The production of ordinary portland cement (OPC) is a CO₂ intensive process. Specifically, OPC clinkering reactions not only require substantial energy in the form of heat, but they also result in the release of CO₂; i.e., from both the decarbonation of limestone and the combustion of fuel to provide heat. To create alternatives to this CO₂ intensive process, this paper demonstrates a new route for clinkering-free cementation by the carbonation of fly ash; i.e., a by-product of coal combustion. It is shown that in moist environments and at sub-boiling temperatures, Ca-rich fly ashes react readily with gas-phase CO₂ to produce robustly cemented solids. After seven days of exposure to vapor-phase CO₂ at 75 °C, such formulations achieve a compressive strength of around 35 MPa and take-up 9% CO₂ (i.e., by mass of fly ash solids). On the other hand, Ca-poor fly ashes due to their reduced alkalinity (i.e., low abundance of mobile Ca- or Mg-species), show limited potential for CO₂ uptake and strength gain—although this deficiency can be somewhat addressed by the provision of supplemental/extrinsic Ca agents. The roles of CO₂ concentration and processing temperature are discussed, and linked to the progress of reactions and the development of microstructure. The outcomes create new pathways for achieving clinkering-free cementation while enabling the beneficial utilization (“upcycling”) of emitted CO₂ and fly ash; i.e., two abundant, but underutilized industrial by-products.

普通硅酸盐水泥（OPC）的生产是CO ₂密集型过程。具体地说，OPC熟料反应不仅需要大量的热能，而且还会释放CO ₂。即从石灰石的脱碳和燃料的燃烧产生热量。为了为这种CO ₂强化工艺创造替代方法，本文演示了通过粉煤灰碳化实现无熟料胶结的新途径。即煤燃烧的副产物。结果表明，在潮湿的环境中和在低于沸点的沸腾温度下，富含Ca的飞灰容易与气相CO _2反应，生成坚固的胶结固体。暴露于气相CO ₂ 7天后在75°C下，此类配方的抗压强度约为35 MPa，吸收的CO _2为9％（即，粉煤灰固体质量）。另一方面，贫钙粉煤灰由于其碱度降低（即，流动性钙或镁物种的丰度较低）而显示出有限的CO ₂吸收和强度增加潜力-尽管这种缺陷可以在一定程度上解决。提供补充/外部钙剂。讨论了CO ₂浓度和加工温度的作用，并将其与反应的进展和微观结构的发展联系起来。结果为实现无熟料胶结创造了新途径，同时使排放的CO ₂得以有效利用（“向上循环”）和飞灰；即，两种丰富但未充分利用的工业副产品。