Effects of Al2O3,SiO2 and Fe2O3 on the properties of sludge-based non-sintered lightweight aggregates
The use of solid waste river and lake sludge as the main raw material to prepare sludge-based non-sintered lightweight aggregates(LWAs)is an effective technological process for the resource utilization of solid waste.The effects of the content of Al2O3,SiO2 and Fe2O3 in the raw materials on the strength,1 h water absorption rate and particle density of LWAs were further systematically explored,and effects mechanism were analyzed by X-ray diffractometer(XRD)and scanning electron microscopy(SEM)characterization techniques,aiming to derive corresponding oxide content parameters to optimize the process.The results show that under the conditions of base material ratio,excessive Al2O3 leads to the crystalline growth of the brittle crystalline phase lawsonite,resulting in a decrease in the strength of the LWAs.The pozzolanic effect and crystalline nucleation effect possessed by SiO2 synergize the hydration reaction to generate more hydrated calcium silicate,and when the SiO2 content is 26％,the internal structure of LWAs is dense and the optimum strength reaches 3.11 MPa.The appropriate amount of the nucleation effect embodied by Fe2O3,which facilitates the generation of crystalline phase can improve the performance of LWAs.
river and lack sludgenon-sintered processlightweight aggregateshydration mechanismoxide
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