Experimental Study On Preparation Of Kerb By Reservoir Sediment

The fundamental issue with reservoir operation is that sediment production leads to reservoir sedimentation,which not only reduces the effective storage capacity of the reservoir but also shortens the service life of the reservoir.Dredging the sediment is required to guarantee the safe functioning of the reservoir.If the sediment is not handled properly,it will also cause harm to the environment.The purpose of this study is to maximize the use of fine-grained reservoir sediment to replace concrete aggregates to prepare kerbs that can be used in municipal engineering infrastructure.In this study,two kinds of fine-grained reservoir sediment were used to replace 0%,30%,50%,70%,and 100% of the aggregate.Silica fume was used to improve the strength of the reservoir sediment.Compressive strength test,flexural strength test,impact test,frost resistance test,water absorption test,scanning electron microscope(SEM)test,and X-ray diffraction(XRD)test were conducted to study the impact of silica fume on the performance of cement-based materials used to replace the aggregate by reservoir sediment.Further research has been carried out on the samples of sediment with smaller particle sizes to replace all concrete aggregates.The effects of three different types of fibers,basalt fiber(BF),polypropylene fiber(PP),and steel fiber(SF),at four different admixtures(0%,0.2%,0.5%,and 1%)on the compressive strength,flexural strength,splitting tensile strength,and impact resistance of the samples have been studied.The main research content and results of this paper are as follows:(1)By testing the compressive strength of the samples with the replacement ratio of 0%,30%,50%,70% and 100% of the sediment replacement aggregate,the results show that the compressive strength of the samples decreases as the replacement ratio of the sediment replacement aggregate increases.When the replacement ratio is greater than 30%,the compressive strength of the sample is already lower than 30 MPa,which cannot meet the requirements of the kerb for compressive strength.The compressive strength of the sample is improved by adding silica fume.The findings demonstrate that the compressive strength of the two types of sediment replacement aggregate samples improves as silica fume content increases and the improvement effect of silica fume on the performance of cement-based materials for reservoir sediment replacement aggregate is relatively dramatic.(2)At a high replacement ratio,it is still difficult for the compressive strength of the two kinds of sediment to reach 30 MPa only by adding silica fume.Therefore,it is considered to add silica fume and appropriately increase the amount of cement.The compressive strength,flexural strength,frost resistance and water absorption of the two kinds of reservoir sediment to replace 100% of aggregate samples meet the requirements for preparing kerbs.The feasibility of replacing all aggregates with reservoir sediment to prepare kerbs is realized,and the utilization content of sediment and silica fume waste accounts for up to 70% of the total sample.(3)The SEM and XRD tests were carried out when the replacement ratio of the two kinds of sediments was 100%.The SEM images and XRD patterns showed that the C-S-H gel content rose while the amount of calcium hydroxide dropped after adding silica fume to the sample.C-S-H produced particles that could fill the pores and firmly bond the sediments,which decreased the number of holes among particles in the sample and made the interior structure more compact.To enhance the mechanical and physical properties of samples.(4)With contents of 0.5%,0.2%,and 1%,respectively,BF,PP,and SF all attain their maximum compressive,flexural,and splitting tensile strength.In general,the improvement effect of the three fibers on the compressive,flexural,and splitting tensile strength of the sample is the best for SF,followed by PP,and the effect of BF is the worst.When the content of the three fibers is 1%,the impact energy consumption of the sample destruction reaches the maximum value.The effect of the fibers on improving the impact performance of the sample is PP>SF>BF.From the analysis of the SEM diagram of fibers,certain fibers can be observed in cracks,and the fibers absorb some of the energy that contributes to crack expansion,enhancing the mechanical characteristics of the sample and minimizing the creation of damaging fractures and pores,preventing the penetration of harmful substances to a certain extent,thus improving the durability of the sample.