TECHNICAL NOTE

Development of Rapid Consolidation Equipmentfor Cohesive Soil

Khairul Anuar Kassim • Ahmad Safuan A. Rashid •

Ahmad Beng Hong Kueh • Chong Siaw Yah • Lam Chee Siang •

Norhazilan Mohd Noor • Hossein Moayedi

Received: 24 January 2014 / Accepted: 9 September 2014

� Springer International Publishing Switzerland 2014

Abstract In this study, rapid consolidation cell

equipment (RACE) was developed as an alternative

device to the conventional consolidation test using

Oedometer to determine the consolidation character-

istic of cohesive soil. RACE operates based on the

constant rate of strain (CRS) consolidation theory,

which is a continuous loading method of testing and

could accelerate the consolidation process for cohe-

sive soil, shortening the time consumption from

1 week (when using Oedometer and Rowe cell tests)

to only a few hours. A slightly modification has been

made on the normal CRS test by proposing a direct

back pressure system to the specimen using a tube to

saturate the soil sample. Four types of sample were

tested with different rates of strain using the RACE

equipment and their results were compared with those

conducted using the Oedometer on the same soil type,

from which fairly good agreements were evident in

many specimens. It was found that, the RACE

equipment is capable to determine the consolidation

characteristic of the cohesive soil. In this study, the

acceptable strain rates were proposed as compared

with the Liquidity Indices for cohesive soil. It was

found that the range of strain rate of CRS test for

LI \ 15 % was between 0.01 and 0.3, while for LI

closed to 25 %, the range was between 0.01 and 0.1.

Keywords Consolidation � Cohesive soil � Constant

rate of strain �Oedometer � Strain rate � Liquidity index

Notation

cc Compression index

cv Coefficient of consolidation

Ho Sample height

r Rate of strain

ua Excess pore water pressure

rv Applied pressure

b Normalized strain rate

1 Introduction

Constant rate of strain (CRS) theory was implement in

consolidation test to accelerate the consolidation

process for cohesive soil, shortening the time

K. A. Kassim � A. S. A. Rashid (&) � H. Moayedi

Department of Geotechnics and Transportation, Universiti

Teknologi Malaysia, 81310 Johor Baharu, Johor,

Malaysia

e-mail: ahmadsafuan@utm.my

A. B. H. Kueh

Construction Research Centre, Universiti Teknologi

Malaysia, Johor Baharu, Johor, Malaysia

C. S. Yah � L. C. Siang

Universiti Teknologi Malaysia, Johor Baharu, Johor,

Malaysia

N. M. Noor

Department of Structure and Materials, Universiti

Teknologi Malaysia, Johor Baharu, Johor, Malaysia

123

Geotech Geol Eng

DOI 10.1007/s10706-014-9819-7

consumption from one week (when using Oedometer

and Rowe cell tests) to only a few hours (Kassim and

Clarke 1999). Several studies have been conducted

previously to determine the consolidation character-

istic of different types of soil (Smith and Wahls 1969;

Wissa et al. 1971; Sallfors 1975; Gorman et al. 1978;

Lee 1981; Kassim and Clarke 1999; Larsson and

Sallfors 1985; Lee et al. 1993; Sheahan and Watters

1997; Ahmadi et al. 2011; Ozer et al. 2012; Raftari

et al. 2014). Kassim and Clarke (1999) have used the

CRS equipment and proposed a procedure in order to

determine the consolidation characteristic of stabilised

soil under different amount of stabiliser agents. They

conducted the tests within 2 h to represent the stiffness

at that age of curing. Thus, it is possible to use the CRS

test to predict the variation of stiffness with age and

stress rather than using the increment loading (IL)

system. Sample and Shackelford (2011) fabricated a

new system of CRS test by varies the height of the

testing chamber to observe the consolidation of slurry

mixed soil. The similar finding was discovered by

Sample and Shackelford (2011) where the CRS testing

apparatus offered a convenient, rapid, and economical

approach for evaluating the consolidation behavior of

the bentonite-ZVI slurry mixed sand.

