Sintered sludge ash (SSA) has garnered attention for its potential to mitigate carbon emissions by replacing cement. This study investigates the consequential changes in the macro and micro properties of cement paste following the addition of SSA. Fluidity tests unveiled that the high specific surface area of SSA was the primary factor contributing to the reduction in fluidity and the delayed setting time. In terms of strength, SSA affected the cement paste to a greater extent at 3 days (3 d) than at 28 days (28 d). X-ray diffraction (XRD) analyses indicated that hydration-inert components such as quartz and feldspar in SSA may be responsible for the observed early hydration retardation. For 28 d strength, thermogravimetric and differential scanning calorimetry (TG/DSC) were employed to quantify Ca(OH) content and the degree of cement hydration. It was found that the participation of SSA in the pozzolanic reaction could additionally produce calcite, which promoted hydration and improved the strength of cement paste at 28 d. Scanning electron microscopy (SEM) revealed that amorphous hydration products, including C–S–H and Ca(OH) crystals covering the SSA surface, formed a robust structure conducive to 28 d strength development. Results from mercury intrusion porosimetry (MIP) were found to be in good contrast with SEM.

中文翻译：

---

烧结污泥灰灰改性水泥净浆性能及微观结构

烧结污泥灰（SSA）因其替代水泥来减少碳排放的潜力而受到关注。本研究研究了添加 SSA 后水泥浆宏观和微观性能的变化。流动性测试表明，SSA的高比表面积是导致流动性降低和凝结时间延迟的主要因素。就强度而言，SSA对水泥浆体的影响在3天（3 d）时比28天（28 d）时影响更大。 X 射线衍射 (XRD) 分析表明，SSA 中的水合惰性成分（例如石英和长石）可能是造成观察到的早期水合延迟的原因。对于 28 d 强度，采用热重分析和差示扫描量热法 (TG/DSC) 来量化 Ca(OH) 含量和水泥水化程度。结果发现，SSA参与火山灰反应可额外生成方解石，促进水化，提高水泥浆体28 d强度。扫描电子显微镜 (SEM) 显示，无定形水化产物，包括覆盖 SSA 表面的 C-S-H 和 Ca(OH) 晶体，形成了有利于 28 d 强度发展的坚固结构。压汞孔隙率测定法 (MIP) 的结果与 SEM 的结果具有良好的对比。