Study On The Preparation Of Sewage Sludge Ash Geopolymer And Its Strength And Pore Structure

With the rapid development of urbanization in China,the amount of sludge discharged from sewage treatment plants is also increasing.How to effectively treat sludge has become an urgent problem.If sludge is used in the production of building materials,it can not only reduce the environmental burden,but also effectively use solid waste.The traditional building materials prepared by sludge usually have low compressive strength and poor durability,which may cause secondary pollution to the environment.However,geopolymer has high strength,good solidification effect on heavy metals,good acid and alkali corrosion resistance,which can make up for the correlation of sludge building materials can be inferior.Therefore,in this project,the sludge ash is used as the main raw material to prepare geopolymer,and the strength and pore structure of the geopolymer are studied,so that the sludge can be used as building materials.First of all,the original sludge was dried and calcined at high temperature to achieve the purpose of reducing and activating pozzolanic activity.The treated sludge was ground to prepare the sludge ash used in the experiment,and its physicochemical analysis and pozzolanic activity research were carried out as the theoretical basis of sludge ash building materials and the theoretical basis of sludge ash geopolymer preparation.Secondly,the mix proportion is designed,and the different mix proportion of Sludge Ash Geopolymer is prepared.By measuring the compressive strength value of each age,the influence of different sludge ash content,alkali activator modulus and alkali equivalent on the compressive strength of sludge ash geopolymer and its strength development law are studied.After optimizing the mix proportion,the pore structure of the geopolymer was studied,and the difference of its strength was explained from the micro point of view.Different models were established to explore the relationship between the strength and pore structure of sludge ash geopolymer,and the relationship between the micro structure and the macro performance was further analyzed.The results show that there are mainly Si O2,Fe2O3,Al2O3 and a small amount of heavy metals in the sludge ash,and the particle size distribution of the sludge ash calcined at 800? after 180 s grinding is better,the specific surface area is larger,the content of amorphous Si O2 is more,and the pozzolanic activity is the highest.The modulus and alkali equivalent of alkali activator have obvious influence on the strength and pore structure of sludge ash geopolymer.If the modulus and alkali equivalent are increased properly,more silicate can be introduced and the alkali solution content of the system can be increased,so that the pozzolanic activity of sludge ash can be activated better,and the pore structure and strength of sludge ash geopolymer can be improved.The correlation between pore structure and compressive strength of sludge ash geopolymer is different under different models.The influence of pore parameters and pore size distribution of geopolymer on its compressive strength should be considered comprehensively.The multi linear model established by this method has high correlation and good applicability.