Presentation by

Laxmikant YaduAssistant Professor

Civil Engineering DepartmentN.I.T. Raipur

Characterization of Fine Grained Soft Subgrade Soils Improved by Locally Available Marginal Materials for

Design and Construction of Rural Roads

AResearch Proposal

on

IntroductionThe latest road development plan vision 2021 has

emphasized on a planned rural road network development at the district level with a target of connecting all habitations with population over 100 by all-weather roads.

Construction of Rural Roads i.e. Low traffic volume has been going on a large scale through various programmes i.e.

Prime Minister Gram Sadak Yojana (PMGSY) Bharat Nirman Mukhay Mantri Gram Sadak Yojana in Chhattisgarh State

IntroductionDesign of Flexible Pavements in India Empirical Method Mechanistic Procedure

IRC Codes for Flexible Pavement Design IRC: 37- 1970 &1984 Consider CBR value of Subgrade. IRC: 37-2001 & 2012 Consider Mechanistic (Stress- Strain)

behaviour of pavement materials. IRC: SP 20 - 2002 - Manual on Route Location, Design,

Construction, and Maintenance of Rural Roads - Consider CBR value of Subgrade.

IRC: SP 72 - 2007 Guidelines for the design of Flexible pavements for Low Volume Rural Roads.

Introduction contd..AASTHO 1993 and IRC 37: 2012 Essential inputs for

analysis of layered systems

Elastic Properties of Pavements MaterialsModulusPoisson Ratio

Requirements Test the Materials under Appropriate Loading and Environmental Conditions

Introduction contd..Resilient Modulus (MR) of Subgrade Soils Can be determined by Repeated Triaxial Test

Repetitive triaxial testing facility is not widely available and is expensive, the default resilient modulus can be estimatedfrom generally acceptable correlations.

Empirical models are available to Estimate MR

But, Their validity under Local Soil Conditions, Local Environment condition and Stabilized soil subgarde case is doubtful,

It is required to establish empirical models to predict a reasonable range of MR for soils and stabilized soils with locally available materials.

Problem with Soft Subgrade soil In various region, soft soil is available as subgrade, that delays the

construction works and increases the cost.

Soft soil turns very hard when dry, but loses strength completely in wet condition.

Wetting and drying process, causes failure of pavements in the form of settlement and cracking.

Probable solution for constructing roads on such soft soils 9 To remove the whole soil and transport new soil from the borrow pit 9 To improve their engineering properties by stabilization

Replacing whole soil is uneconomical

Hence, best approach is stabilizing the soft soil with suitable stabilizers.

Problem with Soft Subgrade soil

Traditional stabilizers i.e. Lime, Cement etc may increase the cost of construction of pavement and work may become uneconomical.

Locally available materials i.e. 9 Fly Ash, 9 Rice Husk Ash, 9 Slate / Stone Dust, 9 Blast furnace slag etc,

may be used as a stabilizer for stabilizing the soft soil to make the sustainable pavement construction at reduced cost.

By this way one can utilize so called waste materials and prevent the surrounding environment and soils from the harmful effect of the same .

Different stabilizers to be used for stabilization of soil, as soil varies from place to place.

Objectives of the proposed research proposal To identify a few locations in Raipur and Durg districts of Chhattisgarh

state with soft subgrade soil and determine their engineering properties by field investigations and laboratory tests.

To identify the locations of locally available marginal materials and study their suitability to improve the properties of the soft subgrade soil.

To carry out laboratory investigations to find the optimum dose of locally available marginal materials for stabilizing soft subgrade soils.

To carry out laboratory investigations for stress-strain behaviour (repeated triaxial test) of stabilized and unstabilised soil to determine the Elastic parameters.

To develop regression models to estimate MR using different parameters such as Index properties of soil, Stress levels, Moisture content, compaction levels and CBR.

Literature Review (National and International Status)

Work Plan1. Literature Review

2. Survey for Finding the Locations of Soft Subgrade Soils

& Locally Available Materials

3. Laboratory Investigation

4. Result Analysis and Development of Regression

models.

Time schedule of activities

Methodology

y Identification of the Locations and Material Collection:

y Experiments and Analysis of Results:

y Determination of Elastic parameters:

y Development of Regression models for Pavement Design:

Budget

Details Estimated Cost (Rs)Research Associate 6.0 lacsField work sampling questionnaire, survey, data tabulation, Labor wages etc.

6.0 lacs

Travelling/field work (Travelling to project sites and visit to premier institutes for discussions)

3.0 Lacs

Conduction of stakeholder consultation and National & International Workshop / conferences for discussion of results

2.0 Lacs

Printing, publishing, computer peripherals stationary and miscellaneous expenses

2.5 Lacs

Total 19.5 Lacs

Investigations carried out at NIT Raipur

y Tatibandh Atari Road - Effectiveness of Rice Husk and Fly Ash as stabilizer for soft subgare soil

y Effectiveness of granulated blast furnace slag (GBS) over sand as overlay for stabilization of soft soil

y Effectiveness of granulated blast furnace slag (GBS) as granular fill in place of conventional material i.e. sand

Referencesy Yadu, L.K., Tripathi, R.K., and Singh, D.V. Laboratory Performance Evaluation of Stabilized Black Cotton

Soil with Rice Husk Ash, Journal of Chhattisgarh Swami Vivekanand Technical University Bhilai, 2011, Volume 4, No. 1, pp 50-55.

y Yadu, L.K., Tripathi, R.K., and Singh, D.V. Comparison of Fly Ash and Rice Husk Ash Stabilized Black Cotton Soil, International Journal of Earth Sciences and Engineering, 2011, Volume 04, No. 06 SPL, pp 42-45..

y Yadu L.K. and Tripathi R.K. Effect of Depth and Number of Layers of Reinforcement on Bearing Capacity Ratio of Strip Footing Resting on Granulated Blast Furnace Slag Reinforced with Geogrid Geo-Congress 2014, ASCE, Geo-characterization and modeling for sustainability.

y Tripathi R.K. and Yadu L.K. Effect on Bearing Capacity Ratio of Strip Footing for Various Granular Fill Thickness and Number of Geogrid Layers in Granular Fill Overlay on Soft Soil Geo-Congress 2014, ASCE, Geo characterization and modeling for sustainability.

Complete Reference List

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