Recommended: Design USE Cement-Modified

IRC 50—1973
RECOMMENDED DESIGN
CRITERIA FOR THE USE
OF
CEMENT-MODIFIED SOIL
IN
ROAD CONSTRUCTION
{First Reprint)
THE INDIAN ROADS CONGRESS

1
IRC : 50—1973
RECOMMENDED DESIGN
CRITERIA FOR THE USE
OF
CEMENT-MODIFIED SOIL
IN
ROAD CONSTRUCTION
(First Reprint)
Published by
THE INDIAN ROADS CONGRESS,

Jamnagar House, Shahjahaii Road,
New Delhi- 11001
1978
Price Rs.60/-
(PIus Packing
& Postage)
IRC : 50-1973
First published in June, 1973
Reprinted April, 1978
{Rights of Publication and Translation are reserved)
Printed at Sagar Printers & Publishers :New Delhi-3 Phone : 618484

IRC : 50-1973
RECOMMENDED DESIGN CRITERIA FOR

THE USE OF CEMENT-MODIFIED SOIL
IN ROAD CONSTRUCTION
1. INTRODUCTION
1.1. Addition of cement to soils has been tried successfully to
improve their resistance to softening action of water, and other beha-
vioural properties. As such, stabilisation with cement has been used
extensively in road construction. The technique commends itself for
adoption especially in areas where the cost of conventional road
aggregates may be high.
1.2. Recommendations in this Standard cover the use of

'cement-modified soil' for sub-bases, as distinct from 'soil-cement'
which is a stronger material, reserved usually for base courses.
1.3. This standard was initially prepared by tiie Soil Engineer-

ing Committee (personnel given below). It was processed and
approved by the Specifications and Standards Committee in their
meeting held on the 29th and 30th September 1972. Later this was
finally approved by the Executive Committee in their meeting held
on the 1th March 1973 and by the Council in their 81st meeting
1
held at Cochin on the 26th April 1973.
Personnel of the Soil ENGinEERiNG CoiMmittee
J.S. Marya Convenor

T.K. Natarajan Member-Secretary
T.N. Bhargava Brig. Harish Chandra
E.G. Chandrasekharan Dr. Jagdish Narain
M.K. Chatlerjee Dr. R.K. Katti
A.K. Deb Kewal Krishan
Y.C. Gokhale Mahabir Prasad
H.D. Gupta H.C. Malhotia
S.N. Gupta M.R. Malya
1
IRC : 504973
S.R. Mehra Ashok C. Shah

A. Muthukumaraswarny R.P. Sinha
A.R. Satyanarayana Rao R. Thiliainayagam
N. Sen Dr. H.L. Uppal
Dr. I.S. Uppal
2. SCOPE
2.1. The extent to which soil properties get modified by
cement action depends greatly on the concentration of cement.
With cement in the range of 7 to 10 per cent, depending on other
factors the mixture may develop considerable compressive strength.
The strength could be around 17.5 kg/cnr or more when tested on
cylindrical specimens after curing for 7 days. A material of this
nature is knovv'n as *'soii-cement" and has found wide usage in many
countries for base course construction. Soil-cement is usually
designed on the basis of unconfined compressive strength, or wet and
dry durabilitytest, limits for which have been laid down in specifica-
tions from these countries.
2.2. On the other hand, considerable advantage could be

gained by the limited improvement of soil as a result of addition of
smaller quantities of cement, without necessarily improving the soil
to the level of soil cement. A soil processed with these objectives is
known as cement-modified soil. Considerable amount of work, in

the laboratory as well as in the field, has been carried out in India
on the utilisation of this material. It has been shown that even with
small concentrations of cement, of the order of 2 to 3 per cent, a soil
could develop adequate strength to satisfy the requirements of a road
sub-base. As an illustration, the strength developed by a typical
soil with different concentrations of cement is indicated in the
Annex lire.
2.3. Recommendations in the Standard are restricted to the

use of cement-modified soil. It is presupposed that the work will be
carried out fully according to construction specifications with
requisite site supervision over the quality of materials and process of
construction.
2
iRC : 50-1973
3. DESIGN CONSIDERATIONS
3.1. Soil Type

3.1.1. Generally, granular soils free of high concentrations of
organic matter or deleterious salts are suitable for cement-stabilisation.
For checking the suitability of soil, it would be advantageous to keep
the following criteria in view :
(i) Plasticity modulus, expressed as the product of PI of soil and per

cent fraction passing 425 micron sieve, should not exceed 250 and
(ii) Uniformity coeflicient of soil should be greater than 5 and prelera-

biy greater than 10.
3.1.2. Soils not suitable for cement-stabilisation are :
(i) Hcav\ clays including black cotton soil having a PI greater than 30
(ii) Soils having organic content higher than 2 per cent
(iii) Highly micaceous soils, and

