Experimental Study On Preparation Of Non-fired Brick By Reservoir Sediment

As time goes by,a large amount of sediment will be produced in the reservoir,which will pose a threat to water quality and aquatic environment,and too thick sediment will also adversely affect the reservoir’s flood storage capacity,so it is urgent to deal with the reservoir sediment.The preparation of unfired bricks with bottom mud can not only avoid the traditional rough production process of fired bricks,but also solve the problem of high energy consumption.It can not only recycle the bottom mud,but also bring certain economic benefits,which has great practical significance to the economy and environment of modern society.In this thesis,unfired bricks are made by using reservoir bottom mud as the main material and cementing materials such as takaolin,lime,fly ash and cement.The best material ratio and curing process are obtained through experiments.The compressive strength,water absorption,softening coefficient and freezing resistance of unfired bricks are studied.The main research contents and conclusions are as follows:（1）Based on the analysis of the domestic and foreign research on the utilization of sediment resources,the experimental scheme of using sediment to prepare unfired bricks was designed.X-ray fluorescence spectrometer（XRF）and X-ray diffractometer（XRD）were used to analyze the composition of sediment.The results show that the main composition of reservoir sediment is Si O₂ and Al₂O₃,which can be activated under alkaline environment,and its main mineral composition is illite,calcium vanadite,albite,calcite,quartz and other minerals.In addition,the XRF detection results of auxiliary materials show that chemical reactions can take place between bottom mud and auxiliary materials to generate cementitious materials.The cementitious materials play the role of filling and cementing bottom mud particles,and the reaction between materials is conducive to the improvement of the performance of unfired bricks.（2）To prepare unfired bricks with different material ratios,to compare and analyze the test results of the influence of different material dosage and curing methods on the performance of unfired bricks,and to fully consider the economy and technology,the following results can be obtained:The optimal ratio of reservoir sediment to prepare unfired bricks is m（reservoir sediment）:m（lime）:m（fly ash）=40:36:24,sodium silicate is 3%,water-material ratio is 0.16,fixed cement-sand ratio is 1:1,curing method is autoclaved curing,autoclaved curing temperature is 216℃,pressure is 2MPa.（3）The unfired bricks of reservoir bottom mud-lime-fly ash system were analyzed by XRD and SEM,and the kinds of minerals in the unfired bricks were characterized.The minerals with higher hardness were mostly in the unfired bricks.SEM analysis results show that with the increase of fly ash content,the microstructure of unfired brick tends to be more compact and stable,and the hydration reaction between materials generates a large amount of calcium silicate hydrate.Calcium silicate hydrate can cement sediment particles and fill structural pores,so that unfired brick can achieve good mechanical properties.