Geotechnical tests were performed on
granite and granite-gneiss rock samples of parts of Minna to know their
suitability as construction aggregates. Eight rock samples were selected for
porosity test, impact value, specific gravity and absorption capacity. The
average porosity of the samples is 0.21, 0.12, 0.30, 0.10, 0.25, 0.25, 0.24 and
0.11 respectively for L1, L14, L15, L19, L21, L23, L25 and L29 which shows they
are normal except L15 with a high porosity. Average impact value of the samples
show they are suitable for wearing surface course in road and bridge
construction, except samples L14 and L19 with average impact value of 32.8 and
34.9 respectively making them suitable only as bituminous macadam (maximum
value = 35%). Sample L1 is not suitable as construction aggregates because it
exceeds the maximum value specified for that purpose. The average specific
gravity of the rocks are L1=2.68, L14=2.65, L15=2.65, L19=2.67, L21= 2.63, L23=
2.71, L25=2.65, and L29=2.69 respectively and which make them suitable as
normal weight materials for construction. The average absorption capacity
values of the rock samples are 0.20%, 0.20%, 0.50%, 0.10%, 0.25%, 0.10%, 0.50%
and 0.20% respectively for samples L1, L14, L15, L19, L21, L23, L25, and L29.
All testing followed the respective ASTM standards.
Geotechnical testing, construction aggregates, granite,
granite-gneiss, Minna, Nigeria.