摘要
以Ca含量和细度不同的粉煤灰制备碱激发粉煤灰(AAFA)胶凝材料,并在水化早期对其进行微波加热养护,研究其抗压强度和微观结构的发展规律,探讨微波加热养护对强度发展的影响机理.结果表明:增加粉煤灰的Ca含量及适当减小粉煤灰的细度均可显著提高微波加热养护后AAFA试件的抗压强度,但会加剧其28 d龄期后的强度倒缩;水化硅(铝)酸钙(C-(A)-S-H)凝胶中的Ca2+溶出后碳化形成致密度较差的海绵状凝胶、水化硅铝酸钠(N-A-S-H)凝胶分解及其体积缩小均是引起微波加热养护后AAFA试件强度倒缩的原因;由超细粉煤灰(D50=3.96μm)制备的AAFA试件呈现出远低于基准试件的抗压强度,不适合采用微波加热养护.
Alkali‑activated fly ash(AAFA)binders were prepared from fly ash with different calcium content and fineness,and were cured by microwave heating at the early stage of hydration.The developments of compressive strength and microstructure of AAFA specimens were studied and the influence mechanism of microwave heating on strength development was discussed.The results show that increasing the calcium content in fly ash and appropriately reducing the fineness of fly ash can significantly improve the compressive strength of AAFA specimens after microwave heating,but aggravate the strength loss after 28 d.The reason for the strength loss of AAFA specimens cured by microwave heating lies in the dissolution and carbonation of calcium ions in aluminum‑modified calcium silicate hydrate(C‑(A)‑S‑H)gel,resulting in the formation of sponge like gel with low density and the decomposition and volume reduction of sodium aluminosilicate hydrate(N‑A‑S‑H)gel.The compressive strength of AAFA specimens prepared from ultrafine fly ash(D50=3.96μm)is much lower than that of the reference specimen,therefore the former is not suitable for microwave-heated curing.
作者
朱绘美
迂晨
张新东
乔沛
李辉
ZHU Huimei;YU Chen;ZHANG Xindong;QIAO Pei;LI Hui(College of Materials Science and Engineering,Xi'an University of Architecture and Technology,Xi'an 710055,China;Ecological Cement Engineering Research Center of Ministry of Education,Xi'an University of Architecture and Technology,Xi'an 710055,China;Shaanxi Ecological Cement&Concrete Engineering Technology Research Center,Xi'an University of Architecture and Technology,Xi'an 710055,China)
出处
《建筑材料学报》
EI
CAS
CSCD
北大核心
2023年第5期449-456,共8页
Journal of Building Materials
基金
固废资源化利用与节能建材国家重点实验室开放基金资助项目(SWR-2021-009)
陕西省重点研发计划项目(2023-YBGY-498)
陕西省教育厅重点研发计划(20JS079)
先进土木工程材料教育部重点实验室(同济大学)开放基金资助项目(202104)。
关键词
碱激发材料
粉煤灰性质
微波加热
强度发展
alkali-activated binder
fly ash property
microwave-heated
strength development
