Development of an Integrated Concrete Sludge Treatment and Recycling System

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The purpose of this study is to discuss an integrated concrete sludge treatment and recycling system that regenerates the concrete sludge discharged from ready-mixed concrete plants into a powdered material of high added value. The following conclusions may be drawn based on the current research project:(1) The coagulant including more than 95% of inorganic substance for the treatment of concrete sludge was developed, and the test data on the optimum dosage and the stirring time of inorganic coagulant were collected.(2) Sludge cake obtained by the process of pressurization and dehydration of sludge water was dried, and then crushed finely by forded air to produce the powdered material (Pulverized Dry Sludge, PDS). The data on the manufacturing condition of PDS were collected. It was found that PDS consisted of rounded ultra fine particles having a size of 3-10μm and a Blaine specific surface area of 8,000-10,000 cm^2/g, and was easy to produce.(3) The experiments on the use of PDS as a … More kind of mineral admixture and the powder material for high-fluidity concrete were carried out, and the good test results were obtained. It was confirmed that in the case of a mineral admixture, PDS had no harmful effects on hardened concrete although the dosage had sometimes to be limited to about 10% of the cement content because high content of concrete sludge significantly increased the demand of mixing water, in the case of high-fluidity concrete, the limitation of PDS content was 30 vol.%, according to Regulation JASS5 for high-fluidity concrete although test results showed that high fluidity concrete containing PDS up to 60% of volume content had a good performance.(4) The application of the complete recycling system developed in this research project to other waste materials other than concrete sludge was discussed. It was found that the ultra fine powder crushing and processing technology will become possible to apply other wastes such as the faulty construction materials, waste glass bottles and casing sand as well as wet wastes such as dirty mud discharged from the quarrying factory and the construction site. Less