With the retirement of coal-fired power stations, wet-stored stockpile fly ash is increasingly receiving attention for use in concrete. An important consideration for dry fly ash in this application is its impact on air entrainment, which can be affected by unburnt carbon present, influencing bubble stability and air-entraining admixture (AEA) dose requirements. Preliminary tests suggest wet storage can influence the process and the present study examined this for laboratory-moistened and stockpile fly ashes. The research indicated that chemical processes lead to product formation on particle surfaces and increases in loss-on-ignition in the material. Agglomeration of fly ash also occurred with wet storage, developing with time. While median particle size and specific surface area (by nitrogen (N₂) adsorption) of fly ash increased, both foam index and Acid Blue 80 adsorption were less with wet storage. Mortar tests mainly gave increased air content at fixed AEA dose for material held under these conditions. The data suggest admixture accessibility to wet-stored fly ash particles influenced behaviour and this increased with the breakdown of particle agglomerates (by grinding). Some influences of particle surface chemistry on the process were also found. A pilot-scale processing trial with stockpile fly ash gave general agreement with effects observed in the laboratory.

中文翻译：

---

湿储对粉煤灰性能的影响与其在加气混凝土中的使用有关

随着燃煤发电站的退役，湿法储存的粉煤灰在混凝土中的应用越来越受到关注。在此应用中，干粉煤灰的一个重要考虑因素是它对空气夹带的影响，空气夹带会受到存在的未燃烧碳的影响，从而影响气泡稳定性和引气剂 (AEA) 剂量要求。初步测试表明湿储存会影响该过程，本研究针对实验室润湿和储存的飞灰对此进行了检查。研究表明，化学过程会导致颗粒表面形成产物，并增加材料的烧失量。粉煤灰的结块也发生在湿储中，并随着时间的推移而发展。而中值粒径和比表面积（通过氮气（N ₂) 吸附) 粉煤灰增加，泡沫指数和酸性蓝 80 吸附量随湿储减少。对于在这些条件下保持的材料，砂浆测试主要给出固定 AEA 剂量的空气含量增加。数据表明，湿法储存的飞灰颗粒的混合物可及性影响了行为，并且随着颗粒附聚物的分解（通过研磨）而增加。还发现了颗粒表面化学对该过程的一些影响。使用堆放飞灰进行的中试规模加工试验与实验室观察到的效果大体一致。