Study On The Preparation And Properties Of Non-fired Wrap Shell Ceramsite From Dredged Sediments

There are a large number of dredged sediment produced in our country every year.The pollutants in sediment cause serious secondary pollution and need to be processed urgently.The use of dredged sludge to produce non-fired ceramsite and ceramsite was wrap shell treated,not only solve the utilization problem of dredged sludge,but also save energy and use of waste and protect the land resources in our country.At present,the preparation process of non-fired ceramsite from dredged sediment is underripe and seldom reported.The paper used way of blasting method.The process is dredged sediment mixed with cementitious materials directly,co m minution granulation and curing to non-fired ceramsite.But the shortages of this ceramsite are low strength,easy to hydration and poor comprehensive durability.Based on the shortages,this topic proposed that using dredged sediment ceramsite to produce wrap shell ceramsite in the first time.Test and analyse the performance of ceramsite and used in bio ceramsite filter and cement specimen.The main research contents and results of this paper are as follows.The result of preparation process and optimum proportion of raw materials of non-fired wrap shell ceramsite from sediment showed:(1)Based on different shell materials,feasibility preparation process are deter mined.The optimal mix designation composes of 70%sediment ceramsite,15%cement,5%ZY-1,1.5%quick lime,3.5%ZY-2 and 5%ZY-9.(2)Performance of ceramsite were analysised and found:the grain size distribution of wrap shell ceramsite is good and concentrated on 3-8 mm.The glass fiber powder in shell of 9#ceramsite enhanced toughness and cylinder pressure strength is maximum of 6.4 MPa.Water resistance and freeze resistance was enhanced by wrap shell treatment and mass loss rate of 9#ceramsite after 25 freeze-thaw cycle is 32.74%.The percentage of damage after 120 min in water erosion experiment is 5.14%.The mass loss rate of it soaked about 240h in 15%NaCl is 15.05%.From SEM analysis,internal structure of wrap shell ceramsite is co MPact and hydration is better.Wrap shell ceramsite used in bio ceramsite filter to treat wastewater showed:(1)The optimal temperature is 30 ?,removal rate of CODCr,NH3-N,SS and TP are 55%,65%,81.5%and 50%.(2)Wrap shell ceramsite was magnetic modified and water purification was explored co MPared with co mmodity sintered ceramsite.It can be seen that water purification of magnetic modified ceramsite is better and removal rate of CODCr,NH3-N,SS and TP are 65%,68.9%,79%and 51%.Associativity of wrap shell ceramsite and cement was researched and showed:(1)The performance of crushed stone cement specimen and pure cement specimen are best.Wrap shell ceramsite specimen is similar to sintered ceramsite cement specimen.Strength of wrap shell is little lower of 0.4 MPa and mass loss rate of freeze-thaw experiment is higher of 14.13%.(2)Co MPared to different specimen in different cracks,it is known that the durability is worse as the cracks increased.