“EFFECT OF MIXING STONE DUST ON ENGINEERING

PROPERTIES OF EXPANSIVE SOIL”

ABSTRACT

In India about one-fifth of land is covered by expansive soil. Due to inherent alternate swell shrink behavior, problems are likely to be introduced to the structures built on this soil. Normally the types of foundations are very depending upon the availability of soil strata as well as cost involvement. Some times it is essential to build heavy structures over a weak soil, in such situation improvement of such soil by some suitable method becomes necessary. Various techniques have been suggested for mitigating such problem of expansive soil. Stabilization of expansive soil with different chemicals such as lime, calcium chloride and fly ash has also been found to be successful in reducing the swell-shrink behavior of these soils. Out of the above said methods mixing stone dust are considered as an effective technique for improving the engineering properties of expansive soil because of their, easy availability and easy adoptability. This paper presents the results of an experimental study where in stone dust is mixed with expansive soil in varying percentage. It is observed that shear strength parameter increases and swelling pressure of expansive soil decreases considerably by mixing of stone dust.

Key Words: Expansive Soil, Stone Dust, Differential Free Swell Index etc.

INTRODUCTION

The strength and settlement characteristics of expansive soil have become of major importance in recent years, as the activities in the construction of earth structure such as embankment for railways and highway and earth dams have increased (Hausmann, 1990). The concept of stabilization is well established and is used in various applications like improvement of shear strength, load bearing capacity, drainage system etc. Soil stabilization technique includes various mechanical, physical and chemical methods (Chen, 1988). The choice of a particular method indeed is governed by the type of soil, location and the cost involved.. At present the greatest use of lime for soil treatment is for highway

Rakesh Kumar Lecturer Dept. of Civil Engineering

M .A .N .I .T ., Bhopal-(MP)Email: rakesh_20777@rediffmail.com

Siddhartha Rokade Lecturer Dept. of Civil Engineering

M .A .N .I .T ., Bhopal-(MP)Email: r_sid@rediffmail.com

Satyavir Singh UG Student Dept. of Civil Engineering

M .A .N .I .T ., Bhopal-(MP)

Proceedings of International Conference on Infrastructure Development on Expansive Soils.

Index-09 ACE Hosur TN 635109

construction in sub grades sub bases and base courses significant use of a similar nature is also made for airfield pavement (IRC 88, 1984).

Lime stabilization improves the strength, stiffness and durability of fine grained material. Lime stabilization has been extensively used to decrease swelling potential and swelling pressure in clays. Treatment and strengthening of the expansive sub grade soil appears to be only methods of construction of pavement structures with good riding quality in the areas of expansive soil. In the present study an attempt has been made to improve the properties of expansive soil by mixing the stone dust.

DETAILS OF THE EXPERIMENTAL PROGRAMME

The experimental investigation consisted of determination engineering properties such as liquid limit, plastic limit, and free swell index of expansive soil and expansive soil mixed with stone dust in different percentage were determined. These properties are indicators of swelling characteristics of the expansive soil. CBR test of expansive soil which is an indicator of strength test, was also. The material used in the study is as follows.

Soil used: In the present study the expansive soil used was collected from MANIT Campus Bhopal. The properties of the soil are given in Table 2. It can be noted from Table 2 that the soil is highly compressible and is likely to be problematic for construction works.

Stone Dust: One of the objectives of the present study is to improve the behavior of expansive by mixing locally available material, hence stone dust, which is locally and easily available material, was selected to mix with expansive soil in different proportions. The stone dust was collected from the crusher situated at Ayodhya Bye pass road. The amounts of stone dust mixed to the soil were taken as 10%, 20%, 30% and 35% by weight of the soil. The particle size distribution of stone dust is given in Table 1.

