EFFECT OF GROUNDNUT SHELL ASH ON LATERITE STABILIZATION

EFFECT OF GROUNDNUT SHELL ASH ON LATERITE STABILIZATION

ABSTRACT

 This study investigate the effects of ground shell ash on laterite stabilization as the mechanical properties of laterite soils encountered in construction works consist of unconfined compressive strength, stiffness, tensile strength, brittle behavior, ductility, and axial strain, undrained shear strength, elasticity, plasticity, permeability, porosity, shrinkage, durability. Index properties of the natural laterite soil showed that, the soil belongs to A-7-6 in AASHTO classification system and CH in USCS classification system. This indicate a poor soil for engineering use. Liquid limit and Plasticity index values of 83.36 % and 89.32 % respectively for the laterite soil suggest that the soil is highly pastic. There was gradual decrease in the free swell to a minimum value of 2.91% at 10% GSA as compared to the natural value of 15.25%.  The soaked CBR for the natural soil is 1.67% which increased to 2.17% at 10% GSA. This value fell short of specification requirement of the CBR value to be used as sub-base or base material. For the electrokinetic test, pH test, considerable increase to a peak value of 9.2 while the peak CEC is 70.50mol/kg at 0% GSA. The durability of samples determined in terms of resistance to lost in strength failed to meet the 80% resistance to loss in strength. This concludes that the groundnut shell ash cannot be used as stabilization for black cotton soil as stated by Stephen (2006)  However, there was increase in strength for UCS of 21 days curing period from a value of 134kN/m² as compared to 313kN/m² for the unstabilized soil.

CHAPTER ONE

INTRODUCTION

1.1       Background of the study

The search for alternative binder or pozzolanic material has become a challenge to national development.  Potential of laterite soil as a reliable and durable construction material is highly locally available and has been one of the major building materials for a long time. One of the various soil types that occur in the tropic and sub-tropic laterite is one of the commonest types and is of special interest in building and road constructions. Laterite soils are highly weathered soil which contains large but extremely variable proportion of iron and aluminum oxides well as quartz and other minerals. 

A problem laterite soil is those that do not yield reproducible result using standard laboratory testing procedures.  The soils are difficult to evaluate as engineering construction materials.  The peculiar problem of this soil have been identified as thermal and mechanical instabilities i.e the susceptibility to significant change on the addition of small levels of the thermal or mechanical energy.

Application of solid waste (Groundnut Shell Ash) disposal for soil stabilization is a significant which serves various benefits to the environment. The term solid waste includes all those solid and semi solid materials that are discarded by the community. Improper management of solid waste causes adverse effects on ecology which may lead to possible outbreaks of diseases and epidemics. The over dependence on industrially manufactured soil improving additives (cement, lime etc) have kept the cost of construction of stabilized road financially high. This hitherto have continued to deter the underdeveloped and poor nations of the world from providing accessible roads to meet the need of their rural dwellers who constitute large percentage of their population which are mostly rural farmers. Furthermore, the World Bank has been expending substantial amount of money on research aimed at harnessing industrial waste products for further usage (Oriola and Moses 2010).

Groundnut Shell is an agricultural waste obtained from milling of groundnut. In the world, the total hectare planted to groundnut is over 20 million hectares per year. It is estimated that over 2 million hectares are planted on groundnut in Nigeria. Groundnuts are mostly intercropped. Groundnut contains about 25% Protein and 45 to 50 % oil. The skins are high in Vitamin B. Groundnut can be decorticated by hand-operated decorticating machine. (NAERLS, 2009).

In this work, an exercise is done to utilize groundnut shell ash (GSA) to improve the engineering performance of laterite soil which may be an economical solution of soil stabilization.

1.2       Justification of the Research

In Nigeria, and the world at large; the cost of constructing stabilized roads is financially high. This is apparently due to the over dependence on industrially manufactured soil improving additives (cement, lime etc). The high amount of money spent has continued to invalidate poor and underdeveloped nations of the world from making accessible roads available to meet the standard of their rural dwellers that constitute large percentage of their population. On the other hand, the safe disposal of waste products from industries and agriculture has been hitherto a challenging issue demanding urgent solution because of the decline effect of these materials on the environment and the hazardous risk it pose to the health of humanity.

Thus, it is greatly required to consider the use of agricultural waste (such as Groundnut Shell Ash- GSA ) in improving the engineering properties of the soil, in this case Laterite Soil (LS) when used in road construction will considerably reduce the cost of construction and as well as eradicate or reduce the environmental and hazardous risk of such wastes. Hence, this research is justifiable in the use of Groundnut Shell ash to stabilized laterite soil.

1.3       AIM OF RESEARCH

This research is aimed at evaluating the possibility of utilizing groundnut shell ash (GSA) in the stabilization of laterite soils.

1.4       OBJECTIVES OF THE RESEARCH

The following objectives are devised for this research work and are summarized below.

• To investigate the pozzolanic  properties of Groundnut Shell Ash.
• To examine the physical and engineering properties of laterite soil treated with various percentage of Groundnut Shell Ash (0% – 10%) using British Standard Light compactive effort.
• To contrast between the engineering properties of laterite soil and engineering properties of the treated soil.
• To investigate the electrokinetic properties of virgin laterite soil treated with GSA
• To carry out durability and strength assessment tests on natural and treated laterite soil

1.5       SCOPE AND LIMITATION OF THE RESEARCH STUDY

This research is focused on stabilizing laterite soil treated with various percentage of Groundnut Shell Ash (0%, 2%, 4%, 6%, 8% and 10% by dry weight of soil). All these tests are carried out at their respective Optimum Moisture Content limited to British Standard Light Compactive effort.