Geotechnical and Geochemical Assessment of Natural Sands in Ahanta West Area, Southwestern Ghana

Asante-Annor Asare,Kwabena Amponsah Ernest

doi:10.4236/gep.2021.912016

Asante-Annor Asare, Kwabena Amponsah Ernest

Open Access

https://doi.org/10.4236/gep.2021.912016

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Abstract

Geotechnical and geochemical assessment of natural sands being used as fine aggregates for construction purposes in Ahanta West and its Environs was carried out, as well as addressing the environmental problems associated with the exploitation of these sand through the sand winning activities. The results from geotechnical and geochemical tests were bench marked with British, American and Ottawa Standards for testing materials. Representative samples were taken from five different sand winning sites namely, Pompuni, Agona Banso, Fretsi, Tumentu stream and Fretsi river. The geotechnical tests carried out were specific gravity, grain size analysis, moisture content, silt content, permeability test using the constant head permeameter method. The photometer (Hydro Test HT 1000) was used to determine silica, sulphate and chloride concentrations in the sand samples. The oxides for the geochemical analysis were determined using the X-ray fluorescence (XRF) method. The results from the study areas showed that except for Fretsi, the specific gravity, grain size analysis, moisture content, silt content and permeability tests were within the acceptable range for natural sands. Sand samples from Pumponi and Agona Banso had the required Cu and Cc values of being well graded. Sulphate and chloride concentrations were within standards for all the samples; however, silica was low for all the samples. Fe2O3, Al2O3, MnO and Na2O did not meet the Ottawa sand standard. Natural sand is not recommended to be used for construction purposes however, these sands may be treated or blended if it is to be used for construction purposes. There are serious environmental implications for the sand-winning activities in the study areas such as stripped overburden, creation of pits and ponds, increased total suspended solids in surface waters, and destruction of aquatic habitats which needs to be addressed.

Highlights

Sand winning refers to the scooping of sand from portions of the earth’s surface for building construction and other developmental purposes (Peprah, 2013). Mattamana et al (2013) state that sand mining has become an industry giving job opportunities for thousands of people
Geotechnical and geochemical assessment of natural sands being used as fine aggregates for construction purposes in Ahanta West and its Environs was carried out, as well as addressing the environmental problems associated with the exploitation of these sand through the sand winning activities
The results from the study areas showed that except for Fretsi, the specific gravity, grain size analysis, moisture content, silt content and permeability tests were within the acceptable range for natural sands

Summary

Introduction

Sand winning refers to the scooping of sand from portions of the earth’s surface for building construction and other developmental purposes (Peprah, 2013). Mattamana et al (2013) state that sand mining has become an industry giving job opportunities for thousands of people. Mining of natural aggregates such as sand serves as the main source of construction aggregate used throughout the world (Musah, 2009). Tetsopgang et al (2020) classified pit sand as the residual soil deposits formed from an in situ weathering of granular rocks such as granites. The open pits start at 0.2 - 2 m depth, depending on the location can be up to a depth of about 100 m. These sand deposits from the soil consist of sharp angular grains which serve as an excellent material for mortar or concrete works (Tetsopgang et al, 2020)

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