Although the alkali activation of fly ash (FA) has been well investigated, the composite application of multiple chemical activators has not been well explored in the high replacement (50% in mass) low-calcium ultrafine FA blended cement (FABC) paste. This study investigated the mechanical enhancement effect of multiple salt activators (CaCl₂, Na₂SO₄ and CaSO₄·2H₂O) on the FABC paste, and compared with the most widely used alkaline activator (NaOH and Ca(OH)₂). The activation mechanisms were analyzed by non-evaporated water content, pH value, XRD and SEM test. The results have shown that the compound activator has a more obvious strength gain for the FABC paste and is higher than that of the control group and the alkali-activated group, which benefits from the higher non-evaporated water content, a mild and lasting alkaline environment (pH value). In addition, the compound activator can play each role of its components, making FA particles participate in hydration reaction earlier. In terms of the cost and environmental impact, FABC paste activated by composite activators is more economical and cleaner than that activated by single alkali and control paste. This paper provides the guidance for the preparation of FABC paste with low alkalinity, high-benefits and eco-friendly.

尽管已经对粉煤灰（FA）的碱活化进行了深入研究，但在高替代量（质量百分比为50％）的低钙超细FA掺和水泥（FABC）浆料中，尚未很好地探索多种化学活化剂的复合应用。本研究研究了多种盐活化剂（CaCl ₂，Na ₂ SO ₄和CaSO ₄ ·2H ₂ O）对FABC糊剂的机械增强作用，并与最广泛使用的碱活化剂（NaOH和Ca（OH）_{2）进行了比较。}）。通过非蒸发水含量，pH值，XRD和SEM测试分析了活化机理。结果表明，该复合活化剂对FABC糊剂具有更明显的强度增加，并且高于对照组和碱活化组，这得益于较高的非蒸发水含量，温和持久的碱环境（pH值）。另外，化合物活化剂可以发挥其组分的各种作用，使FA颗粒更早地参与水合反应。就成本和环境影响而言，复合活化剂活化的FABC浆料比单一碱和对照浆料活化的FABC浆料更经济，更清洁。本文为制备低碱度，高收益，环保的FABC糊料提供了指导。