Assessment of the Engineering Properties and Aggregate Suitability of Fusa Riebeckite Granite, Jos, North-Central Nigeria

Abstract

The suitability of Riebeckite Granite from Fusa, Plateau State, North-Central Nigeria, as a 
potential construction aggregate was evaluated through detailed laboratory investigations of 
its physical properties. The study was undertaken to determine whether the granite meets 
standard engineering requirements for use as aggregate material in civil construction projects 
within Jos and its environs. A total of ten (10) representative rock samples were 
systematically collected from different locations within the study area to ensure adequate 
spatial coverage and reliability of results. Laboratory analyses focused primarily on the 
determination of specific gravity using the pycnometer method, a standard procedure for 
assessing the density characteristics of rock aggregates. The measured specific gravity 
values ranged from 2.597 to 2.654, with an average value falling within the accepted standard 
range (2.50–2.70) for most crystalline igneous rocks used in construction. These values 
indicate that the Fusa Riebeckite Granite possesses sufficient density and strength 
characteristics required for durable aggregate materials. The relatively low percentage 
passing values obtained during aggregate assessment suggest that higher comminution energy 
is required to dislodge or fragment the rock particles. This implies strong interlocking mineral 
grains and resistance to mechanical disintegration, which are desirable properties for 
construction aggregates subjected to load-bearing and abrasive conditions. The comminution 
energy requirement further reflects the competence and mechanical stability of the granite 
compared to weaker rock or soil-derived aggregates. Petrographic evidence from existing 
literature indicates that Riebeckite Granite is predominantly composed of quartz, orthoclase 
feldspar, hornblende, and biotite. The presence of these hard, crystalline mineral phases 
contributes to its relatively high specific gravity (greater than 2.50) and enhances its 
durability and structural integrity. Based on the laboratory results and comparison with 
established engineering standards, the Fusa Riebeckite Granite satisfies the fundamental 
physical requirements for use as construction aggregate. Therefore, it is considered suitable 
for application in concrete production, road construction, and other civil engineering works 
within Jos and surrounding areas.