Evaluating the Quality of Aggregate from a Doubtful Source for Structural Concrete

For the production of structural concrete, sedimentary rock aggregates are frequently used in Nigeria. It is believed to be one of the causes of numerous structural failures in the nation because of its variable quality, strength, and contaminations. In this study, the quality of gravels ranging in size from 8 to 16 mm from Oji River pits was examined. The strength of concrete made from the gravels was optimized using Scheffe's simplex method of optimization, and the resultant mathematical model provided an ideal compressive strength of 11.78 N/mm2 and a mix ratio of 1:1.4:2.5 for a water/cement ratio of 0.53. Because of the small size of this optimum strength and the predictions of the model, it was recommended that such aggregate (8 - 16mm from Oji- River) be limited to oversite concretes, columns and lintels of buildings with load bearing walls and a maximum storey of three; and it shouldn't ever be used for slabs of suspended floors, retaining walls, bridges, and culverts.