Fly ash (FA) is a common solid waste in those countries which depend much on coal resources. The recycling of FA as a partial substitute for cement concrete is significant to reduce the pressure of land source and environmental protection. In this work, ohmic heating (OH) curing method was presented to cure FA/cement mortar (FA-CM) samples under severely low temperature. Results showed that the FA-CM samples with 20 wt% FA cured by 2 days OH curing at −20 °C (FA20-OH) possessed comparable mechanical properties compared with the FA-CM sample without FA cured by 3 days room temperature (RT) curing (FA0-RT), indicating the significant role of OH curing in promoting strength growth under severely low temperature. Mercury intrusion porosimetry (MIP) characterization revealed that OH curing could refine the pore structure, and FA20-OH samples showed comparable total porosity compared with FA0-RT sample. Scanning electron microscopy (SEM) analysis indicated that OH curing could effectively densify the microstructure of FA-CM samples compared with RT curing. Moreover, a higher Ca(OH)₂ content and larger mean chain length were observed in FA20-OH sample from thermogravimetric and differential scanning calorimetry (TG-DSC) analysis and ²⁹Si nuclear magnetic resonance (NMR) measurements to further clarify the positive regulation of OH curing on hydration product and its chemical structure. This study provided insights into the sustainable utilization of FA in construction materials used in severe cold region.

在那些高度依赖煤炭资源的国家中，粉煤灰（FA）是一种常见的固体废物。将FA用作水泥混凝土的部分替代品的回收对于减轻土地资源和环境保护的压力具有重要意义。在这项工作中，提出了欧姆加热（OH）固化方法，以在极低的温度下固化FA /水泥砂浆（FA-CM）样品。结果表明，与未在室温下进行3天固化的FA-CM样品相比，在-20°C下通过2天OH固化（FA20-OH）固化了20 wt％FA的FA-CM样品具有相当的机械性能。 ）固化（FA0-RT），表明OH固化在极低温下促进强度增长的重要作用。汞侵入孔隙率法（MIP）表征表明，OH固化可以改善孔结构，FA20-OH样品的总孔隙率与FA0-RT样品相当。扫描电子显微镜（SEM）分析表明，与RT固化相比，OH固化可以有效地致密化FA-CM样品的微观结构。此外，较高的Ca（OH）通过热重和差示扫描量热法（TG-DSC）分析和²⁹ Si核磁共振（NMR）测量，在FA20-OH样品中观察到₂含量和更大的平均链长，以进一步阐明OH固化对水合产物及其组成的正调控化学结构。该研究为在严寒地区使用的建筑材料中FA的可持续利用提供了见识。