Effect of Rice Husk Ash on Cement Stabilized Laterite

Effect of Rice Husk Ash on Cement Stabilized Laterite

Prameshwar Suthar, Anand Rathor, Ayush Jha, Jitendra Singh

Department of Civil Engineering Poornima Group of Institutions, BT-1, Bio Technology Park, Industrial Area Sitapura, Jaipur

Abstract -Consolidation tests have been prepared at optimum moisture content and maximum dry density by adding 4, 8, 16 and 20% by weight of rice husk ash to the originate soil. Specimens have been subjected to increments of vertical pressure of 0.25, 0.50, 1.00, 2.00 and 4.00 kg/cm2 in a fixed ring consoled meter. [1]Coefficient of compressibility (av) and coefficient of volume compressibility (mv) show no significant quality for variation in values with change in proportion of rice husk ash in the soil at a particular effective stress. It has been observed that there is decrease in the values of these parameters with increase in effective stress for a particular percentage of rice husk ash. Compression index (cc) has been found to decrease significantly with increase in percentage of rice husk ash, hence decreasing consolidation settlement of parent material. It has also been observed that the time required for achieving a given degree of consolidation decreases with increase in the percentage of rice husk ash at a particular effective stress[2]. Overall, it has been observed that rice husk ash effectively increase one- dimensional stiffness and therefore, reduce settlement.

Keywords:- 1-D , Cc , Mv , Av, Rice husk ash (RHA), stabilization, compressibility, characteristics, maximum dry density and optimum moisture content.

1. INTRODUCTION

   Soil stabilization is modification of soil properties to improve its engineering performance. However the original objective of the soil stabilization is to increase the strength or stability of soil but now-a-days stabilization is used to increase or decrease almost every engineering property. Over the last few years, the use of industrial waste has increased as stabilizing materials for naturally occurring fine grained soil .In the present work, compressibility characteristics have been studied for locally available highly plastic clay treated with different percentages of rice husk by conducting a series of one dimensional consolidation tests. Rice Husk is an agricultural waste obtained from milling of rice. About 10 tones of rice husk is generated annually in the world. Meanwhile, the ash has been categorized under pozzolana, with about 67-70% silica and about 4.9% and 0.95% Alumina and iron oxides, respectively[3]. The silica is substantially contained in amorphous form, which can react with the CaOHlibrated during the hardening of cement to further form cementations compounds.

   1. Materials

      1. Clay used in the experiments was collected from Industrial Area , Phase-II, PGI Road Jaipur ( Raj.) . The soil is classified as highly plastic clay

      2. Rice husk ash It was collected from Kohinoor Foods Limited, GT Road, Murthal, District Sonipat, Haryana.

   2. Chemical Properties

      Constituent	Composition (%)
      SiO2	67.3
      Al2O3	4.9
      Fe2O3	.95
      CaO	1.36
      MgO	1.81
      Loss On Ignition (LOI	17.78

   3. Physical Properties

   Physical Properties	Materials
   	Rise husk ash	Parent clay
   Specific Gravity	2.45	1.90
   Liquid Limit	52	NP
   Plasticity Index	29	NP
   OMC%	28	NP
   MDD (g/cc)	1.56	–

2. SAMPLE PREPARATION

   1. Composition of specimens

      Specimens of parent clay and clay treated with 4, 8, 12, 16 and 20% by weight of rice husk ash passing 425 micron) B. Mixing Oven dry soil was dry mixed with various percentages of rice husk ash. Sufficient quantity of water was then added to bring the moisture content to the desired level. The mixture was then manually mixed thoroughly with a spatula.

   2. Mixing

      Oven dry soil was dry mixed with various percentages of rice husk ash. Sufficient quantity of water was then added to bring the moisture content to the desired level.

   3. Static compaction

   Cylindrical specimens were compacted by static compaction in 10 cm diameter consolidation ring to the required height of 2.5 cm. The inner surface of the ring was smeared with mobile oil to help minimize friction between

   inner surface of the ring and the soil sample during consolidation process[5] The wet homogenous mixture was placed inside the specimen ring using spoon and leveled. Sample was placed in specimen ring with extension collar attached to it and both the exposed sides of the sample were covered with filter papers.

   TESTING AND RESULTS

   A series of one-dimensional consolidation tests were conducted to determine the compressibility characteristics of untreated clay and clay stabilized with rice husk ash to evaluate its effect in reducing compressibility of the soil. These characteristics have been illustrated by establishing the relationships between void ratio and effective stress. In order to determine rate and magnitude of consolidation.

   1. Moisture

      Density relationships For parent clay OMC and MDD have been observed as 23.5% and 1.56 g/cc respectively. For clay stabilized with Rice husk ash OMC varies from

      23.7 to 33% and MDD varies from 1.553 to 1.28 g/cc, with increase in percentage of rice husk ash. It has been observed that there is an increase in OMC and decrease in MDD due to an increase in percentage of rice husk ash.

