Study On The Key Technology Of Block Produced From Lake Sediment And Application In Ecological River Bank Protection Engineering

There are numerous lakes and rivers in China.A rich resource of sediments are annually dredged out during the dredging projects.The application of sintered block produced from lake sediment in ecological bank protection engineering is of great significance for recycle of resources and environmental protection.In this paper,according to the requirements of ecological river bank protection materials,lake sediment was chosen as the main raw material for brickmaking at a laboratory scale,including optimization of admixtures,mixture ratio design and research of the process parameters.Subsequently,an industrial-scale experiment and the effect of drying program in tunnel kiln on properties of sintered block were studied in factory.In addition,sintered block was applied to ecological bank protection engineering.The performance of lateral force resistance,durability and ecology of the block revetment were studied to meet the actual engineering needs.Firstly,the optimization of admixtures and the design of mix proportion of brickmaking in laboratory were studied.Shale,gangue,coal cinder and brick powder were selected as blender to lake sediment.Six mixtures were formed,dried and sintered to produce bricks.Combing with the properties such as drying shrinkage,compressive strength,freeze-thaw resistance and the microstructure of six samples,it is found that the samples containing 10%shale and 10%brick powder had the best physical and mechanical properties and excellent durability.Considering the source of these admixtures,shale is the best choice.In addition,the performances of brick with 2%coal declined obviously.Therefore,coal power is not suitable to be added into sintered block.Based on the above result,varying shale additions and sintering temperatures were chosen to make bricks.The mechanical properties and microstructure of bricks were measured to determine the addition of shale and optimum sintering temperature.The results indicate that the samples containing 20%shale and sintering at 950? had the best forming performance and good appearance.The compressive strength and water absorption of samples were 40.1 MPa,15.82%respectively;and the average weight losses were less than 2%after 125 freeze and thaw resistance,thus meeting the requirements of durability and compressive strength of sintered block as ecological bank materials.Moreover,the SEM and X-CT photographs show that the sample has compact structure and low porosity relatively.Secondly,according to the results of laboratory research,an industrial-scale experiment and the effect of drying program in tunnel kiln on properties of sintered block were studied in factory.Study the feasibility of utilization of lake sediment and shale in production of sintered block as ecological bank materials.The results show that revetment block can be manufactured in the actual production by adjusting the process parameters,which meets the corresponding technical standards.Lake sediment is of high drying sensitivity and high shrinkage,therefore drying regime of adobes becomes one of the key factors which determines the properties of sintered block.In this investigation,the properties of block adobes and sintered blocks at three different drying regimes in tunnel dryer were compared to optimize the drying regime.The results revealed that the drying from 1#position to 16#position which have low temperature and high relative humidity in Tunnel Dryer has little drying effects on block specimens.The block specimens with good appearance and best mechanical strength were obtained when drying process started from 16#position and the trolley stopped at each position for 2.5 h.Under this drying regime,the compressive strength of dried blocks and sintered blocks reached 1.6 MPa and 5.3 MPa,respectively,which meets the strength grade of MU 5 for blocks of GB 26538-2011.Results of this study show that increasing the temperature and reducing the relative humidity of the hot air in the front of Tunnel Dryer can enhance the production efficiency.Thirdly,the sintered block produced from lake sediment application in ecological bank protection engineering were studied.The measurement of lateral force resistance of the block revetment showed that the bank protection engineering was safe under soil lateral pressures.The changes of compressive strength and durability of sintered blocks under the condition of wading showed blocks could meet the requirement of the service life and ecological function of revetment engineering.In addition,Demonstration projects of sintered block produced from lake sediment to ecological bank protection were exhibited.