Petrographic Study and Rock Quality Assessment of Some Selected Granitoids of the Kongo area, Upper East Region-Ghana

The suitability of rocks as both construction materials and as sites for construction are heavily dependent on their geological and geotechnical characteristics. Though the Kongo area in Northeastern Ghana is enriched with rocks that can be utilized for engineering activities, details of the qualities of the various distinctive granitic rocks still require further evaluation. This study focused mainly on the petrographic mapping of the area coupled with an examination of the geotechnical characteristics of these rocks to ascertain the suitable engineering applications of the rocks. Sixteen rock samples were collected from the area for petrographic analysis. These samples were then tested for density, abrasive resistance, and porosity. The Pycnometer and Los Angeles Abrasion test methods were adopted to respectively estimate rock density and abrasive resistance. Porosity was measured as a percentage of the ratio of the difference in the soaked and dry weight to the dry weight, whereas wearing percentage was estimated as the abrasive value. The identified granitoids included porphyritic granitoid, Tonalitic rocks, Muscovite-Biotite granitoid and quartz-plagioclase porphyry, as they were studied to be granodioritic in character rather than true granite. The study revealed that, the granitoids were well fractured with joints and faults. Some of the granitoids had low porosity and abrasion resistance, making them suitable for certain engineering works. However, these were restricted in quality by their low densities.