Proceedings of Indian Geotechnical Conference

December 22-24,2013, Roorkee

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CONSTRUCTION OF CEMENT STABILIZED ROAD - A CASE STUDY

A. K. Sinha, Sr. Scientist, CSIR-CRRI, New Delhi, sinha.crri@nic.in

V. G. Havanagi, Principal Scientist, CSIR-CRRI, New Delhi, vasant.crri@nic.in

S. Mathur, Chief Scientist, CSIR-CRRI, New Delhi, mathurs.crri@nic.in

ABSTRACT: Rapid industrialization and large scale road infrastructural development in India, has resulted in

huge scarcity of construction materials. There is a thrust to investigate the methodology to reduce the thickness of

pavement crust to conserve the conventional construction materials viz. soil and aggregate. This is possible by

using chemically (cement) stabilized material in sub grade and sub base layers of road pavement. To investigate

this, a 300 m experimental test track was constructed on Amritsar Wagha section of NH-I which is going to be

widened from two lanes to four lane divided highway. Design and construction was carried out as per IRC 37 and

MORTH guidelines respectively. Cement stabilized layers was used on the left side of widening portion (two lanes)

of the road towards Wagha Border. In order to compare the performance of cement stabilized road vis-s-vis

conventional construction (without stabilization), the test track was divided into two sections. First section was

constructed using conventional local soil/aggregate/bituminous materials of 200m long. In the second section, local

soil and granular sub base materials were stabilized with cement (2.5 %) and used for the construction of sub grade

and granular sub base layers of 100 m long. The paper presents the design of pavement, construction methodology

and results of field investigation during construction of stabilized road. Construction methodology has been

discussed considering the experience gained in the field.

INTRODUCTION

Large scale road infrastructural development is

going on in the country under different

programmes viz. National Highway Development

Program (NHDP), Pradhan Mantri Gram Sadak

Yojana (PMGSY), and State Road Development

programmes etc. Due to, huge quantity of natural

available materials like soil and aggregate are

being utilized in the road construction. This has

created severe scarcity of these conventional

materials, which have to be brought from large

distances increasing the total cost of construction.

Therefore, there is need to search a methodology to

reduce the thickness of pavement layers. Cement

stabilization may be used to improve the properties

of soil and aggregate results the reduced thickness

of pavement layers. Although, it is possible to treat

almost all type of soils with cement to improve

properties. However, it is difficult to treat fine,

clayey materials due to fineness and difficulty in

pulverization, and mixing with cement

homogeneously. Yusuf [1] stated that cement is

most suitable stabilizing agent for non plastic

coarse grain material. A material is regarded to be

suited for treatment with cement if it has physical

parameters like LL < 50, PI< 6 and silt + clay < 35

% [2].The mechanical strength of cement treated

granular material comes from the coupled

contribution of the compacted granular skeleton

and hydration of cement. The compacted granular

skeleton strongly determines the mechanical

stability of cement treated granular material under

loading. The hydration of cement influences the

bonding strength between the particles. Xuan [3]

studied the matrix of cement treated mixture and

found that the aggregate structure is mainly

governed by the type of aggregate, its gradation

and degree of compaction and bonding phase or

matrix is controlled by the cement content, the

fines content, the moisture content, the curing time

and condition. Kennedy [4] studied the effect of

moisture variation on dry density of compacted

cement treated mix. It was found that the dry

density will be maximum at optimum moisture

content and slight variation in moisture content

from optimum moisture content will reduce the dry

density of the cement treated compacted mix.

White et. al. [5] studied the effect of sample

preparation and parent material used on properties

and behaviour of cement treated material. It was

A. K Sinha, V.G.Havanagi & S.Mathur

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found that Material and sample preparation has a

significant effect on the properties and behaviour

of cement treated material. The most appropriate

preparation procedure for sample would be one

that produces laboratory prepared samples which

represent the field conditions as closely as possible.

Yoon and Abu-Farsakh [6] studied the effect of

cement content on maximum dry density of the

cement treated material. It was found that as the

cement content will increase, the value of

maximum dry density will also increase at OMC.

It was also found that there is significant increase

in maximum dry density as compared to cement

treated mixture.

The Amritsar Wagha border section of NH-I was

proposed to be widened from two lanes to four lane

divided highway under Built Operate and Transfer

(BOT) mode which is around 40 km length. On

this section, construction of experimental test track

was carried out using cement stabilization

technique near Verka chowk (fly over), Amritsar,

Punjab. The total length of test track is about 300

m which is divided into two sections. First one,

cement stabilized layer of 100 m from Chainage

462 + 450m to 462 + 550m and other one is

conventional construction (without stabilization) of

200 m from Chainage 462 + 550m to 462 + 750m.

The whole section is constructed on the left side of

widening portion of the road towards (two lanes)

Wagha Border as shown in the Fig.1.

First section was constructed using cement

stabilized technique in the sub grade and granular

sub base layers while second section was

constructed using conventional local

soil/aggregate/bituminous materials. Design of

pavement was carried out considering the design

procedure of stabilized road as per Indian road

congress code [7]. During the construction, quality

checks were carried out viz. density, moisture

content etc. The paper presents the design of

pavement, results of quality check during the

construction and construction methodology.

