Study on the effect of nanocrystalline nucleus early strength agent and silica fume on the properties of fluorine-containing alkali-free accelerator
LI Changfeng
CHEN Junsong
WANG Wei
ZENG Luping
ZHAO Shuang
ZHU Bosong
WU Qingyong
Abstract：In order to solve the problem of slow strength development in the early stage(especially within 24 hours)of shotcrete mixed with fluorine-containing alkali-free accelerator,the improvement effect of nanocrystalline nucleus early strength agent(NEA)and silica fume(SF)on the setting time and compressive strength of cement pastes mixed with fluorine-containing alkali-free accelerator and its mechanism were studied.The results show that the single addition of nanocrystalline early strength agent could significantly shorten the setting time of cement pastes and improve the compressive strength of mortars at 6 h and 1 d,and the higher the addition amount,the more obvious the improvement effect was.The compound addition of NEA and SF could further im-prove the accelerating and early-strengthening effects.When SF of 5%of the cementitious material is internally mixed and NEA of 4%of the cementitious material is externally mixed,the final setting time of cement paste was 100 s,the compressive strength of the mortar at 6 h and 1 d was 1.2 MPa and 13.2 MPa,respectively.Nanocrystalline nucleus early strength agent and silica fume could provide the"nucleation"effect for the hydration products,accelerate the early hydration of cement,alleviate the inhibition effect of calcium fluoride,the characteristic hydration product of the fluorine-containing alkali-free accelerator-cement system,on C-S-H gels,and improve the early strength of mortars.
Keywords：nanocrystalline nucleussilica fumeshotcretealkali-free acceleratorcement hydration
Publication Date：2025-08-25
Online Publishing Date：2025-09-12(First online date of this platform, not the publication date of the document)
Pages：6( 41-46 )