Effect of encasement length on geosynthetic reinforced stone columns
Mking.journal
1. 1
STUDY ON PERMEATION GROUTING IN COARSE GRAINED SOIL
WITH CEMENT BIOPOLYMER GROUT
M.sakthivel, M.K.Krivesh, D.Susinder, M.S Gidieon Raj Kamalesh
Mr. P. Dayakar.
(Department of Civil Engineering, Bharath University, Selaiyur, Chennai, Tamilnadu, India.)
ABSTRACT
The term Ground improvement and ground modification refers to the improvement
or modification to the engineering properties of soil for the proposed Civil Engineering
activity. Permeation grouting is an effective way to improve the engineering properties of
coarse grained soil by injecting the grout into the ground without disturbing the soil
structure. HPMC used along with cement to improve the properties of the cement grout. In
this investigation an attempt is made to study the effect of cement biopolymer (HPMC)
grout, an eco-friendly product in the coarse grain soil using permeation grouting. The
cement biopolymer grout is tested at different specimens by changing water cement ratios
like 4:1, 6:1, 8:1, and 10:1 in the acrylic tank of size 20cmx20cmx20cm. The grouted
samples are subjected to plate load test after 7 of curing period. The results of this study
conclusively proved that the strength of the specimen grouted with HPMC is higher
compared to that of the cement grout specimens and also it revealed that the decrease in
water content in grout increases load carrying capacity of the sandy soil.
INTRODUCTION
The constructional activities in the coastal belt of our country often demand deep
foundations because of the poor engineering properties and the related problems arising from
weak soil at shallow depths. The soil profile in coastal area often consists of very loose sandy
soils extending to a depth of 3 to 4 m from the ground level underlain by clayey soils of medium
consistency. The very low shearing resistance of the foundation bed causes local as well as
punching shear failure. Hence structures built on these soils may suffer from excessive
settlements.
Excavating the poor soil and replacing it with soil having desired properties is normally
economical only when soil has to be treated down to a depth of 3 m and the water table is below
3 m. If the water table is high, lowering of water table prior to excavation has to be carried out by
dewatering techniques, which are expensive. The primary purpose of grouting is to fill the voids
of the formation material by replacing the existing fluids with the grout and thereby improving
the engineering properties of the medium especially reducing the permeability.
2. 2
1. MATERIALS
Engineering properties of materials is playing a very important role in the process of grouting
because of result may depend on that. Materials involved in grouting process are soil and grout
materials. In this project the grout materials are cement and HPMC (cellulose) since it a
biopolymer grout.
For soil samples of soil retained on 75 micron I.S. sieve. The proportion of soil sample retained
on 75 micron I.S. sieve is weighed and recorded weight of soil sample is as per I.S.2720. I.S.
sieves are selected and arranged in the order. The soil sample is separated into various fractions
by sieving through sieves in the order of ; the weight of soil retained on each sieve is recorded.
No particle of soil sample shall be pushed through the sieves.
Table 1.1 Properties of sand
From the above graph, we can calculate coefficient of curvature (Cc) and coefficient of
uniformity (Cu) so that we can find the Classification of the sand with the help of I.S. 460-1962.
Properties Values
D60, mm 1.9
D30, mm 1.5
D10, mm 1
Cc 1.2
Cu 1.9
Classification SP
0.00
10.00
20.00
30.00
40.00
50.00
60.00
70.00
80.00
90.00
100.00
0.010 0.100 1.000 10.000
%Finer
Particle size dia, mm (log)
Soil
3. 3
2. CEMENT
Cement is a binder, a substance that sets and hardens independently, and can bind other materials
together. And we use, Ordinary Portland Cement (OPC) here.
Portland cement is a fine powder comprised of a minimum of 66% calcium silicate, with the
remainder largely being a mix of aluminum, and iron. Portland cement is a hydraulic material,
which requires the addition of water in order to form exothermic bonds, and is not soluble in
water.
3. HPMC
HPMC is a biopolymer which has the ability of thickening, anti-salt, water retention, good film-
forming, anti-enzyme, dispersing, bonding, and low ash content. And so, we are considering
HPMC as our Biopolyerm grout here.
Properties
Type : Hydroxypropyl Methyl cellulose (HPMC)
Appearance : white powder
Formula : (C6H10O5)n
Density : 1.26 – 1.31 g/cm³
pH (25º C) : 6.08
Methoxyl Content (wt%) : 28.1
Appearance : HPMC is a white or light gray pellet or fibril power with
odorless and tasteless.
