Study On Engineering Characteristics Of Ecological Solidification Silt Based On Straw Improvement

This paper presents the ecological improvement of solidified sludge by straw,which provides a new method for straw and sludge treatment.In this paper,the ecological solidified sludge was improved by soaking pretreated straw fiber and straw fiber with different particle sizes.The main engineering characteristics of the improved ecological solidified sludge were studied by rheological test,unconfined compressive strength test,compression test and permeability test.The effects of pretreatment time and straw particle size on flow characteristics,strength characteristics and compression permeability characteristics were discussed.The effects of straw content and sample curing age on the strength characteristics were analyzed.At the same time,the lignocellulose determination test and microscopic test were carried out on the soaking pretreated straw fiber,and the change mechanism of the engineering characteristics of the improved ecological solidified sludge was explained.The main research contents and achievements of this paper include the following aspects:（1）Flow characteristics of straw improved ecological solidified sludge.Through the experiment,it can be known that the flow value of straw improved ecological solidified sludge decreases with the increase of straw fiber pretreatment time,and the rate of decline is faster before 24 h and relatively slow after 24 h.And the flow value increases with the increase of straw fiber particle size.The relationship between the dynamic shear force and the pretreatment time of straw fiber was increasing,and the relationship between the dynamic shear force and viscosity coefficient and the particle size of straw fiber was not obvious.At the same time,compared with the ecological solidified sludge without straw fiber,the flow value,dynamic shear force and viscosity coefficient of the ecological solidified sludge with straw fiber are greater than those without straw fiber.The lignocellulose content of the pretreated straw fibers decreased with the increase of pretreatment time.（2）Strength characteristics of straw improved ecological solidified sludge.The test shows that the stress-strain curve presents four obvious stages,and the failure strain is mainly distributed in 1.5%～2.5%,which improves the plasticity compared with solidified sludge.When the pretreatment time is 24h,straw fiber content is 0.5%for the optimal ratio,namely the maximum strength;for different particle sizes of straw fiber modified ecological solidified sludge,when the particle size of straw fiber is 1.0～2.5mm and the content of straw fiber is 0.3%,it is the optimal ratio,and the strength is the largest.At the same time,the age,deformation coefficient and strength of straw fiber modified solidified sludge were fitted,and the fitting formulas of soaking pretreated straw fiber and different particle size modified solidified sludge were obtained respectively.The fitting formulas of age and strength were q_D/q₂₈=0.3999lnD-0.338,q_D/q₂₈=0.3495lnD-0.2954,and the fitting formulas of deformation coefficient and strength were E₅₀=60.49q_u、E₅₀=63.22q_u.（3）Compression and permeability characteristics of straw improved ecological solidified sludge.Through the test,it can be known that there is an obvious yield point in the two kinds of straw fiber improved ecological solidified sludge.The change trend of yield stress is the same as that of compressive strength,and the maximum value is produced at the pretreatment time of 24 h and the particle size of straw fiber of 1.0～2.5mm.The addition of straw fiber increases the permeability coefficient of solidified sludge.The improved permeability coefficient increases with the increase of pretreatment time.With the increase of straw fiber particle size,the permeability coefficient gradually decreases,and when the particle size is greater than 2.5mm,the order of magnitude changes.Fig 62 Tab 6 Ref 114...