ESTIMATION OF RESERVES AND ROCK SUITABILITY FOR CONSTRUCTION USING BASIC GEOLOGIC MAPPING AND GEOTECHNICAL METHODS: A CASE STUDY OF AN ABANDONED QUARRY SITE AT BUARI, SOUTHWESTERN NIGERIA
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Date
2020-08-27
Journal Title
Journal ISSN
Volume Title
Publisher
NSUK Journal of Science & Technology (NJST)
Abstract
Assessment of economic viability and rock suitability for construction at an abandoned quarry site at Buari village which lies
between co-ordinates 8027’24.1”N to 8027’22.6”N and longitude 004055’36”E to 004055’ 26.4”E in Southwestern Nigeria was
carried out by estimating the reserve tonnage at the area of study. This involves gridding, specific gravity determination, reserve
estimation and life span determination. The entire area was gridded into 50 regular grids and was labeled 1-50. The elevations of
different points on the area were measured in order to produce the contoured elevation map. Rock thickness of each grid was
calculated. To ascertain the suitability of the rock from the area of study geotechnical tests was carried out on a sample. This
involves thin section analysis, bulk density determination, Aggregate Impact Value (AIV) test and Aggregate Crushing Value
(ACV) test. The elevation contoured map shows that the lowest elevation in the study area is 275 m while the highest elevation is
290 m. The 3D model of the rock generated from elevation using Surfer 12 shows that elevation is lowest in the southern part of
the study area .The elevation increases northwards from the previous quarry face to the top of the hill. The Specific Gravity (SG)
= 2.71, Σ (reserve volume of the each grids (RVG) (m3) = 2457.84 m3and the reserve tonnage of rock in the area of study is
6660.75 tons. This can only support an adopted exploitation rate of 18.25 ton per day for one year. Hence, the rock is considered
unsuitable for mining and their economic viability is considered is very low. The specific gravity (SG) of the rock sample tested
is higher than the minimum value of 2.60 recommended for rocks that are suitable for construction purposes. Average value of
the results of Aggregate Impact Value (AIV) of the rock sample is 22.79%. Hence, this value certified the rock sample for use as
concrete and for wearing surfaces, such as runways roads and pavement. Result of the Aggregate Crushing Value (ACV) test
conducted on the selected samples is 11.17%. Hence, the rock sample from the study area is suitable for use as concrete for roads
and pavements and for other structures.