Table 2.1 Properties of cement used
PROPERTIES VALUES
Grade OPC
Specific Gravity 3.15
Fineness, % 93
Consistency, % 35
Initial Setting Time, min 32
4. 4
4. METHODOLOGY
GROUTING
Permeation grouting of sandy soil with cement grout of Hydroxypropyl Methyl Cellulose
is done in an acrylic tank ( 20cm x 20cm x 20cm ) in room temperature of 28o
C (Figure 4.1).The
tank should be completely dry before filling the sand. One-third of the tank is filled with sand.
Then the grout pipe is placed in the tank in manner of dividing it four parts and placed in the
centre of each parts. Thin film foils should place inside the pipe such that the sand should not
enter the grout pipe’s holes. Then the soil is filled in the tank without disturbing all the four grout
pipes.
Figure 4.1 Figure 4.2
Figure 4.3
The films are removed from the grout pipes and do the setup according to the figure. The mixture
of water, cement and HPMC is poured inside the mixing tank as shown in figure. An agitator has
to be placed inside the funnel for continuous mixing of grout solution. By control valves, grout
solution distributes all four grout pipes equally. The mixture will flow easily into the soils
particles. After filling the grout solution into the sandy soil the grout pipes are removed from the
tank gently without disturbing the sand. The gap of the grout pipes is filled with sand.
5. 5
PLATE LOAD TEST
The specimen is placed in axial loading machine, and a steel plate (5cmx5cm) is placed at
the top centre as shown in Figure 4.2. A steel spherical ball is placed over the centre of the
loading test plate. A load cell is placed over the spherical steel ball, in order to take the reading
of the load which is applied. The Linear Variable Differential Transformer (LVDT) which helps
to find the deflections (or) displacement in the plate is placed on the solid part of the acrylic tank
as shown in Figure 4.1. The axial load machine is switched on for applying load at the constant
gear. Form this test the load intensity and the settlement curve is found with the help of load cell
and LVDT which is connected to the data-logger and then to a laptop.
With help of the data logger (Figure 4.3) readings of the load corresponding to the
displacement is noted. Similarly this should be done for all specimens.
PERMEABILITY TEST
The test is performed according to the instrument setup Figure 4.4. Allow water to flow through
the overhead tank until the water level in the tank is constant. Open the bottom outlet, run water
through the discharge pipe until the sand is saturated and no air bubbles appear to flow out of the
pipe (steady flow). Measure the head of water (h), distance between the water surface in the
overhead tank and the bottom outlet of the specimen.
. Figure 4.4
A measuring jar has to be placed to measure the quantity of water discharge from the
sample, start the stop watch and collect the discharge water in the measuring jar. Record the time
of water discharge collected. The process is repeated for two to three times and the concordant
value of k is noted.
6. 6
Co-efficient of permeability,
Here, k is the coefficient of permeability, Q is the discharge of water, L is
the length of the soil column, A is the area of the soil column, h is the head difference and t is the
time taken for the discharge of water.
VISCOSITY
Viscosity is a measure of the resistance of a fluid which is being deformed by either shear or
tensile stress. In everyday terms (and for fluids only), viscosity is "thickness" or "internal
friction". Thus, water is "thin", having a lower viscosity, while honey is "thick", having a higher
viscosity. Put simply, the less viscous the fluid is, the greater its ease of movement (fluidity).
Prepare the cement grout with addition of 10% HMPC for different water cement ratio. Fix the
marsh funnel (Figure 4.3) in the stand and keep the measuring jar under the funnel. Note the
time when measuring jar fill 960 ml. similarly do for all other ratio.
Figure 4.3 Marsh funnel setup
Table 4.1 Viscosity
Water-cement ratio Time in sec
4:1 32.23
6:1 31.63
8:1 29.11
10:1 29.01
7. 7
As the HPMC dosage increases the solution becomes thicker, so we assume 1% HPMC as our
Optimum dosage % for grouting.
Figure 4.4 Graph for Marsh value.
5. PERMEABILITY AND PLATE LOAD TEST RESULTS
We have taken permeability readings for the plate loaded soil to check for grout strength and
least void fills. The graph of the seventh day test samples has plotted as shown in Figure 5.4.
And the plate load test results for both, cement grout and biopolymer grout 7th
day test have
been compared to show the strength or bearing capacity of the soil (shown in Figure 5.3) and
as well as, with biopolymer grout 7th
day test for loose state Vs medium dense (shown in
Figure 5.4).
In the graph, we have given some notation as follows
24.00
25.00
26.00
27.00
28.00
29.00
30.00
4:1 6:1 8:1 10:1
Marshvalue(sec)
W/C Ratio
8. 8
Table 5.1 Notations
Notation for
Biopolymer (HPMC)
grout
Notation for
Cement gout
Meaning
G1 C1 4:1 water cement ratio
G2 C2 6:1 water cement ratio
G3 C3 8:1 water cement ratio
G4 C4 10:1 water cement ratio
Figure 5.1 Plot between load intensity and settlement curve for grouted soil (Cement grout)
- 7days curing.
