Analysis of the Waste Sludge Produced from the Offshore Sand Processing Plants in Sri Lanka

With the increasing demand for sand in the construction sector, off shore sand has been produced daily by Redeco and Asset sand washing plants in Muthurajawela, Sri Lanka. During the processing of off shore sand, off shore sand sludge (OSS) is produced as a by product that accumulates approximately 150 cubes per month. Currently, the sludge is used either in land filling or has been dumped haphazardly at different locations and thus giving rise to different environmental issues. Hence this research study is mainly focused on mediating this emerging environmental problem by utilizing this sludge in the construction industry. The suitability of OSS in terms of chemical and physical properties was investigated for cement-based products in order to use OSS as a building material. Since chemical and physical properties directly affect the properties of the post-produced value-added product, sludge samples from the sand dump were characterized using the XRF method. Sieve Analysis, Loss on Ignition, Water Absorption, Water-soluble chloride, Sulfate content, Total sulfur content and Organic Impurities tests also were carried out to determine the compliance of sludge as a building material. XRF test results revealed that the predominant compounds of OSS are SiO2 and CaO. By analysing the results obtained for particle size distribution, shell content and the chloride and sulfate contents it was concluded this waste sludge can be used as an alternative filler material in the development of cement-based mortar type material. More specifically this study aimed to develop and use this OSS for the production of a cement-based tile adhesive material