Research On Water Storge And Other Properties Of Underlying Surface In Sponge City

With the wide application of low impact development measures?permeable pavement,green roof,grassed swales and rainwater garden?in the constructions of Sponge City.The consumption of non-renewable resources such as clay,gravel,asphalt and cement are gradually increasing.It is urgent to develop new materials that can replace these non-renewable resources.At the same time,large amount of silt resources produced by sponge city and black river regulation projects have not been handled in suitable ways.In 2012,the dredging project of the rivers in the urban area of Suzhou produced 1483,000 square meters of river sludge.If we treat the silt by the ways of stacking and burying,it will not only pollute the surrounding water and soil environment,but also waste the resources of silt.Therefor waste resources such as silt and waste glass were chosen as the main research objects.After treatment by certain technical means,waste materials such as sludge and waste glass are used as new materials in the construction of sponge cities.This paper takes the abandoned resources such as silt in Suzhou as the main research object.Through XRD,XRF,SEM and related experiments,the basic properties of non-burned brick raw materials and the preparation method of non-burnable bricks are discussed.The single factor impact test and orthogonal design test are designed.The physical properties,water permeability,water storage performance and the removal effect of SS and COD pollutants in the initial rainwater runoff were studied for the construction of sponge city.The main conclusions are as follows:?1?The loss of treated silt on ignition was 6.6%and its main components were Al₂O₃?16.00%?and SiO₂?68.84%?,which meant the silt had high activity.The main components of recycled glass were Al₂O₃?0.4%?,SiO₂?72.5%?,Fe₂O₃?5.14%?and the mass fraction of active components was 80.1%.The 28-day strength-activity index of fine glass added with cement in 10%proportion was 89%,better than the fly ash of F class.At the same time,some Na₂O in fine glass can integrate into water,which improved the alkalinity of the solution and promoted the initial hydration process.?2?It was found that the optimum physical property was 5.8 MPa when the content of lime was 18%.With the consistent growth of lime,the internal structure was destroyed with cracks on the surface of samples.The compressive strength increased with the rise of mixing cement content.When the ratio was 30%,the compressive strength reached 15.7 MPa,which met the standard of compressive strength and reached the high rate of recycling materials.?3?After reaching the state of full water,the water content of non-burned brick mixed with SAP decreased by 10.3%⁴2.8%in the first 15 minutes,which had a certain permeability effect.After 100 hours,the ratio of water content was still3.0%⁶.4%.It had good water storage performance.However,the ratio of non-burned brick without SAP was 0,and its performance of water storage was much lower than that of non-burned brick with SAP.The analysis of orthogonal experiments showed that the effects of three factors on water absorption and water retention of non-burned brick were as follows:cement ratio>lipid ratio>grade ratio.However,the degree order on water ratio of non-burned bricks were lipid ratio>grade ratio>cement ratio.When the ratio of three factors was:lipid ratio=0.02,grade ratio=5,cement ratio=3,the performances of non-burned brick:water absorption was 9.43%,water retention was0.49 g/cm²,the volume ratio of water content in 100h was 5.7%.?4?The non-burned brick has certain removal efficiency in SS and COD.When the additive content of non-burned brick was 40g and the initial concentration of simulated solution was 48mg/L,114mg/L,247mg/L,the removal rates of SS were44%,50%and52%respectively.When the initial concentration of simulated solution about COD was 10mg/L,20mg/L,40mg/L,the removal rates of COD were 27%,40%and46%respectively.In the context of same initial concentration,the removal rates of SS were 32%,50%and55%when the additive content of non-burned brick were 20g,40g and 80grespectively and at the same time,the removal rates of COD were 32%,42%and49%respectively.The results of experiments showed that the initial concentration of simulated solution and the addition of non-burned bricks had certain effects on the removal of SS and COD.The removal rate increased with the raise of initial concentration and the addition of non-burned bricks,but the rate was on decrease gradually.