Development of alternative disposals for waste rice husk and dredged harbor sediment by sintering as lightweight...

This study developed the alternative disposals for dredged harbor sediments by co-sintering with waste rice husk into lightweight aggregates (LWA) to benefit resource sustainability and waste valorization. The effects of rice husk addition and sintering temperature on LWA performances such as water absorption, particle density, crushing strength, weight loss, volume shrinkage, and open porosity were investigated. The key parameters (e.g. C/Fe ratio in raw materials) controlling the LWA performances and engineering applications were determined. Results showed that dredged harbor sediments could be made into suitable LWA for engineering applications from the controlled rice husk addition and sintering temperature. The addition of rice husk led to lower LWA particle density, but raised water absorption and reduced crushing strength. The increase of sintering temperature reduced water absorption and improved crushing strength. The aggregates with 10-15% rice husk, sintered at 1150 °C had appropriate particle density (1.60-1.73 g/cm³), water absorption (11.8-16.6%), and crushing strength (6.0-10.6 MPa), which could be suitable for lightweight concrete applications. Low water-soluble chloride and heavy metals leachabilities aligned with Taiwan's regulatory standards for concrete aggregates. Co-treating waste rice husk and dredged harbor sediment into LWA can benefit the waste reduction and circular economy, and reduce the environmental impacts associated with their disposals.