56 91 Total
Specimen
quantity
4 4 4 4 4 4 24
The total number of specimens (with 3 types of cement contents 10%; 15%; 20% cement
contents) cured under 40, and 60°C:
24 x 3 x 2 = 144 (specimens)
Table 1.The total mass of materials for 144 specimens cured under 40, and 60 °C
m(g)
designed
Cement(g) Sand(g)
Total mass 476706.82 54915.41 366876
Table 5.Time schedule for conducting experiment
Time
schedule
08-Mar 09-Mar 10-Mar 12-Mar 13-Mar 14-Mar 15-Mar
Casting 10% 15%
Compression
test
3days(10%) 7days(10%) 3days(15%)
Water
content
3days(10%) 7days(10%) 3days(15%)
TG
TG-3days
10%
MIP
X-ray
Time
schedule
16-Mar 18-Mar 19-Mar 21-Mar 22-Mar 26-Mar 28-Mar
Casting 20%
Compression
test
3
days(20%)
7days(15%) 14days(10%) 7days(20%) 14days(15%) 21days(10%)
Water
content
3
days(20%)
7days(15%) 14days(10%) 7days(20%) 14days(15%) 21days(10%)
TG TG-7days TG-3days TG-3days TG-7days TG-7days
4. 3. Future plan
- Carry out conducting experiments: Casting cement-treated sand (10%, 15%, 20%
cement contents; W/C 100%) and the specimens are cured in water under 20, 40, and
60
C.
- Casting cement treat-soil (change soils type): 50% sand with 50% clay and the
specimens will be sealed and cured in water under 20, 40, and 60
C. The compression
test will also be conducted for the specimens at the ages of 3, 7, 14, 28, 56, and 91 days.
In parallel, physic-chemical tests (thermal analysis, X-ray diffraction (XRD), mercury
intrusion porosimetry (MIP)) are also conducted at the ages of 3, 7, 14, 28, 56, and 91
days.
