Non-Destructive Evaluation of Quality of Concrete Elements in Existing Buildings for Structural Stability in Onitsha, Anambra State, Nigeria

Abstract

Recently, concrete is the most common building material in Nigeria construction industry but had also been reported as one of the major causes of structural failure. However, in spite of the popularity of concrete structures, if not properly constructed and the quality maintained, it can deteriorate prematurely which is often referred to as our crumbling infrastructure. The study aims at evaluating the quality of concrete elements in existing buildings in Onitsha, Anambra State, with a view to establishing their states of stability. The methodology involved a review of the relevant literature and Non-destructive testing of the structural elements (columns, beams and slabs) in  two selected buildings in the study area that have existed for more than thirty years. The study reveals apparently that the buildings and their state of structural stability are inadequate. The buildings are associated with heavy structural defects like cracks, spalling, exposed/corrosion of the embedded metals etc and were observed to have recorded very poor compressive strengths. Based on the deductions made from the low compressive strength test results analysis and the visual observations conducted on the buildings in regards to consideration for strength and quality of the Structural elements, it can be said that one of the buildings have lost its residual design life span and ability to sustain future loads. The study strongly advocates the indulgence of Non-Destructive Test especially in existing deteriorated buildings to avoid building failures and collapses. The study also recommends continuous survey and monitoring of concrete structures during service life as to detect impending failure and examine the performance of the buildings in order to save lives and properties, as the investigation will show the performance of the structural elements and suggest measures for their maintenance in order to sustain structural stability.