Development Of Unburned Steel-slag Ceremsites For Spoge City Construction

Urban waterlogging is a common public disaster which could cause heavy casualties and serious property loss.Therefore,sponge city construction becomes one of the most important measures to curb urban waterlogging disasters.By 2017,it is reported that 30 cities have been designated as the pilots of the Sponge City in China.Porous ceramsite with strong adsorption is an ideal material for Sponge City construction.In order to promote the construction and development of the sponge City,prevent the urban waterlogging disaster and ensure the urban water safety,it is practical significance to carry out the research and development of unburned ceramsite,which has low environmental harm,low cost and good permeability.In order to prepare a high-quality unburned ceramsite steel slag ceramsite,the hot splashing steel slag is first studied to prepare the unburned ceramsite.Because the hydration reaction of f-CaO and f-MgO in steel slag affects the performance of the unburned ceramsite.It is found that the combination of ground slag and steel slag can effectively improve the performance of the unburned ceramsite,the optimum mixing ratio of steel slag and ground slag is 2:3 through the compounding of steel slag and ground slag.Then the effect of cement and aluminum paste on the performance of the unburned ceramsite is studied by single factor analysis,and the result shows that the optimum dosage of cement and aluminum paste is 10%and 1%respectively.In order to study the effect of different admixtures on the performance of the unburned ceramsite,the optimum dosage of admixtures is obtained by orthogonal experiment.It is found that the optimal mixing amounts of additives are lime 4%,dihydrate gypsum 2%,sodium silicate 4%,and sodium hydroxide 4%.The performance test results of the slag unburned ceramsite prepared by the above ratio have been show that the bulk density is821.35 Kg/m~3,the cylinder pressure intensity 13.67 MPa,and the water absorption5.78%,which meet the requirements of the national standard(GB/T 17431.1-2010)for the ceramsites of intermediate and high strength.Due to different chemical composition of different types of steel slag,the performance of the steel slag unburned ceramsite will be affected.Therefore,no matter from the completeness of scientific research or the applicability of technology promotion,it is necessary to study the mixing ratio of different steel slag.Therefore,the influence of cylinder,hot-closed and air-quenched steel slag on the unburned ceramsites property are conducted.The results indicate that the unburned ceramsites of air-quenched steel slag has the maximum bulk density and the minimum cylinder pressure intensity,as 1024.19 kg/m~3 and 8.03MPa,respectively.The unburned ceramsite made of cylinder steel slag had the minimum 1h water absorption,as only 2.54%.However,the properties of the above three categories of unburned ceramsites still meet the requirements for ceramsites with high strength.The application scope of steel slag is expanded by above researches.To investigate the feasibility of using unburned ceramsites in the Sponge City construction,the water-retaining property is evaluated.The results show that the infiltration time of steel slag unburned ceramsite is 6.3min,the seepage within 24h is224g,and the 7d water retention rate is 37.5%,which meet EN ISO 11274-2014 and the construction requirements of Sponge City.In addition,the economy of the steel slag unburned ceramsite and its application prospect in the construction of sponge city are analyzed.The economic analysis of unburned ceramsite shows that the production cost of steel slag ceramsite prepared by the no burning process is lower.The steel slag unburned ceramisite has the characteristics of high strength,water permeability and water retention is good,suitable for sponge city construction and city flood disaster prevention.