Performance And Application Of Sludge Gasification Slag Aggregate Backfill Concrete

With the increase of urban sewage discharge,the resource utilization of sludge has become the focus of social development and environmental protection.Sludge pyrolysis gasification technology is an advanced sludge treatment technology,which can realize the reduction of sludge.However,the sludge gasification slag produced after treatment is difficult to be used in ordinary concrete due to its low strength.In this paper,aiming at the sludge gasification slag produced by sludge pyrolysis and gasification,combined with the specific engineering requirements,it is considered to completely replace the coarse and fine aggregates in concrete to prepare backfill concrete for engineering application.The physical and chemical properties of sludge gasification slag were analyzed to verify its feasibility in concrete.The original sludge gasification slag and the graded sludge gasification slag after crushing and screening were used to prepare backfill concrete,and their properties were studied.Based on this,pilot test and application were carried out in practical engineering.The main research results of this paper are as follows:(1)Feasibility study of sludge gasification slag as concrete aggregate.As a by-product of pyrolysis gasification technology,sludge gasification slag particles have the characteristics of large water absorption,many pores and low cylinder pressure strength.Through the concrete strength test of ordinary gravel(SS),shale ceramsite(TL),saturated sludge gasification slag(BS)and unsaturated sludge gasification slag(WBS),it is found that the water absorption characteristics of sludge gasification slag can play the role of internal curing in concrete,optimize the interface transition zone of concrete,and have the feasibility of being used as aggregate for backfilling concrete.(2)Performance analysis of unsitt sludge gasification slag aggregate backfill concrete.Through the analysis of the rheological properties,pressure bleeding rate and compressive strength of the original sludge gasification slag aggregate concrete,it is obtained that when the water content of the original sludge gasification slag is 4.7%and 21.2%respectively,the optimal water consumption of the concrete mix ratio is 377 kg/m~3 and 276 kg/m~3 respectively.The process of preparing the original sludge gasification slag aggregate concrete is relatively simple,and it can also meet the requirements in performance.It has certain advantages and feasibility,and has a guiding role in specific projects.(3)Performance analysis of graded sludge gasification aggregates backfill concrete.The concrete mix ratio of graded sludge gasification slag aggregate was designed by the response surface method,and the concrete sand rate,the proportion of 5-10mm particle size in coarse aggregate and the pre-wet water consumption in the pre-wet water consumption had the greatest impact on the flow performance of concrete,and the concrete sand rate was 60%,the particle size of 5-10mm in the coarse aggregate was 60%,and the pre-wet water consumption was 90%,and compared with the original sludge gasification residue aggregate,the crushed and screened aggregate had a more regular shape.The advantage of denser stacking and adjustable gradation.(4)Through the pilot test of sludge gasification slag backfill concrete in the active coke adsorption tank and the roof construction project of the second phase control room of the new district in the Nancao project of Zhengzhou Sewage Treatment Plant,it shows that when the sludge gasification slag backfill concrete is applied to the actual project,its working performance,mechanical properties and physical properties meet the requirements of engineering use,and it has the feasibility of application in engineering.