Ozer et al. (2012) reported that the main problem

with continuous loading consolidation is to determine

a proper strain rate for the consolidation test. Many

recommendations had been offered from the previous

researchers for the selection of practically acceptable

test rate, based on several criteria of acceptance (the

relationship of the void ratio, e, against effective

stress, r0, coefficient of consolidation, cv, liquid limit

value, normalized strain rate, b, and ratio of excess

pore pressure to applied total stress, ua/rv) (Smith and

Wahls 1969; Wissa et al. 1971; Sallfors 1975; Gorman

et al. 1978; Lee 1981; ASTM 1982, 1991, 2001, 2008;

Larsson and Sallfors 1985; Lee et al. 1993; Sheahan

and Watters 1997; Ahmadi et al. 2011; Ozer et al.

2012). However, no attempt has been made to study

the acceptable test rate with soil Liquidity Indices (LI),

which is obtained by dividing the difference of in situ

water content and Plastic Limit by the difference of

Liquid Limit and Plastic Limit. This relationship is

important because water is an influencing factor in the

saturation process and the in situ water content keeps

changing due to environmental effects in practice

(Ishak et al. 2012; Rashid et al. 2014; Shahminan et al.

2014).

In this study, Rapid Consolidation Equipment

(RACE) is developed as alternative equipment and

testing to conventional consolidation test, the Oedom-

eter. The objective of this paper is to introduce the

RACE and capability of this equipment to determine

the consolidation of cohesive material. The RACE has

several advantages compared to the conventional

cohesive soil consolidation methods, namely a faster

process time, whereby the invention reduces the time

needed to perform the task, is able to be incorporated

with other standard pieces of equipment in soil

laboratories, standard loading frame, fully automated

and greatly reduces the risk of losing soil samples due

to electrical failure, as a result from the reduced

preparation time. Some modification has been made

based on the standard CRS equipment, allowing for a

back pressure system to directly saturate the sample

before the test is conducted. A series of laboratory

Fig. 1 Schematic diagram and photograph of the Constant Rate

of Strain Consolidation test equipment (Rapid Consolidation

Cell Equipment, RACE)

Geotech Geol Eng

123

works was conducted employing RACE to determine

the consolidation characteristic of various types of

clay obtained in Malaysia. This study only focussed on

the relationship of the void ratio, e, against effective

stress, r0 which contribute to cc value between

Oedometer and CRS tests and normalized strain rate,

b in order to determine the acceptable test rate of the

CRS test. Based on the obtained results, the acceptable

strain rates of CRS test were proposed as compared

with the Liquidity Indices for cohesive soil.

2 Design of CRS Equipment

Constant rate of strain consolidation test equipment

was designed and named as RACE. The major

components of RACE are base, cell top, cell chamber

and the stainless steel ring. Figure 1 shows the general

arrangement of the RACE cell. The RACE equipment

had to operate within a Triaxial load frame using the

pressure systems available in the laboratory. The cell

chamber made from a transparent Perspex cylinder

which allowed observing the specimen during a test.

25 mm thick aluminium end caps held in place by four

bolts. O-rings were used to seal the cell by placing at

the top and bottom of the cylinder. The top cap has a

guide built into ensure that the loading platen remains

perpendicular to the specimen surface. The loading

piston is guided by two O-rings, which also act as

seals.

The 100 mm diameter specimen is contained

within a steel ring that sits within the perspex cell

designed to withstand pressures of up to 500 kPa with

a 25 mm height. The maximum contact pressure with

a 10 kN load frame is 1250 kPa, allowing comparisons

to be made with results from Oedometer tests on

specimens consolidated to 1,250 kPa. Porous stones

are placed on the top and bottom of the specimen

within the steel ring. Since the steel ring is 25 mm

height, a specimen thickness of 23.5 mm is produced.

A perforated loading platen sits on top of the top

porous disk through which the back pressure is

applied. The steel ring is clamped in place by the cell,

thus providing the necessary external seal between the

top and bottom of the specimen. This means that flow

can occur only within the specimen and the pore

pressures between the loading piston and the top cap is

taken into account at the top and bottom of a specimen

can be different.

Two O-ring are installed between the stainless steel

ring and cell chamber to avoid any leakage from the

bottom of the specimen to the top side. High loading

pressure will be applied to the soil sample in the CRS

test. This may cause the stainless steel ring in the

RACE cell being lifted up, therefore PVC holder is

placed on the steel ring to hold down the steel ring.

Loading piston is used to transfer the load to loading

platen and sample. The friction between the loading

piston and the top cell is reduced using ball bearing.

