Optimization of the Compressive strength of Concrete made with Sedimentary Rock Aggregates of 12-mm maximum size, from Neyi-Aguleri Gravel Quarry

Abstract

Sedimentary rocks have mechanical properties that vary from one rock outcrop to the other. It is not always easy to predict the strength of concrete made with sedimentary rock aggregate, because of this variability, making it a poor substitute for granite in major constructions. This report is centered on 12-mm aggregate from Neyi-Aguleri gravel pit that has extra problem of silt contaminations which causes greater uncertainty about the strength characteristics of its concrete. This report produced a mathematical model for the strength of concrete made with 12-mm aggregate from Neyi-Aguleri as a means of characterizing this aggregate in terms of quality and limitations of application. The model gave an optimum strength of 11.110 N/mm2 for mix proportions of 1: 1.6: 3.1, and water-cement ratio of 0.551.This strength was found to be very low when compared with recommendable values from code of practice. It was therefore, recommended that the aggregate be avoided in structural concrete for bridges, culverts, columns of building above three storeys and any other structural element where stress can be above the calculated optimum value. It was recommended for short lintel beams of all buildings, when used at the obtained optimum mix proportion.