DESIGN OF PAVEMENT

Design of pavement (stabilised and unstabilised)

was carried out as per Indian road congress code

[7] considering the average annual traffic growth

rate of 7.5 %, life of pavement of 20 years, CBR

value of sub grade = 7 % and traffic of 20 MSA.

Pavement crust thickness for unstabilized and

stabilised sections is given in Tables 1 & 2

respectively.

Table 1. Pavement crust thickness of unstabilized

section

Sl. No. Layers Thickness, mm

1 BC 40

2 DBM 90

3 WMM 250

4 GSB 300

5 Sub grade, soil

CBR > 7 %

500

Table 2. Pavement crust thickness of stabilized

section

Sl.

No.

Layers Thickness,

mm

1 BC 40

2 DBM 90

3 WMM 150

4 GSB-I with 2.5 % cement 260

5 Sub grade top layer with

2.5 % cement

200

6 Sub grade lower layer

CBR = 7 %

300

Fig. 1 Pictorial view of cement stabilized road

Stabilised section

462+750 m

Unstabilised section

462+550 m

462+450 m Amritsar

Wagha border

Construction of cement stabilised road

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PAVEMENT LAYERS

Sub grade layer

Grain size analysis results indicate that soil

contains 38 % sand and 62 % silt+clay. Liquid

limit of soil was observed to be 25 % and plastic

limit = 10 %. The soil was classified as per Indian

Standard procedure as ML [8]. The maximum dry

density and optimum moisture content were

observed to be 19.9 kN/m3 and 10 % respectively

of blended mix of soil and cement. The CBR value

was determined in the range of 8 10 %.

Granular Sub Base (GSB) Layers

Granular sub base layer of thickness 260 mm was

constructed in two layers viz. 130 mm upper layer

of grade II (close graded) and 130 mm lower

layer of grade III (coarse graded). The maximum

dry density and optimum moisture content was

observed to be 23 kN/m3 and 6 % respectively.

Design mix of GSB having 53 mm size of 35 %, 20

mm and 10 mm size of 15 % each and stone dust

35 %.

Wet Mix Macadam (WMM) Layer

Wet Mix Macadam is designed as per requirement

of MORTH specifications. The coarse and fine

aggregate were mixed proportionally to arrive at

the design mix. WMM layer of thickness 250 mm

was constructed in two layers viz. 125 mm each.

The maximum dry density and optimum moisture

content was observed to be 23.2 kN/m3 and 5 %

respectively. Design mix of GSB having 40 mm

size of 35 %, 20 mm size of 20 %, 10 mm size of

22 % and stone dust 23 %.

Bituminous Layer

Two layers of bituminous were designed over

laying on WMM layer viz. Dense Bituminous

Macadam (DBM) and Bituminous Concrete (BC)

layers of road pavement. Dense Bituminous

Macadam and Bituminous Concrete was designed

as per requirement of MORTH specifications. The

coarse and fine aggregate were mixed

proportionally to arrive at the design mix.

Thickness of DBM/BC layers were designed as

90/40 mm respectively.

Stabilised Layer

Sub grade soil (top) of 200 mm thickness was

mixed with 2.5 % cement. Granular sub base of

thickness 130 mm in two layers were mixed with

2.5 % cement.

CONSTRUCTION OF STABILISED

SECTION

The site of proposed experimental test track is

passing through water logging area due to lower

natural ground level (small pond) and domestic

sewage storage. The water was removed by

pumping and slush of 1m depth was removed.

After that, natural ground was compacted and

around 2 m high embankment was constructed. 500

mm sub grade layer was constructed in two layers

over embankment. On top of sub grade, 100 m

length of road was measured and small

compartment of size 10m 3m were marked on

the sub grade layer as shown in the Fig. 2.

Amount of cement by weight of soil was

determined based on thickness (200mm) of top sub

grade layer, width (3m) and length (10 m) of

compartment and density of mix of soil +cement

(19.9 kN/m3). After that, required amount of

cement bags were kept in each compartment as

shown in the Fig. 2. Each cement bag was open

and spreaded manually on the top of sub grade

layer.

Cement and soil were mixed/blended by grader at

natural moisture content upto 200mm as soil was in

moist condition.

Fig. 2 Cement bag staked in the compartment

Fig. 3 Mixing of soil and cement by grader

A. K Sinha, V.G.Havanagi & S.Mathur

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Harrowing and leveling method was adopted for

mixing as shown in the Fig.3.

Proper soil-cement mix and depth of mix were

observed after three times of harrowing and

leveling. Completion of homogeneous mix was

checked manually through visualization

considering the colour & depth of mix, quantity of

soil and cement etc. After that, proper profile was

checked by total station as shown in the Fig. 4.

Then, water is sprinkled to achieve optimum

moisture content (around 2 % more of OMC).

Compaction was carried out by vibratory roller.