(iv) Soils with soluble sulphate or carbonate concentration gicater than
0.2 per cent.
3.3. Concentration of Cement
3.3.1. The amount of cement will depend on the type of soil,
design requirements, and overall economic Becauseconsiderations.

of difficulties of uniform mixing, however, cement content of even
2 per cent may be necessary in the case of hand mixing.
3.3.2. In every case, cement concentration must be expressed

as per cent by weight of the dry soil.
3.4. Degree of Pulverisation

3.4.1. For effective stabilisation, it is necessary that the soil
must be in a well pulverised state bet ore cement is added. The degree
of pulverisation should be such
80 per cent of soil
that at least
passes through 4.75 micron sieve and there are no lumps larger than
25 mm.
3
IRC : 50 1973 "
. • •
3.5. Strength Criteria
3.5.1, Cement-modified soil mixes should be designed on the

basis of their soaked CBR value.
3.5.2. For design purposes, field CBR should be regarded

only as 45 to 60 per cent of that obtained depen- in the laboratory,
ding on the efficiency of mixing, placing, curing and other related
factors.
3.6. Mix Design
3.6.1. The proporations for cement-modified soil mix should

be determined in the laboratory. The following procedure may be
adopted for this :
(i) The soil should be tested for PI, sand fraction sulphate/carbonate
concentration, and organic content, in order to assess its suitability
for stabilisation (vide para 3.1.);
(ii) Moisture-density relationship for the soil should be established as

per IS: 2720 (P.ut VII)— 1974;
(iii) After pulverising the soil to the degree indicated in para. 3.4, CBR
specimens with varying percentages of cement should be prepared
at maximum dry density and optimum moisture content correspon-
ding to 2720 (Part VIl)-1974. The specimens should be
IS:
initially cured for 3 days followed by soaking in water for 4 days
prior to their testing as per IS 2720 (Part XVI)— 1965. At least
:
3 specimens should be tested for each cement concentration; and
(iv) On the basis of strength results, the design mix should be chosen
keeping in view the criteria set out in paras 3.3. and 3.5.
4
IRC : 50—1973
Annexure
LABORATORY TEST RESULTS FOR A TYPICAL SOIL

STABILISED WITH DIFFERENT PERCENTAGES
OF CEMENT
Cement content {per cent CBR value of specimens

by wt. of dry soil) compacted at proctor
density
0 g**
I 20*
2 43*
2.5 60*
3 65*
4 85*
** Soaked in water for 4 days prior to testing.
* Cured for 6 days and thereafter soaked in water for 4 days before
testing
NB : These results are for a soil witli PI ranging between 5 and 10 and
fraction coarser than 75 micron sieve of not less than 50 per cent.
5
(
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IRC 50—1973

THE INDIAN ROADS CONGRESS

THE INDIAN ROADS CONGRESS,

First published in June, 1973

Reprinted April, 1978

{Rights of Publication and Translation are reserved)

Printed at Sagar Printers & Publishers :New Delhi-3 Phone : 618484

RECOMMENDED DESIGN CRITERIA FOR

1.2. Recommendations in this Standard cover the use of

1.3. This standard was initially prepared by tiie Soil Engineer-

held at Cochin on the 26th April 1973.

Personnel of the Soil ENGinEERiNG CoiMmittee

J.S. Marya Convenor

S.R. Mehra Ashok C. Shah

tions from these countries.

2.2. On the other hand, considerable advantage could be

known as cement-modified soil. Considerable amount of work, in

2.3. Recommendations in the Standard are restricted to the

3.1. Soil Type

(i) Plasticity modulus, expressed as the product of PI of soil and per

(ii) Uniformity coeflicient of soil should be greater than 5 and prelera-

3.1.2. Soils not suitable for cement-stabilisation are :

(ii) Soils having organic content higher than 2 per cent

(iii) Highly micaceous soils, and

3.3. Concentration of Cement

3.3.1. The amount of cement will depend on the type of soil,

design requirements, and overall economic Becauseconsiderations.

3.3.2. In every case, cement concentration must be expressed

3.4. Degree of Pulverisation

3.5. Strength Criteria

3.5.1, Cement-modified soil mixes should be designed on the

3.5.2. For design purposes, field CBR should be regarded

3.6. Mix Design

3.6.1. The proporations for cement-modified soil mix should

(ii) Moisture-density relationship for the soil should be established as

3 specimens should be tested for each cement concentration; and

LABORATORY TEST RESULTS FOR A TYPICAL SOIL

Cement content {per cent CBR value of specimens

** Soaked in water for 4 days prior to testing.

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