Study On The Structure And Properties Of Non-fired Brick From Dredged Sludge

There are a large number of dredged sludge produced in our country every year.The dredged sludge not only covers an area widely,but also cause serious secondary pollution,and need to be processed.In recent years,much attention has been paid to studies of dredged sludge resource utilization.The paper is dedicated to explore make use of dredged sludge to produce non-fired brick,not only solve the utilization problem of dredged sludge,but also conform to the national policy guidance,save energy and use of waste,protect the land resources in our country.At present,the preparation process of non-fired brick from dredged sludge was mixed dredged sludge with cementitious materials directly,press-forming the mixtures into non-fired brick and curing,but the shortages of this brick are low strength,easy to hydration and poor comprehensive durability.Based on the physical and chemical properties analysis of non-fired brick,the strength forming mechanism of non-fired brick is studied.This topic proposed that using dredged sludge ceramsite to produce non-fired brick in the first time.Test and analyse the effects and mechanisms of dredged sludge ceramsite on non-fired brick.The main research contents and results of this paper are as follows.(1)Studied the preparation process and optimum proportion of raw materials of non-fired brick from non-fired ceramsite.According to different initial moisture content of dredged sludge as raw materials,two kinds of feasibility preparation process of dredged sludge ceramsite are determined.The optimal mix designation composes of 80%non-fired ceramsite,3%cement,3%lime,5%fly ash,6%sodium silicate.Combining with the particle size distribution,the strength of cylinder pressure,determination of bulk density and water absorption to characterize the performance of non-fired dredged sludge ceramsite.The microstructure of dredged sludge ceramsite were analyzed through SEM,TG/DTG and SEM.(2)Studied the feasibility preparation process of non-fired brick from dredged sludge.The strength of non-fired brick made from dredged sludge directly is low,and easy to hydration.The feasibility preparation process is non-fired brick made from dredged sludge ceramsite.The strength of non-fired brick made from dredged sludge ceramsite is improved greatly,excellent resistance to water and comprehensive durability.(3)Explored the best formulation of non-fired brick from dredged sludge ceramsite.Used orthogonal experiments to study the effects of the dosage of ceramsite,cement and composite cementitious materials on the strength of non-fired brick.Determined the best formulation of non-fired brick is cement 54.17%,cement 12.5%,fly ash 12.5%,lime 6.97%and gypsum 1.99%.The best grading for ceramsite is L1:<5mm,67%,5-8mm,33%.(4)Focus on the study of the effects and mechanisms of dredged sludge ceramsite on non-fired brick.Contrasting to non-fired brick made from fly ash,testing its compressive strength,flexural strength,contact angle,bibulous rate,density,salt freezing resistance,acid and alkali corrosion resistance to characterize the effects of dredged sludge ceramsite on non-fired brick.The microstructure of non-fired ceramsite brick were analyzed through SEM,TG/DTG and SEM.The results show that the characteristics of the non-fired ceramsite brick such as salt freezing resistance,acid and alkali corrosion resistance are excellent,which has good comprehensive durability.But low concentration of salt solution environment need to be avoided using.The strength of non-fired ceramsite brick can be reached with non-fired brick from fly ash,both non-fired brick from ceramsite or fly ash have hydrophobic surface,excellent water resistance and similar microstructure,and the density of non-fired ceramsite brick is lower,the structure of non-fired ceramsite brick is more compact,the internal material hydration more fully.