Experimental study on the mechanical properties of fly ash paste filling material synergistically enhanced by high-power ultrasound and alkali activation
Yin Bo
Jia Xiaolei
Huang Pingping
Lian Quandong
Zhou Nan
Li Xianfeng
Wu Xiang
Yang Ruizhou
Yang Xiaoyan
Abstract：Objectives To address the problem of low early strength of fly ash paste filling material,this study investigates the mechanism and effectiveness of synergistic modification using high-power ultrasound and alkali activation.Methods Single-factor experiments were conducted to analyze the effects of ultrasound time,ultrasound power,Na2SiO3 concentration,and NaOH concentration on the 1 d,3 d,and 7 d peak strengths of fly ash paste filling material.Based on a three-factor,five-level central composite design(CCD)within the response surface methodology,the synergistic modification parameters of ultrasound and alkali activation were optimized.Furthermore,the microstructural changes after modification and the syner-gistic modification mechanism were systematically investigated.Results The results indicate that the peak strength of fly ash paste filling material first increases and then decreases with increasing ultrasound time,ultrasound power,Na2SiO3 concentration,and NaOH concentration.The degree of influence of the four fac-tors on peak strength follows the order:Na₂SiO₃ concentration>ultrasound time>ultrasound power>NaOH concentration.The optimal experimental conditions for the synergistic modification were an ultra-sound time of 28.62 min,an ultrasound power of 700 W,and a Na2SiO3 concentration of 0.57 mol·L-1.The synergistic action of high-power ultrasound and alkali activation significantly enhanced the peak strength of the fly ash paste filling material,in which alkali activation played a dominant role,while high-power ultra-sound exerted a strengthening effect.Conclusions The synergistic effect of high-power ultrasound and alkali activation further accelerates the hydration reaction rate of fly ash paste filling material,increases the for-mation of hydration products,reduces material porosity,and consequently improves its mechanical proper-ties.
Keywords：fly ash paste filling materialhigh-power ultrasoundalkali activationsynergistic effect
Publication Date：2026-03-31
Online Publishing Date：2026-03-04(First online date of this platform, not the publication date of the document)
Pages：12( 64-75 )