TITLE:
Defects in Concrete Elements: A Study of Residential Buildings of 30 Years and above in Onitsha Metropolis, Anambra State, Nigeria
AUTHORS:
Chiamaka Ogochukwu Obiora, Fidelis Okechukwu Ezeokoli, Christopher Chidi Belonwu, Francisca Nkachukwu Okeke
KEYWORDS:
Construction Industry, Building Professionals, Concrete Elements, Defects, Residential Buildings, Structural Stability, Non-Destructive Test, Compressive Strength
JOURNAL NAME:
Journal of Building Construction and Planning Research,
Vol.10 No.3,
September
28,
2022
ABSTRACT: Building defect is an issue in existing buildings that needs urgent tackling to prevent further problems. This study assessed the defects in concrete elements in residential buildings of 30 years and above in the Onitsha metropolis of Anambra State, Nigeria. Data collection instruments in the study include structured questionnaire, interviews, visual inspection/observations, archival records, recordings, photographs; and non-destructive testing of the concrete elements in an existing building in the study area. The population of this study constituted of the construction registered professionals and the existing buildings in study area. The sample for the study was based on the calculated sample size using Taro Yamani Formula. A total of 158 registered professionals were sampled from the population of 260. The questionnaires were purposively distributed to the registered professionals up to the required sample sizes of 158 and 129 questionnaires were properly filled and returned. The study used the SPSS and Microsoft Excel to analyze the data. The results were analyzed in percentages and figures using descriptive statistics and presented in the form of pie charts and tables. The finding of the study revealed that the causes and effects of structural defects on the concrete elements in existing buildings in the study area according to the rating are; exposed/corrosion of the embedded metals, faulty workmanship, overload and impacts, chemical attack, freeze-thaw deterioration, fire/heat, restraint to volume change. The visual observation revealed that the structural elements are characterized by heavy defects such as deep vertical, horizontal and diagonal cracks, exposed/ corrosion of the embedded metals, spalling of the concrete slabs. The existence of defects in the concrete members led to the low compressive strength of the concrete elements and the structural instability of the existing buildings as revealed by the non-destructive test. The non-destructive test result revealed that most of the tested concrete elements have low compressive strength value and such were remarked poor as they did not satisfy the assumed value. Essentially, the study concluded by recommending that regular monitoring, inspections and non-destructive testing of concrete elements should be conducted on existing aged and defected buildings to detect the structural stability of the buildings; and it is imperative to evacuate occupants from heavy structurally deteriorated and defected buildings since most of them have lost their residual design life span and ability to sustain imposed loads.