Curing: After completion of compaction of

stabilized sub grade layer, GSB layer was laid

immediately and kept sub grade covered for 7

days.

After that, stabilized GSB first layer of thickness

130 mm is constructed as stabilised sub grade layer

and kept for 7days curing, covering the layer by

spreading of second layer of GSB. Similarly, after

7 days, second layer of GSB was mixed with

cement, compacted and cured for 7 days covering

with loose WMM layer. Remaining pavement

layers were constructed as same as conventional

method.

FIELD INVESTIGATIONS DURING

CONSTRUCTION

Quality of construction was evaluated by carrying

out different field tests viz. sand replacement

method and unconfined compression test as

discussed below.

Degree of Compaction

During construction, density of compacted each

layer was carried out by sand replacement method

as per Indian standard procedure [9]. The results of

degree of compaction of sub grade and GSB layers

were given in Table 3. It was observed that degree

of compaction was more than 98 % required as per

MORTH specifications [10].

Table 3 Degree of compaction of stabilized sub

grade and GSB layers

Chainage Field Dry

density

(kN/m3)

Moisture

content

(%)

Degree of

compaction

(%)

A

462+400 m 19.8 10 99

462+420 m 19.2 12 96

462+430 m 19.4 11 97

462+435 m 19.5 10 98

462+445 m 19.6 13 98

462+460 m 19.4 12 97

462+475 m 19.7 11 99

462+495 m 18.8 10 94

B

462+430 m 22.5 6 98

462+440 m 23.0 7 100

462+450 m 22.8 8 99

462+470 m 22.9 6 100

462+495 m 23.2 7 101 A Stabilised sub grade layer, B- GSB layer

Unconfined Compressive Strength (UCS):

Undisturbed sample of stabilized sub grade layer

was taken out after 7 days from the site of size 38

mm diameter in the Shelby tube. proper waxing on

Fig. 4 Checking of profile for leveling

Fig. 3 Mixing of cement and soil by grader

Construction of cement stabilised road

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both side of the Shelby tube was completed and

brought to CRRI. Unconfined compressive strength

value was determined in the laboratory as per

Indian standard procedure [11]. It was observed

that UCS value is in the range of 1500 to 1800

kN/m2. Undisturbed samples of GSB layers were

not taken out with available indigenous equipment.

As the GSB layer having granular particles, it was

very difficult to penetrate the compacted layer even

by using bigger size Shelby tube of 100mm

diameter. It may possible if cement content in the

GSB layer will be more than 2.5%.

CONCLUSIONS Design and construction of cement stabilized road

was carried out at Amritsar, Punjab. Based on

experience gained during the construction,

following conclusions were arrived as given

below.

Design of pavement was carried out for stabilised and unstabilised roads.

Proper mixing of soil and cement was observed after three times of harrowing and leveling by

grader.

Degree of compaction of stabilised sub grade and GSB layers was achieved more than 98 %

as specified by MORTH specifications.

Unconfined compressive strength of stabilised sub grade layer was observed in the range of

1500 to 1800 kN/m2.

NEED FOR FURTHER STUDY

The performance study of experimental test

sections (stabilized and unstabilized) is being

carried out by measuring rebound deflection

(Benkelman beam) and International roughness

index (dip stick) for at least two monsoon seasons.

REFERENCES

1. Yusuf, M. (2005), Investigating the potential for incorporating Tin Slag in road pavement,

Ph.D. thesis submitted to University of

Nottingham.

2. Pengpeng, Wu. (2011), Cement-Bound Road Base Materials, Submitted to Delft University

of Technology, Delft, Netherlands.

3. Xuan, D. (2012), Cement Treated Recycled Crushed Concrete and Masonry Aggregates

for Pavements, MS thesis submitted to Wuhan

University of Technology, China.

4. Kennedy, J. (1983), Cement bound Materials for Subbases and Road Slough bases, Cement

and Concrete Association, Publication No.

46.027, UK.

5. White, G. W. and Gnanendran (2002), The characterization of cementitious in-situ

stabilised pavement materials: the past, the

present and the future, Road & Transport

Research Journal, Vol. 11(4), 56-69.

6. Yoon, S. and Abu-Farsakh, M. (2009), Laboratory investigation on the strength

characteristics of cement-sand as base

material, KSCE Journal of Civil Engineering

13(1), 15-22.

7. IRC 37 (2012), Guidelines for the design of flexible pavement, Published by Indian Road

Congress, New Delhi, India.

8. IS 1498 (1970), Classification and identification of soils for general engineering

purposes, Published by Beauro of Indian

standard, New Delhi, India.

9. MORTH (2001), Specifications for road and bridge works, Published by Ministry of Road

and Highway Transport, New Delhi, India.

10. IS 2720 part 28(1974), Methods of test for soils: Determination of dry density of soils in

place by sand replacement method, Published

by Bureau of Indian Standards, New Delhi.

11. IS 4332-part-5(1970), Methods of test for stabilized soils: Determination of unconfined

compressive strength of stabilized soil,

Published by Bureau of Indian Standards, New

Delhi.