DOI: 10.5176/2301-394X_ACE14.40
Authors: William Tchoundi Mbadie, Williams Kupolati, Julius Ndambuki, Rotimi Sadiku
Abstract:
The use of waste materials in concrete is promoted for the greening of the environment. However, their implementation faces their engineering properties that may be less good than those of conventional aggregates. In order to achieve requirements for specific applications, many statistical method of optimization can be developed and are generally functions of the number of the concrete ingredients and the number of characteristics to be optimized. The aim of this research was to optimize the compressive strength of concrete made with glass wastes as partial replacement of cement and sand. The cement was partially replaced by Glass Powder (GLP) passing through 75 μm mesh and the sand was partially replaced by Superfine Glass Waste (SGW) with Fineness Modulus (FM) of 1.88 and 3.59, respectively. The optimization was based on the correlation of the compressive strengths and the proportion of GLP and SGW, used from 0 to 30{6e6090cdd558c53a8bc18225ef4499fead9160abd3419ad4f137e902b483c465} and 0 to 60{6e6090cdd558c53a8bc18225ef4499fead9160abd3419ad4f137e902b483c465} replacement of cement and sand, respectively. The proportion of the other ingredients remained constant as for the control mix designed for 25 MPa Characteristic Strength (CS). The Experiment Design (ED) method of optimization was followed. Data of the compressive strengths obtained in laboratory were analyzed with Excel (2007) and MatLab (2010), in order to determine adequate mathematical models at 3, 7 and 28 days and the optimum mix proportion (that exhibits highest strength at 28 days). The optimum mix proportion was obtained graphically, as the coordinates of the highest point between the different curves fitted in MatLab. It was found that, the correlation of the two variables and the compressive strength could not well be explained linearly. Only Polynomial models of 3rd and 4th degrees were found adequate and the optimum mix proportion was a combination of 20{6e6090cdd558c53a8bc18225ef4499fead9160abd3419ad4f137e902b483c465} of GLP and 10{6e6090cdd558c53a8bc18225ef4499fead9160abd3419ad4f137e902b483c465} of SGW. In overall, the optimization enhanced the strength of the highest strength previously obtained in laboratory by 3.4 {6e6090cdd558c53a8bc18225ef4499fead9160abd3419ad4f137e902b483c465}. The re-use of glass wastes in optimum proportion can enhance the properties of the concrete and their implementation can contribute to the greening of the environment.
Keywords: Glass wastes; Compressive strength; Experiment Design; Coefficient of determination; Optimum mix proportion
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