Uncovering the role of micro silica in hydration of ultra-high performance concrete (UHPC)

This study aims to clarify the role of micro silica in hydration of UHPC. The behavior of two different types of micro silica in UHPC was investigated with regard to their filler effect and pozzolanic reaction by using analytical techniques; XRD, TG, 29Si and 27Al NMR spectroscopy, and MIP. The micr...

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Bibliographic Details
Published in:Cement and concrete research 2018-02, Vol.104, p.68-79
Main Authors: Lee, Nam Kon, Koh, K.T., Kim, Min Ook, Ryu, G.S.
Format: Article
Language:English
Subjects:
Aluminum
Compressive strength
Concrete
Dicalcium silicate
Filler effect
Hydration
Hydration product
Mechanical properties
Micro silica
Microstructure
NMR
NMR spectroscopy
Nuclear magnetic resonance
Porosity
Silica
Silica fume
Silicon dioxide
Studies
Substitution reactions
Tricalcium silicate
UHPC
Ultra high performance concrete
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Summary:This study aims to clarify the role of micro silica in hydration of UHPC. The behavior of two different types of micro silica in UHPC was investigated with regard to their filler effect and pozzolanic reaction by using analytical techniques; XRD, TG, 29Si and 27Al NMR spectroscopy, and MIP. The micro silica with high pozzolanic activity led to the higher level of Al-substitution for Si in C-S-H and the denser structure, thus increasing compressive strength, whereas that facilitating filler effect limited the consumption of Ca(OH)2 even after high temperature curing and led to the higher amount of AFm phase. In the UHPC showing high filler effect, additional hydration of C3S and C2S occurred at later ages, increasing the fraction of Q1 site in C-S-H and decreasing the porosity in the pore diameter region below 10nm. Consequently, a significant increase in the compressive strength of this UHPC was achieved.
ISSN:0008-8846
1873-3948
DOI:10.1016/j.cemconres.2017.11.002