0.00
1.00
2.00
3.00
4.00
5.00
6.00
0.00 1.00 2.00 3.00 4.00 5.00
Displacement(mm)
Load, kN/m2
G1 G2 G3 G4
9. 9
Figure 5.2 Graph for Plate load test on loose state grouted soil (HPMC) at 7days curing
period
Figure 5.3 Graph for Plate load test on medium dense state grouted soil (HPMC) at 7days curing
period
0.00
3.00
6.00
9.00
12.00
15.00
18.00
0 100 200 300 400
Settlement(mm)
Load intensity, kN/m2
C1 C2 C3 C4
0
1
2
3
4
5
6
7
8
0.00 1.00 2.00 3.00 4.00 5.00 6.00 7.00
Displacement(mm)
Load kN/m2
G1 G2 G3 G4
10. 10
5.1.1 Comparison of plate load tests
Figure 5.3 Plot between specimen type and load intensity curve of cement grout and biopolymer
(HPMC) grout - 7days curing period.
Figure 5.4 Graph for Comparison of Plate Load test for Loose state - Medium dense state grouted
soil (both with HPMC) for 7days curing period.
0.00
100.00
200.00
300.00
400.00
500.00
600.00
C1 / G1 C2 / G2 C2 / G3 C4 / G4
Loadintensity(kN/m2)
Loose state
Cement
Hpmc + cement
0
1
2
3
4
5
6
G1 G2 G3 G4
AxisTitle
7 days Test
Loose state
Medium dense
11. 11
CONCLUSION
After testing all the samples of different water cement ratio at 7th
day test. From the test result, we get
the displacement in mm to that of the load in kN/m2
and the graphs where plot displacement against
Load. Finally, when we analyze the graphs (Figure 5.1 to 5.3), Normally we come to know that as the
water cement ratio of grout decreases the displacement also decreases i.e., it shows the strength or the
bearing capacity of soil increases. And from Figure 5.2 and 5.3, we conclude that adding of HPMC which
increases the Viscosity of the grout (Table 4.1) also shows that, the HMPC gives viscosity to the cement
grout.
We did also study, the strength of grouted samples by 7th
day curing periods. From comparison graphs
(Figure 5.3 and 5.4), it shows that as the days increase the displacement is decrease. Therefore from the
Figure 5.3, it is easily understood that the Biopolymer grout (HPMC) is good binding agent than cement
grout for grouting techniques like permeation grouting.
Thus, when we study in direction of soil strata i.e., loose soil state and medium dense soil state
(from comparison graph Figure 5.4) the G2 value clearly shows a wide variation, although we
grout and reduce the voids in sandy soil medium dense soil state, it gives less displacement or in
other word this gives high barring capacity when compared to loose soil state.
REFERENCE
1. A.Bezuijen, A.F. Van Tol, M.P.M. Sander (2007), “Mechanism that detremine between
fracture and compaction grouting in sand”, Journal of Scientific Research, Vol 25 No. 2
(2007), pp 234-247.
2. Dr. Abdel-Monem Moussa, Dr. Fatma El-Zaharaa Baligh, Dr. Tahia Abdel-Monem
Awad, Asmaa El- Rokh (2007), “Sandy soil improvement using grouting”, 12th
ICSCE,
Cairo, Egypt.
3. I.S for Permeation grouting I.S 4999 as per Bureau of Indian Standards.
4. I.S for Plate load test I.S 1888 as per Bureau of Indian Standards.
5. I.S for Sieve Analysis I.S 2720 part 4 1985 as per Bureau of Indian Standards.
6. I.S for Specific Gravity I.S 2720 part 3 (sec 1 & 2) 1985 as per BIS.
7. James C.NI, Wen-Chieh Cheng, (2009) “Using fracture grouting to lift structure in clayey
sand” Appl Phys& Eng 2010, pp 879-886.
8. Motoyuki Asda, Hitoshi Nakashima, Takashi Ishii, Sumaio Horiuchi (2006), “Field test of
Ethanol/ Bentonite Slurry Grouting into Rock Fracture”. Tokyo-Japan Material Research
Society journal vol, 932.
9. N.G.Terezopoulos and R.N.Singh (1987), “Ground Water contol by grouting in tunnels
for a pumped storage scheme”, international journal of mine, vol 6, pp 32 – 48.
10. Tahia Award (2005), “Bond Capacity of Grouted Anchours Embedded In Sand”, Cairo –
Egypt 2005@ 11 th
ICSGE, pp E05GE26-1 to E05GE26-14.