Sealing is achieved by O-rings at the junctions of the

cell top and the bottom of the chamber. The cell top,

cell chamber and the cell base is hold together by

screws and nuts. Drainage is permitted from both end

of the sample where first drainage outlet is used for

drainage purposes, and the second drainage outlet is

used to measure pore pressure of the specimen.

A modification has been made on the back pressure

system where the back pressure is applied directly

through the sample by using a tube. In order to ensure

accurate measurement on the back pressure applied on

the sample, two O-rings were used between load

platen and stainless steel ring to seal the specimen. It is

also possible to either apply the same back pressure to

the base of the specimen or prevent drainage from the

base and measure the pore pressure at the base. During

the saturation stage the back pressure is applied to both

top and bottom of the specimen; during the consoli-

dation stage it is applied only to the top of the

specimen. RACE is mounted on the loading frame

platform. The loading frame with multi speed drive

unit is the main loading machine used in the CRS test.

It can provide constant motor drive speed ranging

from 0.0001 to 9.0 mm/min.

Three types of measuring devices were used in the

CRS test for data measurement. These measuring

devices were linear variable displacement transducer

(LVDT), pressure transducer and the load cell. A

50 mm LVDT with an accuracy of 0.001 mm was

used to measure vertical displacement of the soil

sample in the CRS test. This LVDT was attached to the

loading piston during the CRS test. 1,500 kPa pressure

transducers with an accuracy of 0.1 kPa were used to

measure back pressure and the pore pressure from the

top and the bottom of the specimen. All tubings

connecting to pore pressure and back pressure must be

saturated to ensure accurate readings of pressures. A

907 kilogram capacity S type load cell was used for

load measurement which can provide a maximum

Geotech Geol Eng

123

pressure of 1,100 kPa on the 100 mm diameter soil

specimen. The load cell was attached between the

loading frame and the load piston that transfer the load

to the load platen and subsequently to the soil sample.

The load cell can give to the nearest 0.001 kN.

3 System Calibration

The load cell and displacement transducers are

calibrated against a dead weight system and microm-

eter gauge respectively. The transducers are connected

to the Data Acquisition Unit (ADU) during the

calibration so that the output includes the signal

processing of the ADU. These calibrations proved to

be linear and repeatable with accuracies of less than

0.1 % over the full working range.

System calibration of the equipment was essential

to get the accuracy of test results which is based on the

compression and the load-pressure measurement.

Frictional error between the specimen ring and the

load platen could be minimised by applying the silicon

grease to the internal surface of the specimen ring.

Setting up of the system calibration was similar to the

CRS test except the soil specimen inside the ring was

change to the uncompressible solid steel within the

range up to 10 kN. Then the loading frame was started

and the load and displacement were recorded by

transducers with ADU. The load calibration was

continued until the maximum load of the load cell

was achieved. Figure 2 shows the displacement of the

loading system expressed in terms applied load and the

dimensions of the specimen. The measured displace-

ment during consolidation is corrected for this

displacement.

For the RACE cell loading calibration, data needed

to be collected were load and the pore pressure at the

bottom of the cell. Soil specimen in the ring was

changed to the water to let the load applied to the water

act as pore water pressure at the bottom of the cell.

Loading applied to the water was measured by the load

cell and the pore pressure was measured by the

transducer. Figure 3 shows the relationship between

the applied load and the pore pressure. The main

purpose of this calibration was to find out the corrected

pressure applied on the soil specimen.

4 Preparation of Soil Sample

The soil samples were collected from Air Papan,

Gemas and Kluang, which are located in the southern

part of West Malaysia. Also, Kaolin clay was used as

the control material in the investigation. The classi-

fication properties of the soil samples are presented in

Table 1 based on Unified Soil Classification System.

Remoulded sampler preparation equipment with an

internal diameter of 150 mm was used to prepare the

sample under different maximum pre-consolidation

pressures (100, 200 and 300 kPa) as shown in Fig. 4.

One kilogram of oven dried soil sample was mixed

with distilled water at 1.4 times the liquid limit to form

into slurry before putting it into the remoulded sampler

equipment. Porous stone was placed at the bottom of

the sampler to drain water from the sample. The soil

sample was then loaded using steel load platen.

Pressure was applied on the steel load platen usingFig. 2 Displacement calibration curve for the RACE testing

system

Fig. 3 Loading pressure calibration curve for the RACE testing

system

Geotech Geol Eng

123

water pressurised by compressed air. Two O-rings

were used to seal the load platen to prevent the water

from seeping through into the soil sample and disturb

the properties of the remoulded sample.