Table 1 Particle Size Distribution of Stone Dust

Sieve size in mm 4.75 2.3 1.2 0.6 0.425 0.35 0.15 0.075% Finer 100.00 73.80 54.58 38.48 30.64 27.32 14.60 8.48

RESULTS AND DISCUSSION

The results obtained during various laboratory tests conducted on soil samples of expansive soil mixed with stone dust in varying proportion from 10% to 35% are given in Table2.

Table 2 Summarized Test Results of Expansive soil Mixed with Stone Dust

Test parameterStone Dust Mixed by weight of raw soil

0% 10% 20% 30% 35%

L.L. % 58 52 48Not

determinate-

P.L. % 34 30 28 - -

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Rakesh Kumar, Siddhartha Rokade, Satyavir Singh

P.I. % 24 22 20 - -DFS % 60 44 35 25 20OMC % 26.50 26.10 22.50 18.10 18.00

MDD kN/m3 16.80 17.4 17.65 18.0 18.05C.B.R.

(soaked), %2.50 3.4 5.50 7.80 8.20

Effect of Mixing Stone Dust on Engineering Properties of Expansive Soil

In present study the effect of mixing stone dust on the properties of expansive soil is studied. By conducting number of tests on expensive soil mixed with stone dust alone and in varying proportions from 10% to 35%. From present study it is observed that liquid limit, plastic limit and plasticity index decreased as the amount of stone dust mixed to the expansive soil increased.

Effect of Mixing Stone Dust on Compaction Characteristics of Expansive Soil

From results of present study it is observed that the optimum moisture content of the soil mixed with stone dust 10%, 20%, 30% and 35% has gradually decreased from 26.50% to 18.00% and maximum dry density gradually increased from 16.80 kN/m3to 18.05 kN/m3. The above observation is quite obvious .The coarse grained stone dust requires less water and is likely to have higher dry density on compaction. Thus the compressibility of the stone dust mixed black cotton soil has improved.

Effect of Mixing Stone Dust on CBR Value of Expansive Soil

From results of present study it is observed that the CBR value of the soil mixed with stone dust in various percentages varying from 10% to 35%, is gradually increased from 2.5 to 8.2.

From the discussion made above it may be concluded that the strength behavior of the stone dust mixed of expensive soil has improved substantially.

Effect of Mixing Stone Dust on Differential Free Swells of Expansive Soil

From results of present study it is observed that the differential free swell value of the soil mixed with stone dust in varying percentage from 10% to 35%, has gradually decreased from 60% to 20%. Hence the stone dust blended with expansive soil will be more volumetrically stable than the raw soil.

CONCLUSIONS

In the present study the following conclusions are made.

The maximum dry density of soil increases as the amount of stone dust mixed to the soil increased.

The optimum moisture content of soil decreases as the amount of stone dust mixed to the soil increased.

The addition of stone dust in soil sample increases CBR value substantially. The CBR value of soil sample increase 2.5 to 8.2 percent when 35% of soil is replaced by stone dust.

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The addition of stone dust reduced the differential free swell from 60% to 20%.

Thus the properties of expansive soil are changing by addition of stone dust reflecting improved engineering behavior of expansive soil, which could act as a good sub grade material.

REFERENCES

1. Chen, F.H. (1988), “Foundations on Expansive Soils” Elsevier Science, Amsterdam, The Netherlands.

2. Choudhary, A.K. (1994), “Influence of Fly –Ash on the Characteristics of Expansive Soil” Proceedings of the Indian Geo–technical Conference, Warangal.

3. Hausmann, M.R.,(1990) “Engineering Principles of Ground Modification” Mc.Graw Hill Publishing Company , New York.

4. IRC 88-1984 “Guidelines for Improvement in Highway Construction” Indian Road Congress New Delhi.

5. Katti, R.K. (1978), “Search for Solutions to Problem in Black Cotton Soil”, First annual lecture, Indian Geo–technical Society at IIT, Delhi.

6. Lambe, T.W (1962) “Foundation Engineering” Editor G A Leaonards, McGraw-Hill Book Company, Inc., Newyork.

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