Utilization of top aluminum-zinc dross in the manufacture of pervious concrete
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Dross is a waste product from the galvanizing process that contains useful substances in large percentages that can be harvested and transformed or reused in production processes to earn a profit. Dross from Roofings Rolling Mills Ltd galvanization process is harvested from the galvanizing bath, cast into blocks and sold to companies that have the technology to extract and process the valuable elements they contain. Though dross from Roofings Rolling Mills Ltd is sold off to other industries that need it, the economic value generated from its sale is not commensurate to the number of valuable products trapped in it. The enormous number of useful products in dross can be utilized in the development of previous concrete slabs to be used in water seepage applications. Top Al-Zn dross from Roofings Rolling Mills Ltd was analyzed to determine its physical and chemical properties. Top Al-Zn dross was beaten when hot at temperatures below its melting point with a sledgehammer to reduce its size, sorted into three different sizes and mixed to come up with top Al-Zn dross samples. Top Al-Zn dross samples were mixed with portland pozzolana cement and water of weight 50% mass equivalent of cement to develop top Al-Zn dross/ portland pozzolana cement slabs. The developed top Al-Zn dross/ portland pozzolana cement slabs were further subjected to tests of density, porosity, coefficient of permeability and compressional strength. Top Al-Zn dross from Roofings Rolling Mills Ltd was composed of mainly aluminium and zinc with traces of other elements combined to form different compounds that are responsible for the variations in the hardness value across its surface. Top Al-Zn dross samples, portland pozzolana cement and water mixture on casting foamed with a noticeable rise in temperature, with porosity confirmed in all the top Al-Zn dross/ portland pozzolana cement slabs. The analysis of top Al-Zn dross/ portland pozzolana cement slabs revealed varied physical properties depending on the amount of top Al-Zn dross added in the mixture, for instance, density, porosity, and permeability increased with further addition while the compressional strength after seven days of curing reduced. The coefficient of permeability of top Al-Zn dross/ portland pozzolana cement slabs varied inversely with the compressional strength. Top Al-Zn dross/ portland pozzolana cement slabs produced from a mixture containing 39% top Al-Zn dross possessed a combination of both maximum coefficients of permeability and compressional strength. From the results of the experiment conducted, top Al-Zn dross from Roofings Rolling Mills Ltd can be used as a foaming agent when mixed with portland pozzolana cement and water to develop slabs that can be used for water seepage applications. Further development of top Al-Zn dross/ portland pozzolana cement slabs should be investigated with uniformed sized top Al-Zn dross particles and with the addition of other ceramic materials wastes like broken bricks, tiles, etc. The costs involved in development of top Al-Zn dross/ portland pozzolana cement slabs should be further studied including the analysis of water filtered through them to determine the level of toxicity.