Another two O-rings were put between the cell top

and the load platen to avoid the water draining out

from the top of the cell, which cause reduce pressure

applied to the soil sample. The air pressure applied to

the soil sample was based on the maximum applied

pressure needed for remoulded sample preparation.

Settlement of the remoulded sample was taken from

the dial gauge attached on the top of the load platen.

For each maximum pressure, a step loading method

was applied to ensure the sample was uniformly

consolidated. For each level, the air pressure applied

was maintained for 24 h. The slurry will form into a

150 mm diameter slurry cake. Steel ring of diameter

50 and 100 mm were used to press on the compressed

slurry cake for Oedometer and CRS tests respectively.

Each sample was then trimmed and placed inside the

cell. RACE tests were conducted such that the

resulting compression curves can be compared with

those from Oedometer tests. The result from the

RACE tests is considered acceptable if a similar shape

of curve is obtained. In this study, the Oedemeter tests

were conducted in 7 stages of loading (maximum

1,200 kPa) and 4 stages of unloading (minimum

25 kPa). Moisture content of the samples were deter-

mined after the CRS and Oedometer tests were

completed.

5 Test Procedure

In this study 12 major tests had been conducted for 4

samples of soil under 3 different intensities of pre-

consolidation pressures. A simple notation was used to

label the soil samples under different pressures as

shown in Table 2 e.g. Air Papan 100 denotes Air

Papan soil with a pre-consolidation pressure of

100 kPa. Two Oedometer tests were conducted on

each sample to provide confidence as to the repeat-

ability of the test preparation methods. Meanwhile, for

the CRS test, the undrained and drained tests were

employed. Equation 1 proposed by Lee (1981) is used

in this study to determine the normalized strain rate, b,

where the b should be less than 0.1 based on Lee

(1981) suggestion.

b ¼ rH0

cv

ð1Þ

where Ho is the sample’s height, r is the rate of strain

and cv is the coefficient of consolidation from the

Oedometer test. The values of the normalized strain

rate, b, and strain rate for all samples are listed in

Table 2 based on Eq. 1.

6 Validation of the CRS Test

Figure 5 shows the curve of e/eo against effective

stress for Gemas 100 sample from Oedometer and

CRS tests. The void ratio had been normalized with

that of initial, e/eo due to inconsistency of the initial

void ratio. Two rates of strain, which are 0.03 mm/min

Table 1 Classification properties of soil samples

Soil Characteristics Soil types

Kaolin

clay

Gemas

clay

Air papan

clay

Kluang

clay

Liquid limit (%) 51.40 47.02 40.47 53.19

Plastic limit (%) 28.40 24.53 19.53 26.87

Plastic index (%) 23.00 22.49 20.95 26.32

Water content (%) 33.96 27.72 24.71 33.26

Liquidity index (%) 24.17 14.18 24.74 24.28

Specific gravity Gs 2.64 2.60 2.59 2.55

Soil classification CH CI CI CH

Fig. 4 Schematic diagram of remoulded sampler preparation

equipment

Geotech Geol Eng

123

(b = 0.025) and 0.061 mm/min (b = 0.05), were

applied in the CRS test for the Gemas 100. The

relationships of e/eo versus log r0v produced from both

the CRS test and the standard Oedometer test are in

good agreement. It was found that a slower strain rate

of CRS test produces a better result with respect to that

of Oedometer. This finding was similar as

recommended by Leonards (1985) to use a slow rate

of strain.

Table 2 summarizes all measured consolidation

properties obtained from the Oedometer and CRS

tests. The compression indices, cc, obtained from the

compression curve based on the normalized void ratio

for all four types of soil under different pre-consoli-

dation pressures, match closely those obtained from

the conventional Oedometer test, ensuring therefore

the acceptability of cc produced by the CRS test.