   2. Coefficient of compressibility (av)

      Based on the analysis of variation in equilibrium void ratio for various values of effective stress, the coefficient of compressibility (av) values, for all stabilized clay samples have been determined over a range of consolidation pressures. For parent clay the value of av decreases from

      13.9 x 10-2 to 5.97 x 10-2 cm2/kg as the pressure increases from 0.25 kg/cm2 to 4.0 kg/cm2, which shows that compressibility of soil decreases with the increase in effective stress[8]. It has been observed that values of av vary from 9.3 x 10-2 to 0.60 x 10-2 cm2/kg for various percentages of rice husk ash at different effective stresses. [9]

   3. Coefficient of volume compressibility (mv)

      Based on the analysis of variation in equilibrium void ratio for various values of effective stress, the coefficient of volume compressibility (mv) values, for all stabilized clay samples have been determined over a range of consolidation pressures. For parent clay the value of mv decreases from 8.99 x 10-2 to 3.82 x 10-2 cm2/kg as the pressure increases from 0.25 kg/cm2 to 4.0 kg/cm2, which shows that volume compressibility of soil decreases with the increase in effective stress.

   4. Compression index (cc)

      Based on the analysis of pressure-void ratio curves on semi-log plot i.e. virgin compression curves, compression index (Cc) values, for all stabilized clay samples have been determined[6] The value of Cc for parent clay is observed as 0.458. It has been observed that values of Cc vary from

      0.508 to 0.181 for various percentages of rice husk ash. It has been observed that there is a general decrease in value of Cc with an increase in rice husk ash content.

   5. Coefficient of consolidation (cv)

   Based on the analysis of variation of dial gauge readings at various time intervals for a particular stress level with respect to square root of time, the coefficient of consolidation (Cv), for all stabilized clay samples have been determined over a range of consolidation pressures. For parent clay, the value of Cv decreases from 0.347 x 10- 3to 0.0732 x 10-3 cm2/sec as the pressure increases from

   1. kg/cm2 to 4.0 kg/cm2,[7]which shows that the time required for the soil to reach a given degree of consolidation increases with increase in effective stress. It has been observed that the values of Cv vary from 0.151 x 10-3 to 1.4899 x 10-3 cm2/sec for various percentages of rice husk ash at different effective stresses.

3. CONCLUSIONS

The study demonstrates the influence of rice husk ash on the compressibility characteristics of highly plastic locally available clay. The following conclusions have been drawn based on the laboratory investigations carried out in this study:

1. The addition of rice husk ash to the parent material results in an increase in optimum moisture content and decrease in maximum dry density with increase in rice husk ash content.

2. Compressibility analysis of the parent clay and clay stabilized with various industrial wastes indicates that coefficient of compressibility (av) shows no significant trend with the variation in the percentage of rice husk ash for a particular effective stress.

3. However, a decrease in value of av has been observed with an increase in effective stress at a particular percentage of rice husk ash.

REFERENCES

1. Osinubi K. J., Bajeh I., Bituminous stabilization of laterite, Spectrum Journal, 1994, 1(2), p. 104-112.

2. Mustapha M. A., Effect of Bagasse Ash on Cement Stabilized Laterite. Seminar Paper Presented in the Department of Civil Engineering, Ahmadu Bello University, Zaria, Nigeria, 2005

3. Neville A. M., Properties of Concrete, 4th edition. Pearson Education Asia Ltd, Malaysia, 2000.

4. Sear L. K. A., Should you be Using More PFA, In Cement Combination for Durable Concrete, Proceeding of the International Conference held at the University of Dundee, Scotland, UK. Edited by Dhir, R. K, Harrison, T. A and Newland, M. D. Thomas Telford Ltd, London, pp. 696, 2005.

5. Oyetola E. B., Abdullahi M., The Use of Rice Husk Ash in Low-Cost Sandcrete Block Production, Leonardo Electronic Journal of Practice and Technologies, 2006, 8, p. 58-70.

6. IS: 2720 (Part 15) (1986), Indian Standard Methods of Test for Soils: Determination of Consolidation Properties, Bureau of Indian Standards.

7. Rao, D. Koteswara, Raju, G.V.R. Prasada and Kumar, K. Ashok (2011), Consolidation Characteristics of Treated Marine Clay for Foundation Soil Beds, International Journal of Engineering Science and Technology (IJEST), Vol. 2, No.3, 788-796.

8. Ranjan, Gopal and Rao, A.S.R. (2000), Basic and Applied Soil Mechanics, New Age International (P) Ltd., New Delhi.

9. Singh, Alam and Chowdhary, G.R. (1994), Soil Engineering in Theory and Practice, GeotechnicalTesting and Instrumentation.