Investigating the effect of partial replacement of steel slag as a coarse aggregate in pervious concrete.

Abstract

Background: The need to improve the manufacture composition and sustainability of porous concrete with a major construction material that is environmentally friendly especially construction application of relatively light loads led to this research. Steel slag is an alternative that can be to replace the natural aggregates and it is a by-product of steel manufacturing and approximately 160 kg of steel slag is generated per ton of steel produced. Since steel slag is a waste material it helps in preserving the natural resources and reducing solid waste disposal making it environmentally friendly. Methods: Steel slag was used to partially replace natural coarse aggregates. Tests like Gradation of the aggregates, bulk density, specific gravity, Aggregate Crushing value, Aggregate impact Value and flakiness index to determine the physical and chemical properties of the aggregates. Steel slags’ application as an aggregate that has great strength and permeability was demonstrated using CCD of Response Surface Methodology and tests conducted using the obtained mix ratios. The effect on compressive strength and permeability was obtained from plots of varying the steel slag and cement percentages. Using CCD, experiments were carried out and the response modeled using quadratic equations as functions of variables. A cost effectiveness comparison was done to determine if it was less costly to use steel slag as a partial replacement of coarse aggregates. Results: The optimum values of the variables were found to be 25.99079(Steel slag) and 16%(cement) with responses of compressive strength and permeability. Using CCD, quadratic equations were obtained to demonstrate the relationship between the cement and steel slag aggregates. Conclusions: It was expected that the increase of steel slag aggregates would increase the strength of pervious concrete. From the tests, Steel slag can be used adequately as a coarse aggregate up to about 25% (with a cement percentage of 16%) above which, the compressive strength reduces. The replacement proved to have some environmental benefits and would be an economical or cost- effective technique in concreting in the future. In this project, solid waste was utilized and there was no hazardous effect on strength. key words: Steel slag, Pervious concrete, Compressive strength, permeability, Economic, Environmental.