7 Discussion

In this study, the rate of the CRS test used was based

on the normalized strain rates, b method and relation-

ship of the void ratio, e, against effective stress, r0

which produce the cc results. In general, normalized

strain rates, b used in this study which is range from

0.01 to 0.1 have produce an acceptable cc values

between the CRS and Oedometer tests. In addition,

based on the regression analysis on the relationship

between cc value of CRS and Oedometer tests, good

Table 2 Summary of

measured consolidation

characteristic from CRS and

Oedometer tests

Soil types with

different

pre- consolidation

pressures

Average cv

from Oedometer test

cc from

Oedometer

test

ß value Strain rate

for CRS test

(mm/min)

cc from

CRS test

Air Papan 100 12.09 0.2345 0.025 0.0125 0.2329

0.05 0.025 0.2348

Air Papan 200 10.62 0.1875 0.05 0.02125 0.1914

0.075 0.0325 0.1923

Air Papan 300 16.08 0.1875 0.025 0.015 0.1873

0.05 0.0325 0.1884

Gemas 100 30.44 0.2090 0.025 0.03 0.2108

0.05 0.061 0.2134

Gemas 200 27.72 0.20800 0.01 0.01 0.2076

0.025 0.0275 0.2081

Gemas 300 32.41 0.2160 0.01 0.0125 0.2063

0.025 0.0325 0.2063

Kaolin 100 45.00 0.2850 0.01 0.0175 0.3159

Kaolin 200 47.16 0.3050 0.025 0.047 0.3068

0.05 0.094 0.3071

Kaolin 300 50.22 0.2700 0.025 0.05 0.2549

0.05 0.1 0.2583

Kluang 100 3.05 0.3586 0.10 0.01225 0.3584

Kluang 200 3.59 0.2877 0.10 0.01425 0.2867

Kluang 300 3.09 0.2325 0.10 0.01225 0.2327

0.4

0.5

0.6

0.7

0.8

0.9

1.0

10 100 1000 10000

e/e o

Effective Stress (kPa)

Oedometer 1Oedometer 2CRS 0.03mm/minCRS 0.061mm/min

Fig. 5 e/eo versus effective stress relationship for the Gemas

100 sample

Geotech Geol Eng

123

agreement between both parameter was obtained

where the coefficient of determination, R2 is greater

than 0.96 as shown in Fig. 6. The strain rate used

during the test was range from 0.01 to 0.09 mm/min

where it was found that the soil with a lower cv value

(Kluang) used a lower rate of strain. Therefore, it is

important that the acceptable normalized strain rates,

b, should be determined from the compatibility of cv

values with the conventional Oedometer test results

(Fig. 6).

As mentioned in the introduction section, the in situ

water content keeps changing due to environment

effect in practice. Therefore, an acceptable strain rate

range of CRS test was introduced based on Liquidity

Index value of cohesive soils. Figure 7 shows the

range of strain rate with LI for cohesive soil, whereby

LI is obtained by the following Eq. 2.

LI ¼ Wc � PLð Þ= LL� PLð Þ ð2Þ

where LI is Liquidity Index, Wc is final water content

determine after the CRS test listed in Table 1, and PL

and LL are plastic and liquid limit of the soil

respectively (Gofar and Kassim 2007). The degree of

saturation based on the Wc, Gs and final void ratio was

approximately 100 % for all tested soils which means

the sample were fully saturated. Based on the results, it

can concluded that the range of strain rate of CRS test

for LI \ 15 % was between 0.01 and 0.3, while for LI

closed to 25 %, the range was between 0.01 and 0.1.

However, this results only applicable for the soil with

PI range between 20 to 27 %. Further investigation is

required in order to cover a bigger range of soil PI

especially for the soil with PI less than 10 % and

different range of strain rate.

8 Conclusions

From the current study, several conclusions based on

four investigated soil types using Oedometer and CRS

tests are listed below.

1. A new RACE has been developed adopting CRS

method for cohesive soil consolidation test,

reducing testing time from 1 week to merely a

few hours.

2. It can be observed that the relationships of e/eo

versus log r0v produced from both the CRS test

and the standard Oedometer test are in good

agreement.

3. The cc values produced by the CRS test are within

the maximum and minimum limits of the standard

Oedometer test results.

4. The range of strain rate of CRS test for LI \ 15 %

was between 0.01 and 0.3, while for LI closed to

25 %, the range was between 0.01 and 0.1.

