As known, calcium oxide (CaO) is an alkaline material, which can be used widely to increase the clay-containing soils load carrying capacity, to produce aerated concrete and calcium aluminate cement. In the last few years, introducing CaO into alkali-activated materials (AAMs) became a hot topic and attained more attention than other times. Generally, CaO can be incorporated into AAMs as an additive/a part of the main precursor and a sole activator without/with an auxiliary activator. Incorporating CaO into the matrices may improve some properties and worsen others. This mainly depends on the ratio of CaO, curing conditions, activator type and activator concentration, precursor type and testing age. This review collected, summarized and analyzed the available studies focused on the effect of CaO on the fresh (reaction kinetic, workability, setting time) and hardened (mechanical strength, durability and length change) properties of AAMs. In addition, some recommendations for future works were included. The results showed that the inclusion of CaO in AAMs decreased workability and setting time. In spite of there are contradictory results about the effect of CaO on the compressive strength of AAMs, most of them reported higher compressive strength, especially at the early ages. The incorporation of CaO up to 5% in the matrix is more effective than the incorporation of higher ratios. The inclusion of CaO in the matrix decreased water absorption, decreased total porosity, increased wetting/drying as well as acid attack resistivity. The CaO (5–10%) can be used as a sole activator for precursors. Auxiliary activators such as Al₂(SO₄)₃, Na₂CO₃, Na₂SiO₃, Na₂SO₄, CaSO₄, NaOH, Ca(NO₃)₂, NaNO₃, Mg(NO₃)₂, Mg(HCOO)₂, Ca(HCOO)₂, SO₃, gypsum and MgO can be used to enhance the compressive strength of CaO-activated materials, especially at the early ages.

众所周知，氧化钙（CaO）是一种碱性材料，可广泛用于提高含粘土土壤的承载能力，生产加气混凝土和铝酸钙水泥。在过去的几年里，将CaO引入碱激活材料（AAM）成为了一个热门话题，并且比以往任何时候都受到了更多的关注。一般来说，CaO 可以作为添加剂/主要前体的一部分和单独的活化剂（不带/带辅助活化剂）掺入 AAM 中。将 CaO 掺入基质中可能会改善某些性能，但会恶化其他性能。这主要取决于CaO的比例、固化条件、活化剂类型和活化剂浓度、前体类型和测试龄期。本综述收集、总结和分析了现有的研究，重点关注 CaO 对 AAM 的新鲜（反应动力学、可加工性、凝结时间）和硬化（机械强度、耐久性和长度变化）性能的影响。此外，还包括对未来工作的一些建议。结果表明，AAM 中包含 CaO 会降低和易性并缩短凝结时间。尽管关于 CaO 对 AAM 抗压强度的影响存在矛盾的结果，但大多数都报道了较高的抗压强度，特别是在早期。在基体中掺入高达 5% 的 CaO 比掺入更高比例的 CaO 更有效。基质中加入 CaO 可降低吸水率、降低总孔隙率、增加润湿/干燥以及耐酸侵蚀性。CaO (5–10%) 可用作前驱体的唯一活化剂。辅助活化剂如Al ₂ (SO ₄ ) ₃、Na ₂ CO ₃、Na ₂ SiO ₃、Na ₂ SO ₄、CaSO ₄、NaOH、Ca(NO ₃ ) ₂、NaNO ₃、Mg(NO ₃ ) ₂、Mg (HCOO) ₂、Ca(HCOO) ₂、SO ₃、石膏和MgO可用于增强CaO活化材料的抗压强度，特别是在早期阶段。