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Influence of Cement Particle‐Size Distribution on Early Age Autogenous Strains and Stresses in Cement‐Based Materials
Author(s) -
Bentz Dale P.,
Jensen Ole Mejlhede,
Hansen Kurt Kielsgaard,
Olesen John F.,
Stang Henrik,
Haecker ClausJochen
Publication year - 2001
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1151-2916.2001.tb00619.x
Subject(s) - cement , shrinkage , materials science , composite material , cracking , ettringite , relative humidity , microstructure , particle (ecology) , particle size distribution , particle size , mineralogy , portland cement , chemical engineering , chemistry , geology , oceanography , physics , engineering , thermodynamics
The influence of cement particle‐size distribution on autogenous strains and stresses in cement pastes of identical water‐to‐cement ratios is examined for cement powders of four different finenesses. Experimental measurements include chemical shrinkage, to quantify degree of hydration; internal relative humidity development; autogenous deformation; and eigenstress development, using a novel embedded spherical stress sensor. Because the latter three measurements are conducted under sealed conditions, whereas chemical‐shrinkage measurements are made under “saturated” conditions, the National Institute of Standards and Technology cement hydration and microstructure development model is used to separate the effects of differences in hydration rates (kinetics) from those caused by the different initial spatial arrangement of the cement particles. The initial arrangement of the cement particles controls the initial pore‐size distribution of the cement paste, which, in turn, regulates the magnitude of the induced autogenous shrinkage stresses produced by the water/air menisci in the air‐filled pores formed throughout the hydration process. The experimental results indicate that a small autogenous expansion (probably the result of ettringite formation), as opposed to a shrinkage, may be produced and early age cracking possibly avoided through the use of coarser cements.