Study On Strength Characteristics And Influencing Factors Of Industrial Residue Composite Solidified Loess

Fly ash and desulphurized gypsum are two kinds of industrial waste residue in coal-fired power plants,and it can still play a certain value if appropriate methods are used properly.Using industrial waste residue along with cement for soil solidification is an effective measure to increase soil strength and improve waste residue utilization,it can be used for foundation treatment such as cushion method and deep mixing pile.It has obvious economic and environmental benefits.Fly Ash-Desulfurization Gypsum-Cement ternary gel system is selected to solidify loess in this paper,meanwhile use Ca?OH?₂ and NaOH as activator to form a new kind of composite loess firming agent.At first,by orthogonal experiments,the influence degree of each component of the firming agent on strength is judged by unconfined compressive strength,and the optimum mixing ratio is selected;Then,effects of loess water content,water cement ratio?solidified soil initial water content?and early strength agent on strength are studied using the optimum mixing ratio;Finally,analyze hydration products and the microstructure of solidified loess through XRD and SEM,the reinforcement mechanism is studied.The results showed that:?1?The hydration reaction of fly as his slow but durable,improve the fly ash mixing ratio can significantly increase strength,with age increasing,the influence of fly ash mixing ratio on the strength of composite solidified loess increased significantly;For other components,the influence of Ca?OH?₂ was more significant,embody its effect of activity excitation.?2?The initial water content that makes composite solidified loess strength highest in each age is around 20%;Low initial water content results insufficient hydration reaction and low strength,high initial water content causes internal cracks to make the strength lower;Triethanolamine and sodium silicate can be used as early strength agent for composite solidified loess,while CaCl₂cannot.?3?90d strength of composite solidified loess is higher than 17%cement loess,that shows the substitution effect of industrial waste residue and activator on cement;The strength growth rate of the former is higher than that of the latter,and its strength development sustainability is better.?4?Composite solidified loess's hydration reaction resultant and main source of strength is ettringite and hydrated calcium silicate,ettringite increases its strength obviously,meanwhile cement loess has only hydrated calcium silicate;With the increase of age,the microstructure of composite solidified loess and cement loess is more compact and the pores are reduced,it can be observed that the dense internal force system is formed by hydration reaction resultant and soil particles form.This study has preliminarily recognized the characteristics and reinforcement mechanism of composite solidified loess,which can lay a solid foundation for the application of fly ash and desulphurization gypsum in loess solidification and research works of other aspects.