三元工业废渣协同水泥固化土的基本特性和机理分析

Basic Characteristics and Mechanism of Soil Solidified with Ternary Industrial Waste and Cement

为了资源化利用工业固废的胶凝活性以求减少水泥使用量,设置10%和20%两种固化剂总掺量,并以纯水泥固化土作为对照组,将赤泥、电石渣和磷石膏3种工业废渣部分代替35%、45%、55%的水泥。研究每种配比方案下固化土的强度、电阻率、抗渗性和浸出液pH值变化规律,并结合SEM、FTIR和XRD谱图揭示三元工业废渣协同水泥固化土的微观机理。结果表明:工业废渣代替水泥存在最优替代率问题,当固化剂总掺量为10%和20%,且三元废渣占比<45%时,力学性能优于零废渣纯水泥固化土,废渣占比达到55%时力学强度低于纯水泥固化土,且固化剂总掺量和养护龄期越大强度越高;无损化的电阻率测试技术对于强度的预测具有较高精度,浸出液的pH值随龄期的增大而降低,含废渣固化土的pH值低于零废渣固化土,不同掺量和龄期固化土的pH值均小于腐蚀性鉴别限值;三元废渣协同水泥固化土的抗渗性优于零废渣水泥固化土。微观试验结果表明固化土中生成了钙矾石、水化硅酸钙和碳酸钙等水化产物,三元工业废渣掺入能产生更多的胶结物,使固化土结构更加致密。

In order to reduce cement usage by effectively utilizing the cementitious activity of industrial solid waste,we added three types of industrial waste in combination(red mud,calcium carbide slag,and phosphogypsum) to partially replace cement as curing agent to prepare solidified soil specimens.We designed two proportions(10%and 20%) of total curing admixture,in which the industrial waste combination substituted different amounts(35%,45%,and 55%) of cement;and in the meantime,we set pure cement-solidified soil as control group.Through tests,we investigated variations in the strength,electrical resistivity,impermeability,and pH value of leachate of the solidified soil specimens with varied mix ratio.Furthermore,we employed the SEM,FTIR,and XRD spectra to unveil the microscopic mechanism of solidifying soil specimens with industrial waste in combination with cement.Findings indicate an optimal substitution rate of industrial waste for cement.When the total curing agent content is10% or 20% and the industrial waste percentage is below 45%,mechanical properties surpass those of pure cement-solidified soil.However,when industrial waste percentage reaches 55%,mechanical strength falls below that of pure cement solidified soil.Moreover,higher total curing agent content and aging duration lead to increased strength.The non-destructive resistivity testing method accurately predicts strength.The pH value of leachate decreases over time and remains lower than that of pure cement-solidified soil,consistently remaining below the corrosivity threshold at different dosing levels and aging stages.Solidified soil specimens with both industrial waste and cement demonstrates enhanced impermeability compared to the pure cement-solidified ones.Microscopic analyses reveal the formation of hydration products including calcium aluminate,hydrated calcium silicate,and calcium carbonate in the solidified soil.Incorporating ternary industrial waste generates more cementitious materials,resulting in a denser structure.