Concrete is a major construction composite material commonly and regularly used on buildings, following sequence of events occurs in the production of any cast- in - place reinforced concrete building those are casting of fresh concrete on the properly placed and tied reinforcement bar on the erected formwork. Therefore, quality control in every step of production is important in order to produce reinforced concrete as specified in the specification. Lack of quality due to deficient

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... quality management is detected through non-conformance to established requirements. These established requirements can be technical specifications. In construction, non-conformance occurs when the finished state of a project and its components deviates from the established requirements. The research is carried out by collecting sample compressive strength test result data and information on qualities of concrete ingredients and methods of concrete production through interview and site observation. The findings of the investigation have shown that in most of the projects sufficient tests are not conducted for the ingredients of concrete. This indicates that a lot has to be done to improve concrete quality in the building construction industry. According to the results, 14.77 % of the project sites contain defective or non-complying lots for tests made on samples taken for compressive strength test results in accordance with the requirement set on the EBCS 2, 1995 and according to the new Ethiopian code EN ES 1992:2015 16.86 % of the project sites contain defective or non-complying lots. Additionally, as per the American standard ACI, 318 and British standard BS 5328: 1990 only 4.17 % and 8.33 % of lots have defective lots respectively. According to ACI, standard for the quality control using the standard deviation and coefficient of variation, and it shows 50% of the projects under investigation have poor quality control standards, 25% of the projects have a very good and the remaining 25% of the projects h [...]