Study On Road Performance And Reinforcement Mechanism Of Solidified Sludge By Composite Stabilizer

After solidification,sludge as a good filling material can be widely used in adjacent dyke reinforcement projects,such as municipal engineering,road engineering and reclamation engineering.This not only protects the ecological environment,but also saves a large amount of building materials resources for engineering activities.Solidification provides practical ideas for effective treatment of sludg.It is of great significance to China's sustainable development strategy.In this paper,the typical offshore marine sludge in Ningde area of Fujian Province was taken as the research object,and the corresponding curing countermeasures were proposed.The suitable solidifying materials were selected as the composite stabilizer.The strength of solidified sludge and the optimal ratio of the composite stabilizer were investigated by single-mixing test and orthogonal test.In order to evaluate the road performance of solidified sludge,indoor tests such as unconfined compressive strength test,direct shear test,consolidation test,water immersion test,dry-wet cycle test and exudate test were carried out,respectively.And the mechanics and stability of the solidified sludge were studied.Combined with a series of micro-test techniques,the solidification mechanism of the composite stabilizer was discussed from the aspects of material composition,pore structure characteristics and surface electrochemistry.The main contents and research results of the thesis are as follows:?1?Study on compound curing agent formulaAccording to the characteristics of sludge,cement,quicklime,potassium ferrate and water absorbing resin were selected as solidifying materials.The 7-day unconfined compressive strength was used as the evaluation index.The strength of solidified sludge and the optimal ratio of the composite stabilizer was investigated by single-mixing test and orthogonal test.The test results show that the ratio of the composite stabilizer is:cement content 6%,quick lime content 2%,potassium ferrate dosage 0.5%,water absorption resin dosage 2.0%.Under this ratio,the price of treating 1m³ sludge is about221 yuan,and the 7-day unconfined compressive strength of solidified sludge is 4.098MPa.?2?Study on mechanical properties of solidified sludgeThrough the unconfined compression test,direct shear test and consolidation test,the systematic study on the change law of the mechanical properties such as strength and deformation of solidified sludge is compared with the traditional treatment method?mixed with 15%cement?.The test results show that the solidified sludge is superior to the solidified sludge treated by the traditional solidification method in many indexes such as compressive strength,shear strength and compressibility.?3?Study on stability of solidified sludgeThrough the immersion test,dry-wet cycle test and exudate test,the wet environment,the extreme temperature and humidity environment and the long-term seepage environment were simulated respectively.The effect of the composite stabilizer and the road performance of the solidified sludge were further evaluated.The test results show that the solidified sludge has good water stability and durability.Composite stabilizer can effectively reduce the concentration of copper,zinc and lead ions in the exudate.?4?Study on curing mechanism of composite curing agentThrough a series of micro-experimental techniques,the mechanism of the composite stabilizer from various aspects such as material composition,pore structure and surface electrochemistry were explored.The test results show that after adding the composite stabilizer,the organic macromolecules in the solidified sludge are oxidatively cracked by potassium ferrate.The organic macromolecules are converted into organic small molecules and inorganic salts.At the same time,a large amount of pore water is converted into bound water in the water absorbing resin or the hydration reaction of cement and quicklime occurs.The process promotes the formation of ettringite and hydration gelled products CAH and CSH,combined with potassium ferrate-reducing product Fe?OH?₃ and gel-like water-absorbing resin,which together fill pores and strengthen soil particle bonding.This process achieves the purpose of solidifying sludge.