The Dolerites of Cross River State (DCRS): Physical and Mechanical Properties

Dolerite occurs in appreciable quantity in Cross River State and these have been locally quarried for construction without proper evaluation of its suitability as construction stones. The physical and mechanical properties as well as the general mineralogy were analyzed in this work to determine the suitability of these dolerites as construction aggregate. Results shows that uniaxial compressive strength (UCS) ranges from 34.2 N/mm2 to 56 N/mm2, durability 96.9% to 99.21%, specific gravity (SG) 2.46 to 3, water absorption 0.14% to 1.59 % with an average porosity of 1.19. The medium/strong compressive strength, low porosity and water absorption, average density and specific gravity and high durability makes it suitable for construction but the presence of plagioclase and pyroxene which sometimes alters to clays and chlorite causing swelling when wet and shrinking when dry is a major limitation. Thus these dolerites without proper treatment/stabilization are not suitable for industrial/heavy traffic construction but can be readily and effectively applied in concrete for light foundation loads and buildings. Results also show that these dolerite are hard, tough, compact and durable and can replace the more expensive/competent construction stones (granite and /or gneiss) for light construction works, however the environmental conditions within which it would be applied should be evaluated and the first few meters around a dolerite sill or dyke should be avoided during quarrying for construction stones as the more softer rocks are found there.