References

Ahmadi H, Rahimi H, Soroush A (2011) Investigation on the

characteristics of pore water flow during CRS consolida-

tion test. Geotech Geol Eng 29:989–997

ASTM (1982) Standard test method for one-dimensional con-

solidation properties of soils using controlled-strain load-

ing. ASTM standard D4186-82. American Society of

Testing Materials, West Conshohocken, Pa. 04.08:534–538

y = 1.0008xR² = 0.9668

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4

c cob

tain

ed f

rom

CR

S te

st

cc obtained from Oedometer test

Fig. 6 Comparison between cc values obtained from Oedom-

eter and CRS tests

10

15

20

25

30

0 0.05 0.1 0.15 0.2 0.25 0.3 0.35

Liq

uidi

ty I

ndex

(%

)

Strain rate (mm/min)

Air Papan

Gemas

Kaolin

Kluang

Fig. 7 Strain rate range with liquidity index for cohesive soils

Geotech Geol Eng

123

ASTM (1991) Standard test method for one-dimensional con-

solidation properties of soils using controlled-strain load-

ing. ASTM standard D4186-89. American Society of

Testing Materials, West Conshohocken, Pa. 04.08:

565–569

ASTM (2001) Standard test method for one-dimensional con-

solidation properties of soils using controlled-strain load-

ing. ASTM standard D4186-89 (reapproved 1998).

American Society of Testing Materials, West Cons-

hohocken, Pa. 04.08:512–517

ASTM (2008) Standard test method for one-dimensional con-

solidation properties of soils using controlled-strain load-

ing. ASTM standard D4186-06. American Society of

Testing Materials, West Conshohocken, Pa. 04.08:520–533

Gofar N, Kassim KA (2007) Introduction to geotechnical

engineering part 1, revised edition. Prentice-Hall Inc,

Singapore

Gorman CT, Hopkins TC, Drnevich VP (1978) Constant-rate-

of-strain and controlled-gradient consolidation testing.

Geotech Test J 1(1):3–15

Ishak F, Ali N, Kassim A (2012) Tree induce suction for sus-

tainability slope. Proceedings of 3rd International Con-

ference on Soil Bio- and Eco-engineering. The Use of

Vegetation to Improve Slope Stability

Kassim KA, Clarke BG (1999) Constant rate of strain consoli-

dation equipment and procedure for stabilized soils. Geo-

tech Test J 22:13–21

Larsson R, Sallfors G (1985) Automatic continuous consolida-

tion testing in Sweden. In: Consolidation of soils: testing

and evaluation, Proceedings of the ASTM Committee D-18

Symposium on Soil and Rock, Orlando, Fla., 24 January

1985. American Society for Testing and Materials, West

Conshohocken, pp 299–328

Lee K (1981) Consolidation with constant rate of deformation.

Geotechnique 31(2):215–229

Lee K, Choa V, Lee SH, Quek SH (1993) Constant rate of strain

consolidation of Singapore marine clay. Geotechnique

43(3):471–488

Leonards, G.A. (1985). Discussion of theme lecture no. 2. by

Jamiolkowski et al. Proceedings of the 11th International

Conference on Soil Mechanics and Foundation Engineer-

ing, San Francisco 5:2674–2675

Ozer AT, Lawton EC, Bartlett SF (2012) New method to

determine proper strain rate for constant rate-of-strain

consolidation tests. Can Geotech J 49(1):18–26

Raftari M, Rashid ASA, Kassim KA, Moayedi H (2014) Eval-

uation of kaolin slurry properties treated with cement. J Int

Meas Confed 50:222–228

Rashid ASA, Kalatehjari R, Noor NM, Yaacob H, Moayedi H,

Sing LK (2014) Relationship between liquidity index and

stabilized strength of local subgrade materials in a tropical

area. Measurement 55:231–237

Sallfors G (1975) Preconsolidation pressure of soft, high-plastic

clays, PhD Thesis, Geotechnical Department, Chalmers

University of Technology, Goteborg

Sample KM, Shackelford CD (2011) Apparatus for constant

rate-of-strain consolidation of slurry mixed soils. Geotech

Test J 35(3):409–419

Shahminan DNIAA, Rashid ASA, Bunawan AR, Yaacob H,

Noor NM (2014) Relationship between strength and

liquidity index of cement stabilized laterite for subgrade

application. Int J Soil Sci 9(1):16–21

Sheahan TC, Watters PJ (1997) Experimental verification of

CRS consolidation theory. J Geotech Geoenvironmental

Eng 123(5):430–437

Smith RE, Wahls HE (1969) Consolidation under constant rates

of strain. J Soil Mech Found Div ASCE 95(SM2):519–539

Wissa AEZ, Christian JT, Davis EH, Heiberg S (1971) Con-

solidation at constant rate of strain. J Soil Mech Found Div

ASCE 97(SM10):1393–1413

Geotech Geol Eng

123