INVESTIGATING THE GEOTECHNICAL PROPERTIES OF A LATERITIC SOIL AS A SUB-GRADE MATERIAL FOR ROAD CONSTRUCTION –USING COCONUT HUSK ASH

Abstract

Waste management world-wide plays a major role in socio-economic development over the years. The increase in population over the years has contributed to the rate at which wastes are generated. One major waste generated in Ghana is coconut shell waste. Out of the world producing of coconut, Ghana is ranked 16 th . The management of these agricultural waste has become a vital challenge to the development to the Ghanaian economy and communities within which these wastes materials are generated. To eliminate the issues related to solid waste management, one advantage is to explore for various ways of utilizing these waste materials. In view of this, lateritic soil was collected from Heaven Nkwanta in the Western region of Ghana. The soil sample was treated with burnt coconut husk ash (CHA) collected from the local coconut sellers from Tarkwa Nsuem Municipality. The lateritic soil was stabilized using 0 %, 2 %, 4 %, 6 %, 8 %, 10 % and 12 % of burnt coconut husk ash. The various test performed include Atterberg limit, Compaction and California Bearing Ratio in accordance with BS: 1377 and AASHTO – M145. The liquid limit was reduced from 47.9 % to 46.0 %, plastic limit was increased from 31.02 % to 34.80 % and plasticity index was also reduced from 16.88% to 11.12 % at 12 % addition of the coconut husk ash (CHA). The maximum dry densities (MDD) ranges between 2.09 % to 2.11 % and optimum moisture content (OMC) ranges from 14.00 % to 14.20 % at 6 % addition of coconut husk ash. The California Bearing Ratio (CBR, soaked) ranges from 64 % to 76 % at 12 % addition of the coconut husk ash (CHA). From the results obtained, coconut husk ash plays an effective role in improving the geotechnical properties of lateritic soils with low California Bearing Ratio (CBR). In conclusion coconut husk ash in this studies is an effective stabilizer for soils with low California Bearing Ratio (CBR).